Part 629 -- GLOSSARY OF LANDFORM AND GEOLOGIC TERMS

Table of Contents

> PART TITLE PAGE

[629.00 Definition and Purpose. 629-1](#definition-and-purpose.)

[629.01 Responsibilities. 629-1](#responsibilities.)

[629.02 Definitions. 629-1](#definitions.)

> [(a) Reference Codes. 629-1](#a-reference-codes.)
>
> [(b) Clarifying comments included with glossary defintions.
> 629-4](#b-clarifying-comments-included-with-glossary-definitions.)
>
> [(a) Glossary Terms and Definitions. 629-5](#a-current-references.)

[629.03 References. 629-87](#references.)

> [(a) Current references. 629-87](#a-current-references.)
>
> [(b) Classic references. 629-91](#b-classic-references.)

[Exhibit 629-1 Lists of Landscape, Landform, Microfeature, and
Anthropogenic Feature\
Terms Defined in the Glossary
629-94](#exhibit-629-1-lists-of-landscape-landform-microfeature-and-anthropogenic-feature-terms-defined-in-the-glossary)

[Exhibit 629-2 List of Materials or Material-Related, Structure, or
Morphological-Feature\
Terms Contained in the Glossary. 629-117](#__RefHeading___Toc164067419)

[Exhibit 629-3 Genesis - Process Terms and Geologic Time Terms Contained
in the Glossary.
629-120](#exhibit-629-3-genesis---process-terms-and-geologic-time-terms-contained-in-the-glossary.)

[Exhibit 629-4 North American Glacial Episodes and General Geologic Time
Scale.
629-122](#exhibit-629-4-north-american-glacial-episodes-and-general-geologic-time-scale.)

[Exhibit 629-5 Till Terms. 629-124](#exhibit-629-5-till-terms.)

[Exhibit 629-6 Pyroclastic Terms.
629-125](#exhibit-629-6-pyroclastic-terms.)

**\
Part 629 - GLOSSARY OF LANDFORM AND GEOLOGIC TERMS\
**

## 629.00 Definition and Purpose. {#definition-and-purpose. .600.00}

This glossary provides the Soil Survey, soil scientists, and natural
resource specialists with landform, geologic, and related terms and
their definitions to:

-   Improve soil landscape description with a standard, single source
    landform and geologic glossary;

-   Enhance geomorphic content and clarity of soil map unit description
    by use of accurate, defined terms;

-   Establish consistent geomorphic term usage in soil science,
    especially in the NCSS;

-   Provide standard geomorphic definitions for data bases and soil
    survey technical publications; and

-   Train soil scientists and related professionals in soils as
    landscape and geomorphic entities.

## 629.01 Responsibilities. {#responsibilities. .600.00}

This glossary serves as the official National Cooperative Soil Survey
(NCSS) reference for landform, geologic, and related terms. The National
Soil Survey Center, Lincoln, NE, is responsible for maintaining and
updating this glossary. MLRA office soil scientists and National
Cooperative Soil Survey participants may, and are encouraged to, propose
additions and changes for use in pedeon or soil map unit descriptions
and soil survey publications. The Glossary of Geology (AGI, 1997) serves
as a major source for many glossary terms. Permission was granted
(letters dated 9/11/85 and 9/22/93) to the USDA-Natural Resource
Conservation Service (formerly the Soil Conservation Service) by the
American Geological Institute (AGI), to use existing definitions.
Modifications to original AGI definitions are explained below.

## 629.02 Definitions. {#definitions. .600.00}

## (a) Reference Codes.  {#a-reference-codes. .TOC-Heading-(a)}

Sources from which definitions were taken, whole or in part, are
identified by a code (e.g. GG) following each definition. Underlined
codes (e.g. [GG]{.underline}) signify a definition modification form the
original source. The reference codes are:

BFM Boothroyd, J.C., Friedrich, N.E., and McGinn, S.R. 1985. Geology of
microtidal coastal lagoons: Rhode Island. Marine Geology 63:35-76.

BHM Buol, S.W., Hole, F.D., McCracken, R.J., and Southard, R.J. 1997.
Soil genesis and classification, 4^th^ Ed. Iowa State University Press,
Ames, IA; 527p.

CC Cowardin, L.M., Carter, V., Golet, F.C., and Laroe, E.T. 1979.
Classification of wetlands and deepwater habitats of the United States.
US Dept. Interior, US Fish and Wildlife Service, US Government Printing
Office, Washington, DC.

CF Clayton, L. and Freers, T.F. (eds.) 1967. Glacial geology of the
Missouri Coteau and adjacent areas. Guidebook 18th annual field
conference Midwest Friends of the Pleistocene. North Dakota Geological
Survey Miscellaneous Series #30, 170 p.

CV Cruden, D.M., and Varnes, D.J. 1996. Landslide types and processes.
*In:* Turner, A.K., and Schuster, R.L., (eds). 1996. Landslides:
investigations and mitigation. National Research Council, Transportation
Research Board Special Report No. 247; National Academy Press,
Washington, DC; 673 p.

DV Varnes, D. 1978. Slope movement types and processes. *In:* Schuster,
R.L., and R.J. Krizek. (eds). 1978. Landslides: analysis and control.
National Academy Sciences, Transportation Research Board Special Report
No. 176; 234 p.

FC Freeze, A.L. and Cherry, J.A. 1979. Groundwater. Prentice-Hall, Inc.,
Englewood Cliffs, NJ, 604 p.

FFP Peterson, F.F. 1981. Landforms of the Basin and Range Province
defined for soil survey. Nevada Agricultural Experiment Station
Technical Bulletin No. 28, Reno, NV. 52p.

GG Jackson, J.A. (ed) 1997. Glossary of geology, 4th Ed. American
Geological Institute, Alexandria, VA. 769p. ISBN 0-922152-34-9

GG'87 Bates, R.L., and Jackson, J.A. (ed) 1987. Glossary of geology, 3rd
Ed. American Geological Institute, Alexandria, VA.788p.

DA Davis, R.A. 1994. Barrier island systems - a geologic overview. P.
1-46. *In:* Davis, R.A. ed.) 1994. Geology of Holocene barrier island
systems. Springer-Verlag, New York, NY.

DR Ritter, D.F., Kochel, R.C., and Miller, J.R. 1995. Process
geomorphology, 3^rd^ ed. Wm. C. Brown, Publishers, Dubuque, IA.

FS Fisher, J.J., and Simpson, E.J. 1979. Washover and tidal
sedimentation rates as environmental factors in development of a
transgressive barrier shoreline; pp.127-148. *In:* Leatherman, S.P.
(ed.) 1979. Barrier islands from the Gulf of St Lawrence to the Gulf of
Mexico. Academic Press, New York, NY.

GD Demas, G.P. 1998. Subaqueous soil of Sinepuxent Bay, Maryland. PhD
dissertation, Department of Natural Resources and Landscape
Architecture, University of Maryland, College Park, MD.

GHG Gile, L.H., Hawley, J.W., and Grossman, R.B. 1981. Soils and
geomorphology in the Basin and Range area of southern New Mexico --
Guidebook to the Desert Project. Memoir 39. New Mexico Bureau of Mines &
Mineral Resources, Socorro, NM; 222 p.

GM Goldthwaite, R.P. and Matsch, C.L. (eds.) 1988. Genetic
classification of glaciogenic deposits: final report of the commission
on genesis and lithology of glacial Quaternary deposits of the
International Union for Quaternary Research (INQUA). A.A. Balkema,
Rotterdam; 294 p.

GS Green, J., and Short, N.M. 1971. Volcanic landforms and surface
features: A photographic atlas and glossary. Springer -- Verlag, New
York, NY. 519 p.

GSST Soil Science Society of America. 2001. Glossary of Soil Science
terms. Soil Science Society of America, Madison, WI. 135p.

HD Holdorf, H. and Donahue, J. 1990. Landforms for soil surveys in the
Northern Rockies. Montana Forest and Conservation Experiment Station,
School of Forestry, University of Montana, Misc. Publ. No. 51. 26 p.

HF Fisk, H.N. 1959. Padre Island and the Laguna Madre flats, coastal
south Texas. Louisiana State University, 2^nd^ Coastal Geography
Conference; pp. 103-151.

HP Hawley, J.W., and Parsons, R.B. 1980. Glossary of selected geomorphic
and geologic terms. Mimeo. USDA Soil Conservation Service, West National
Technical Center, Portland, OR. 30 p.

KST Soil Survey Staff. 1994. Keys to Soil Taxonomy, 6th Ed. USDA -
Natural Resources Conservation Service (p.54).

MA MacDonald, G.A. and A.T. Abbott. 1970. Volcanoes in the sea, the
geology of Hawaii. University of Hawaii Press, 441p.

NL Lancaster, N. 1995. Geomorphology of desert dunes. Routledge, New
York, NY. 209p.

NRC National Research Council of Canada. 1988. Glossary of permafrost
and related ground ice terms. Associate Committee Geotechnical Research,
Technical Memorandum 142; 156 p

RF Fairbridge, R .W. (ed.). Encyclopedia of geomorphology. 1968.
Encyclopedia of Earth Sciences Series, vol. 3. Reinhold Book
Corporation, New York, NY

RD Daniels, Raymond B. (personal communication).

RR Ruhe, Robert V. 1975. Geomorphology: Geomorphic processes and
surficial geology. Houghton-Mifflin, Boston, MA, 246p.

SJ Sugden, D.E. and John, B.S. 1976. Glaciers and landscape, a
geomorphological approach. Halsted Press, John Wiley and Sons, Inc., New
York, NY, 376 p.

SM McGinn, S.R. 1982. Facies distribution of Ninigret Pond. Masters
thesis, University of Rhode Island, Kingston, RI.

SS Summer, M.E., and Stewart, B.A. (eds). 1992. Soil crusting in
Australia. *In:* Soil crusting: chemical and physical process. Advances
in Soil Science, Lewis Publishing, Boca Raton, FL.

SSM Soil Survey Staff. 1993. Soil Survey Manual. USDA - Soil
Conservation Service, Agricultural Handbook No. 18, U.S. Gov. Print.
Office, Washington, DC.

SSS Subaqueous Soils Subcommittee. 2005. Glossary of terms for
subaqueous soils, landscapes, landforms, and parent materials of
estuaries and lagoons. National Cooperative Soil Survey Conference,
USDA-NRCS, National Soil Survey Center, Lincoln, NE.

ST Soil Survey Staff. 1975. Soil Taxonomy. A basic system of soil
classification for making and interpreting soil surveys. USDA - Soil
Conservation Service Agricultural Handbook #436, U.S. Gov. Print.
Office, Washington, DC, 754 p.

SW Schoeneberger, P.J. and Wysocki, D.A. (personal communication),
National Soil Survey Center, NRCS, Lincoln, NE.

WA Way, D.S. 1973. Terrain analysis. Harvard University, Dowden,
Hutchinson & Ross, Inc., Stroudsburg, PA. 392p.

WCHP

> Wells, D.V., Conkwright, R.D., Hill, J.M., and Park, M.J. 1994. The
> surficial sediments of Assawoman Bay and Isle of Wight Bay, Maryland:
> Physical and chemical characteristics. Coastal and Estuarine Geology
> File Report Number 94-2, Maryland Geological Survey, Baltimore, MD.

WM Monroe, W.H. 1980. Some tropical landforms of Puerto Rico. US
Geological Survey Professional Paper 1159, U.S. Govt. Print. Office,
Washington, DC.

WT Thornbury, W.D. 1969. Principles of geomorphology; 2nd Ed. John Wiley
and Sons, Inc., New York, NY; 594 p.

WW White, W.B. 1988. Geomorphology and hydrology of karst terrains.
Oxford Univ. Press, New York, NY; 478 p.

## (b) Clarifying comments included with glossary definitions. {#b-clarifying-comments-included-with-glossary-definitions. .TOC-Heading-(a)}

**(not recommended)** **use** -- denotes an unacceptable term (obsolete,
poorly-defined, or erroneous) [that should not be used]{.underline}. The
glossary provides an alternate term, if available.

**(not preferred) refer to** -- denotes a technically acceptable, but
poorly-defined or outdated term that [should be avoided]{.underline} to
prevent confusion and redundancy. Preferred alternatives are provided.

**(colloquial: )** -- denotes a regionally-derived or applied term and
identifies the region where it has been used. A colloquial term is
either not widely accepted or unknown outside the geographic area where
it originates. A colloquial term [should be avoided]{.underline} if a
more widely recognized alternative exists.

**Compare** -- Follows a term definition and indicates additional
glossary entries that are similar or related to that term.

**(c) Glossary terms and definitions**.

**\`a\`a lava** - A type of basaltic lava (material) having a rough,
jagged, clinkery surface and a vesicular interior. Compare -- block
lava, pahoehoe lava, pillow lava. [GG]{.underline} & [MA]{.underline}

\`**a\`a lava** **flow** - A type of basaltic lava flow dominated by
\`**a\`a** lava and a characteristically rough, jagged, clinkery
surface. Compare - pahoehoe lava flow. Compare -- block lava flow,
pahoehoe lava flow, pillow lava flow. GG & [MA]{.underline}

**ablation till** - A general term for loose, relatively permeable,
earthy material deposited during the downwasting of nearly static
glacial ice, either contained within or accumulated on the surface of
the glacier. Compare - till, ground moraine. [GG]{.underline}

**accretion** \[sedimentology\] - The gradual increase or extension of
land by natural forces acting over a long period of time, as on a beach
by the washing up of sand from the sea or on a flood plain by the
accumulation of sediment deposited by a stream. Synonym: aggradation.
[GG]{.underline}

**active layer** - The top layer of ground subject to annual thawing and
freezing in areas underlain by permafrost. [NRC]{.underline}

**active slope** - (not recommended)

**aeolian** - (not recommended; obsolete) use eolian.

**aggradation** - The building-up of the Earth\'s surface by deposition;
specifically, the accumulation of material by any process in order to
establish or maintain uniformity of grade or slope; also called
accretion. Compare - degradation. [GG]{.underline}

**alas** - A type of thermokarst depression with steep sides and a flat,
grass-covered floor, found in thermokarst terrain, produced by thawing
of extensive areas of very thick and exceedingly ice-rich permafrost.
Compare - thermokarst depression. [NRC]{.underline} and [GG]{.underline}

**alluvial** - Pertaining to material or processes associated with
transportation and/or subaerial deposition by concentrated running
water. Compare - colluvial. [GSST]{.underline}

**alluvial cone** -- A semi-conical type of alluvial fan with very steep
slopes; it is higher, narrower, and steeper (e.g., \> 40% slopes) than a
fan, and composed of coarser, and thicker layers of material deposited
by a combination of alluvial episodes and to a much lesser degree,
landslides (e.g., debris flow). Coarsest materials tend to concentrate
at the cone apex. Compare -- alluvial fan, talus cone. SW

**alluvial fan** - A low, outspread mass of loose materials and/or rock
material, commonly with gentle slopes, shaped like an open fan or a
segment of a cone, deposited by a stream (best expressed in semiarid
regions) at the place where it issues from a narrow mountain or upland
valley; or where a tributary stream is near or at its junction with the
main stream. It is steepest near its apex which points upstream and
slopes gently and convexly outward (downstream) with a gradual decrease
in gradient. [GG]{.underline}

**alluvial flat - (**a) (colloquial: western U.S.A.) A nearly level,
graded, alluvial surface in bolsons and semi-bolsons that lacks distinct
channels, terraces, or flood plain levels.\
Compare -- flood-plain step, terrace, valley flat. [FFP]{.underline},
[GG]{.underline}, & SW. (b) (not preferred) A general term for a small
flood plain bordering a river, on which alluvium is deposited during
floods. GG

**alluvial plain** - (a) A large assemblage of fluvial landforms
(braided streams, terraces, etc.,) that form low gradient, regional
ramps along the flanks of mountains and extend great distances from
their sources (e.g., High Plains of North America. SW (b) (not
recommended, use flood plain.) **A** general, informal term for a broad
flood plain or a low-gradient delta. Compare - alluvial flat.
[FFP]{.underline}.

**alluvial plain remnant -** An erosional remnant of an alluvial plain
which retains the surface form and alluvial deposits of its origin but
was not emplaced by, and commonly does not grade to a present-day stream
or drainage network. Compare - alluvial plain, erosional remnant,
paleoterrace. SW

**alluvial terrace** - (not preferred) refer to stream terrace.

**alluvium** - Unconsolidated, clastic material subaerially deposited by
running water, including gravel, sand, silt, clay, and various mixtures
of these. Compare - colluvium, slope alluvium. HP

**alpine** - (a) \[geomorphology\] - (adjective) Characteristic of, or
resembling the European Alps, or any lofty mountain or mountain system,
especially one so modified by intense glacial erosion as to contain
cirques, horns, etc. (ex. alpine lake) [GG]{.underline} ; (b) (not
recommended as a landform term). An ecological community term for
high-elevation plant communities. SW & [GG]{.underline}

**alpine glacier** -- a) Any glacier in a mountain range except an ice
cap or ice sheet. It usually originates in a cirque and may flow down
into a valley previously carved by a stream. Compare -- continental
glacier. [GG]{.underline} b) (not preferred -- refer to U-shaped
valley): (relict) - landforms or sediments formed, modified or deposited
by a glacier in or on mountains or high hills that has since melted
away. Compare -- glacial-valley floor, glacial-valley wall. SW

**angle of repose** - The maximum angle of slope (measured from a
horizontal plane) at which loose, cohesionless material will come to
rest. [GG]{.underline}

**annular drainage pattern** -- A drainage pattern in which subsequent
streams follow a roughly circular or concentric path along a belt of
weak rocks, resembling in plan view, a ring-like pattern where the
bedrock joints or fracturing control the parallel tributaries. It is
best displayed in streams draining a maturely dissected granitic or
sedimentary structural dome or basin where erosion has exposed rimming
sedimentary strata of greatly varying degrees of hardness, as in the Red
Valley which nearly encircles the domal structure of the Black Hills,
SD. SW & [GG]{.underline} & [WA]{.underline}

**anthropogenic feature -** An artificial feature on the earth's surface
(including those in shallow water), having a characteristic shape and
range in composition, composed of unconsolidated earthy, organic
materials, artificial materials, or rock, that is the direct result of
human manipulation or activities; can be either constructional (e.g.,
artificial levee) or destructional (quarry). SW

**anticline** - (a) \[landform\] A unit of folded strata that is convex
upward and whose core contains the stratigraphically oldest rocks, and
occurs at the earth's surface. In a single anticline, beds forming the
opposing limbs of the fold dip away from its axial plane. Compare -
monocline, syncline, fold. SW & [HP]{.underline} (b) \[structural
geology\] A fold, at any depth, generally convex upward whose core
contains the stratigraphically older rocks. [GG]{.underline}

**aquiclude** - A layer of soil, sediment, or rock that may or may not
be saturated, that is incapable of transmitting significant quantities
of water under ordinary hydraulic gradients. Compare -- aquitard.
[FC]{.underline}

**aquifer** - A saturated, permeable geologic unit of sediment or rock
that can transmit significant quantities of water under hydraulic
gradients. [FC]{.underline}

**aquitard** - A body of rock or sediment that retards but does not
prevent the flow of water to or from an adjacent aquifer. It does not
readily yield water to wells or springs but may serve as a storage unit
for groundwater. [GG]{.underline}

**arete** - A narrow, jagged mountain crest, often above the snowline,
sculptured by alpine glaciers and formed by backward erosion of
adjoining cirque walls. HP

**arroyo** - (colloquial: southwest U.S.A.) The channel of a
flat-floored, ephemeral stream, commonly with very steep to vertical
banks cut in unconsolidated material; sometimes called a wash. It is
usually dry but can be transformed into a temporary watercourse or
short-lived torrent after heavy rain within the watershed. Where arroyos
intersect zones of ground-water discharge, they are more properly
classed as intermittent stream channels. [HP]{.underline}

**artificial collapsed depression** -- A collapse basin, commonly a
closed depression, which is the direct result of surficial subsidence
associated with subsurface mining (e.g., long-wall mining). SW**.**

**artificial** **drainage pattern** -- Human-made networks of drainage
structures (ditches, canals, etc.) built primarily to lower or control
the local water table in low lying, flat topography such as glacial
lakebeds, broad flood plains, low coastal plains, or marshes most
commonly in humid climates. (Irrigation ditches found in arid and
semiarid climates, which bring water into the fields, should not be
confused with drainage structures). SW & [WA]{.underline}

**artificial levee** - An artificial embankment constructed along the
bank of a watercourse or an arm of the sea, to protect land from
inundation or to confine streamflow to its channel. [GG]{.underline}

**ash** \[volcanic\] - Unconsolidated, pyroclastic material less than 2
mm in all dimensions. Commonly called \"volcanic ash" Compare - block
\[volcanic\], cinders, lapilli, tephra. SW & [KST]{.underline}

**ash flow** - (not preferred -- see pyroclastic flow, pyroclastic
surge) A highly heated mixture of volcanic gases and ash, traveling down
the flank of a volcano or along the surface of the ground; produced by
the explosive disintegration of viscous lava in a volcanic crater, or by
the explosive emission of gas-charged ash from a fissure or group of
fissures. The solid materials contained in a typical ash flow are
generally unsorted and ordinarily include volcanic dust, pumice, scoria,
and blocks in addition to ash. (Also called a *pyroclastic* flow.)
Compare - nueé ardente, lahar, pyroclastic. [GG]{.underline}

**aspect** - The direction toward which a slope faces with respect to
the compass or to the rays of the Sun; also called *slope* aspect.
[GSST]{.underline}

**atoll** - A coral reef appearing in plan view as roughly circular, and
surmounted by a chain of closely spaced, low coral islets that encircle
or nearly encircle a shallow lagoon in which there is no land or islands
of non-coral origin; the reef is surrounded by open sea.
[GG]{.underline}

**avalanche** - A large mass of snow, ice, soil, or rock, or mixtures of
these materials, falling, sliding, or flowing very rapidly under the
force of gravity. Velocities may sometimes exceed 500 km/hr.
[GG]{.underline}

**avalanche chute** - \[preferred term\] The central, channel-like
corridor, scar, or depression along which an avalanche has moved. An
eroded surface marked by pits, scratches, and grooves. [GG]{.underline}

**avalanche track** - (not recommended as a landform term - use
avalanche chute). The path formed by an avalanche. It may take the form
of an open path in a forest, with bent and broken trees, or an eroded
surface marked by pits, scratches, and grooves. Compare - avalanche
chute [GG]{.underline}

**avulsion** - A sudden cutting off or separation of land by a flood or
by abrupt change in the course of a stream, as by a stream breaking
through a meander or by a sudden change in current whereby the stream
deserts its old channel for a new one. Compare - crevasse, flood-plain
splay. [GG]{.underline}

**axial stream** - (a) The main stream of an intermontane valley,
flowing in the deepest part of the valley and parallel to its longest
dimension. (b) A stream that follows the axis of a syncline or
anticline. [GG]{.underline}

**back-barrier beach** - A narrow, elongate, intertidal, sloping
landform that is generally parallel with the shoreline located on the
lagoon or estuary side of the barrier island, or spit. Compare --
barrier island. SSS

**back-barrier flat -** A subaerial, gently sloping landform on the
lagoon side of the barrier beach ridge composed predominantly of sand
washed over or through the beach ridge during tidal surges; a portion of
a barrier flat. Compare -- washover-fan flat. SSS

**backshore** - The upper or inner, usually dry, zone of the shore or
beach, lying between the high-water line of mean spring tides and the
upper limit of shore-zone processes; it is acted upon by waves or
covered by water only during exceptionally severe storms or unusually
high tides. It is essentially horizontal or slopes gently landward, and
is divided from the foreshore by the crest of the most seaward berm.
Compare - washover fan. [GG]{.underline}

**backshore terrace** - (not preferred) refer to berm.

**backslope** - The hillslope profile position that forms the steepest
and generally linear, middle portion of the slope. In profile,
backslopes are commonly bounded by a convex shoulder above and a concave
footslope below. They may or may not include cliff segments (i.e. free
faces). Backslopes are commonly erosional forms produced by mass
movement, colluvial action, and running water. Compare - summit,
shoulder, footslope, toeslope. [GSST]{.underline} & [HP]{.underline}

**backswamp** - A flood-plain landform. Extensive, marshy or swampy,
depressed areas of flood plains between natural levees and valley sides
or terraces. Compare - valley flat. [HP]{.underline}

**backswamp** **deposit -** Laminated of silt and clay deposited in the
flood basin between valley sides or terraces and the natural levees of a
river. Compare - slackwater. [GG]{.underline}

**backwearing -** Slope erosion that causes the parallel retreat of an
escarpment or the slope of a hill or mountain or the sideways recession
of a slope without changing its general slope; a process contributing to
the development of a pediment. [GG]{.underline}

**badlands** - A landscape which is intricately dissected and
characterized by a very fine drainage network with high drainage
densities and short, steep slopes with narrow interfluves. Badlands
develop on surfaces with little or no vegetative cover, overlying
unconsolidated or poorly cemented materials (clays, silts, or in some
cases sandstones) sometimes with soluble minerals such as gypsum or
halite. [GG]{.underline}

**bajada** - (colloquial: southwestern U.S.A.) A broad, gently inclined,
alluvial piedmont slope extending from the base of a mountain range out
into a basin and formed by the lateral coalescence of a series of
alluvial fans. Typically it has a broadly undulating transverse profile,
parallel to the mountain front, resulting from the convexities of
component fans. The term is generally restricted to constructional
slopes of intermontane basins. Synonym - coalescent fan piedmont.
Compare - fan apron. HP & SW

bald -- (not preferred; colloquial: southeastern USA; use summit,
mountaintop, etc.) An ecological term for the grass or shrub covered
(naturally tree-less) summit of a high elevation hill or mountain,
flanked by forested slopes; not above the local tree-line. Compare --
glade. SW & [GG]{.underline}

**ballena** - (colloquial: western U.S.A.) A fan remnant having a
distinctively-rounded surface of fan alluvium. The ballena\'s
broadly-rounded shoulders meet from either side to form a narrow summit
and merge smoothly with concave side slopes and then concave, short
pediments which form smoothly-rounded drainageways between adjacent
ballenas. A partial ballena is a fan remnant large enough to retain some
relict fan surface on a remnant summit. Compare - fan remnant. SW &
[FFP]{.underline}.

**ballon** - (colloquial: western U.S.A.) A rounded, dome-shaped hill,
formed either by erosion or uplift. GG

**bar** - \[streams\] A general term for a ridge-like accumulation of
sand, gravel, or other alluvial material formed in the channel, along
the banks, or at the mouth of a stream where a decrease in velocity
induces deposition; e.g. a channel bar or a meander bar. \[coast\] - A
generic term for any of various elongate offshore ridges, banks, or
mounds of sand, gravel, or other unconsolidated material submerged at
least at high tide, and built up by the action of waves or currents,
especially at the mouth of a river or estuary, or at a slight distance
offshore from the beach. Compare - longshore bar. [GG]{.underline} &
[GSST]{.underline}

**bar** \[Microfeature\] -- A small, sinuous or arcuate, ridge-like
lineation on a flood plain and separated from others by small channels
or troughs; caused by fluvial processes and common to flood plains and
young alluvial terraces; a constituent part of *bar and channel*
*topography*. Compare -- meander scroll. SW

**bar and channel topography** -- A local-scale topographic pattern of
recurring, small, sinuous or arcuate ridges separated by shallow troughs
irregularly spaced across low-relief flood plains(slopes generally 2 --6
%); the effect is one of a subdued, sinuously undulating surface that is
common on active, meandering flood plains. Micro-elevational differences
between bars and channels generally range from \<0.5 to 2 m and are
largely controlled by the competency of the stream. The ridge-like bars
often consist of somewhat coarser sediments compared to the finer
textured sediments of the micro-low troughs. Compare -- meander scroll,
meander belt. SW

**barchan dune** - A crescent-shaped dune with tips extending leeward
(downwind), making this side concave and the windward (upwind) side
convex. Barchan dunes tend to be arranged in chains extending in the
dominant wind direction. Compare - parabolic dune. [HP]{.underline}

**barrier bar** - (not recommended) use longshore bar

**barrier beach** - (a) A narrow, elongate, coarse-textured, intertidal,
sloping landform that is generally parallel with the beach ridge
component of a barrier island or spit and adjacent to the ocean. Compare
-- barrier island. SSS (b) \[relict\] (colloquial: western U.S.A.) A
wide, gently-sloping portion of a bolson floor comprising numerous,
parallel, closely-spaced, relict longshore-bars and lagoons built by a
receding pluvial lake. Synonym, offshore barrier, offshore beach, bar
beach. Compare - bar \[coast\], barrier island. [GG]{.underline} and
[FFP]{.underline}

**barrier cove -** A subaqueous area adjacent to a barrier island or
submerged barrier beach that forms a minor embayment or cove within the
larger basin. Compare -- cove, mainland cove. SSS

**barrier flat** - A relatively flat, low-lying area, commonly including
pools of water, separating the exposed or seaward edge of a barrier
beach or barrier island from the lagoon behind it. An assemblage of both
deflation flats left behind migrating dunes and /or storm washover
sediments; may be either barren or vegetated. Compare -- barrier beach,
back-barrier flat. SSS

**barrier island** - A long, narrow, sandy island, that is above high
tide and parallel to the shore that commonly has dunes, vegetated zones,
and swampy **or marshy** terrains extending lagoonward from the beach.
Compare -- barrier beach. [GG]{.underline}

**barrow pit** - (not preferred) refer to borrow pit

**basal till** - (a) (not preferred; obsolete) refer to subglacial till.
Unconsolidated material of mixed composition deposited at the base
(bottom) of a glacier \[ The term emphasizes only the relative position
of deposition; e.g. subglacial till\]. Types of basal till include
lodgment, melt-out, and flow till. [GG]{.underline} & SW (b) \[obsolete-
use lodgment till\] - A firm, dense, clay-rich till containing many
abraded stones (coarse fragments) dragged along beneath a moving glacier
and deposited upon bedrock or other glacial deposits. [GG]{.underline}

**base level** - The theoretical limit or lowest level toward which
erosion of the Earth\'s surface constantly progresses but seldom, if
ever, reaches; especially the level below which a stream cannot erode
its bed. The general or ultimate base level for the land surface is sea
level, but temporary base levels commonly exist locally.
[GG]{.underline}

**base slope** \[geomorphology\] - A geomorphic component of hills
consisting of the concave to linear slope (perpendicular to the contour)
which, regardless of the lateral shape is an area that forms an apron or
wedge at the bottom of a hillside dominated by colluvial and slope wash
processes and sediments (e.g., colluvium and slope alluvium). Distal
base slope sediments commonly grade to, or interfinger with, alluvial
fills, or gradually thin to form pedisediment over residuum. Compare -
head slope, side slope, nose slope, interfluve, free face. SW

**basin** - (a) Drainage basin; (b) A low area in the Earth\'s crust, of
tectonic origin, in which sediments have accumulated. [GG]{.underline}
(c) (colloquial: western USA) A general term for the nearly level to
gently sloping, bottom surface of an intermontane basin (bolson).
Landforms include playas, broad alluvial flats containing ephemeral
drainageways, and relict alluvial and lacustrine surfaces that rarely,
if ever, are subject to flooding. Where through-drainage systems are
well developed, flood plains are dominant and lake plains are absent or
of limited extent. Basin floors grade mountainward to distal parts of
piedmont slopes. [FFP]{.underline}

**basin floor** - A general term for the nearly level, lower-most part
of intermontane basins (i.e. bolsons, semi-bolsons). The floor includes
all of the alluvial, eolian, and erosional landforms below the piedmont
slope. Compare - basin, piedmont slope. [FFP]{.underline}

**basin-floor remnant** - (colloquial: western U.S.A.) A relatively
flat, erosional remnant of any former landform of a basin floor that has
been dissected following the incision of an axial stream.
[FFP]{.underline}

**batholith** -- A large, generally discordant plutonic rock body
exposed at the land surface, with an aerial extent \> 40 sq. mi. (100
km^2^) and no known bottom (e.g. Idaho batholith). Compare -- stock. SW
& [GG]{.underline}

**bay** \[coast\] -- a) A wide, curving open indentation, recess, or arm
of a sea (e.g. Chesapeake Bay) or lake (e.g. Green Bay, WI) into the
land or between two capes or headlands, larger than a cove \[coast\],
and usually smaller than, but of the same general character as, a gulf.
b) A large tract of water that penetrates into the land and around which
the land forms a broad curve. By international agreement a bay is a
water body having a baymouth that is less than 24 nautical miles wide
and an area that is equal to or greater than the area of a semicircle
whose diameter is equal to the width of the bay mouth. Compare -- gulf.
[GG]{.underline}

**bay** \[geom.\] - (a) Any terrestrial formation resembling a bay of
the sea, as a recess or extension of lowland along a river valley or
within a curve in a range of hills, or an arm of a prairie extending
into, or partly surrounded by, a forest. (b) A Carolina Bay.
[GG]{.underline} & [GSST]{.underline}.

**bay bottom -** The nearly level or slightly undulating central portion
of a submerged, low-energy, depositional estuarine embayment
characterized by relatively deep water (1.0 to \>2.5 m). Compare --
lagoon bottom. SSS

**bayou** - A term applied to many local water features in the lower
Mississippi River basin and in the Gulf Coast region of the U.S. Its
general meaning is a creek or secondary watercourse that is tributary to
another body of water; especially a sluggish and stagnant stream that
follows a winding course through alluvial lowlands, coastal swamps or
river deltas. Compare - oxbow, slough. GG

**beach** - (a) A gently sloping zone of unconsolidated material,
typically with a slightly concave profile, extending landward from the
low-water line to the place where there is a definite change in material
or physiographic form (such as a cliff) or to the line of permanent
vegetation (usually the effective limit of the highest storm waves); a
shore of a body of water, formed and washed by waves or tides, usually
covered by sand or gravel; (b) the relatively thick and temporary
accumulation of loose water-borne material (usually well-sorted sand and
pebbles) accompanied by mud, cobbles, boulders, and smoothed rock and
shell fragments, that is in active transit along, or deposited on, the
shore zone between the limits of low water and high water.
[GG]{.underline}

**beach plain** - A continuous and level or undulating area formed by
closely spaced successive embankments of wave-deposited beach material
added more or less uniformly to a prograding shoreline, such as to a
growing compound spit or to a cuspate foreland. Compare - wave-built
terrace, chenier plain. [GG]{.underline}

**beach ridge** - A low, essentially continuous mound of beach or
beach-and-dune material heaped up by the action of waves and currents on
the backshore of a beach, beyond the present limit of storm waves or the
reach of ordinary tides, and occurring singly or as one of a series of
approximately parallel deposits. The ridges are roughly parallel to the
shoreline and represent successive positions of an advancing shoreline.
GG

**beach sands** \[soil survey\] -- Well sorted, sand-sized, clastic
material transported and deposited primarily by wave action and
deposited in a shore environment. Compare - eolian sands. SW

**beach terrace** - (a) A landform that consists of a wave-cut scarp and
wave-built terrace of well-sorted sand and gravel of marine and
lacustrine origin. (b) (colloquial: western U.S.A.) relict shorelines
from pluvial lakes, generally restricted to valley sides. Compare -
strandline, shoreline. [FFP]{.underline}

**beaded drainage pattern** - (not recommended; use beaded stream
pattern.)

**beaded stream pattern** - A characteristic pattern of small streams in
areas underlain by ice wedges. The course of the stream channel is
controlled by the pattern of the wedges, with beads (pools) occurring at
the junctions of the wedges. NRC

**bed** \[stratigraphy\] - The layer of sediments or sedimentary rocks
bounded above and below by more or less well-defined bedding surfaces.
The smallest, formal lithostratigraphic unit of sedimentary rocks. The
designation of a bed or a unit of beds as a formally named
lithostratigraphic unit generally should be limited to certain
distinctive beds whose recognition is particularly useful. Coal beds,
oil sands, and other layers of economic importance commonly are named,
but such units and their names usually are not a part of formal
stratigraphic nomenclature. Compare - formation. [GG]{.underline}

**bedded** - Formed, arranged, or deposited in layers or beds, or made
up of or occurring in the form of beds; especially said of a layered
sedimentary rock, deposit, or formation. GG

bedding plane -- A planar or nearly planar bedding surface that visibly
separates each successive layer of stratified sediment or rock (of the
same or different lithology) from the preceding or following layer; a
plane of deposition. It often marks a change in the circumstances of
deposition, and may show a parting, a color difference, a change in
particle size, or various combinations. A term commonly applied to any
bedding surface even when conspicuously bent or deformed by folding. SW
& [GG]{.underline}

**bedrock** - A general term for the solid rock that underlies the soil
and other unconsolidated material or that is exposed at the surface.
Compare - regolith, residuum. [GG]{.underline}

**bench** - (not preferred) refer to structural bench.

**berm** - \[beach\] A low, impermanent, nearly horizontal or
landward-sloping shelf, ledge, or narrow terrace on the backshore of a
beach, formed of material thrown up and deposited by storm waves; it is
generally bounded on one side or the other by a beach ridge or beach
scarp. Some beaches have no berms, others have one or several.
[GG]{.underline}

**beveled base** -- The lower portion of a canyon wall or escarpment
marked by a sharp reduction in slope gradient from the precipitous cliff
above, and characteristically composed of thinly mantled colluvium (e.g.
\< 1 m) and / or carapaced with a thin surficial mantle of large rock
fragments from above, which overly residuum of less resistant rock
(e.g., shale) whose thin strata intermittently outcrop at the surface; a
zone of erosion and transport common in the canyonlands of the
semi-arid, southwestern USA. Compare -- talus slope. SW

**beveled cut** -- A bank or slope portion of a cut excavated into
unconsolidated material (regolith) or bedrock as in a roadcut, whose
slope gradient has been mechanically reduced to a subdued angle (e.g. to
\< 33 %) to increase slope stability, reduce erosion, or to facilitate
revegetation. Compare -- cut, cutbank, roadcut. SW

**blind valley** - A valley, commonly in karst, that ends abruptly
downstream at the point at which its stream disappears underground.
[GG]{.underline}

**block** \[volcanic\] - A pyroclast that was ejected in a solid state;
it has a diameter greater than 64 mm. Compare - bomb**,** cinder,
lapilli, tephra. GG

**block field** - A thin accumulation of stone blocks, typically
angular, with only coarse fragments in the upper part, over solid or
weathered bedrock, colluvium, or alluvium, without a cliff or ledge
above as an apparent source. Block fields occur on high mountain slopes
above tree-line, or in polar or paleo-periglacial regions; they are most
extensive along slopes parallel to the contour; and they generally occur
on slopes of less than 5%. Synonym - felsenmeer. Compare - block stream,
talus slope, scree slope. [GG]{.underline}

**block glide** \[mass movement\] -- The process, associated sediments
(block glide deposit) or resultant landform characterized by a slow type
of slide, in which largely intact units (blocks) of rock or soil slide
downslope along a relatively planar surface, such as a bedding plane,
without any significant distortion of the original mass; a type of
translational rock slide. Compare -- rotational landslide, debris slide,
lateral spread, landslide. SW & [DV]{.underline}

**block lava** - Lava having a surface of angular blocks; it is similar
to **\`**a\`a lava but the fragments are larger and more regular in
shape, somewhat smoother, and less vesicular. Compare -- **\`**a\`a
lava, pahoehoe lava, pillow lava. [GG]{.underline}

**block lava flow** -- A lava flow dominated by block lava. Compare
--**\`**a\`a lava flow, pahoehoe lava flow, pillow lava flow.
[SW]{.underline}

**block stream** - An accumulation of boulders or angular blocks, with
no fine sizes in the upper part, overlying solid or weathered bedrock,
colluvium, or alluvium, and lying below a cliff or ledge from which
coarse fragments originate. Block streams usually occur at the heads of
ravines as narrow bodies that are more extensive downslope than along
the slope. They may exist on any slope angle, but ordinarily not steeper
than 90 percent slope (approx. 40 degrees). Compare - block field.
[GG]{.underline}

**blowout** -- A saucer**-,** cup-, or trough-shaped depression formed
by wind erosion on a preexisting dune or other sand deposit, especially
in an area of shifting sand, loose soil, or where protective vegetation
is disturbed or destroyed; the adjoining accumulation of sand derived
from the depression, where recognizable, is commonly included. Commonly
small, some blowouts may be large (kilometers in diameter**)**. Compare
-- deflation basin. [GG]{.underline}

**blue rock** \[volcanic\] -- (colloquial -- Hawaii) The very dense
(e.g. 2.75 g/cc), extremely hard and massive, nominally vesicular lava
that commonly forms the inner core of an \`a\`a lava flow. SW

**bluff** - (a) A high bank or bold headland, with a broad, precipitous,
sometimes rounded cliff face overlooking a plain or body of water,
especially on the outside of a stream meander; ex. a river bluff. (b)
(not preferred) use cliff. Any cliff with a steep, broad face.
[GG]{.underline}

**bog** - Waterlogged, spongy ground, consisting primarily of mosses,
containing acidic, decaying vegetation such as sphagnum, sedges, and
heaths that may develop into peat. Compare - fen, marsh, swamp.
[GG]{.underline}

**bolson** - (colloquial: western USA.) A term applied to an internally
drained (closed) intermontane basin in arid regions where drainages from
adjacent mountains converge toward a central depression. Bolsons are
often tectonically formed depressions. According to Peterson, a bolson
can include alluvial flat, alluvial plain, beach plain, barrier beach,
lake plain, sand sheet, dune, and playa landforms. The piedmont slope
above a bolson includes erosional (pediments) and older depositional
surfaces (fans) that adjoin the mountain front. A semi-bolson is an
externally drained (open) bolson. Synonym - intermontane basin.
[GG]{.underline} and [FFP]{.underline}.

**bomb** \[volcanic\] - A pyroclast \> 64 mm in at least one dimension
that was ejected while still viscous and solidified into it's rounded
form in flight. Compare - block, cinder, lapilli, tephra.
[GG]{.underline}

**borrow pit** -- An excavated area from which earthy material has been
removed typically for construction purposes offsite; also called barrow
pit. [GG]{.underline}

**bottomland** - (not recommended) use flood plain. An obsolete,
informal term loosely applied to varying portions of a flood plain. SW

**boulder field** - (not recommended) use block stream. Compare - block
field.

**bowl** \[gilgai\] -- A cup-or trough-shaped subsurface feature
centered under and surrounding the micro-low of a gilgai, commonly 3--5
m across and 1.5--3 m thick, containing numerous slickensides (oblique
slip / shear faces) within it and bounded at its base by master
slickensides. A bowl contains turbated material produced in soils with
substantial smectitic clay (e.g. Vertisols). Bowl morphology is distinct
from that in adjacent micro-highs (chimney) and underlying horizons:
Substratum morphology is not preserved within the bowl. Compare --
chimney \[gilgai\], intermediate position \[gilgai\], gilgai. SW

**box canyon** a) A narrow gorge or canyon containing an intermittent
stream following a zigzag course, characterized by high, steep rock
walls and typically closed upstream by a similar wall, giving the
impression, as viewed from its bottom, of being surrounded or "boxed in"
by almost vertical walls. b) A steep-walled canyon heading against a
cliff a dead-end canyon. [GG]{.underline}

**braided channel** - (not recommended) use braided stream.

**braided stream** - A channel or stream with multiple channels that
interweave as a result of repeated bifurcation and convergence of flow
around inter-channel bars, resembling (in plan view) the strands of a
complex braid. Braiding is generally confined to broad, shallow streams
of low sinuosity, high **bed load**, non-cohesive bank material, and a
steep gradient. At a given bank-full discharge, braided streams have
steeper slopes and shallower, broader, and less stable channel cross
sections than meandering streams. Compare - meandering channel,
flood-plain landforms. HP

**break** - (slopes) An abrupt change or inflection in a slope or
profile (as in "a break in slope"). Compare - knickpoint, shoulder,
escarpment. (geomorphology) A marked variation of topography, or a tract
of land distinct from adjacent land, or an irregular or rough piece of
ground. Compare - breaks. [GG]{.underline}

**breaks** - (colloquial: western USA) A landscape or large tract of
steep, rough or broken land dissected by ravines and gullies and marks a
sudden change in topography as from an elevated plain to lower hilly
terrain, or a line of irregular cliffs at the edge of a mesa or a river
(e.g., the Missouri River breaks). SW & GG

**breccia** - A coarse-grained, clastic rock composed of angular rock
fragments (larger than 2 mm) commonly bonded by a mineral cement in a
finer-grained matrix of varying composition and origin. The consolidated
equivalent of rubble. Compare - conglomerate. [GSST]{.underline}

**broad interstream divide** -- (colloquial: southeastern USA) A type of
very wide, low gradient (level to nearly level) interfluve that lacks a
well developed drainage network such that large portions of the local
upland lack stream channels or other drainageways; extensive in lower
coastal plains and some lake plains, till plains and alluvial plain
remnants. Compare -- interfluve. SW & RD

**brook** \[streams\] -- (not preferred, refer to ephemeral stream)
Generally a very small, ephemeral stream, especially one that issues
from a spring or seep and conducts less water volume and over shorter
distances than a creek. Compare -- intermittent stream. [GG]{.underline}

**burial mound** -- A small human-made hill, composed of debris
accumulated during successive occupations of the site, or of earth
heaped up to mark a burial site; also called mound. [GG]{.underline}

**buried** - (adjective) Landforms, geomorphic surfaces, or paleosols
covered by younger sediments (e.g. eolian, glacial, and alluvial).
Compare - exhumed, relict. [HP]{.underline}

**buried soil** - Soil covered by an alluvial, loessal, or other earthy
mantle of more recent material, typically to depths exceeding 50 cm;
recent surface deposits \< 50 cm thick are generally considered as part
of the ground soil. Compare - ground soil, exhumed, relict,.
[GSST]{.underline} & [ST]{.underline}

**butte** - An isolated, generally flat-topped hill or mountain with
relatively steep slopes and talus or precipitous cliffs and
characterized by summit width that is less than the height of bounding
escarpments, commonly topped by a caprock of resistant material and
representing an erosion remnant carved from flat-lying rocks. Compare -
mesa, plateau, cuesta. [HP]{.underline} & GG

**caldera** - A large, more or less circular depression, formed by
explosion and/or collapse, which surrounds a volcanic vent or vents, and
whose diameter is many times greater than that of the included vent, or
vents. Compare - crater. GG

**caliche** - A general term for a prominent zone of secondary carbonate
accumulation in surficial materials in warm, subhumid to arid areas.
Caliche is formed by both geologic and pedologic processes. Finely
crystalline calcium carbonate forms a nearly continuous surface-coating
and void-filling medium in geologic (parent) materials. Cementation
ranges from weak in non-indurated forms to very strong in types that are
indurated. Other minerals (carbonates, silicate, sulfate) may be present
as accessory cements. Most petrocalcic and some calcic horizons are
caliche. [HP]{.underline}

**canyon** - A long, deep, narrow, very steep-sided valley cut primarily
in bedrock with high and precipitous walls in an area of high local
relief (e.g., mountain or high plateau terrain), often with a perennial
stream at the bottom; similar to but larger than a gorge. Compare --
gorge, box canyon, slot canyon. SW, [HP]{.underline} & [GG]{.underline}

**canyon bench** -- One of a series of relatively narrow, flat landforms
occurring along a canyon wall and caused by differential erosion of
alternating strong and weak horizontal strata; a type of structural
bench. [GG]{.underline}

**canyonlands** -- A deeply and extensively dissected landscape composed
predominantly of relatively narrow, steep-walled valleys with small
flood plains or valley floors; commonly with considerable outcrops of
hard bedrock on steep slopes, ledges, or cliffs, and with broader
summits or interfluves than found in badlands. Side slopes exhibit
extensive erosion, active back-wearing, and relatively sparse
vegetation. SW

**caprock** -- a) A hard rock layer, usually sandstone, lava or in arid
environments, limestone, that lies above shale or other less resistant
bedrock or sediments; specifically a rock layer that forms relatively
level, resistant topmost strata that holds up hills, ridges, mesas,
etc., and commonly forms cliffs or escarpments. Also spelled cap rock.
SW & [GG]{.underline} b) A hard rock layer, usually sandstone,
over-lying the shale above a coal bed. Also spelled cap rock. GG

**captured stream** - A stream whose course has been diverted into the
channel of another stream by natural processes. GG

**Carolina Bay** - Any of various shallow, often oval or elliptical,
generally marshy, closed depressions in the Atlantic coastal plain (from
southern New Jersey to northeastern Florida, especially developed in the
Carolinas) which share an approximately parallel orientation of their
long axes. They range from about 100 meters to many kilometers in
length, are rich in humus, and under native conditions contain trees and
shrubs different from those of the surrounding areas. Also called Grady
ponds (colloquial: Georgia and Alabama) and Delmarva Bays (colloquial:
Maryland). Compare - pocosin. [GG]{.underline}

**cat clay** - (not recommended - obsolete) Wet, clay dominated soils
containing ferrous sulfide which become highly acidic when drained.
[GSST]{.underline}

**catena** - \[as used in USA\] A sequence of soils across a landscape,
of about the same age, derived from similar parent material, and
occurring under similar climatic conditions, but have different
characteristics due to variations in relief and in drainage.
[GSST]{.underline}

**catsteps** - (not preferred, refer to terracettes). A terracette;
especially one produced by slumping of loess deposits as in western
Iowa. [GG]{.underline}

**centripetal** **drainage pattern** -- A drainage pattern in which the
streams converge inward toward a central depression; generally
indicative of a structural basin, volcanic crater, caldera, breached
dome, bolson, or the end of an eroded anticline or syncline. SW,
[GG]{.underline} , [WA]{.underline}

**channel** - (a) \[stream\] The hollow bed where a natural body of
surface water flows or may flow. The deepest or central part of the bed
of a stream, containing the main current and occupied more or less
continuously by water. (b) (colloquial: western U.S.A.) The bed of a
single or braided watercourse that commonly is barren of vegetation and
is formed of modern alluvium. Channels may be enclosed by banks or
splayed across and slightly mounded above a fan surface and include bars
and mounds of cobbles and stones. (c) \[Microfeature\] Small,
trough-like, arcuate or sinuous channels separated by small bars or
ridges, caused by fluvial processes; common to flood plains and young
alluvial terraces; a constituent part of *bar and channel* topography.
[GG]{.underline}, [FFP]{.underline}, & SW.

**chenier** - A long, narrow, vegetated marine beach ridge or sandy
hummock, 1 to 6 m high, forming roughly parallel to a prograding
shoreline seaward of marsh and mud-flat deposits, enclosed on the
seaward side by fine-grained sediments, and resting on foreshore or
mud-flat deposits. It is well drained, often supporting trees on higher
areas. Widths range from 45 - 450 m and lengths may exceed several tens
of kilometers. [GG]{.underline}

**chenier plain** - A mud-rich strand plain, occupied by cheniers and
intervening mud-flats with marsh and swamp vegetation. Compare -
chenier, strand plain. [GG]{.underline}

**chert** - A hard, extremely dense or compact, dull to semivitreous,
cryptocrystalline sedimentary rock, consisting dominantly of
interlocking crystals of quartz less than about 30 mm in diameter; it
may contain amorphous silica (opal). It sometimes contains impurities
such as calcite, iron oxide, or the remains of siliceous and other
organisms. It has a tough, splintery to conchoidal fracture and may be
white or variously colored gray, green, blue, pink, red, yellow, brown,
and black. Chert occurs principally as nodular or concretionary
segregations in limestones and dolomites. [GG]{.underline}

**chimney** \[gilgai\] -- A subsurface feature that forms a crude cone
or wave-crest structure centered under a micro-high (e.g. a low mound or
rim) and extending at least part-way under adjacent intermediate
positions, composed of substratum material that appears to upwell and
reaches close to the surface. A chimney is commonly bounded by master
slickensides in the subsoil with maximum angles of dip reaching 60 - 75
degrees under the micro-high. Its morphology is distinct from the soil
solum of the adjacent micro-lows (e.g. lighter colored and more alkaline
and contain carbonate or gypsum concretions absent under micro-lows).
Compare -- puff \[gilgai\], bowl \[gilgai\], intermediate position
\[gilgai\], gilgai. SW

**chimney and bowl topography** -- (not recommended; use gilgai**)**.

**cinder cone** - A conical hill formed by the accumulation of cinders
and other pyroclastics, normally basaltic or andesitic composition.
Slopes generally exceed 20 percent. [GG]{.underline}

**cinders** - Uncemented vitric, vesicular, pyroclastic material, more
than 2.0 mm in at least one dimension, with an apparent specific gravity
(including vesicles) of more than 1.0 and less than 2.0. Compare - ash
\[volcanic\], block \[volcanic\], lapilli, scoria, tephra. KST

**circle** - A form of patterned ground whose horizontal mesh is
dominantly circular. Compare - Nonsorted circle, patterned ground. GG

**circular gilgai** -- A type of gilgai dominated by circular closed
depressions (micro-lows) separated by low mounds (micro-highs); the
prevailing type of gilgai on relatively level terrain (slopes \< 3 %).
Distance from micro-high to the center of an adjacent micro-low is
generally 4 -- 8 m. Compare -- elliptical gilgai, linear gilgai, gilgai.
SW

**cirque** -- A steep-walled, half bowl-like recess or hollow,
crescent-shaped or semicircular in plan, commonly situated at the head
of a glaciated mountain valley or high on the side of a mountain, and
produced by the erosive activity of a mountain glacier. It often
contains a small round lake (tarn). Compare -- cirque floor, cirque
platform, cirque wall. SW & [GG.]{.underline}

**cirque floor** -- The comparatively level bottom of a cirque, thinly
mantled with till and consisting of glacially-scoured knolls and
hillocks separated by depressions, flat areas and small lakes (tarn);
commonly it is bounded by a slightly elevated rock lip at its exit. SW &
[HD]{.underline}

**cirque headwall** -- The glacially-scoured, steep and arcuate side or
wall of a cirque, dominated by rock-outcrops, rubble, and colluvium.
Compare -- headwall. SW & [HD]{.underline}

**cirque platform** -- A relatively level or bench-like surface formed
by the coalescence of several cirques. [GG]{.underline} & SW

**cirque wall** -- (not preferred) refer to cirque headwall.

**clast** - An individual constituent, grain, or fragment of sediment or
rock, produced by the mechanical weathering (disintegration) of a larger
rock mass. HP

**clastic** - (adjective) Pertaining to rock or sediment composed mainly
of fragments derived from preexisting rocks or minerals and moved from
their place of origin. The term indicates sediment sources that are both
within and outside the depositional basin. Compare - detritus,
epiclastic, pyroclastic, volcaniclastic. [GG]{.underline}

**claypan** - A dense, compact, slowly permeable layer in the subsoil,
with a much higher clay content than overlying materials from which it
is separated by a sharply defined boundary. Claypans are usually hard
when dry, and plastic and sticky when wet. [GSST]{.underline}

**cliff** - Any high, very steep to perpendicular or overhanging face of
rock or earth; a precipice. Compare -- bluff**,** beveled base.
[GG]{.underline}

**climbing dune** -- A dune formed by the piling-up of sand by wind
against a cliff or mountain slope; very common in arid regions with
substantial local relief and strong, prevailing winds. Compare - sand
ramp. [GG]{.underline} & SW

**closed depression** -- A generic name for any enclosed area that has
no surface drainage outlet and from which water escapes only by
evaporation or subsurface drainage; an area of lower ground indicated on
a topographic map by a hachured contour line forming a closed loop.
Compare -- open basin. SW & GG

**coalescent fan piedmont** - (not preferred) refer to fan piedmont. HP

**coastal plain** - A low, generally broad plain that has as its margin
an oceanic shore and its strata horizontal or gently sloping toward the
water, and generally represents a strip of recently prograded or emerged
sea floor; e.g. the coastal plain of the southeastern U.S. which extends
for 3000 km from New Jersey to Texas. [GG '87]{.underline}

**coastal marl** -- An earthy, unconsolidated deposit of gray to
buff-colored mud of low bulk density (dry) composed primarily of very
fine, almost pure calcium carbonate formed in subaqueous settings that
span freshwater lacustrine conditions (e.g. Florida Everglades) to
saline intertidal settings (e.g. Florida Keys) formed by the chemical
action of algal mats and organic detritus (periphyton); other marl
varieties associated with different environments (e.g. freshwater marl,
glauconitic marl) also occur. Coastal marl can be quite pure or it can
be finely disseminated throughout living root mats (e.g. mangrove roots)
and / or organic soil layers. Compare -- marl, freshwater marl. SW

**cockpit** -- A crudely star-shaped, closed depression (i.e. large
sinkhole) in tropical karst having an inverted conical or slightly
concave floor, with an irregular or serrate perimeter formed by
subsidiary solution channels and corridors into adjacent hills, and
surrounded by residual hills with steep, concave side slopes; the
dominant type of closed depression in cockpit karst. Compare --
sinkhole, kegel karst. SW, WW & [GG]{.underline}

**cockpit karst** -- A karst landscape dominated by subsurface drainage
and serrate or star-shaped depressions (cockpits) that range widely in
size and density but typically are considerably larger than sinkholes
(dolines), and are separated by intermediate residual hills with concave
side slopes; a common type of tropical karst (e.g. Jamaica). Compare --
kegel karst, karst. SW & WW

**col** - A high, narrow, sharp-edged pass or saddle through a divide or
between two adjacent peaks in a mountain range; especially a deep pass
formed by the headward erosion and intersection of two cirques.
Compare - gap, pass, saddle. [GG]{.underline}

**collapsed ice-floored lakebed** - A lakebed formed in a lake on
glacial ice and subsequently \"let down\" or collapsed by the melting of
underlying ice, resulting in contortion or folding of the lacustrine
sediment and sedimentary structures. These modified or distorted
lacustrine sediments cap present-day topographic highs and generally lie
at elevations higher than the surrounding disintegration moraine.
Compare - collapsed lake plain, collapsed ice-walled lakebed. SW &
[CF]{.underline}

**collapsed ice-walled lakebed** - A lakebed that formed in a lake
bounded by stagnant ice, but floored by solid ground, usually till.
Collapse features are limited to the lakebed margins. Presently, these
materials and sedimentary structures generally occur as roughly
circular-shaped hills of till capped by lacustrine sediments, generally
at elevations higher than surrounding disintegration moraine. Compare -
collapsed ice-floored lakebed, collapsed lake plain. SW &
[CF]{.underline}

**collapsed lake plain** - A lake plain formed on, and bounded by,
glacial ice and subsequently \"let down\" or collapsed by the melting of
underlying ice resulting in contortion or folding of the sediments and
sedimentary structures. Lacustrine sediments cap present topography.
Compare - lake plain. SW & [CF]{.underline}

**collapsed outwash plain** - An outwash plain which forms on glacial
ice (inside the glacial margin), and is subsequently let down or
collapsed when the underlying ice melts, resulting in contortion or
folding of the sediments and sedimentary structures to the extent that
little of the original plain or it's gradient remain. Outwash sediments
commonly cap present-day topography. Compare - collapsed lake plain,
pitted outwash plain. SW & [CF]{.underline}

**collapse sinkhole** -- A type of sinkhole that is formed by collapse
of a cave within the underlying soluble bedrock (e.g., limestone,
gypsum, salt). Compare -- solution sinkhole. SW, WW, & [GG]{.underline}

**colluvial** - (adjective) Pertaining to material or processes
associated with transportation and/or deposition by mass movement
(direct gravitational action) and local, unconcentrated runoff (overland
flow) on side slopes and/or at the base of slopes. Compare -- alluvial,
fluvial. [HP]{.underline}

**colluvial apron** - A landform with a concave to planar surface
composed of a thick wedge-shaped deposit of colluvium and/or slope
alluvium that forms the base (footslope) of a bluff, escarpment or steep
slope . Compare -- beveled base. SW

**colluvium** - Unconsolidated, unsorted earth material being
transported or deposited on side slopes and/or at the base of slopes by
mass movement (e.g. direct gravitational action) and by local,
unconcentrated runoff. Compare - alluvium, slope alluvium, scree, talus,
mass movement. [HP]{.underline}

**competence** - The ability of a current of water or wind to transport
sediment, in terms of particle size rather than amount, measured as the
diameter of the largest particle transported. It depends upon velocity:
a small but swift current for example, may have greater competence than
a larger but slower moving current. [GG]{.underline}

**complex landslide** \[mass movement\] -- A category of mass movement
processes, associated sediments (complex landslide deposit) or resultant
landform**s** characterized by a composite of several mass movement
processes none of which dominates or leaves a prevailing landform.
Numerous types of complex landslides can be specified by naming the
constituent processes evident (e.g. a *complex earth spread -- earth
flow* landslide). Compare -- fall, topple, slide, lateral spread, flow,
landslide. SW & DV

**compound sinkhole** -- (not preferred) refer to karst valley.

**cone karst** -- A variety of kegel karst topography, common in the
tropics (e.g. Puerto Rico, Pacific Basin Islands) characterized by
steep-sided, cone-shaped residual hills and ridges separated by
star-shaped depressions, broader valleys, or lagoons. These hills and
ridges have steep, convex side slopes and rounded tops that are
dissected into secondary karst surfaces with shafts and various forms of
karren microfeatures. Compare -- karst cone, cockpit karst, fluviokarst,
sinkhole karst, tower karst. SW & [GG]{.underline}, [WW]{.underline}

**conformity** - The mutual and undisturbed relationship between
adjacent sedimentary strata that have been deposited in orderly sequence
with little or no evidence of time lapses; true stratigraphic continuity
in the sequence of beds without evidence that the lower beds were
folded, tilted, or eroded before the higher beds were deposited. Compare
-- unconformity. GG

**congelifraction** - (not preferred) refer to frost shattering.

**congeliturbate** - (not recommended) use cryoturbate.

**congeliturbation** - (not recommended) use cryoturbation.

**conglomerate** - A coarse-grained, clastic sedimentary rock composed
of rounded to subangular rock fragments larger than 2 mm, commonly with
a matrix of sand and finer material; cements include silica, calcium
carbonate, and iron oxides. The consolidated equivalent of gravel.
Compare - breccia. HP

**conservation terrace** -- An earthen embankment constructed across a
slope for conducting water from above at a regulated flow to prevent
accelerated erosion and to conserve water. Compare -- hillslope terrace.
SW & [GSST]{.underline}

**constructional** \[geomorphology\] - (adjective) Said of a landform
that owes its origin, form, position, or general character to
depositional (aggradational) processes, such as the accumulation of
sediment (e.g., alluvial fan**,** volcanic cone). Compare - aggradation,
destructional, erosional. [GG]{.underline}

**continuous permafrost** - Permafrost occurring everywhere beneath the
exposed land surface throughout a geographic region. Compare -
discontinuous permafrost, sporadic permafrost. [NRC]{.underline}

**continental glacier** -- A glacier of considerable thickness
completely covering a large part of a continent or an area of at least
50,000 square km, obscuring the underlying surface, such as the ice
sheets covering Antarctica or Greenland. Continental glaciers occupied
northern portions of the coterminous USA and Alaska in the past (e.g.,
Pleistocene) and usage commonly implies former continental glacier
conditions. Compare -- alpine glacier. SW & [GG]{.underline}

**coppice mound** (also called coppice dune) - (not recommended:
obsolete) use shrub-coppice dune.

**coprogenous earth** \[Soil Taxonomy\] - A type of limnic layer
(sedimentary peat) composed predominantly of fecal material derived from
aquatic animals. ST

**coprogenic material** \[soil survey\] - The remains of fish excreta
and similar materials that occur in some organic soils. GSST

**corda** -- Small, tightly bunched, parallel ridges or corrugations of
lava, commonly \< 1 m in amplitude (high) and \< 3 m in period (wide) on
the surface of corded pahoehoe lava (ropy lava). SW & [GS]{.underline}

**corrosion** \[geomorphology\] - A process of erosion whereby rocks and
soil are removed or worn away by natural chemical processes, especially
by the solvent action of running water, but also by other reactions,
such as hydrolysis, hydration, carbonation, and oxidation.
[GG]{.underline}

**coulee** - (colloquial: northwest USA, and ND) A dry or intermittent
stream valley or wash with an underfit stream, especially a long,
steep-walled gorge representing a Pleistocene overflow channel that
carried meltwater from an ice sheet; e.g. the Grand Coulee in Washington
State. HP

**country rock** - A general term for the non-igneous rock surrounding
an igneous intrusion. [GG]{.underline}

**cove** \[coast\] -- a) \[water\] A small, narrow sheltered bay, inlet,
creek or recess in an estuary, often inside a larger embayment. Compare
-- lagoon bottom. SSS & [GG]{.underline} b) A small, often circular,
wave-cut indentation in a cliff; it usually has a restricted or narrow
entrance. c) A fairly broad, looped embayment in a lake shoreline. d) A
shallow tidal river, or the backwater near the mouth of a tidal river.
Compare - estuary. [GG]{.underline}

**cove** \[geom.\] -- a) A walled and rounded or cirque-like opening at
the head of a small steep valley. b) (colloquial - southern
Appalachians, USA) A smooth-floored, somewhat oval-shaped \"valley\"
sheltered by hills or mountains; e.g., Cades Cove in eastern Tennessee.
[GG]{.underline}

**coral island** -- a) A relict coral reef that stands above sea level
and surrounded by water (e.g. Florida Keys). Carbonate sands rich in
coral and shell fragments generally mantle the underlying flat coral
platform. b) An oceanic island formed from coral accumulations lying
atop or fringing volcanic peaks or platforms. SW & [GG]{.underline}

**cradle and knoll topography** -- (not recommended) use tree-tip pit
and mound topography.

**crag and tail** -- An elongate hill or ridge of subglacially
streamlined drift, having at the stoss end (up-ice) a steep, often
precipitous face or knob of ice-smoothed, resistant bedrock (the "crag")
obstructing the movement of the glacier, and at the lee end (down-ice) a
tapering, streamlined, gentle slope (the "tail") of intact, weaker rock
and / or drift protected by the crag; also called lee-side cone. Compare
-- drumlin, drumlinoid ridge, flute, stoss and lee. [GG]{.underline},
SW, & GM

**crater** \[volcanic\] - A basin-like, rimmed structure, usually at the
summit of a volcanic cone. It may be formed by collapse, by an explosive
eruption or by the gradual accumulation of pyroclastic material into a
surrounding rim. Compare - caldera. [GG]{.underline}

**craton** - A part of the earth\'s crust that has attained stability,
and has been minimally deformed for a prolonged period. The term is now
restricted to continental areas of largely Precambrian rocks.
[GG]{.underline}

**creek** \[streams\] -- (not preferred, refer to intermittent stream) A
general term used throughout the USA (except New England), Canada, and
Australia for a small, intermittent stream that is larger than a brook
but smaller than a river. [GG]{.underline}

**creep** \[mass movement\] - The process, surficial sediments, (creep
deposit) and/or landform that results from very slow downslope mass
wasting of unconsolidated earthy material driven primarily by gravity,
but facilitated by water saturation and by and freeze-thaw. Sometimes
redundantly called soil creep. Compare - mudflow, flow, landslide,
solifluction. [SW]{.underline}

**crest** **-** (a) The commonly linear, narrow top of a ridge, hill, or
mountain. It is appropriately applied to elevated areas where retreating
backslopes are converging such that these high areas are almost
exclusively composed of convex shoulders; (b) (not preferred) Sometimes
used as an alternative for the hillslope component *summit*. Compare -
summit (*part b*), saddle. [FFP]{.underline} & SW

**crest** \[geomorphology\] -- A geomorphic component of hills
consisting of the convex slopes (perpendicular to the contour) that form
the narrow, roughly linear top area of a hill, ridge, or other upland
where shoulders have converged to the extent that little or no summit
remains; dominated by erosion, slope wash and mass movement processes
and sediments (e.g., slope alluvium, creep). Commonly, soils on crests
are more similar to those on side slopes than to soils on adjacent
interfluves. Compare -- interfluve, head slope, side slope, nose slope.
SW

**crevasse** \[geomorphology\] - (a) A wide breach or crack in the bank
of a river or canal; especially one in a natural levee or an artificial
bank of the lower Mississippi River. Compare - flood-plain splay,
avulsion. (b) A wide, deep break or fissure in the Earth after an
earthquake. \[glaciology\] A deep, nearly vertical fissure, crack, or
rift in a glacier or other mass of land ice. [GG]{.underline}

**crevasse filling** - A short, straight ridge of stratified sand and
gravel believed to have been deposited in a crevasse of a wasting
glacier and left standing after the ice melted; a variety of kame. May
also occur as long, sinuous ridges and linear complexes of till or
drift. GG

**crevasse splay** - (not recommended) use flood-plain splay. Compare -
crevasse.

**cross-bedding** - (a) Cross-stratification in which the cross-beds are
more than 1 cm in thickness. (b) A cross-bedded structure; a cross-bed.
Compare - cross-lamination. GG

**cross-lamination** - (a) Cross-stratification characterized by
cross-beds that are less than 1 cm in thickness. (b) A cross-laminated
structure; a cross-lamina. Compare - cross-bedding. GG

**cross-stratification** - Arrangement of strata inclined at an angle to
the main stratification. This is a general term having two subdivisions;
cross-bedding, in which the cross-strata are thicker than 1 cm, and
cross-lamination, in which they are thinner than 1 cm. A single group of
related cross-strata is a set and a group of similar, related sets is a
coset. GG

**cryoplanation** - The reduction and modification of a land surface by
processes associated with intensive frost action, such as solifluction,
supplemented by the erosive and transport actions of running water,
moving ice, and other agents. GG

**cryoturbate -** A mass of soil or other unconsolidated earthy material
moved or disturbed by frost action, and usually coarser than the
underlying material; especially a rubbly deposit formed by solifluction.
GG

**cryoturbation** - A collective term used to describe all soil
movements due to frost action, characterized by folded, broken and
dislocated beds and lenses of unconsolidated deposits. Compare -
pedoturbation. NRC

**cryptogamic crust -** A type of microbiotic crust consisting of a
thin, biotic layer at the ground surface composed predominantly of
cryptogams (i.e. algae, lichen, mosses, lichens and liverworts); most
commonly found in semiarid or arid environments. Compare - microbiotic
crust. SW & SS

**cuesta** - An asymmetric ridge capped by resistant rock layers of
slight to moderate dip, commonly less than 10**º** (approximately \< 15
percent); a homocline type produced by differential erosion of
interbedded resistant and weak rocks. A cuesta has a long, gentle slope
on one side (dip slope), that roughly parallels the inclined beds, and
on the opposite side has a relatively short, steep or cliff-like slope
(scarp slope) that cuts the tilted rocks. Compare -- hogback, homoclinal
ridge**,** mesa, dipslope, scarp slope, cuesta valley. SW &
[HP]{.underline}

**cuesta valley -** An asymmetric depression adjacent to a cuesta that
lies parallels to the strike of the underlying strata; a type of strike
valley. It's formed by differential erosion of weaker strata interbedded
with, or stratigraphically adjacent to more resistant rocks. It may or
may not contain a local drainage network but commonly lies above and is
unconnected to the regional drainage system. Compare - cuesta, strike
valley. SW

**cut** \[geology\] -- A passage, incision, or space from which material
has been excavated, such as a road cut or a railroad cut.
[GG]{.underline}

**cut and fill** -- A *process* of leveling, whereby material eroded
from one place by waves, currents, streams, or winds is deposited nearby
until the surfaces of erosion and deposition are continuous and
uniformly graded; especially lateral erosion on the concave banks of a
meandering stream accompanied by deposition within its loops. Compare --
flood-plain step, stream terrace, terrace. GG

cutbank -- a) A slope or wall portion of a cut excavated into
unconsolidated material (regolith) or bedrock, as in a borrow pit. It
may stand nearly vertical resulting from collapse as the base is
undercut during excavation or by erosion, or it may be reduced by
subsequent erosion to a more subdued angle by slope wash. Compare --
cut, beveled cut, roadcut. SW b) (not preferred -- refer to escarpment,
meander scar, bluff) \[colloquial -- western USA\] -- A steep, bare
slope formed by lateral migration of a stream. [GG]{.underline}

**cutoff** \[streams\] - The new and relatively short channel formed
when a stream cuts through a narrow strip of land and thereby shortens
the length of its channel. GG

cutter \[karst\] -- A dissolution groove or trench formed along vertical
bedrock fractures beneath soil and usually buried beneath regolith with
little or no ground surface expression, commonly wider than a solution
fissure (widths commonly range from 0.5 to 3 meters) and tapering down
to a crack or a bedrock floored trench; also called grike (not
preferred), or subsurface karren. Compare -- karren, solution fissure,
solution corridor. SW & WW

**cyclothem** - A series of beds deposited during a single sedimentary
cycle of the type that prevailed during the Pennsylvanian Period. It is
an informal, lithostratigraphic unit equivalent to \"formation\".
Cyclothems are typically associated with unstable shelf or interior
basin conditions in which alternate marine transgression and regressions
occur. The term has also been applied to rocks of different ages and of
different lithologies from the Pennsylvanian cyclothems. Compare -
rhythmite. GG

**dead-ice** - (not recommended) use stagnant ice.

**dead-ice moraine** - (not recommended) use disintegration moraine.

**debris** - Any surficial accumulation of loose material detached from
rock masses by chemical and mechanical means, as by decay and
disintegration. It consists of rock clastic material of any size and
sometimes organic matter. [GG]{.underline}

**debris avalanche** \[mass movement\] -- The process, associated
sediments (debris avalanche deposit) or resultant landform characterized
by a very rapid to extremely rapid type of *flow* dominated by the
sudden downslope movement of incoherent, unsorted mixtures of soil and
weathered bedrock which, although comparatively dry, behave much as a
viscous fluid when moving. Compare -- debris flow, rock fragment flow,
debris avalanche, earthflow, landslide. SW &

**debris fall** \[mass movement\] -- The process, associated sediments
(debris fall deposit) or resultant landform characterized by a rapid
type of *fall* involving the relatively free, downslope movement or
collapse of detached, unconsolidated material which falls freely through
the air (lacks an underlying slip face); sediments have substantial
proportions of both fine earth and coarse fragments; common along
undercut stream banks. Compare -- rock fall, soil fall, landslide. SW

**debris flow** \[ mass movement\] - The process, associated sediments
(debris flow deposit) or resultant landform characterized by a very
rapid type of *flow* dominated by a sudden downslope movement of a mass
of rock, soil, and mud (more than 50% of the particles are \> 2mm), and
whether saturated or comparatively dry, behaves much as a viscous fluid
when moving. Compare -- lahar, mudflow, landslide. SW

**debris slide** \[ mass movement\] - The process, associated sediments
(debris slide deposit) or resultant landform characterized by a rapid
type of *slide*, composed of comparatively dry and largely
unconsolidated earthy material which slides or rolls downslope (does not
exhibit backward rotation) and resulting in an irregular, hummocky
deposit somewhat resembling a moraine. Compare -- rotational landslide,
block glide, lateral spread, landslide. SW & [GG]{.underline}

**debris spread** \[mass movement\] -- The process, associated sediments
(debris spread deposit) or resultant landforms characterized by a very
rapid type of *spread* dominated by lateral movement in a soil and rock
mass resulting from liquefaction or plastic flow of underlying materials
that may be extruded out between intact units; sediments have
substantial proportions of both fine earth and coarse fragments. Compare
-- earth spread, rock spread, landslide. SW & [DV]{.underline}

**debris topple** \[mass movement\] -- The process, associated sediments
(debris topple deposit) or resultant landform characterized by a
localized, very rapid type of *topple* in which large blocks of soil and
rock material literally fall over, rotating outward over a low pivot
point; sediments have substantial proportions of both fine earth and
coarse fragments. Portions of the original material may remain intact,
although reoriented, within the resulting debris pile. Compare -- earth
topple, rock topple, landslide. SW

**deflation** - The sorting out, lifting and removal of loose, dry,
fine-grained soil particles (clays, silts, and fine sands) by the
turbulent eddy action of the wind; a form of wind erosion.
[GG]{.underline} & [GSST]{.underline}

**deflation basin** - A topographic basin excavated and maintained by
wind erosion which removes unconsolidated material and commonly leaves a
rim of resistant material surrounding the depression. Unlike a blowout,
a deflation basin does not include adjacent deposits derived from the
basin. Compare - blowout. [GG]{.underline}

**deflation flat -** (colloquial -- US Gulf Coast) A series of low
ridges and troughs on an essentially flat surface on barrier islands
formed by dune field migration during alternating wet and dry periods; a
type of interdune. Troughs are eroded down to the wet sand level during
drought periods (dune slack), while the ridges are stabilized by
vegetation that invades the edge of dune fields during wet periods.
Compare -- blowout, deflation basin. [HF]{.underline}

**degradation** \[geomorphology\] - The wearing down or away, and the
general lowering of the land surface by natural processes of weathering
and erosion (e.g., the deepening by a stream of its channel) and may
infer the process of transportation of sediment. Compare -
destructional. [GG]{.underline}

**Delmarva Bay** -- see Carolina Bay

**delta** - A body of alluvium, nearly flat and fan-shaped, deposited at
or near the mouth of a river or stream where it enters a body of
relatively quiet water, usually a sea or lake. HP

**delta plain** - The level or nearly level surface composing the
land-ward part of a large delta; strictly, a flood plain characterized
by repeated channel bifurcation and divergence, multiple distributary
channels, and interdistributary flood basins. [GG]{.underline}

**dendritic drainage pattern** - A common drainage pattern in which the
tributaries join the gently curving mainstream at acute angles,
resembling in plan view the branching habit of an oak or chestnut tree;
it is produced where a consequent stream receives several tributaries
which in turn are fed by smaller tributaries. It indicates streams
flowing across horizontal rock strata and homogenous soil typified by
the landforms of soft sedimentary rocks, volcanic tuff, old dissected
coastal plains, or complex crystalline rocks offering uniform resistance
to erosion. SW, [WA]{.underline}, [GG]{.underline}

**deposit** - Either consolidated or unconsolidated material of any type
that has accumulated by natural processes or by human activity. SW

**deposition** - The laying down of any material by any agent such as
wind, water, ice or by other natural processes. HP

**depression** - Any relatively sunken part of the Earth\'s surface;
especially a low-lying area surrounded by higher ground. A closed
depression has no natural outlet for surface drainage (e.g. a sinkhole).
An open depression has a natural outlet for surface drainage. Compare --
closed depression, open depression. [GG]{.underline}

**deranged** **drainage pattern** -- A distinctively disordered drainage
pattern of nonintegrated streams which indicates a complete lack of
underlying structural and bedrock control, resulting from a relatively
young landscape having a flat or undulating topographic surface and a
high water table. It is characterized by relatively few, irregular
streams with few, short tributaries, that flow into and out of
depressions containing swamps, bogs, marshes, ponds, or lakes;
interstream areas are swampy. Regional streams may meander through the
area but do not influence its drainage. These drainage patterns commonly
occur on young, thick till plains, end moraines, flood plains, and
coastal plains. SW, [WA]{.underline}

**desert pavement** - A natural, residual concentration or layer of
wind-polished, closely packed gravel, boulders, and other rock
fragments, mantling a desert surface. It is formed where wind action and
sheetwash have removed all smaller particles or where coarse fragments
have migrated upward through sediments to the surface. It usually
protects the underlying, finer-grained material from further deflation.
Compare -- erosion pavement, stone line. SW, [GSST]{.underline} &
[GG]{.underline}

**desert varnish** - (not preferred) refer to rock varnish.

**destructional** \[geomorphology\] - (adjective) Said of a landform
that owes its origin, form, position, or general character to the
removal of material by erosion and weathering (degradation) processes
resulting from the wearing-down or away of the land surface. Compare -
constructional. [GG]{.underline}

**detritus** \[geology\] - A collective term for rock and mineral coarse
fragments occurring in sediments, that are detached or removed by
mechanical means (e.g. disintegration, abrasion) and derived from
pre-existing rocks and moved from their place of origin. Compare -
clastic, epiclastic, pyroclastic. [GG]{.underline}

**diamict** - (not preferred; refer to diamicton) A general term that
includes both diamictite (coherent rock) and diamicton (unconsolidated
sediments). [GG]{.underline}

**diamictite** - A general term for any nonsorted or poorly sorted,
noncalcareous, terrigenous sedimentary *rock* (e.g., pebbly mudstone)
containing a wide range of particle sizes. Compare - diamicton. GG

**diamicton** - A generic term for any nonlithified, nonsorted or poorly
sorted *sediment* that contains a wide range of particle sizes, such as
coarse fragments contained within a fine earth matrix (e.g. till) and
used when the genetic context of the sediment is uncertain. Compare -
diamictite. SW & [GG]{.underline}

**diapir** - A dome or anticlinal fold in which the overlying rocks or
sediments have been ruptured by the squeezing-out of plastic core
material. Diapirs in sedimentary strata usually contain cores of salt or
shale; igneous intrusions may also show diapiric structure. GG

**diatomaceous earth -** A geologic deposit of fine, grayish, siliceous
material composed chiefly or wholly of the remains of diatoms. It may
occur as a powder or a rigid material. Also called diatomaceous
materials. GSST

**diatreme** -- A breccia-filled volcanic pipe that was formed by a
gaseous explosion (e.g. hydrovolcanic eruption); commonly, but not
exclusively associated with exposed throat or neck of maar, as in the
Hopi Buttes area of Arizona. Compare -- neck \[volcanic\]. SW & GG

**dike** \[intrusive rocks\] - A tabular igneous intrusion that cuts
across the bedding or foliation of the country rock. Compare - sill. GG

**dip** -- \[soil survey\] A geomorphic component (characteristic piece)
of flat plains (e.g., lake plain, low coastal plain, low-relief till
plain) consisting of a shallow and typically closed depression that
tends to be an area of focused groundwater recharge but not a permanent
water body and that lies slightly lower and is wetter than the adjacent
talf, and favors the accumulation of fine sediments and organic
materials. SW

**dip** - The maximum angle that a structural surface, (e.g. a bedding
or fault plane) makes with the horizontal, measured perpendicular to the
strike of the structure and in the vertical plane; used in combination
with "dip" to describe the orientation of bedrock strata. SW &
[GG]{.underline}

**dip slope** - A slope of the land surface, roughly determined by and
approximately conforming to the dip of underlying bedded rocks; (i.e.
the long, gently inclined surface of a cuesta). Compare - scarp slope.
[HP]{.underline}

**discontinuity** - \[stratigraphy\] Any interruption in sedimentation,
whatever its cause or length, usually a manifestation of nondeposition
and accompanying erosion; an unconformity. [GG]{.underline}

**discontinuous permafrost** - Permafrost occurring in some areas
beneath the exposed land surface throughout a geographic region where
other areas are free of permafrost. Compare - continuous permafrost,
sporadic permafrost. NRC

**disintegration moraine** - A drift topography characterized by chaotic
mounds and pits, generally randomly oriented, developed in supraglacial
drift by collapse and flow as the underlying stagnant ice melted. Slopes
may be steep and unstable and there will be used and unused stream
courses and lake depressions interspersed with the morainic ridges.
Characteristically, there are numerous abrupt, lateral and vertical
changes between unconsolidated materials of differing lithology.
[SJ]{.underline} & SW

**distal** \[sedimentology\] - (adjective) Said of a sedimentary deposit
consisting of fine clastics and deposited farthest from the source area.
Compare - proximal. [GG]{.underline}

**distributary** \[streams\] - (a) A divergent stream flowing away from
the main stream and not returning to it, as in a delta or on a flood
plain. It may be produced by stream deposition choking the original
channel. (b) One of the channels of a braided stream; a channel carrying
the water of a stream distributary. [GG]{.underline}

**ditch** - An open and usually unpaved (unlined), channel or trench
excavated to convey water for drainage (removal) or irrigation
(addition) to or from a landscape; smaller than a canal; some ditches
are modified natural waterways. [GG]{.underline}

**divide** - A summit area or tract of high ground, which can vary from
broad to narrow, or a line of separation that constitutes a watershed
boundary between adjacent drainage basins; a divide separates surface
waters that flow naturally in one direction from those that flow in a
different or opposite direction. Compare -- interfluve. [GG]{.underline}

**doline** -- (not preferred; refer to synonym "sinkhole")

**doline karst** -- (not preferred) refer to sinkhole karst.

**dolomite** \[mineral\] - A common rock-forming rhombohedral carbonate
mineral: CaMg(CO~3~)~2~. [GG]{.underline}

**dolomite** \[rock\] -A carbonate sedimentary rock consisting chiefly
(more than 50 percent by weight or by areal percentages under the
microscope) of the mineral dolomite. [GG]{.underline}

**dolostone** - (not recommended - use dolomite) An obsolete term
proposed for the sedimentary rock called dolomite, in order to avoid
confusion with the mineral of the same name. Compare - dolomite.
[GG]{.underline}

**dome** - (a) \[structural geology\] An uplift or anticlinal structure,
either circular or elliptical in outline, in which the rocks dip gently
away in all directions. A dome may be small (e.g. a salt dome) or many
kilometers in diameter. (b) \[geomorphology\] A landform that is a
smoothly rounded rock mass such as a rock-capped mountain summit that
roughly resembles a building dome. (e.g., the rounded granite peaks of
Yosemite, CA). [GG]{.underline}

**double-bedding mound** -- Raised, linear mounds with subdued, convex
slope cross-sections constructed by mounding and shaping spoil material
dredged from adjacent drainage ditches and placed over natural soil. The
mounds serve as preferred, better-drained bedding areas for managed
timber plantations; common in the lower coastal plains of the Atlantic
and Gulf coasts, USA. SW

**drainage basin** - A general term for a region or area bounded by a
drainage divide and occupied by a drainage system. [GG]{.underline}

**drainage network -** (not preferred) refer to drainage pattern.

**drainage pattern** - The configuration or arrangement, in plan view,
of stream courses in an area, including gullies or first-order
channelized flow areas, higher order tributaries, and main streams.
Drainage pattern is related to local geologic materials and structure,
geomorphologic features, and geomorphic history of an area; major
drainage pattern types include dendritic, trellis, artificial, etc. Also
called drainage network. SW, [GG]{.underline}, [WA]{.underline}

**drainageway** - (a) A general term for a course or channel along which
water moves in draining an area. [GG]{.underline}; (b) \[soil survey\] a
term restricted to relatively small, roughly linear or arcuate
depressions that move concentrated water at some time, and either lack a
defined channel (e.g. head slope, swale) or have a small, defined
channel (e.g. low order streams). SW

**drainhead complex** -- An irregular series of low, broad depressions
that form the uppermost reaches of surface drainage networks in low
relief / low gradient terrain such as coastal plains, and separated by
slightly higher and drier areas (e.g. flatwoods). They
characteristically lack defined stream channels but contribute surface
water to the drainage system further downstream through a network of
subtle topographic lows. SW

**draw** - A small, natural watercourse cut in unconsolidated materials,
generally more open with a broader floor and more gently sloping sides
than an arroyo, ravine or gulch, and whose present stream channel may
appear inadequate to have cut the drainageway that it occupies. SW

> **dredged channel** - A roughly linear, deep water area formed by a
> dredging operation for navigation purposes (after Wells et al., 1994;
> dredged hole). Compare -- dredge-deposit shoal. SSS
>
> **dredge-deposit shoal** - A subaqueous area, substantially shallower
> than the surrounding area that resulted from the deposition of
> materials from dredging and dumping (modified from Demas 1998).
> Compare -- dredged channel, shoal. SSS

**dredge spoils** -- Unconsolidated, randomly mixed sediments composed
of rock, soil, and/or shell materials extracted and deposited during
dredging and dumping activities. Dredge spoils lie unconformably upon
natural, undisturbed soil or regolith and can form anthropogenic
landforms (e.g. dredge spoil bank). SW

> **dredge spoil bank** - A subaerial mound or ridge that permanently
> stands above the water composed of dredge spoils; randomly mixed
> sediments deposited during dredging and dumping. Compare -- dredged
> channel, dredge-deposit shoal, filled marshland. SW

**drift** \[glacial geology\] - A general term applied to all mineral
material (clay, silt, sand, gravel, boulders) transported by a glacier
and deposited directly by or from the ice, or by running water emanating
from a glacier. Drift includes unstratified material (till) that forms
moraines, and stratified deposits that form outwash plains, eskers,
kames, varves, and glaciofluvial sediments. The term is generally
applied to Pleistocene glacial deposits in areas that no longer contain
glaciers. [GG]{.underline}

**dropstone -** An oversized stone (compared to the matrix sediments) in
laminated sediment that depresses the underlying laminae and can be
covered by "draped laminae". Most dropstones originate through
ice-rafting; another source is floating tree roots. Compare - erratic,
ice-rafting. [GG]{.underline}

**drumlin** - A low, smooth, elongated oval hill, mound, or ridge of
compact till that has a core of bedrock or drift. It usually has a blunt
nose facing the direction from which the ice approached and a gentler
slope tapering in the other direction. The longest axis is parallel to
the general direction of glacier flow. Drumlins are products of
streamline (laminar) flow of glaciers, which molded the subglacial floor
through a combination of erosion and deposition. Compare -- drumlinoid
ridge. SW, HP, & [GG]{.underline}

**drumlin field** - Groups or clusters of closely spaced drumlins or
drumlinoid ridges, distributed more or less en echelon, and commonly
separated by small, marshy tracts or depressions (interdrumlins).
[SW]{.underline}

**drumlinoid ridge** -- A rock drumlin or drift deposit whose form
approaches but does not fully attain that of a classic drumlin, even
though it seemingly results from similar processes of moving ice.
Compare -- drumlin, interdrumlin. SW & [GG]{.underline}

**dry wash** - (not preferred **-** refer to wash). A dry, ephemeral
stream channel, especially in semiarid regions which only moves water in
response to intense, infrequent precipitation. Compare - arroyo. SW

**dump** -- An area of smooth or uneven accumulations or piles of waste
rock, earthy material, or general refuse that without major reclamation
are incapable of supporting plants. Compare -- sanitary landfill, fill.
[GSST]{.underline}

**dune** - A low mound, ridge, bank or hill of loose, windblown,
subaerially deposited granular material (generally sand), either barren
and capable of movement from place to place, or covered and stabilized
with vegetation, but retaining its characteristic shape. (See barchan
dune, parabolic dune, parna dune, shrub-coppice dune, seif dune,
transverse dune). SW & [GG]{.underline}

**dune field** -- An assemblage of moving and/or stabilized dunes,
together with sand plains, interdune areas, and the ponds, lakes, or
swamps produced by the blocking of waterways by migrating dunes. See
dune lake. SW & SSS

**dune lake** -- (a) A lake occupying a deflation basin as in a blowout
on a dune. (b) A lake occupying a basin formed by the blocking of a
stream by sand dunes migrating along a shore (e.g. Moses lake, WA).
[GG]{.underline}

**dune slack** -- A damp depression or trough between dunes in a dune
field or dune ridges on a shore, caused by intersecting the capillary
fringe of the local water table; a moist type of interdune. Compare --
interdune, dune lake. SW & [GG]{.underline}

**dune traces** -- A series of linear to semi-concentric micro-ridges
and intervening troughs, on the floor of a dune slack or interdune that
were exposed by deflation or dune migration. The ridges are remnant
bases of slip face lamina held together by soil moisture and /or
cemented by evaporites. SW

**earth dike** - (not preferred) refer to levee (stream).

**earth fall** -- see soil fall.

**earthflow** \[mass movement\] -- The process, associated sediments
(earthflow deposit), or resultant landform characterized by slow to
rapid flow dominated by downslope movement of soil, rock, and mud (more
than 50% of the particles are \< 2 mm), and whether saturated or
comparatively dry, behaves as a viscous fluid when moving. Compare --
debris flow (coarser, less fluid), mudflow (finer, more fluid). SW

**earth hummock** - A type of hummock consisting predominantly of a core
of silty and clayey mineral soil and showing evidence of cryoturbation.
Earth hummocks are a type of nonsorted circle. Compare - turf hummock,
hummock \[patterned ground\], non-sorted circle, patterned ground.
[NRC]{.underline}

**earth pillar** - A tall, conical column of unconsolidated to
semi-consolidated earth materials (e.g. clay till, or landslide debris)
produced by differential erosion and usually capped by a flat, hard rock
fragment that shields the underlying, softer material from erosion. It
can measure up to 6-20 m in height, and its diameter is a function of
the width of the protective boulder. Compare - hoodoo. [GG]{.underline}

**earth spread** \[mass movement\] -- The process, associated sediments
(earth spread deposit) or resultant landforms characterized by a very
rapid type of *spread* dominated by lateral movement in a soil mass
resulting from liquefaction or plastic flow of underlying materials that
may be extruded out between intact units. Compare -- debris spread, rock
spread, landslide. SW & [DV]{.underline}

**earth topple** \[mass movement\] -- The process, associated sediments
(earth topple deposit) or resultant landform characterized by a
localized, very rapid type of *topple* in which large blocks of soil
material literally fall over, rotating outward over a low pivot point;
sediments \< 2 mm predominate. Portions of the original material may
remain intact, although reoriented, within the resulting deposit.
Compare --debris topple, rock topple, landslide. SW

**elevation** \[survey\] - The height of a point on the earth's surface
relative to mean sea level (msl). Compare - relief. SW

**elevated lake plain** - (not preferred) refer to collapsed lake plain,
collapsed ice-floored lakebed.

**elliptical gilgai** -- A type of gilgai dominated by elliptical,
closed and semi-closed depressions (micro-lows) separated by low mounds
or ridges (micro-highs); the prevailing type of gilgai on mildly sloping
terrain (slopes 3 -- 8 %); as slope increases, basins become more
eccentric and the occurrence of interconnected micro-lows increases.
Compare -- circular gilgai, linear gilgai, gilgai. SW

**end moraine** - A ridge-like accumulation that is being or was
produced at the outer margin of an actively flowing glacier at any given
time; a moraine that has been deposited at the outer or lower end of a
valley glacier. Compare - terminal moraine, recessional moraine, ground
moraine. [GG]{.underline}

**Eocene -** An epoch (from 35.4 to 56.5 million years ago) of the
Tertiary Period of geologic time that follows the Paleocene and precedes
the Oligocene epoch; also the corresponding (time-stratigraphic)
"series" of earth materials. SW

**eolian** - Pertaining to material transported and deposited (eolian
deposit) by the wind. Includes clastic materials such as dune sands,
sand sheets, loess deposits, and clay (e.g. parna). [HP]{.underline}

**eolian deposit** \[soil survey\] -- Sand, silt or clay-sized clastic
material transported and deposited primarily by wind, commonly in the
form of a dune or a sheet of sand or loess. Conventionally, primary
volcanic deposits (e.g. tephra) are handled separately. Compare --
loess, parna, beach sands. SW

**eolian sands** \[soil survey\] - Sand-sized, clastic material
transported and deposited primarily by wind, commonly in the form of a
dune or a sand sheet. Compare - beach sands. SW

**ephemeral stream** -- Generally a small stream, or upper reach of a
stream, that flows only in direct response to precipitation. It receives
no protracted water supply from melting snow or other sources and its
channel is above the water table at all times. Compare -- arroyo,
intermittent stream, perennial stream. [HP]{.underline}

**epiclastic** - Pertaining to any clastic rock or sediment other than
pyroclastic. Constituent fragments are derived by weathering and erosion
rather than by direct volcanic processes. Compare - pyroclastic,
volcaniclastic, clastic, detritus. HP

**eroded fan remnant** -- All, or a portion of an alluvial fan that is
much more extensively eroded and dissected than a fan remnant; sometimes
called an *erosional fan remnant* (FFP). It consists primarily of a)
eroded and highly dissected sides (*eroded fan-remnant sideslopes*)
dominated by hillslope positions (shoulder, backslope, etc.), and b) to
a lesser extent an intact, relatively planar, relict alluvial fan
"summit" area best described as a tread. SW & [FFP]{.underline}

**eroded fan-remnant sideslope** -- A rough or broken margin of an
*eroded fan remnant* highly dissected by ravines and gullies that can be
just a fringe or make up a large part of an eroded alluvial fan; its
bounding escarpments (risers), originally formed by inset channels, have
become highly dissected and irregular such that terrace components
(tread and riser) have been consumed or modified and replaced by
hillslope positions and components (shoulder, backslope, footslope,
etc.); sometimes referred to as *fan remnant sideslopes* (FFP). Compare
-- eroded fan remnant. SW & [FFP]{.underline}

**erosion** - The wearing away of the land surface by running water,
waves, or moving ice and wind, or by such processes as mass wasting and
corrosion (solution and other chemical processes). The term \"geologic
erosion\" refers to natural erosion processes occurring over long
(geologic) time spans. \"Accelerated erosion\" generically refers to
erosion in excess of what is presumed or estimated to be naturally
occurring levels, and which is a direct result of human activities (e.g.
cultivation, logging, etc.). SW & [HP]{.underline}

**erosional** \[geomorphology\] - (adjective) Owing its origin, form,
position or general character to degradational processes by water, wind,
ice or gravity. Compare - constructional. [HP]{.underline}

**erosional outlier** - (not preferred) refer to erosion remnant.

**erosional pavement** -- see erosion pavement.

**erosion pavement** -- A surficial lag concentration or layer of gravel
and other rock fragments that remains on the soil surface after sheet or
rill erosion or wind has removed the finer soil particles and that tends
to protect the underlying soil from further erosion. Compare -- desert
pavement, stone line. SW, [GSST]{.underline}, [GG]{.underline}

**erosion remnant** - A topographic feature that remains or is left
standing above the general land surface after erosion has reduced the
surrounding area; e.g., a monadnock, a butte, or a stack. GG

**erosion surface** - A land surface shaped by the action of erosion,
especially by running water. GG

**erratic** - A rock fragment carried by glacial ice, or by floating ice
(ice-rafting), and subsequently deposited at some distance from the
outcrop from which it was derived, and generally, though not
necessarily, resting on bedrock or sediments of different lithology.
Coarse fragments range in size from a pebble to a house-size block.
[GG]{.underline}

**escarpment** - A relatively continuous and steep slope or cliff
produced by erosion or faulting and that topographically interrupts or
breaks the general continuity of more gently sloping land surfaces . The
term is most commonly applied to cliffs produced by differential
erosion. Synonym: \"scarp.\" SW & [HP]{.underline}

**esker** - A long, narrow, sinuous and steep-sided ridge composed of
irregularly stratified sand and gravel deposited as the bed of a stream
flowing in an ice tunnel within or below the ice (subglacial) or between
ice walls on top of the ice of a wasting glacier, and left behind as
high ground when the ice melted. Eskers range in length from less than a
kilometer to more than 160 kilometers, and in height from 3 to 30
meters. Compare - kame, crevasse filling, glaciofluvial deposits,
outwash. SW

**estuarine deposit** - Fine-grained sediments (very fine sand, silt and
clay) of marine and fluvial origin commonly containing decomposed
organic matter, laid down in the brackish waters of an estuary;
characteristically finer sediments than deltaic deposits. Compare --
fluviomarine deposit, lacustrine deposit, lagoonal deposit, marine
deposit, overbank deposit. [GG]{.underline}

**estuarine subaqueous soils** - Soils that form in sediment found in
shallow-subtidal environments in protected estuarine coves, bays,
inlets, and lagoons. Excluded from the definition of these soils are any
areas "permanently covered by water too deep (typically greater than 2.5
m) for the growth of rooted plants". SSS

**estuary** - (a) A seaward end or the widened funnel-shaped tidal mouth
of a river valley where fresh water comes into contact with seawater and
where tidal effects are evident; e.g., a tidal river, or a partially
enclosed coastal body of water where the tide meets the current of a
stream. (b) A portion of an ocean or an arm of the sea affected by fresh
water. (c) A drowned river mouth formed by the subsidence of land near
the coast or by the drowning of the lower portion of a non-glacial
valley due to the rise of sea level. Compare -- lagoon. [GG]{.underline}

**everglades** -- (colloquial -- southern USA) A large expanse of marshy
land, covered mostly by grasses, e.g. the Florida Everglades.
[GG]{.underline}

**exfoliation** - The process by which concentric scales, plates, or
shells of rock, from less than a centimeter to several meters in
thickness, are successively spalled or stripped from the bare surface of
a large rock mass. It often results in a rounded rock mass or
dome-shaped hill. [GG]{.underline}

**exhumed** - (adjective) Formerly buried landforms, geomorphic
surfaces, or paleosols that have been re-exposed by erosion of the
covering mantle. Compare - relict, buried, ground soil. HP

**extramorainic** - (not preferred) refer to extramorainal

**extramorainal** - (adjective) Said of deposits and phenomena occurring
outside the area occupied by a glacier and its lateral and end moraines.
Compare - intramorainal. GG

**extrusive** - (adjective) Said of igneous rocks and sediments derived
from deep-seated molten matter (magmas), deposited and cooled on the
earth\'s surface (e.g. including lava flows and tephra deposits).
Compare - intrusive, volcanic. [HP]{.underline}

**faceted spur** - The inverted V-shaped end of a ridge that has been
truncated or steeply beveled by steam erosion (e.g. meander scar or
bluff), glacial truncation, or fault scarp displacement. Compare - spur.
SW

**facies** \[stratigraphy\] - A distinctive group of characteristics
that distinguish one group from another within a stratigraphic unit; the
sum of all primary lithologic and paleontological characteristics of
sediments or sedimentary rock that are used to infer its origin and
environment; the general nature of appearance of sediments or
sedimentary rock produced under a given set of conditions; e.g.:
contrasting river-channel facies and overbank-flood-plain facies in
alluvial valley fills. [HP]{.underline}

**fall** \[mass movement\] - (a) A category of mass movement processes,
associated sediments (fall deposit), or resultant landforms (e.g., rock
fall, debris fall, soil fall) characterized by very rapid movement of a
mass of rock or earth that travels mostly through the air by free fall,
leaping, bounding, or rolling, with little or no interaction between one
moving unit and another. Compare -- topple, slide, lateral spread, flow,
complex landslide, landslide. SW & [DV]{.underline}; (b) The mass of
material moved by a fall. [GG]{.underline}

**falling dune** -- An accumulation of sand that is formed as sand is
blown off a mesa top or over a cliff face or steep slope, forming a
solid wall, sloping at the angle of repose of dry sand, or a fan
extending downward from a re-entrant in the mesa wall. Compare --
climbing dune, sand ramp. [GG]{.underline}

**fall line** - (not recommended; obsolete) An imaginary line or narrow
zone connecting the water falls on several adjacent or near-parallel
rivers, marking the points where these rivers make a sudden descent from
an upland to a lowland, as at the edge of a plateau; specifically, the
Fall Line marking the boundaries between the ancient, resistant
crystalline rocks of the Piedmont Plateau and the younger, softer
sediments of the Atlantic Coastal Plain of the Eastern United States. It
also marks the limit of navigability of the rivers. Now considered an
archaic term because Coastal Plain materials occur several miles west or
inland of the Fall Line and current research is showing it to be a broad
zone of high-angle reverse faults. [GG]{.underline}

**fan** \[geomorphology\] - (a) A gently sloping, fan-shaped mass of
detritus forming a section of a low-angle cone commonly at a place where
there is a notable decrease in gradient; specifically an alluvial fan
(not preferred -- use alluvial fan). Compare -- alluvial fan, alluvial
cone. (b) A fan-shaped mass of congealed lava that formed on a steep
slope by the continually changing direction of flow. [GG]{.underline}

**fan apron** - A sheet-like mantle of relatively young alluvium and
soils covering part of an older fan piedmont (and occasionally alluvial
fan) surface, commonly thicker and further down slope (e.g., mid-fan or
mid-fan piedmont) than a fan collar. It somewhere buries an older soil
that can be traced to the edge of the fan apron where the older soil
emerges as the land surface, or relict soil. No buried soils should
occur within a fan-apron mantle itself. Compare -- fan collar.
[FFP]{.underline}

**fan collar** -- A landform comprised of a thin, short, relatively
young mantle of alluvium along the very upper margin (near the proximal
end or apex) of a major alluvial fan. The young mantle somewhere buries
an older soil that can be traced to the edge of the collar where the
older soil emerges at the land surface as a relict soil. Compare -- fan
apron. [FFP]{.underline}

**fanglomerate** - A sedimentary rock consisting of waterworn,
heterogeneous fragments of all sizes, deposited in an alluvial fan and
later cemented into a firm rock. [GG]{.underline}

**fanhead trench** - A linear depression formed by a drainageway that is
incised considerably below the surface of an alluvial fan. GG

**fan piedmont** - The most extensive landform on piedmont slopes,
formed by (a) the lateral, downslope, coalescence of mountain-front
alluvial fans into one generally smooth slope with or without the
transverse undulations of the semi-conical alluvial fans, and (b)
accretions of fan aprons. [FFP]{.underline}

**fan remnant** - A general term for landforms that are the remaining
parts of older fan-landforms, such as alluvial fans, fan aprons, inset
fans, and fan skirts, that either have been dissected (erosional
fan-remnants) or partially buried (nonburied fan-remnants). An erosional
fan remnant must have a relatively flat summit that is a relict
fan-surface. A nonburied fan-remnant is a relict surface in its
entirety. Compare -- eroded fan remnant, ballena. [FFP]{.underline}.

**fan remnant sideslope** -- (not preferred) refer to eroded fan-remnant
sideslope.

**fan skirt** - The zone of smooth, laterally-coalescing, small alluvial
fans that issue from gullies cut into the fan piedmont of a basin or
that are coalescing extensions of the inset fans of the fan piedmont,
and that merge with the basin floor at their toeslopes. These are
generally younger fans which onlap older fan surfaces. [FFP]{.underline}

**fan terrace** - (not preferred) refer to fan remnant

**fault** - A discrete surface (fracture) or zone of discrete surfaces
separating two rock masses across which one mass has slid past the
other. [GG]{.underline}

**fault block** - A displaced crustal unit, formed during block
faulting, that is bounded by faults, either completely or in part, and
behaves as a coherent unit during tectonic activity. SW &
[GG]{.underline}

**fault-block mountains** - Mountains that formed primarily by block
faulting, and commonly exhibit asymmetrical rotation and vertical
displacement from a horizontal plane by large, coherent fault-block
units hinged along fault lines; common in , but not limited to, the
Basin and Range region of the US.. The term is not applied to mountains
formed by thrust-faulting. SW & [GG]{.underline}

**fault line** - The trace of a fault plane on the ground surface or on
a reference plane. Compare - fault-line scarp. GG

**fault-line scarp** - (a) A steep slope or cliff formed by differential
erosion along a fault line, as by the more rapid erosion of soft rock on
the side of a fault as compared to that of more resistant rock on the
other side; e.g. the east face of the Sierra Nevada in California. (b)
(not recommended) A fault scarp that has been modified by erosion. This
usage is not recommended because the scarp is usually not located on the
fault line. [GG]{.underline}

**fault zone** -- A fault that is expressed as a zone of numerous small
fractures or of breccia or fault gouge. A fault zone may be as wide as
hundreds of meters. Compare -- fault, fault-scarp. GG

**felsenmeer** - refer to block field. GG

**felsic rock** - A general term for igneous rock containing abundant,
light-colored minerals (granite, etc); also applied to those minerals
(quartz, feldspars, feldspathoids, muscovite) as a group. Compare -
mafic rock. [GG]{.underline}

**fen** - Waterlogged, spongy ground containing alkaline decaying
vegetation, characterized by reeds, that develops into peat. It
sometimes occurs in sinkholes of karst regions. Compare - bog, marsh,
swamp. [GG]{.underline}

**fenster** -- see window.

**fill** \[eng. geol\] -- (a) Human-constructed deposits of natural
earth materials (e.g., soil, gravel, rock) and waste materials (e.g.,
tailings or spoil from dredging) used to fill a depression, to extend
shore land into a body of water, or in building dams. (b) Soil or loose
rock used to raise the surface level of low-lying land, such as an
embankment to fill a hollow or ravine in roads construction.
[GG]{.underline}

**filled marshland** - A subaerial soil area composed of fill materials
(construction debris, dredged or pumped sandy or shell-rich sediments,
etc.) deposited and smoothed to provide building sites and associated
uses (e.g. lawns, driveways, parking lots). These fill materials are
typically 0.5 to 3 m thick and have been deposited unconformably over
natural soils. Compare -- dredge spoil bank. SW

**finger ridge** -- One in a group of small, tertiary spur ridges that
form crudely palmate extensions of erosional remnants along the flanks
or nose of larger ridges. Compare -- ballena, rib. SW

**first bottom** - (not recommended; colloquial: Midwest USA) refer to
flood-plain step. An obsolete, informal term loosely applied to the
lowest flood-plain steps that experience regular flooding. However, the
frequency of flooding is inconsistently specified. SW

**fissure vent** -- An opening in earth's surface of a volcanic conduit
in the form of a crack or fissure rather than a localized crater; a
roughly linear crack or area along which lava, generally mafic and of
low viscosity, wells up to the surface, usually without any explosive
activity. The results can be an extensive lava plateau (e.g. Columbia
River Plateau). Compare -- crater \[volcanic\]. SW & [GG]{.underline}

**fjord** - A long, narrow, winding, glacially eroded, U-shaped and
steep-walled, generally deep inlet or arm of the sea between high rocky
cliffs of slopes along a mountainous coast. Typically it has a shallow
sill or threshold of solid rock or earth material submerged near its
mouth and becomes deeper far inland. A fjord usually represents the
seaward end of a deep, glacially excavated valley that is partially
submerged by drowning after melting of the ice. [GG]{.underline}

**flat** -\[geomorphology\] - (a) (adjective) Said of an area
characterized by a continuous surface or stretch of land that is smooth,
even, or horizontal, or nearly so, and that lacks any significant
curvature, slope, elevations, or depressions. (b) (noun) An informal,
generic term for a level or nearly level surface or small area of land
marked by little or no local relief. Compare - mud flat. (c) (not
recommended) A nearly level region that visibly displays less relief
than its surroundings. [GG]{.underline}.

**flat** - \[lake\] (a) (not preferred) refer to lakebed. The low-lying,
exposed, flat land of a lake delta or of a lake bottom. Compare - lake
plain. (b) (not preferred) The flat bottom of a desiccated lake in the
arid parts of western USA. Compare - playa, pluvial lake.
[GG]{.underline}

**flatwoods** -- (colloquial -- southeastern US) Broad, low gradient
(generally \< 1 % slope but up to 2% near drainageways), low relief
interstream areas and characterized by non-hydric, poorly drained soils
(seasonal saturation or water table) at depths of 15 -45 cm (6 -- 18"),
and naturally forested by pines that dominate the Lower Coastal Plain of
the southeastern US. Regional differences occur in dominant vegetation
and soil material (e.g. in south Florida, soils are dominantly sandy
Spodosols and the understory is dominantly saw palmetto).
Hydropedologically and elevationally this landform occurs slightly above
minor depressions (which have a seasonal water table at or above the
surface), drainageways, and drainhead complexes, but lies below better
drained and slightly higher small rises or knolls. Generally they are
most extensive toward the interiors of low, broad interstream divides
and away from drainageways. SW

**flood plain** - The nearly level plain that borders a stream and is
subject to inundation under flood-stage conditions unless protected
artificially. It is usually a constructional landform built of sediment
deposited during overflow and lateral migration of the streams.
[HP]{.underline}

**flood-plain landforms** - A variety of constructional and erosional
features produced by stream channel migration and flooding, e.g.,
backswamp, braided stream, flood-plain splay, meander, meander belt,
meander scroll, oxbow lake, and natural levee. [HP]{.underline}

**flood-plain playa** - A landform consisting of very low gradient,
broad, barren, axial-stream channel segments in an intermontane basin.
It floods broadly and shallowly and is veneered with barren
fine-textured sediment that crusts. Commonly, a flood-plain playa is
segmented by transverse, narrow bands of vegetation, and it may
alternate with ordinary narrow or braided channel segments. FFP

**flood-plain splay** - A fan-shaped deposit or other outspread deposit
formed where an overloaded stream breaks through a levee (natural or
artificial) and deposits its material (often coarse-grained) on the
flood plain. Compare - crevasse. [GG]{.underline}

**flood-plain step** - An essentially flat, terrace-like alluvial
surface within a valley that is frequently covered by flood water from
the present stream (e.g., below the 100 year flood level); any
approximately horizontal surface still actively modified by fluvial
scour and/or deposition (i.e., cut and fill and/or scour and fill
processes). May occur individually or as a series of steps. Compare --
stream terrace. SW & [RR]{.underline}

> **flood-tidal delta** - A largely subaqueous (sometimes intertidal),
> crudely fan-shaped deposit of sand-sized sediment formed on the
> landward side of a tidal inlet (modified from Boothroyd et al., 1985;
> Davis, 1994; Ritter et al., 1995). Flood tides transport sediment
> through the tidal inlet and into the lagoon over a flood ramp where
> currents slow and dissipate (Davis, 1994). Generally, flood-tidal
> deltas along microtidal coasts are multi-lobate and unaffected by
> ebbing currents (modified from Davis, 1994). Compare -- flood-tidal
> delta slope. SSS
>
> **flood-tidal delta flat** - The relatively flat, dominant component
> of the flood-tidal delta. At extreme low tide this landform may be
> exposed for a relatively short period (modified from Boothroyd et al.,
> 1985). SSS

**flood-tidal delta slope** - An extension of the flood-tidal delta that
slopes toward deeper water in a lagoon or estuary, composed of flood
channels, inactive lobes (areas of the flood-tidal delta that are not
actively accumulating sand as a result of flood tides), and parts of the
terminal lobe of the flood-tidal delta (modified from Boothroyd et al.,
1985). SSS

**floodwall** - (not recommended) use levee.

**floodway** -- a) A large-capacity channel constructed to divert
floodwaters or excess streamflow from populous, flood-prone areas, such
as a bypass route bounded by levees. b) The part of the flood plain kept
clear of encumbrances and reserved for emergency diversion of
floodwaters. GG

**floor** \[geomorphology\] - (a) A general term for the nearly level,
lower part of a basin or valley; (not preferred) refer to basin floor,
valley floor, (b) The bed of any body of water; e.g., the nearly level
surface beneath the water of a stream, lake, or ocean. [GG]{.underline}

**flow** \[mass movement\] - A category of mass movement processes,
associated sediments (flow deposit) and landforms characterized by slow
to very rapid downslope movement of unconsolidated material which,
whether saturated or comparatively dry, behaves much as a viscous fluid
as it moves. Types of flows can be specified based on the dominant
particle size of sediments (i.e. debris flow (e.g., lahar), earth flow
(creep, mudflow), rock fragment flow (e.g., rockfall avalanche), debris
avalanche\]. Compare - fall, topple, slide, lateral spread, complex
landslide, landslide. SW & [DV]{.underline}

**flowtill** - A till, commonly supraglacial that is modified and
transported by plastic mass flow**;** also spelled *flow till*.
Compare - ablation till, basal till, lodgment till, mass-movement till,
slump-till, supraglacial melt-out till. [GG]{.underline}

**flute** \[glacial\] - A lineation or streamlined furrow or ridge
parallel to the direction of ice movement, formed in newly deposited
till or older drift. They range in height from a few centimeters to 25
m, and in length from a few meters to 20 km. Compare -- glacial groove.
[GG]{.underline}

**fluve** - (refer to drainageway) A roughly linear or elongated
depression (topographic low) of any size, along which water flows, at
some time. Compare - interfluve. [FFP]{.underline} & SW.

**fluvial** -- (adjective) Of or pertaining to rivers or streams;
produced by stream or river action. Compare -- alluvial, colluvial.
[HP]{.underline}

**fluviokarst** -- A karst landscape dominated by both 1) karst features
(deranged and subsurface drainage, blind valleys, swallow holes, large
springs, closed depressions, and caves), generally limited to low-lying
interfluve areas, and 2) surface drainage by large rivers, with
associated fluvial features (adjacent stream terraces) and sediments
(alluvium), that commonly maintain their surface courses and are fed by
underground tributaries; the dominant karst in the eastern USA. Compare
-- sinkhole karst, pavement karst, glaciokarst, karst. SW, WW, &
[GG]{.underline}

**fluviomarine bottom** - The nearly level or slightly undulating,
relatively low-energy, depositional environment with relatively deep
water (1.0 to \>2.5 m) directly adjacent to an incoming stream and
composed of interfingered and mixed fluvial and marine sediments
(fluviomarine deposits). SSS

**fluviomarine deposit** -- Stratified materials (clay, silt, sand, or
gravel) formed by both marine and fluvial processes, resulting from
non-tidal sea level fluctuations, subsidence and/or stream migration
(i.e. materials originally deposited in a nearshore environment and
subsequently reworked by fluvial processes as sea level fell). Compare
-- estuarine deposit, lacustrine deposit, lagoonal deposit, marine
deposit, overbank deposit. SW

**fluviomarine terrace** -- A constructional coastal strip, sloping
gently seaward and/or down valley, veneered or completely composed of
fluviomarine deposits (typically silt, sand, fine gravel). Compare --
terrace, stream terrace, marine terrace. SW

**fly ash** -- All particulate matter that is carried in a gas stream,
especially in stack gases at a coal-fired plant for the generation of
electric power; also name given to sediments from the same source, stock
piled in settling ponds or spoil piles. SW & [GG]{.underline}

**fold** \[structural geology\] - A curve or bend of a planar structure
such as rock strata, bedding planes, foliation, or cleavage. GG

**foothills** - A steeply sloping upland composed of hills with relief
of 30 up to 300 meters and fringes a mountain range or high-plateau
escarpment. Compare - hill, mountain, plateau. SW & [HP]{.underline}

**footslope** - The hillslope profile position that forms the concave
surface at the base of a hillslope. It is a transition zone between
upslope sites of erosion and transport (shoulder, backslope) and
downslope sites of deposition (toeslope). Compare - summit, shoulder,
backslope, and toeslope. SW

**foredune** - A coastal dune or dune ridge oriented parallel to the
shoreline, occurring at the landward margin of the beach, along the
shoreward face of a beach ridge, or at the landward limit of the highest
tide, and more or less stabilized by vegetation. [GG]{.underline}

**formation** \[stratigraphy\] - The basic lithostratigraphic unit in
the local classification of rocks. A body of rock (commonly a
sedimentary stratum or strata, but also igneous and metamorphic rocks)
generally characterized by some degree of internal lithologic
homogeneity or distinctive lithologic features (such as chemical
composition, structures, textures, or general kind of fossils), by a
prevailing (but not necessarily tabular) shape, and is mappable at the
earth\'s surface (at scales of the order of 1:25,000) or traceable in
the subsurface. Formation may be combined into Groups or subdivided into
members. Compare - bed. [HP]{.underline}

**fosse** \[glacial geology\] - A long, narrow depression or trough-like
hollow between the edge of a retreating glacier and the wall of its
valley, or between the front of a moraine and its outwash plain. GG

**free face** - The part of a hillside or mountainside consisting of an
outcrop of bare rock (scarp or cliff) that sheds colluvium to slopes
below and commonly stands more steeply than the angle of repose of the
colluvial slope (e.g. talus slope**)** immediately below. SW &
[GG]{.underline}

**free face** \[geomorphology\] -- A geomorphic component of hills and
mountains consisting of an outcrop of bare rock that sheds rock
fragments and other sediments to, and commonly stands more steeply than
the angle of repose of, the colluvial slope immediately below; most
commonly found on shoulder and backslope positions, and can comprise
part or all of a nose slope or side slope. Compare -- interfluve, crest,
nose slope, side slope, head slope, base slope. SW

**freshwater marl** -- A soft, grayish to white, earthy or powdery,
usually impure calcium carbonate precipitated on the bottoms of
present-day freshwater lakes and ponds largely through the chemical
action of algal mats and organic detritus, or forming deposits that
underlie marshes, swamps, and bogs that occupy the sites of former
(glacial) lakes. The calcium carbonate may range from 90% to less than
30%. Freshwater marl is usually gray; it has been used as a fertilizer
for acid soils deficient in lime. Syn.: *bog lime*. Compare -- marl,
coastal marl. SW

**fringe-tidal marsh** - Narrow salt marsh adjacent to a relatively
higher energy environment. SSS

**frost boil** - A small mound of fresh soil material formed by frost
action. A type of nonsorted circle commonly found in fine-grained
sediment underlain by permafrost, or formed in areas affected by
seasonal frost. Compare - patterned ground. [NRC]{.underline}

**frost bursting** - (not recommended) use frost shattering.

**frost churning** - (not recommended) use cryoturbation.

**frost polygons** - (not recommended) use (periglacial) patterned
ground.

**frost riving** - (not recommended) use frost shattering.

**frost shattering** - The mechanical disintegration, splitting, or
breakup of a rock or soil caused by the pressure exerted by freezing
water in cracks or pores, or along bedding planes. Sometimes referred to
as congelifraction. [GG]{.underline}

**frost splitting** - (not recommended) use frost shattering.

**frost stirring** - (not recommended) use cryoturbation.

**frost weathering** - (not recommended) use frost shattering.

**frost wedging** - (not recommended) use frost shattering.

**furrow** -- A linear or arcuate opening left in the soil after a plow
or disk has opened a shallow channel at the soil surface. A shallow
channel cut in the soil surface, usually between planted rows for
controlling surface water and soil loss, or for conveying irrigation
water. GSST

**gap** - A sharp break or opening in a mountain ridge, or a short pass
through a mountain range; e.g., a wind gap. GG

**gelifraction** - (not recommended) use frost shattering.

**gelivation** - (not recommended) use frost shattering.

**geomorphic component -** A fundamental, three dimensional piece or
area of a geomorphic setting (i.e., hills, mountains, terraces, flat
plains) that has unique and prevailing kinetic energy dynamics and
sediment transport conditions which result in their characteristic form,
patterns of sedimentation and soil development. SW

**geomorphic component - flat plains:** - A group of fundamental, three
dimensional pieces or areas of flat plains. In descending elevational
order, the geomorphic components of a simple, flat plain (e.g. lake
plain, low coastal plain, etc.) are the *rise* \[a broad, slightly
elevated area with comparatively greater gradients (e.g., 1-3% slopes\],
and the *talf* \[a comparatively level (e.g., 0-1% slopes), laterally
extensive, non-fluvial area\], and *dip* \[a slight depression that is
not a permanent water body nor part of an integrated drainage network\].
Compare - geomorphic component - terraces. SW

**geomorphic component - hills: -** A set of fundamental,
three-dimensional areas and positions that geomorphically define a hill
or ridge. In descending topographic order, the geomorphic components are
*interfluve* (stable summit area) ; *crest* (unstable summit -converged
shoulders); three geometric slope areas defined by plan shape and its
influence on overland flow and throughflow: These are: *head slope*
(convergent flow), *side slope* (parallel flow), and *nose slope*
(divergent flow); *free face* (rock outcrop); and *base slope* (concave
accretion area (colluvium / slope alluvium) at hill bottom). SW

**geomorphic component - mountains: -** A group of fundamental, three
dimensional pieces or areas of mountains. In descending elevational
order, the geomorphic components of a simple mountain are the
*mountaintop* (roughly analogous to the crest or summit);
*mountainflank* (the long slope along the sides of mountains which can
be further subdivided into three portions based on the relative slope
location: *upper third-*, *middle third-*, or *lower third
mountainflank*); *free face* (rock outcrop); and the *mountainbase*
(colluvium / slope alluvium apron at the bottom of the mountain). SW

**geomorphic component -- terraces, stepped landforms: -** A group of
fundamental, three dimensional pieces or areas of terraces**,**
flood-plain steps, and other stepped landforms (e.g. stacked lava flow
units). In descending elevational order, the geomorphic components are
the *tread* (the level to gently sloping, laterally extensive top of a
terrace**,** flood-plain step, or other stepped landform); and the
*riser* (the comparatively short escarpment forming the more steeply
sloping edge that descends to another level or **a** channel). SW

**geomorphic surface** - A mappable area of the earth\'s surface that
has a common history; the area is of similar age and is formed by a set
of processes during an episode of landscape evolution. A geomorphic
surface can be erosional, constructional or both. The surface shape can
be planar, concave, convex, or any combination of these. Compare
constructional, erosional. [RR]{.underline}

**geomorphology** - The science that treats the general configuration of
the earth\'s surface; specifically the study of the classification,
description, nature, origin, and development of landforms and their
relationships to underlying structures, and of the history of geologic
changes as recorded by these surface features. The term is especially
applied to the genetic interpretation of landforms. [GG]{.underline}

**geyser** -- A type of hot spring that intermittently erupts jets of
hot water and steam, the result of ground water coming in contact with
rock or steam hot enough to create steam under conditions preventing
free circulation; a type of intermittent spring. Compare -- mud pot, hot
spring. GG

**geyser** basin -- A valley that contains numerous springs, geysers,
and steam fissures fed by the same ground-water flow. GG

**geyser cone** -- A low hill or mound built up of siliceous sinter
around the orifice of a geyser. GG

**giant ripple** - A ripple that is more than 30 m in length; e.g., the
jokulhlaup derived giant ripples in Camas Prairie, MT.; it usually
exhibits superimposed megaripples. Compare - ripple mark.
[GG]{.underline}

**gilgai** - A microfeature pattern of soils composed of a succession of
microbasins and microknolls on level areas, or of microtroughs and
microridges parallel to the slope on sloping areas, and produced by
expansion / contraction and shear / thrust processes with changes in
soil moisture. Found in soils containing large amounts of smectitic clay
that swell and shrink considerably with wetting and drying. Various
types of gilgai can be recognized based on the dominant shape of
micro-highs and micro-lows: circular gilgai, elliptical gilgai, and
linear gilgai. Also referred to, in part or in total, as crabhole, Bay
of Biscay, or hushabye in older literature. SW & [GSST]{.underline}

**glacial** - (adjective) (a) Of or relating to the presence and
activities of ice and glaciers, as in glacial erosion. (b) Pertaining to
distinctive features and materials produced by or derived from glaciers
and ice sheets, as in glacial lakes. (c) Pertaining to an ice age or
region of glaciation. GG

**glacial drainage channel** - A channel formed by an ice-marginal,
englacial, or subglacial stream during glaciation. [GG]{.underline}

**glacial drift** - (not recommended) use drift.

**glacial groove** -- A deep, wide, usually straight furrow cut in
bedrock by the abrasive action of a rock fragment embedded in the bottom
of a moving glacier; it is larger and deeper than a glacial striation,
ranging in size from a deep scratch to a small glacial valley. Compare
-- flute. [GG]{.underline}

**glacial lake** - (a) A lake that derives much or all of its water from
the melting of glacier ice, fed by meltwater, and lying outside the
glacier margins (e.g. proglacial lake) or lying on a glacier (e.g.
ice-walled lake, ice-floored lake) and due to differential melting. (b)
A lake occupying a basin produced by glacial deposition, such as one
held in by a morainal dam. (c) A lake occupying a basin produced in
bedrock by glacial erosion (scouring, quarrying); e.g., cirque lake,
fjord. (d) A lake occupying a basin produced by collapse of outwash
material surrounding masses of stagnant ice. (e) \[relict\] An area
formerly occupied by a glacial lake. [GG]{.underline}

**glacial-marine sedimentation** - The accumulation of glacially eroded,
terrestrially derived sediment in the marine environment. Sediment may
be introduced by fluvial transport, by ice rafting, as an ice-contact
deposit, or by eolian transport. Compare - glaciomarine deposits. GG

**glacial outwash** - (not recommended) use outwash.

**glacial till** - (not recommended; use till). Till should only be used
for describing glacial sediments, therefore \"glacial till\" is
redundant. GM

**glacial-valley floor** -- The comparatively flat bottom of a mountain
valley predominantly mantled by till but which can grade from glacial
scour (scoured rock-outcrop) near it's head to a thick mantle of till,
and ultimately merging with alluvium or colluvium further down valley.
Some glacial-valley floors descend downstream in a series of
scour-derived steps which may contain sequential tarn lakes (*pater
noster lakes*); (not preferred: colloquial -- western USA) sometimes
called a trough bottom. SW

**glacial-valley wall** -- The comparatively steep, glacially scoured,
concave sides of a u-shaped, mountain valley mantled by colluvium with
little or no till; (not preferred: colloquial -- western USA) sometimes
called a trough wall. SW

**glaciation** - The formation, movement and recession of glaciers or
ice sheets. A collective term for the geologic processes of glacial
activity, including erosion and deposition, and the resulting effects of
such action on the earth\'s surface. [GG]{.underline}

**glacier** - a) A large mass of ice formed, at least in part, on land
by the compaction and recrystallization of snow, moving slowly by creep
downslope or outward in all directions due to the stress of its own
weight, and surviving from year to year. Included are small mountain
glaciers as well as ice sheets continental in size, and ice shelves
which float on the ocean but are fed in part by ice formed on land. b) A
stream-like landform having the appearance of, or moving like a glacier;
e.g. a rock glacier. Compare -- snowfield, rock glacier.
[GG]{.underline}

glacier outburst flood -- A sudden, often annual, release of meltwater
from a glacier or glacier-damned lake sometimes resulting in a
catastrophic flood, formed by melting of a drainage channel or buoyant
lifting of ice by water or by subglacial volcanic activity; also called
jokuhlaup. Compare -- scabland, giant ripple. GG

**glaciofluvial deposit** - Material moved by glaciers and subsequently
sorted and deposited by streams flowing from the melting ice. The
deposits are stratified and may occur in the form of outwash plains,
valley trains, deltas, kames, eskers, and kame terraces. Compare - drift
and outwash. HP

glaciokarst -- Karst in glaciated terrain developed on bedrock
susceptible to dissolution (e.g. limestone), thinly mantled (e.g. \< 5 -
30 m) with glacial drift and characterized by surficial, closed
depressions formed by post-glacial, subsurface karstic collapse (e.g.
sinkholes) rather than by glacial processes (e.g. ice-block melt-out);
common in IN, MI. Compare -- karst. SW & [GG]{.underline}

**glaciolacustrine deposit** - Material ranging from fine clay to sand
derived from glaciers and deposited in glacial lakes by water
originating mainly from the melting of glacial ice. Many are bedded or
laminated with varves or rhythmites. HP

**glaciomarine deposit** - Glacially eroded, terrestrially derived
sediments (clay, silt, sand, and gravel) that accumulated on the ocean
floor. Sediments may be accumulated as an ice-contact deposit, by
fluvial transport, ice-rafting, or eolian transport. [GG]{.underline} &
[GM]{.underline}

**glade** -- (colloquial -- Ozark uplands, USA) (a) A largely treeless,
open, grassy area (e.g., oak savanna) on high, broad interfluves and
hillsides, commonly with shallow soils. Compare -- park. SW (b) (not
preferred) refer to park: An ecological term for a grassy, open
depression or small valley as in a high meadow; sometimes marshy and
forming the headwaters of a stream, or a low, grassy marsh that is
periodically inundated. [GG]{.underline} & SW

**glauconite pellets** -- Silt to sand-sized, nodular aggregates with a
characteristic greenish color, dominantly composed of the clay mineral
glauconite; formed in near-shore marine sediments and subsequently
exposed by a drop in sea level or rise of a land mass, as on a coastal
plain. Glauconite pellets have a high potassium content and higher CEC
and moisture retention compared to other mineral sands. Compare --
greensands. SW

**gorge** - (a) A narrow, deep valley with nearly vertical, rocky walls,
smaller than a canyon, and more steep-sided than a ravine; especially a
restricted, steep-walled part of a canyon. (b) A narrow defile or
passage between hills or mountains. [GG]{.underline}

**graben** - An elongate trough or basin bounded on both sides by
high-angle, normal faults that dip towards the interior of the trough.
It is a structural form that may or may not be geomorphically expressed
as a rift valley. Compare -- horst, half graben. GG

**granitoid** -- a) In the (International Union of Geological Sciences)
IUGS classification, a preliminary term (for field use) for a plutonic
rock with Q (quartz) between 20 and 40 (%). b) A general term for all
phaneritic igneous rocks (*mineral crystals visible unaided and all
about the same size)* dominated by quartz and feldspars. SW &
[GG]{.underline}

**Grady pond** -- see Carolina Bay

**grassy organic materials -** see organic materials

**gravel pit** -- A depression, ditch or pit excavated to furnish gravel
for roads or other construction purposes; a type of borrow pit. SW

**greensands** -- a) An unconsolidated, near-shore marine sediment
containing substantial amounts of dark greenish glauconite pellets,
often mingled with clay or sand (quartz may form the dominant
constituent); prominent in Cretaceous and Tertiary coastal plain strata
of New Jersey, Delaware and Maryland; has been commercially mined for
potassium fertilizer. The term is loosely applied to any glauconitic
sediment. b) (Not Preferred -- use glauconitic sandstone) A sandstone
consisting of greensand that is commonly poorly cemented, and has a
greenish color when unweathered but an orange or yellow color when
weathered. Compare -- glauconite pellets. SW

**grike** -- (not preferred) refer to cutter.

**groove** -- A small, natural, narrow drainageway on high angle slopes
which separate tertiary spur ridges or mini-interfluves and is a
constituent part of *rib and groove topography*; common in well
dissected uplands. Compare -- rib. SW

**ground moraine** - (a) Commonly an extensive, low relief area of till,
having an uneven or undulating surface, and commonly bounded on the
distal end by a recessional or end moraine; (b) A layer of poorly sorted
rock and mineral debris (till) dragged along, in, on, or beneath a
glacier and deposited by processes including basal lodgment and release
from downwasting stagnant ice by ablation. Compare - end moraine,
recessional, moraine, terminal moraine. SW

**ground soil** -- Any soil at the present-day land surface and actively
undergoing pedogenesis, regardless of its history (i.e., relict,
exhumed). Compare -- buried soil. SW & RR

**grus** - The fragmental products of in situ granular disintegration of
granite and granitic rocks, dominated by inter-crystal disintegration.
Compare - saprolite. SW & [GG]{.underline}

**gulch** - (colloquial: western U.S.A.; not preferred -- refer to
ravine) A small stream channel, narrow and steep-sided in cross section,
and larger than a gully, cut in unconsolidated materials. General
synonym - ravine. Compare - arroyo, draw, gully, wash. [HP]{.underline}

**gulf** \[coast\] -- A relatively large part of an ocean or sea
extending far into the land, partly enclosed by an extensive sweep of
the coast, and opened to the sea through a strait (e.g. Gulf of Mexico);
the largest of various forms of inlets of the sea. It is usually larger,
more enclosed, and more deeply indented than a bay. Compare -- bay. GG

**gully** - A small channel with steep sides caused by erosion and cut
in unconsolidated materials by concentrated but intermittent flow of
water usually during and immediately following heavy rains or ice / snow
melt. A gully generally [is]{.underline} an obstacle to wheeled vehicles
and too deep (e.g., \> 0.5 m) to be obliterated by ordinary tillage; (a
rill is of lesser depth and can be smoothed over by ordinary tillage).
Compare - rill, ravine, arroyo, swale, draw. [HP]{.underline} &
[GSST]{.underline}

**gut** - (a) (colloquial: U.S. Virgin Islands, Caribbean Basin) A
gully, ravine, small valley, or narrow passage on land. (b) \[stream\]
(not preferred -- use tidal channel). A tidal stream connecting two
larger waterways within a lagoon, estuary or bay. SW & [GG]{.underline}

**half graben** -- An elongate, structural trough or basin bounded on
one side by a normal fault. It may or may not produce a topographic
basin. Compare -- graben. GG

**hanging valley** - A tributary valley whose floor at the lower end is
notably higher than the floor of the main valley in the area of
junction. [GG]{.underline}

**head** \[geomorphology\] - (a) The source, beginning, or upper part of
a stream. (b) The upper part or end of a slope or valley. GG

**headland** \[coast\] - (a) An irregularity of land, especially of
considerable height with a steep cliff face, jutting out from the coast
into a large body of water (usually the sea or a lake); a bold
promontory or a high cape. (b) The high ground flanking a body of water,
such as a cove. (c) The steep crag or cliff face of a promontory.
[GG]{.underline}

**head-of-outwash** -- A sloping and sometimes high relief landform
composed predominantly of glaciofluvial sediment that delimits a former
ice-margin of a relatively static, rapidly wasting glacier. A steep
*ice-contact slope* forms the ice-proximal face of the landform; a more
gently sloping surface dips away on the distal slope, if not slumped.
Compare -- ice-margin complex. SW

**head slope** \[geomorphology\] - A geomorphic component of hills
consisting of a laterally concave area of a hillside, especially at the
head of a drainageway, resulting in converging overland water flow (e.g.
sheet wash); head slopes are dominated by colluvium and slope wash
sediments (e.g., slope alluvium); contour lines form concave curves.
Slope complexity (downslope shape) can range from simple to complex.
Headslopes are comparatively moister portions of hillslopes and tend to
accumulate sediments (e.g., cumulic profiles) where they are not
directly contributing materials to channel flow. Compare - side slope,
nose slope, free face, interfluve, crest, base slope. SW.

**headwall** - A steep slope at the head of a valley; e.g. the rock
cliff at the back of a cirque. Compare -- cirque headwall.
[GG]{.underline}

**herbaceous organic materials** - see organic materials.

**herbaceous peat** \[Soil Taxonomy\] - An accumulation of organic
material, decomposed to some degree that is predominantly the remains of
sedges, reeds, cattails and other herbaceous plants. Compare - moss
peat, sedimentary peat, woody peat, peat, muck, and mucky peat. SSM

**high-center polygon** - A polygon whose center is raised relative to
its boundary. Compare - low center polygon. [NRC]{.underline}

**high hill** -- A generic name for an elevated, generally rounded land
surface with high local relief, rising between 90 meters (approx. 300
ft.) to as much as 300 m (approx. 1000 ft.) above surrounding lowlands.
Compare -- low hill, hill, hillock. SW

**highmoor bog** - A bog, often on the uplands, whose surface is covered
by sphagnum mosses which, because of their high degree of water
retention, make the bog more dependent upon precipitation than on the
water table. The bog often occurs as a raised peat bog or blanket bog.
Compare - lowmoor bog, raised bog. [GG]{.underline}

**hill** - A generic term for an elevated area of the land surface,
rising at least 30 m (100 ft.) to as much as 300 meters (approx. 1000
ft.) above surrounding lowlands, usually with a nominal summit area
relative to bounding slopes, a well-defined, rounded outline and slopes
that generally exceed 15 percent. A hill can occur as a single, isolated
mass or in a group. A hill can be further specified based on the
magnitude of local relief: *low hill* (30 -- 90 m) or *high hill* (90 -
300 m). Informal distinctions between a hill and a mountain are often
arbitrary and dependent on local convention. Compare - hillock, plateau,
mountain, foothills, hills. SW & [HP]{.underline}

**hillock** -- A generic name for a small, low hill, generally between 3
-- 30 m in height and slopes between 5 and 50% (e.g., bigger than a
mound but smaller than a hill); commonly considered a microfeature.
Compare -- mound, hill. SW

**hills** -- A landscape dominated by hills and associated valleys. SW

**hillside** - (not recommended) use hillslope.

**hillslope** - A generic term for the steeper part of a hill between
its summit and the drainage line, valley flat, or depression floor at
the base of the hill. Compare -- mountain slope. [HP]{.underline}

**hillslope-profile position** - Discrete slope segments found along a
transect line that runs perpendicular to the contour, beginning at a
divide and descending to a lower, bounding stream channel or valley
floor; a discrete piece of a two-dimensional cross profile of a hill.
Positions are commonly separated from one another by inflection points
along the line. In descending elevational order, the hillslope-profile
positions of a simple hillslope include summit, shoulder, backslope,
footslope, and toeslope. Not all of these segments (positions) are
necessarily present along a particular hillslope. Complex hillslopes
include multiple sequences or partial sequences, or partial sequences.
Compare - geomorphic components - hills. SW, [HP]{.underline}, &
[RR]{.underline}

**hillslope terrace** -- A raised, generally horizontal strip of earth
and/or rock bounded by a down-slope berm or retaining wall, constructed
along a contour on a hillslope to make land suitable for tillage and to
prevent accelerated erosion; common in steep terrain, both archaic (e.g.
Peru) and modern (e.g. Nepal). Compare -- conservation terrace. SW &
GSST

**hill top** (not recommended) use summit.

**hogback** - A sharp-crested, symmetric ridge formed by highly tilted
resistant rock layers; a type of homocline produced by differential
erosion of interlayered resistant and weak rocks with dips greater than
about 25 o (or approximately \> 45 % slopes). Compare -- homoclinal
ridge, cuesta. SW & [HP]{.underline}

**Holocene** - The epoch of the Quaternary Period of geologic time
following the Pleistocene Epoch (from the present to about 10 to 12
thousand years ago); also corresponding (time-stratigraphic) "series" of
earth materials. SW

**homoclinal** \[structural geomorphology\] - (adjective) Pertaining to
strata that dip in one direction with a uniform angle. Compare - cuesta,
hogback, homoclinal ridge. [HP]{.underline}

**homoclinal ridge** -- A homocline that forms an asymmetric ridge with
a dip slope commonly between 10 to 25**º** (15 to 45 %). A homoclinal
ridge has steeper dip than a cuesta, but lower dip than a hogback.
Compare - cuesta, hogback. SW & [RF]{.underline}

**homocline** - A general term for a series of rock strata that dip in
one direction with a uniform angle; e.g. one limb of a fold, a tilted
fault block, or an isocline. Compare - cuesta, homoclinal ridge,
hogback. [GG]{.underline}

**hoodoo -** A bizarrely shaped column, pinnacle, or pillar of rock
produced by differential weathering or erosion in a region of
sporadically heavy rainfall. Formation is facilitated by joints and
layers of varying hardness. Compare - earth pillar. [GG]{.underline}

**horn** \[glacial geology\] - A high, rocky, sharp pointed,
steep-sided, mountain peak with prominent faces and ridges, bounded by
the intersecting walls of three or more cirques that have been cut back
into the mountain by headward erosion of glaciers. [GG]{.underline}

**horst** - An elongate block that is bounded on both sides by normal
faults that dip away from the interior of the horst. It is a structural
form and may or may not be expressed geomorphically. [GG]{.underline}

**hot spring** -- A natural, geothermally heated spring whose
temperature is above that of the human body. Compare -- geyser, mud pot.
[GG]{.underline}

**human transported material** -- Organic or mineral soil material (or
any other material that can function as a soil material) that has been
moved horizontally onto a pedon from a source area outside of that pedon
by directed human activity, usually with the aid of machinery. There has
been little or no subsequent reworking by wind, gravity, water, or ice.
Human transported materials are most commonly associated with building
sites, mining or dredging operations, land fills, or other similar
activities that result in the formation of a constructional
anthropogenic landform. ICOMANTH.

**hummock** - \[geomorphology\] (a) (not preferred -- see hillock). An
imprecise, general term for a rounded or conical mound or other small
elevation. (b) (not preferred) A slight rise of ground above a level
surface. [GG]{.underline}.

**hummock** -\[patterned ground\] A small, irregular knob of earth
(earth hummock) or turf (turf hummock). Neither type of hummock is
diagnostic of permafrost, but both are most common in subpolar or alpine
regions. Both require vegetative cover. [GG]{.underline}

**ice age** - (not recommended) use Pleistocene.

**ice-contact slope** -- A steep escarpment of predominantly
glaciofluvial sediment that was deposited against a wall of glacier ice,
marking the position of a relatively static ice-margin; an irregular
scarp against which glacier ice once rested. Compare -- head-of-outwash.
SW & [GG]{.underline}

**ice-marginal stream** -- A stream drainage along the side or front of
a glacier. Relict ice-marginal streams are used to trace the former
position of a glacier; also called ice-marginal drainage. SW &
[GG]{.underline}

**ice-margin complex** -- An assemblage of landforms constructed
proximal to a relatively static, rapidly wasting continental glacial
margin. Constituent landforms can include fosse, head-of-outwash,
ice-contact slope, ice-contact delta, kame, kame moraine, kettle,
outwash fan, small outwash plain, glacial sluiceway, and small
proglacial lake. Moraines, if present, are of limited occurrence (except
kame moraines which can be extensive). Glaciofluvial sediments dominate
but glaciolacustrine sediments, till, and diamictons can be present in
minor amounts. SW

**ice-pushed ridge** - An asymmetrical ridge of local, essentially
non-glacial material (such as deformed bedrock, with some drift
incorporated in it) that has been pressed up by the shearing action of
an advancing glacier. It is typically 10 - 60 m high, about 150 - 300 m
wide, and as much as 5 km long. Examples are common on the Great Plains
where such ridges occur on the sides of escarpments formed of relatively
incompetent rocks that face the direction from which the ice moved. GG

**ice-rafting** - The transportation of rock fragments of all sizes on
or within icebergs, ice floes, or other forms of floating ice. Compare -
dropstone, erratic. GG

**ice segregation** - The formation of ice by the migration of pore
water to the frozen fringe where it forms into discrete layers or
lenses. It commonly ranges in thickness from hairline to more than 10 m
and often occurs in alternating layers of ice and soil. NRC

**ice wedge** - A massive, generally wedge-shaped body with its apex
pointing downward, composed of foliated or vertically banded, commonly
white, ice. NRC

**ice wedge cast** - A filling of sediment in the space formerly
occupied by an ice wedge. NRC

**ice wedge polygon** - Patterned ground in areas of ice wedges. These
polygons are commonly in poorly-drained areas and may be high-centered
or low-centered. [NRC]{.underline}

**igneous rock** - Rock formed by cooling and solidification from magma,
and that has not been changed appreciably by weathering since its
formation; major varieties include plutonic and volcanic rocks.
Examples: andesite, basalt, granite. Compare - intrusive, extrusive,
metamorphic rock. [GSST]{.underline} & [HP]{.underline}

**inlet** - A short, narrow waterway connecting a bay, lagoon, or
similar body of

water. Compare -- tidal inlet. [GG]{.underline}

**impact crater** -- a) \[anthropogenic\] A generally circular or
elliptical depression formed by hypervelocity impact of an experimental
projectile or ordinance into earthy or rock material. Compare --
caldera, crater, meteorite crater. SW; b) (not recommended -- use
meteorite crater) A generally circular crater formed by the impact of an
interplanetary body (projectile) on a planetary surface. GG

**inselberg** - A prominent, isolated, residual knob, hill, or small
mountain, usually smoothed and rounded, rising abruptly from an
extensive lowland erosion surface in a hot dry region; generally bare
and rocky although the lower slopes are commonly buried by colluvium.
Compare - monadnock, nunatak. [GG]{.underline}

**inset fan** - (colloquial; southwestern USA) The flood plain of an
ephemeral stream that is confined between the fan remnants, ballenas,
basin-floor remnants, or closely-opposed fan toeslopes of a basin.
[FF]{.underline} & SW.

**integrated drainage** - A general term for a drainage pattern in which
stream systems have developed to the point where all parts of the
landscape drain into some part of a stream system, the initial or
original surfaces have essentially disappeared and the region drains to
a common base level. Few or no closed drainage systems are present. SW

**interbedded** - Said of beds lying between or alternating with others
of different character; especially said of rock material or sediments
laid down in sequence between other beds, such as \"interbedded\" sands
and gravels. GG

**interdrumlin** -- The concave to relatively flat bottomed, roughly
linear depressions ranging from small saddles or swales to small valleys
that separate drumlins or drumlinoid ridges in drumlin fields. Streams,
if present, have not had a dominant impact on the formation of the
depression. Compare -- drumlin, drumlinoid ridge. SW

**interdrumlin swale** -- see interdrumlin

**interdune** - The relatively flat surface, whether sand-free or
sand-covered, between dunes. GG

**interdune valley** -- A broad interdune area consisting of a
low-lying, relatively flat surface commonly found between very large
dunes, and which lies in close proximity to the local groundwater table
(if present). SW

**interfluve** - A landform composed of the relatively undissected
upland or ridge between two adjacent valleys containing streams flowing
in the same general direction. An elevated area between two drainageways
that sheds water to those drainageways. Compare - divide. GG & FFP

**interfluve** \[geomorphology\] - A geomorphic component of hills
consisting of the uppermost, comparatively level or gently sloped area
of a hill; shoulders of backwearing hillslopes can narrow the upland
(e.g., ridge) or merge (e.g., crest, saddle) resulting in a strongly
convex shape. Compare -- crest, side slope, head slope, nose slope, free
face, base slope. SW

**interior valley** -- A large, flat-floored closed depression in a
karst area whose drainage is ultimately subsurface and its floor is
commonly covered by alluvium. Some interior valleys may become ephemeral
lakes during periods of heavy rainfall, when sinking streams that drain
them cannot manage the runoff; also called polje (not preferred).
Compare -- karst valley, sinkhole. GG

**intermediate position** \[gilgai\] -- A nearly level area, including
the lower part (footslope) of a micro-high that is a transition zone
between the slightly elevated micro-high (i.e. microknoll; *mound* in
Russia) and the outer edge of an adjacent micro-low (i.e. microbasin,
microtrough; *depression* in Russia) in gilgai or other patterned
ground. Where present, it can make up a majority of the ground surface
area in gilgai; called *slope* in Russia. Compare -- gilgai. SW

**intermittent stream** - A stream, or reach of a stream, that does not
flow year-round (commonly dry for 3 or more months out of 12) and whose
channel is generally below the local water table; it flows [only
when]{.underline} it receives a) base flow (i.e. solely during wet
periods), or b) ground-water discharge or protracted contributions from
melting snow or other erratic surface and shallow subsurface sources.
Compare - ephemeral stream. [HP]{.underline}

**intermontane basin** - A generic term for wide structural depressions
between mountain ranges that are partly filled with alluvium and called
\"valleys\" in the vernacular. Intermontane basins may be drained
internally (bolsons) or externally (semi-bolson). FFP

**interstream divide -** (a) (not preferred) A synonym for divide. (b)
(colloquial - esp. southeastern USA). *Broad* interstream divide - A
wide, relatively level area between incised drainageways; a broad,
nearly level **"**summit" or interfluve. Compare - broad interstream
divide, interfluve. SW

**intertidal** - (adjective) The coastal environment between mean low
tide and mean high tide that alternates between subaerial and subaqueous
depending on the tidal cycle. Compare -- subtidal. SSS

**intramorainal** - said of deposits and phenomena occurring within a
lobate curve of a moraine (e.g. within the area occupied by a glacier).
Compare - extramorainal. [GG]{.underline}

**intrusive** - Denoting igneous rocks derived from molten matter
(magmas) that invaded pre-existing rocks and cooled below the surface of
the earth. Compare - extrusive. HP

**island** - (a) An area of land completely surrounded by water. Compare
-- barrier island, coral island. (b) An elevated area of land surrounded
by swamp, or marsh, or isolated at high water or during floods.
Compare - barrier island. [GG]{.underline}

**joint** \[geology\] - A surface of actual or potential fracture or
parting in a rock, without displacement; the surface is usually planar
and often occurs with parallel joints to form part of a joint set. HP

**jokulhlaup** - An Icelandic term for a glacial outburst flood,
especially when an ice dam impounding a glacial lake breaks. Such breaks
drained glacial Lake Missoula and created the Channeled Scablands in the
Pacific Northwest. (Pronounced: yo-kool-loup, the last syllable as in
\"out\".) Compare -- glacier outburst flood, scabland, giant ripple. SW
& [GG]{.underline}

**kame** - A low mound, knob, hummock, or short irregular ridge,
composed of stratified sand and gravel deposited by a subglacial stream
as a fan or delta at the margin of a melting glacier; by a supraglacial
stream in a low place or hole on the surface of the glacier; or as a
ponded deposit on the surface or at the margin of stagnant ice.
Compare - crevasse filling, kame moraine, kame terrace, esker, outwash.
[GG]{.underline}

**kame moraine** - (a) An end moraine that contains numerous kames. (b)
A group of kames along the front of a stagnant glacier, commonly
comprising the slumped or erosional remnants of a formerly continuous
outwash plain built up over the foot of rapidly wasting or stagnant ice.
[GG]{.underline}

**kame terrace** - A terrace-like ridge consisting of stratified sand
and gravel (a) deposited by a meltwater stream flowing between a melting
glacier and a higher valley wall or lateral moraine, and (b) left
standing after the disappearance of the ice. It is commonly pitted with
\"kettles\" and has an irregular ice-contact slope. HP

**karren** -- Repeating, surficial solution channels, grooves or other
forms etched onto massive, bare limestone surfaces; types range in depth
from a few millimeters to \> 1 m and separated by ridges; the total
complex (all varieties) of surficial solution forms found on compact,
pure limestone. Many types can be specified. Compare -- solution
fissure. SW & [GG]{.underline}

**karst** - A kind of topography formed in limestone, gypsum, or other
soluble rocks by dissolution, and that is characterized by closed
depressions, sinkholes, caves, and underground drainage. Various types
of karst can be recognized depending upon the dominant surface features:
karst dominated by closed depressions (*sinkhole karst* -- temperate
climates; *cockpit karst* -- humid tropical climates), closed
depressions and large rivers (*fluviokarst*), bare rock dominated by
dissolution joints (*pavement karst*), tropical cone-, tower- or
domed-hills (*kegel karst*), or karst thinly mantled with glacial drift
(*glaciokarst*), etc. SW & WW

**karst cone** -- A conically-shaped residual hill in karst with a
rounded top and relatively steep, convex (e.g. parabolic) side slopes,
commonly in tropical climates. Compare -- karst tower, mogote. SW & WW

**karst** **drainage pattern** -- A drainage pattern that lacks an
integrated drainage system associated with soluble rocks with little or
no surface drainage but a considerable underground, internal drainage
system; characteristic of karst landscapes underlain by limestone,
gypsum, or salt. SW

**karstic** -- (adjective) Having the attributes of karst. SW &
[GG]{.underline}

**karstic marine terrace** -- A relict, wave-cut terrace or solution
platform formed across soluble bedrock (e.g. limestone), and
subsequently subaerially weathered by solution resulting in prominent
karst features (e.g. sinkholes, karst valleys, solution pipes, etc.); a
type of marine terrace, extensive across the Florida peninsula.
Dunefields and sand sheets of reworked coastal / fluviomarine sands are
common capping materials. SW

**karst lake** -- A large area of standing water in an extensive closed
depression in soluble bedrock (e.g. limestone) and commonly is directly
connected to and controlled by the subsurface karst drainage network. SW
& GG

**karstland** -- (not preferred) use karst. A landscape dominated by
dissolution features (e.g., sinkhole, blind valley, closed depressions,
underground drainage) formed in soluble rocks. SW & [GG]{.underline}

**karst tower** -- An isolated, separate hill or ridge in a karst region
consisting of an erosional remnant of limestone or other sedimentary
rocks with vertical or near-vertical, convex side slopes and commonly
surrounded by an alluvia**l** plain, lagoon, or deep rugged ravines.
Compare -- mogote, karst cone. SW

**karst valley** -- A closed depression formed by the coalescence of
multiple sinkholes; an elongate, solutional valley. Its drainage is
subsurface, diameters range from several hundred meters to a few
kilometers, and it usually has a scalloped margin inherited from the
sinkholes. It may have nominal, local channel flow (small streams),
sequential sinkhole inlets (springs) and outlets (swallow hole, etc.);
also called compound sinkhole (not preferred), uvala (not preferred).
Compare -- sinkhole, interior valley. SW & [GG]{.underline}

**kegel karst** -- A general name used to describe several types of
humid tropical karst landscapes characterized by numerous, closely
spaced cone- (cone karst), hemispherical- (halbkugelkarst), or
tower-shaped (tower karst) hills with vertical or near-vertical walls
and having intervening closed depressions and narrow steep-walled karst
valleys or passageways. Compare -- cockpit karst. [GG]{.underline} & SW

**kettle** - A steep-sided, bowl-shaped depression commonly without
surface drainage (closed depression) in drift deposits, often containing
a lake or swamp, and formed by the melting of a large, detached block of
stagnant ice that had been wholly or partly buried in the drift. Kettles
range in depth from 1 to tens of meters, and with diameters up to 13 km.
Compare - pothole. [GG]{.underline}

**kipuka** - A low \"island\" of land surrounded by a younger (more
recent) lava flow. Compare - steptoe. [MA]{.underline}

**kluftkarren** -- (not preferred) refer to solution fissure.

**knickpoint** - (a) A point of abrupt inflection in the longitudinal
profile of a stream or of its valley (e.g. a waterfall); it marks the
maximum headward erosion of a new erosion cycle that grades to a new,
lower base level; (b) Any interruption or break in slope. SW

**knob** - (a) A rounded eminence, a small hill or mountain; especially
a prominent or isolated hill with steep sides, commonly found in the
Southern United States. (b) A peak or other projection from the top of a
hill or mountain. Also, a boulder or group of boulders or an area of
resistant rocks protruding from the side of a hill or mountain. Compare
-- stack \[geom\]. GG

**knoll** - A small, low, rounded hill rising above adjacent landforms.
HP

**lacustrine deposit** - Clastic sediments and chemical precipitates
deposited in lakes. HP

**lagoon** - \[coast\] A shallow stretch of salt or brackish water,
partly or completely separated from a sea or lake by an offshore reef,
barrier island, sandbank or spit. [GG**'**87.]{.underline} \[relict
landform\] A nearly level, filled trough or depression behind the
longshore bar on a barrier beach and built by a receding pluvial or
glacial lake. Compare - sewage lagoon. [FFP]{.underline}

**lagoonal deposit** -- Sand, silt or clay-sized sediments transported
and deposited by wind, currents, and storm washover in the relatively
low-energy, brackish to saline, shallow waters of a lagoon. Compare --
estuarine deposit, fluviomarine deposit, marine deposit. SSS

**lagoon bottom** - The nearly level or slightly undulating central
portion of a submerged, low-energy, depositional estuarine basin
(McGinn, 1982) characterized by relatively deep water (1.0 to \>2.5 m).
Compare -- bay bottom. SSS

**lagoon channel** - A subaqueous, sinuous area within a lagoon that
likely represents a relict channel (paleochannel) (Wells et al., 1994)
that is maintained by strong currents during tidal cycles (Short, 1975).
SSS

**lahar** - The process, associated sediments or resultant landform
characterized by a mudflow composed chiefly of volcaniclastic materials
on or near the flank of a volcano. The debris carried in the flow
includes pyroclastic material, blocks from primary lava flows, and
epiclastic material. Thick flows can exhibit a crude (poorly sorted)
upward-fining sediment sequence. Compare - mudflow. SW &
[GG]{.underline}

**lake** \[water\] - An inland body of permanently standing water fresh
or saline, occupying a depression on the Earth's surface, generally of
appreciable size (larger than a pond) and too deep to permit vegetation
(excluding subaqueous vegetation) to take root completely across the
expanse of water. GG

**lakebed** - (a) \[relict\] The flat to gently undulating ground
underlain or composed of fine-grained sediments deposited in a former
lake. (b) The bottom of a lake; a lake basin. [GG]{.underline}

**lake plain** - A nearly level surface marking the floor of an extinct
lake filled by well-sorted, generally fine-textured, stratified
deposits, commonly containing varves. [GG]{.underline}

**lakeshore** - The narrow strip of land in contact with or bordering a
lake; especially the beach of a lake. GG

**lake terrace** - A narrow shelf, partly cut and partly built, produced
along a lake shore in front of a scarp line of low cliffs and later
exposed when the water level falls. GG

**lamella** - (a) \[soil\] A thin (\< 7.5 cm thick), discontinuous or
continuous, generally horizontal layer of fine material (especially clay
and iron oxides) that has been pedogenically concentrated (illuviated)
within a coarser (e.g. sandy), eluviated layer (several centimeters to
several decimeters thick). Compare - lamina. SW & [ST]{.underline} (b)
\[mineralogy\] A thin scale, leaf, lamina, or layer, e.g. one of the
units of a polysynthetically twinned mineral, such as plagioclase.
[GG]{.underline}

**lamina** - (noun) The thinnest recognizable layer (commonly \< 1 cm
thick) of original deposition in a sediment or sedimentary rock,
differing from other layers in color, composition, or particle size.
Several laminae constitute a bed. Compare - lamella. [GG]{.underline}

**lamination -** (not recommended) see lamina.

**landfill -** (see sanitary landfill). Compare - dump.

**landform** - Any physical, recognizable form or feature on the
earth\'s surface, having a characteristic shape, internal composition,
and produced by natural causes; a distinct individual produced by a set
of processes. Landforms can span a large size (e.g., *dune* encompasses
a number of feature including *parabolic dune*, which is tens-of-meters
across and *seif dune,* which can be up to a 100 kilometers across.
Landforms provide an empirical description of the earth\'s surface
features. SW & [GG]{.underline}

**landscape** \[soils\] A broad or unique land area comprised of an
assemblage or collection of landforms that define a general geomorphic
form or setting (e.g., mountain range, lake plain, lava plateau, or
loess hill) Landforms within a landscape are spatially associated, but
may vary in formation processes and age. SW & [GSST]{.underline}

**landslide** \[mass movement\] -- A general, encompassing term for most
types of mass movement landforms and processes involving the downslope
transport and outward deposition of soil and rock materials, caused by
gravitational forces and which may or may not involve saturated
materials. Names of landslide types generally reflect the dominant
process and/or the resultant landform. The main operational categories
of mass movement are *fall* (rockfall, debris fall, soil fall), *topple*
(rock topple, debris topple, soil topple), *slide* (rotational
landslide, block glide, debris slide, lateral spread), *flow* \[rock
fragment flow (especially rockfall avalanche), debris avalanche, debris
flow (e.g., lahar), earthflow, (creep, mudflow)\], and *complex
landslides*. Compare -- solifluction. SW & [DV]{.underline}

**land-surface form** - The description of a given terrain unit based on
empirical analysis of the land surface rather than interpretation of
genetic factors. Surface form may be expressed quantitatively in terms
of vertical and planimetric slope-class distribution, local and absolute
relief, and patterns of terrain features such as interfluve crests,
drainage lines, or escarpments. HP

**lapilli** - Non or slightly vesicular pyroclastics, 2.0 to 76 mm in at
least one dimension, with an apparent specific gravity of 2.0 or more.
Compare - ash \[volcanic\], block \[volcanic\], cinders, tephra. KST

**lateral moraine** - A ridge-like moraine carried on and deposited at
the side margin of a valley glacier. It is composed chiefly of rock
fragments derived from valley walls by glacial abrasion and plucking, or
colluvial accumulation from adjacent slopes. [GG]{.underline}

**lateral spread** \[mass movement\] --A category of mass movement
processes, associated sediments (lateral spread deposit) or resultant
landforms characterized by a very rapid *spread* dominated by lateral
movement in a soil or fractured rock mass resulting from liquefaction or
plastic flow of underlying materials; also called spread. Types of
lateral spreads can be specified based on the dominant particle size of
sediments (i.e. debris spread, earth spread, rock spread. Compare --
fall, topple, slide, flow, complex landslide, landslide. SW,
[DV]{.underline} & [GG]{.underline}

**lava** -- A general term for a molten extrusive, also the rock
solidified from it. GG

**lava channel** -- see lava trench.

**lava field** -- An area covered primarily by lava flows whose terrain
can be rough and broken or relatively smooth; it can include vent
structures (e.g., small cinder cones, spatter cones, etc.), surface flow
structures (e.g., pressure ridges, tumuli, etc.) and small, intermittent
areas covered with pyroclastics. Compare -- lava plain, volcanic field.
SW

**lava flow** - A solidified body of rock formed from the lateral,
surficial outpouring of molten lava from a vent or fissure, often lobate
in form. Compare - \`**a\`a** lava flow, lava flow unit, pahoehoe lava
flow. [GG]{.underline}

**lava flow unit** -- A separate, distinct lobe of lava that issues from
the main body of a lava flow; a specific outpouring of lava, a few
centimeters to several meters thick and of variable lateral extent that
forms a subdivision within a single flow. A series of overlapping lava
flow-units together comprise a single lava flow. Also called flow unit.
Compare -- lava flow. GS & [GG]{.underline}

**lava plain** - A broad area of nearly level land, that can be
localized but is commonly hundreds of square kilometers in extent,
covered by a relatively thin succession of primarily basaltic lava flows
resulting from fissure eruptions. Compare -- lava plateau, lava field,
volcanic field. SW & [GG]{.underline}

**lava plateau** - A broad elevated tableland or flat-topped highland
that may be localized but commonly is many hundreds or thousands of
square kilometers in extent, underlain by a thick succession of basaltic
lava flows resulting from fissure eruptions (e.g. Columbia River
Plateau). Compare -- lava plain, lava field. [GG]{.underline}

**lava trench** -- A natural surface channel in a lava flow that never
had a roof, formed by the surficial draining of molten lava rather than
by erosion from running water; also called lava channel. Compare --
mawae, lava tube. SW

**lava tube** - A natural, hollow tunnel beneath the surface of a
solidified lava flow through which the lava flow was fed; the tunnel was
left empty when the molten lava drained out. [MA]{.underline} &
[GG]{.underline}

**ledge** - (a) A narrow shelf or projection of rock, much longer than
wide, formed on a rock wall or cliff face, as along a coast by
differential wave action on softer rocks; erosion is by combined
biological and chemical weathering. (b) A rocky outcrop; solid rock. (c)
A shelf-like quarry exposure or natural rock outcrop. Compare -
structural bench. [GG]{.underline}

**lee** -- (adj.) Said of a side or slope that faces away from an
advancing glacier or ice sheet, and facing the downstream ("down-ice")
side of a glacier and relatively protected from its abrasive action.
Compare -- stoss, stoss and lee, crag and tail. [GG]{.underline}

**levee** \[streams\] - An artificial or natural embankment built along
the margin of a watercourse or an arm of the sea, to protect land from
inundation or to confine streamflow to its channel. Compare artificial
levee, natural levee. [GG]{.underline}

**leveled land** -- A land area, usually a field, that has been
mechanically flattened or smoothed to facilitate management practices
such as flood irrigation; as a result the natural soil has been
partially or completely modified (e.g., truncated or buried). SW

**limestone** - A sedimentary rock consisting chiefly (more than 50
percent) of calcium carbonate, primarily in the form of calcite.
Limestones are usually formed by a combination of organic and inorganic
processes and include chemical and clastic (soluble and insoluble)
constituents; many contain fossils. HP

**limestone pavement** -- (not preferred) refer to pavement karst.

**linear gilgai** -- A type of gilgai dominated by parallel micro-low
troughs separated by low ridges (micro-highs) and oriented perpendicular
to the topographic contour (i.e., up and down slopes); the prevailing
type of gilgai on sloping terrain (slopes \> 8 %). Compare -- circular
gilgai, elliptical gilgai, gilgai. SW

**lithification** - The conversion of unconsolidated sediment into a
coherent and solid rock, involving processes such as cementation,
compaction, desiccation, crystallization, recrystallization, and
compression. It may occur concurrently with, shortly after, or long
after deposition. HP

**lithologic** - (adjective) Pertaining to the physical character of a
rock. HP

**local relief** - A general term referring to the prevailing difference
in elevation between the lowest and highest parts of the landscape at a
given locale (e.g. the average difference in elevation between a
representative portion of a valley floor and the tops of the bounding
valley walls). SW

**lodgment till** - A basal till commonly characterized by compact,
fissile (\"platy\") structure and containing coarse fragments oriented
with their long axes generally parallel to the direction of ice
movement. Compare - till, flow-till, melt-out till. [GG]{.underline}

**local relief -- A generic term referring to the collective, relative
differences in elevation of a land surface on a broad scale; also called
"relief". SSM**

**loess** - Material transported and deposited by wind and consisting
predominantly of silt-size particles. Commonly a loess deposit thins and
the mean-particle size decreases as distance from the source area
increases. Loess sources are dominantly from either glacial meltwaters
(i.e. "cold loess") or from non-glacial, arid environments, such as
deserts (i.e. "hot loess"). \[soil survey\] Several types of loess
deposits can be recognized based on mineralogical composition
(calcareous loess, non-calcareous loess). SW & [GSST]{.underline}

**loess bluff** - A bluff composed of a thick deposit of coarse loess,
formed immediately adjacent to the edges of flood plains, as along the
Mississippi River valley or China. Sometimes referred to as a bluff
formation (not preferred). SW & [GG]{.underline}.

**loess hill** - A hill composed of thick deposits of loess, as in IA,
MO, NE and the Palouse Hills of WA & ID. SW

log landing -- A comparatively level area, usually with road access,
constructed or cut into steeper slopes and used for sorting logs during
timber harvest operations. Compare -- skid trail. SW

**longitudinal dune** -- A long, narrow sand dune, usually symmetrical
in cross profile, oriented parallel to the prevailing wind direction ;
it is wider and steeper on the windward side but tapers to a point on
the lee side. It commonly forms behind an obstacle in an area where sand
is abundant and the wind is strong and constant. Such dunes can be a few
meters high and up to 100 km long. Compare -- seif dune, transverse
dune. [GG]{.underline}

**long run-out landslide** -- (not recommended; see rockfall avalanche).

**longshore bar** \[relict\] - A narrow, elongate, coarse-textured ridge
that once rose near to, or barely above, a pluvial or glacial lake and
extended generally parallel to the shore but was separated from it by an
intervening trough or lagoon; both the bar and lagoon are now relict
features. [GG]{.underline}

**louderback** - A hill or ridge composed of a lava flow remnant that
caps or is exposed in a tilted fault block and bounded by a dip slope.
Used as evidence of block faulting in Basin-and-Range terrain (western
USA). Compare -- hogback. [GG]{.underline}

**low-center polygon** - A polygon whose center is depressed relative to
its boundary. Compare - high-center polygon. [NRC]{.underline}

**low hill** -- A generic name for an elevated, generally rounded land
surface with low local relief, rising between 30 meters (100 ft.) to as
much as 90 m (approx. 300 ft.) above surrounding lowlands. Compare --
high hill, hill, hillock. SW

**lowland** - (a) An informal, generic, imprecise term for low-lying
land or an extensive region of low-lying land, especially near a coast
and including the extended plains or country lying not far above tide
level. (b) (not preferred) A generic, imprecise term for a landscape of
low, comparatively level ground of a region or local area, in contrast
with the adjacent higher country. (c) (not recommended -- use valley,
bolson, etc.) A generic term for a large valley. Compare - upland. SW

**low marsh** - (refer to mud flat). The flat, usually bare ground
situated seaward of a salt marsh and regularly covered and uncovered by
the tide; e.g., a mud flat. GG

**lowmoor bog** - A bog that is at or only slightly above the water
table, on which it depends for accumulation and preservation of peat
(chiefly the remains of sedges, reeds, shrubs, and various mosses).
Compare - highmoor bog, raised bog. GG

**maar** -- A low relief, broad volcanic crater formed by multiple,
shallow explosive eruptions. It is surrounded by a crater ring in the
form of low ramparts of gently dipping (i.e. \< 25 degrees), well-bedded
ejecta; may be partially or completely filled by water (*maar lake*). SW
& [GG]{.underline}

**mafic rock** - A general term for igneous rock composed chiefly of one
or more ferromagnesian, dark-colored minerals; also said of those
minerals. Compare - felsic rock. [GG]{.underline}

**mainland cove -** A subaqueous area adjacent to the mainland or a
submerged mainland beach that forms a minor recess or embayment within
the larger basin. Compare -- cove, barrier cove. SSS

**main scarp** - The steep surface on undisturbed ground at the upper
edge of a landslide, caused by movement of displaced material away from
the undisturbed ground; it is visible a part of the surface of rupture
(slip surface). Compare -- minor scarp, toe. [CV]{.underline} & SW

**mangrove swamp** - A tropical or subtropical marine swamp formed in a
silty, organic, or occasionally a coralline substratum and characterized
by abundant mangrove trees along the seashore in a low area of salty or
brackish water affected by daily tidal fluctuation but protected from
violent wave action by reefs or land; dominated by saturated soils,
commonly sulfaquents. SW & [GG]{.underline}

**marine deposit -** Sediments (predominantly sands, silts and clays) of
marine origin; laid down in the waters of an ocean. Compare - estuarine
deposit, lagoonal deposit. SW

**marine lake** **\[water\]** - An inland body of permanently standing
brackish or saline water, occupying a depression on the Earth's surface
whose water level is commonly influenced by ocean tides through
subterranean cavities connecting to nearby lagoons; generally of
appreciable size (larger than a pond) and too deep to permit emergent
vegetation to take root completely across the expanse of water. Such
water bodies can have unique biota (e.g. sting-less jellyfish of Palau).
SW

**marine terrace** - A constructional coastal strip, sloping gently
seaward, veneered by marine deposits (typically silt, sand, fine
gravel). Compare - terrace, wave-built terrace. [GG]{.underline}

**marl** - A generic term loosely applied to a variety of materials,
most of which occur as an earthy, unconsolidated deposit consisting
chiefly of an intimate mixture of clay and calcium carbonate formed
commonly by the chemical action of algae mats and organic detritus
(periphyton); specifically an earthy substance containing 35 - 65 % clay
and 65-35% calcium carbonate mud; formed primarily under freshwater
lacustrine conditions, but varieties associated with more saline
environments and higher carbonate contents also occur. Compare --
coastal marl, freshwater marl, SW & [HP]{.underline}

**marsh** - Periodically wet or continually flooded areas with the
surface not deeply submerged. Covered dominantly with sedges, cattails,
rushes, or other hydrophytic plants. Compare - salt marsh, swamp, bog,
fen. [GSST]{.underline}

**mass movement** - A generic term for any process or sediments (mass
movement deposit) resulting from the dislodgment and downslope transport
of soil and rock material as a unit under direct gravitational stress.
The process includes slow displacements such as creep and solifluction,
and rapid movements such as landslides, rock slides, and falls,
earthflows, debris flows, and avalanches. Agents of fluid transport
(water, ice, air) may play an important, if subordinate role in the
process. [HP]{.underline}

**mass-movement till** - (not preferred) refer to \"till\"

**mass wasting** - (not preferred) refer to mass movement.

**mawae** - (colloquial: Hawaii) A natural surface channel commonly
found near the middle of an a\'a lava flow, formed by the surficial
draining of molten lava rather than by erosion from running water; a
type of lava trench. Compare - lava tube. [MA]{.underline}

**meander** \[streams\] - One of a series of regular freely developing
sinuous curves, bends, loops, turns, or windings in the course of a
stream. GG.

**meander belt** - The zone within which migration of a meandering
channel occurs; the flood-plain area included between two imaginary
lines drawn tangential to the outer bends of active channel loops.
Landform components of the meander-belt surface are produced by a
combination of gradual (lateral and down-valley) migration of meander
loops and avulsive channel shifts causing abrupt cut-offs of loop
segments. Landforms flanking the sinuous stream channel include: point
bars, abandoned meanders, meander scrolls, oxbow lakes, natural levees,
and flood-plain splays. Meander belts may not exhibit prominent natural
levee or splay forms. Flood plains of broad valleys may contain one or
more abandoned meander belts in addition to the zone flanking the active
stream channel. HP

**meandering channel** - The term \"meandering\" should be restricted to
loops with channel length more than 1.5 to 2 times the meander wave
length. Meandering stream channels commonly have cross sections with low
width-to-depth ratios, cohesive (fine-grained) bank materials, and low
gradient. At a given bank-full discharge, meandering streams have
gentler slopes, and deeper narrower, and more stable channel cross
sections than braided streams. Compare - meander, braided stream,
flood-plain landforms. [HP]{.underline} & [RR]{.underline}

**meander scar** - (a) A crescent-shaped, concave or linear mark on the
face of a bluff or valley wall, produced by the lateral erosion of a
meandering stream which impinged upon and undercut the bluff; if it's no
longer adjacent to the modern stream channel it indicates an abandoned
route of the stream. SW; (b) (not recommended -- refer to oxbow) An
abandoned meander, commonly filled in by deposition and vegetation, but
still discernable. [GG]{.underline}

**meander scroll** - (a) One of a series of long, parallel, close
fitting, crescent-shaped ridges and troughs formed along the inner bank
of a stream meander as the channel migrated laterally down-valley and
toward the outer bank. Compare - meander belt, point bar. (b) (not
recommended; refer to oxbow lake) - A small, elongate lake on a flood
plain in a well-defined part of an abandoned stream channel.
[GG]{.underline}

**medial moraine** - (a) An elongate moraine carried in or upon the
middle of a glacier and parallel to its sides, usually formed by the
merging of adjacent and inner lateral moraines below the junction of two
coalescing valley glaciers. (b) A moraine formed by glacial abrasion of
a rocky protuberance near the middle of a glacier and whose debris
appears at the glacier surface in the ablation area. (c) The irregular
ridge left behind in the middle of a glacial valley, when the glacier on
which it was formed has disappeared. GG

**melt-out till** - Till derived from slow melting of debris-rich
stagnant ice buried beneath sufficient overburden to inhibit deformation
under gravity, thus preserving structures derived from the parent ice.
Compare - flow-till, lodgment till. GG

**mesa** - A broad, nearly flat-topped, and usually isolated landmass
bounded by steep slopes or precipitous cliff and capped by layers of
resistant, nearly horizontal, rocky summit width greater than the height
of bounding escarpments. (Colloquial: western USA; not preferred) Also
used to designate broad structural benches and alluvial terraces that
occupy intermediate levels in stepped sequences of platforms bordering
canyons and valleys. Compare - butte, plateau, cuesta. HP &
[GG]{.underline}

**metamorphic rock** - Rock of any origin altered in mineralogical
composition, chemical composition, or structure by heat, pressure, and
movement at depth in the earth\'s crust. Nearly all such rocks are
crystalline. Examples: schist, gneiss, quartzite, slate, marble. HP

**metasediment** - A sediment or sedimentary rock that shows evidence of
having been subjected to metamorphism. GG

**meta-stable slope** - (not recommended)

**meteorite crater** -- An impact crater formed by the falling of a
large meteorite onto the earth's surface; e.g., Barringer Crater (AZ).
Compare -- crater, impact crater. SW & [GG]{.underline}

**microbiotic crust** - A thin, surface layer (crust) of soil particles
bound together primarily by living organisms and their organic
byproducts; thickness can range up from \< 1 cm up to 10 cm; aerial
coverage of the ground surface can range from 10 - 100%. Crusts
stabilize loose earthy material. Other types of surface crusts include
chemical crusts (e.g., salt crusts) and physical crusts (e.g.,
raindrop-impact crust). SW & SS

**micro-depression** - (not preferred) refer to microlow.

**microfeature** \[soil survey\] - Small, local, natural forms
(features) on the land surface that are too small to delineate on a
topographic or soils map at commonly used map scales (e.g. 1:24,000 to
1:10,000). Examples include earth pillar, patterned ground, frost boil.
Compare - microrelief. SW

**microhigh** - A generic microrelief term applied to slightly elevated
areas relative to the adjacent ground surface; changes in relief range
from several centimeters to several meters; cross-sectional profiles can
be simple or complex and generally consist of gently rounded, convex
tops with gently sloping sides; also spelled *micro-high*. SW.

**micro-knoll** - (not preferred) refer to microhigh.

**microlow**- A generic microrelief term applied to slightly lower areas
relative to the adjacent ground surface (e.g. shallow depression);
changes in relief range from several centimeters to several meters;
cross-sectional profiles can be simple or complex and generally consist
of subdued, concave, open or closed depressions with gently sloping
sides**;** also spelled *micro-low*. SW.

**microrelief** - (a) \[soil survey\] Slight variations in the height of
a land surface that are too small or intricate to delineate on a
topographic or soils map at commonly used map scales (e.g. 1:24,000
through 1:10,000). Examples include microhigh, microlow. Compare -
microfeature. SW (b) (not preferred - refer to microfeature) Generically
refers to local, slight irregularities in form and height of a land
surface that are superimposed upon a larger landform, including such
features as low mounds, swales, and shallow pits. [GG]{.underline}

**midden** - A mound or stratum of refuse (broken pots, ashes, food
remains, etc.) normally found on the site of an ancient settlement.
[GG]{.underline}

**mima mound** - A term used for one of numerous low circular or oval
domes composed of loose, unstratified, gravelly, silty, or sandy
material. The basal diameter varies from 3 meters to more than 30
meters, and the height from 30 centimeters to about 2 meters. Compare -
pimple mound, patterned ground, shrub-coppice dune. [GG]{.underline}

**mine spoil, coal extraction** -- Randomly mixed, earthy materials
artificially deposited as a result of either surficial or underground
coal mining activities; a type of mine spoil. SW

**mine spoil, metal-ore extraction** -- Randomly mixed, earthy materials
artificially deposited as a result of either surficial or underground
metal-ore mining activities; a type of mine spoil. SW

**mine spoil or earthy fill** \[soil survey\] - An accumulation of
displaced earthy material, rock, or other waste material removed during
mining or excavation. SW & [GSST]{.underline}

**minor scarp** -- A steep surface on the displaced material of a
landslide, produced by differential movements within the sliding mass.
Compare -- main scarp, toe. [CV]{.underline}

**Miocene** - An epoch of the Tertiary Period of geologic time
(approximately 5.2 to 23 million years ago) that immediately follows the
Oligocene and precedes the Pliocene Epoch; also the corresponding
(time-stratigraphic) \"series\" of earth materials. [HP]{.underline}

**mogote** -- (colloquial: Caribbean Basin) An isolated, steep-sided,
commonly asymmetrical hill or ridge composed of limestone, generally
steeper on its leeward side (prevailing downwind side) and surrounded by
nearly level to sloping coastal plain composed of marine and alluvial
sediments; a type of karst tower. They range in height from a few feet
(\< 1 m) to over 150 ft (50 m). Most are isolated and cover small areas
but some form clusters of hills or ridges rising out of the surrounding
blanket deposits. Mogotes are extensive in northern Puerto Rico. SW,
Monroe (1976, 1980), & WW.

**monadnock** - An isolated hill or mountain of resistant rock rising
conspicuously above the general level of a lower erosion surface in a
temperate climate representing an isolated remnant of a former erosion
cycle in an area that has largely been beveled to its base level.
Compare - inselberg, nunatak. [GG]{.underline}

**monocline** - (a) \[landform\] A unit of folded strata that dips from
the horizontal in one direction only, is not part of an anticline or
syncline, and occurs at the earth's surface. This structure is typically
present in plateau areas where nearly flat strata locally assume steep
dips caused by differential vertical movements without faulting.
Compare - anticline, syncline, fold. SW & [HP]{.underline} (b)
\[structural geology\]- A local steepening in an otherwise uniform
gentle dip. GG

**moraine** \[glacial geology\] - (a) \[material\] A mound, ridge, or
other topographically distinct accumulation of unsorted, unstratified
glacial drift, predominantly till, deposited primarily by the direct
action of glacier ice, in a variety of landforms. (b) \[landform\] A
general term for a landform composed mainly of till that has been
deposited by a glacier; a kame moraine is a type of moraine similar in
exterior form to other types of moraines but composed mainly of
stratified outwash materials. Types of moraine include: disintegration,
end, ground, kame, lateral, recessional, and terminal. SW

**mossy organic materials -** see organic materials

**moss peat** \[Soil Taxonomy\] - An accumulation of organic material
that is predominantly the remains of mosses (e.g. sphagnum moss).
Compare - Herbaceous peat, sedimentary peat, woody peat, peat, muck, and
mucky peat. SSM

**mound** - (a) A low, rounded natural hill of unspecified origin,
generally \< 3 m high and, composed of earthy material; (b) A small,
human-made hill, composed either of debris accumulated during successive
occupations of the site (e.g. tell) or of earth heaped up to mark a
burial site (e.g. burial mound). (c) A structure built by colonial
organisms (e.g. termite mound). [GG]{.underline}

**mountain** - A generic term for an elevated area of the land surface,
rising more than 300 meters above surrounding lowlands, usually with a
nominal summit area relative to bounding slopes and generally with steep
sides (greater than 25 percent slope) with or without considerable
bare-rock exposed. A mountain can occur as a single, isolated mass or in
a group forming a chain or range. Mountains are primarily formed by
tectonic activity and/or volcanic action and secondarily by differential
erosion. Compare - hill, hillock, plateau, foothills, mountains. SW &
[HP]{.underline}

**mountainbase -** A geomorphic component of mountains consisting of the
lowermost area, consisting of the strongly to slightly concave colluvial
apron or wedge at the bottom of mountain slopes; composed of
long-transport colluvium and slope alluvium sediment. It can extend out
onto more level valley areas where it ultimately interfingers with, is
buried by alluvium or is replaced by re-emergent residuum. Compare -
mountaintop, mountainflank, free face, geomorphic component. SW

**mountainflank -** A geomorphic component of mountains consisting of
the side area of mountains, characterized by very long, complex
backslopes with comparatively high slope gradients and composed of
highly-diverse, colluvial sediment mantles, complex near-surface
hydrology, mass movement processes and features (e.g., creep,
landslides); rock outcrops or structural benches may be present. The
mountainflank can be subdivided by the general location along the
mountainside (i.e., upper third, middle third, or lower third
mountainflank). Compare - mountaintop, mountainbase, free face,
geomorphic component. SW

**mountain range** -- A single, large mass consisting of a succession of
mountains or narrowly spaced mountain ridges, with or without peaks,
closely related in position, direction, orientation, formation, and age;
a component part of a mountain system. Compare -- mountain system,
mountains. [GG]{.underline}

**mountains** -- A region or landscape characterized by mountains and
their intervening valleys; a generic name for any group, cluster, or
sequence of mountains or narrowly spaced mountain ridges, with or
without peaks, closely related in position, orientation, direction,
formation, or age, and whose summits commonly exceed 300 m (approx. 1000
ft). Compare -- foothills, hills, mountain range, mountain system. SW.

**mountainside** - (not recommended) use mountain slope.

**mountain slope** - A part of a mountain between the summit and the
foot. Compare -- mountainflank, hillslope. GG

**mountain system** -- A group of mountain ranges exhibiting certain
unifying features, such as similarity in form, structure and alignment,
and presumably originating from the same general causes; especially a
series of mountain ranges belonging to an orogenic belt. Compare --
mountain range, mountains. [GG]{.underline}

**mountaintop -** A geomorphic component of mountains consisting of the
uppermost, comparatively level or gently sloped area of mountains,
characterized by relatively short, simple slopes composed of bare rock,
residuum, or short-transport colluvial sediments. In humid environments,
mountaintop soils can be quite thick and well developed. Compare -
mountainflank, mountainbase, free face, geomorphic component. SW

**mountain valley** - (a) Any small, externally drained V-shaped
depression (in cross-section) cut or deepened by a stream and floored
with alluvium, or a broader, U-shaped depression modified by an alpine
glacier and floored with either till or alluvium, that occurs on a
mountain or within mountains. Several types of mountain valleys can be
recognized based on their form and valley floor sediments (i.e.,
*V-shaped valley*, *U-shaped valley*). Compare -- valley. SW (b)
(colloquial: Basin and Range, USA) A relatively small, structural
depression within a mountain range that is partly filled with alluvium
and commonly drains externally to an intermontane basin, bolson, or
semi-bolson. Compare - valley flat. SW & [FFP]{.underline}

**muck** - Unconsolidated soil material consisting primarily of highly
decomposed organic material in which the original plant parts are not
recognizable (i.e. \"sapric\" in Soil Taxonomy). It generally contains
more mineral matter and is usually darker in color, than peat. Compare -
peat, mucky peat, herbaceous peat. [GSST]{.underline}

**mucky peat** - Unconsolidated soil material consisting primarily of
organic matter that is in an intermediate stage of decomposition such
that a significant part of the original material can be recognized and a
significant part of the material can not be recognized (i.e. \"hemic\"
in Soil Taxonomy). Compare - peat, muck, herbaceous peat. SSM

**mud flat** -- **(not preferred -- use tidal flat)** A relatively level
area of fine grained material (e.g. silt) along a shore (as in a
sheltered estuary) or around an island, alternately covered and
uncovered by the tide or covered by shallow water, and barren of
vegetation. Compare -- low marsh, tidal flat, tidal marsh.
[GG]{.underline}

**mudflow** \[mass movement\] -- The process, associated sediments
(mudflow deposit) or resultant landform characterized by a very rapid
type of *earthflow* dominated by a sudden, downslope movement of a
saturated mass of rock, soil, and mud (more than 50 % of the particles
are \< 2 mm), that behaves as much as a viscous fluid when moving.
Compare -- debris flow, flow, landslide. SW & [DV]{.underline}

**mud pot** -- A type of hot spring containing boiling mud, usually
sulfurous and often multicolored, as in a paint pot. Mud pots are
commonly associated with geysers and other hot springs in volcanic
areas, especially in Yellowstone Natl. Park, WY. Compare -- geyser, hot
spring. GG

**mudstone** - (a) A blocky or massive, fine-grained sedimentary rock in
which the proportions of clay and silt are approximately equal; (b) A
general term that includes clay, silt, claystone, siltstone, shale, and
argillite, and that should be used only when the amounts of clay and
silt are not known or cannot be precisely identified. [GG]{.underline}

**muskeg** - A bog, usually a sphagnum bog, frequently with grassy
tussocks (hummocks), growing in wet, poorly drained boreal regions, with
deep accumulations of organic material, often in areas of permafrost; a
moss-covered muck or peat bog of boreal regions. [GG]{.underline} and
[HP]{.underline}

**natural levee** - A long, broad low ridge or embankment of sand and
coarse silt, built by a stream on its flood plain and along both sides
of its channel, especially in time of flood when water overflowing the
normal banks is forced to deposit the coarsest part of its load. It has
a gentle slope away from the river and toward the surrounding
floodplain, and its highest elevation is closest to the river bank.
Compare - levee, artificial levee, meander belt. [GG]{.underline}

**neck** \[volcanic\] -- A vertical, pipe-like tower of solidified lava
or consolidated fragmental igneous rock that represents a former
volcanic vent whose surrounding material (e.g. tuff and tephra) has been
largely removed by erosion. Compare -- plug \[volcanic\], diatreme. SW,
[GG]{.underline}, & [GS]{.underline}

**net (nonsorted)** - (not preferred) refer to patterned ground.

**net (sorted)** - (not preferred) refer to patterned ground.

**nivation** - The process of excavation of a shallow depression or
nivation hollow on a mountain side by removal of fine material around
the edge of a shrinking snow patch or snow bank, chiefly through
sheetwash, rivulet flow, and solution in melt water. Freeze-thaw action
is apparently insignificant. [GG]{.underline}

**nivation hollow** -- A shallow, non-cliffed depression or hollow on a
mountain side permanently or intermittently occupied by a snow bank or
snow patch and produced by nivation. If the snow completely melts each
summer the hollow is deepened; otherwise not; may be a cirque precursor
if further enlarged and deepened by alpine glaciation. [GG]{.underline}

**nonsorted circle** - A type of patterned ground whose mesh (shape) is
dominantly circular and has a nonsorted appearance due to the absence of
a boarder of coarse fragments. Vegetation characteristically outlines
the pattern by forming a bordering ridge. Diameters commonly range from
0.5 to 3 m. Nonsorted circles include mud boils, earth hummocks, turf
hummocks, and frost boils. Nonsorted circles have various origins. Some,
such as mud and earth hummocks and frost boils, involve cryoturbation
activity and differential heave of frost-susceptible materials. Others,
such as mud boils, involve hydraulic pressures and diapir-like
displacement of water-saturated sediments. Compare - sorted circle,
frost boil, patterned ground. [NRC]{.underline} and [GG]{.underline}

**nonsorted polygon** - (not preferred) refer to patterned ground.

**nose slope** \[geomorphology\] - A geomorphic component of hills
consisting of the projecting end (laterally convex area) of a hillside,
resulting in predominantly divergent overland water flow (e.g., sheet
wash); contour lines generally form convex curves. Nose slopes are
dominated by colluvium and slope wash sediments (e.g., slope alluvium).
Slope complexity (downslope shape) can range from simple to complex.
Nose slopes are comparatively drier portions of hillslopes and tend to
have thinner colluvial sediments and profiles. Compare - head slope,
side slope, free face, interfluve, crest, base slope. SW

**notch** - (a) (colloquial - northeast USA) A narrow passageway, or
short defile between mountains; a deep, close pass. Compare - gap. (b) A
breached opening in the rim of a volcanic crater. [GG]{.underline}

**novaculite** - A dense, even-textured, extremely finely grained,
siliceous, sedimentary rock recrystallized from chert with
microcrystalline quartz dominant over chalcedony (cryptocrystalline
quartz). It is hard, white to grayish-black in color, translucent on
thin edges, has a dull to waxy luster, and displays smooth conchoidal
fracture when broken. Novaculite occurs in the Ouachita Mountains of AR
and OK and the Marathon Uplift of TX where it forms erosion resistant
ridges. At the Ouachita Mountain type occurrence, novaculite formed by
low-grade, thermal metamorphism of bedded chert. This rock serves widely
as a whetstone or oilstone. Compare - chert. SW & [GG]{.underline}

**nuée ardente** - A swiftly flowing, turbulent gaseous cloud, sometimes
incandescent, erupted from a volcano and containing ash and other
pyroclastics in its lower part; a density current of pyroclastic flow.
Compare - lahar. GG

**nunatak** - An isolated hill, knob, ridge, or peak of bedrock that
projects prominently above the surface of a glacier and is completely
surrounded by glacier ice. Compare - inselberg, monadnock. GG

**ocean** -- The continuous salt-water body that surrounds the
continents and fills the Earth's great depressions; also, one of its
major geographic divisions. Compare -- sea. GG

**offshore bar** - (not recommended) use barrier beach.

**Oligocene** - The epoch (from 23.3 to 35.4 million years ago) of the
Tertiary Period of geologic time, which follows the Eocene and precede
the Miocene Epoch; also the corresponding (time-stratigraphic) "series"
of earthy materials. SW

open depression -- A generic name for any enclosed or low area that has
a surface drainage outlet whereby surface water can leave the enclosure;
an area of lower ground indicated on a topographic map by contour lines
forming an incomplete loop or basin indicating at least one surface
exit. Compare -- closed basin. SW

**openpit mine** -- A relatively large depression resulting from the
excavation of material and redistribution of overburden associated with
surficial mining operations. Compare -- quarry, surface mine. SW &
[GG]{.underline}

**organic materials -** \[soil survey\] Unconsolidated sediments or
deposits in which carbon is an essential, substantial component. Several
types of organic materials (deposits) can be identified based on the
composition of the dominant fibers (grassy organic materials, herbaceous
organic materials, mossy organic materials, woody organic materials).
Compare - herbaceous peat, moss peat, sedimentary peat, woody peat. SW

**outcrop** - (a) That part of a geologic formation or structure that
appears at the surface of the earth. (b) \[soil survey\] An actual
exposure of bedrock at or above the ground surface. Compare - cliff. SW
& [GG]{.underline}

**outwash** \[glacial geology\] - Stratified and sorted sediments
(chiefly sand and gravel) removed or \"washed out\" from a glacier by
melt-water streams and deposited in front of or beyond the end moraine
or the margin of a glacier. The coarser material is deposited nearer to
the ice. Compare - pitted outwash, drift, esker, kame, till. SW &
[GG]{.underline}

**outwash delta** -- A relict (inactive) delta composed of glaciofluvial
sediments formed where a sediment laden outwash river emptied into an
open lake, commonly a proglacial lake. Sediment attributes include very
gently dipping topset beds (coarser textures) and steeply dipping
foreset beds (finer textures). SW & [GM]{.underline}

**outwash fan** - A fan-shaped accumulation of outwash deposited by
meltwater streams in front of the end or recessional moraine of a
glacier. Coalescing outwash fans form an outwash plain. [GG]{.underline}

**outwash plain** - An extensive lowland area of coarse textured,
glaciofluvial material. An outwash plain is commonly smooth; where
pitted, due to melt-out of incorporated ice masses (pitted outwash
plain), it is generally low in relief and largely retains its original
gradient. Compare - outwash, pitted outwash plain, collapsed outwash
plain, kettles**;** also called sandur. SW & HP

**outwash terrace** - A flat-topped bank of outwash with an abrupt outer
face (scarp or riser) extending along a valley downstream from an
outwash plain or terminal moraine; a valley train deposit. Compare -
kame terrace, valley train. SW

**overbank deposit -** Fine-grained sediments (silt and clay) deposited
from suspension on a flood plain by floodwaters that cannot be contained
within the stream channel. GG

**overburden -** (a) The upper part of a sedimentary deposit,
compressing and consolidating the materials below. (b) The loose soil or
other unconsolidated material overlying bedrock, either transported or
formed in place (synonym for regolith). [GG]{.underline}

**overflow stream channel --** A watercourse that is generally dry but
conducts flood waters that have overflowed the banks of a river,
commonly from large storms, annual meltwater, or glacial meltwaters. SW

**overprinting** -- The process of superimposing a new set of features
over a preexisting set due to a shift in environmental conditions such
as a change in climate or local hydrology. The resulting composite
morphology retains features that would not form under present
conditions. Compare -- overprinted soil. SW

**overprinted soil** - A soil in which new soil morphology has developed
and is superimposed upon that of a pre-existing soil due to a shift in
pedogenic conditions such as a change in climate or hydrology; the
composite morphology retains some relict features that would not form
under present day conditions. (not preferred) Sometimes called welded
soil. SW.

**overthrust** - A low angle thrust fault of large scale, with
displacement generally measured in kilometers. GG

**oxbow** - A closely looping stream meander having an extreme curvature
such that only a neck of land is left between the two parts of the
stream. (colloquial: northeastern U.S.A.) the land enclosed, or partly
enclosed, within an oxbow. Compare - meander belt, oxbow lake, bayou.
[GG]{.underline}

**oxbow lake** - The crescent-shaped, often ephemeral body of standing
water situated by the side of a stream in the abandoned channel (oxbow)
of a meander after the stream formed a neck cutoff and the ends of the
original bend were silted up. Compare - meander belt, oxbow. GG

**paha** - (colloquial: Midwestern USA) Commonly a low, elongated,
rounded ridge or hill cored by an erosional remnant of drift, rock, or
windblown sand, silt, or clay and capped with a thick cover (e.g. up to
10 m) of loess; found especially in northeast Iowa. Height varies
between 10 and 30 m. SW & [GG]{.underline}

**pahoehoe** **lava** - A type of basaltic lava (material) with a
characteristically smooth, billowy or rope-like surface and vesicular
interior. Compare - \`a\`a lava, block lava, pillow lava.
[GG]{.underline} & [MA]{.underline}

**pahoehoe** **lava** **flow**- A type of basaltic lava flow with a
characteristically smooth, billowy or rope-like surface. Compare -
\`a\`a lava flow, block lava flow, pillow lava flow. [GG]{.underline} &
[MA]{.underline}

**Paleocene** - The earliest epoch (from 56.5 to 65.0 million years ago)
of the Tertiary Period of geologic time that follows the Cretaceous
Period and precedes the Eocene Epoch; also the corresponding
(time-stratigraphic) "series" of earthy materials. SW

**paleosol** - A soil that formed on a landscape in the past with
distinctive morphological features resulting from a soil-forming
environment that no longer exists at the site. The former pedogenic
process was either altered because of external environmental change or
interrupted by burial. A paleosol (or component horizon) may be classed
as relict if it has persisted in a land-surface position without major
alteration of morphology by processes of the prevailing pedogenic
environment. An exhumed paleosol is one that formerly was buried and has
been re-exposed by erosion of the covering mantle. Most paleosols have
been affected by some subsequent modification of diagnostic horizon
morphologies and profile truncation. HP

**paleoterrace -** An erosional remnant of a terrace which retains the
surface form and alluvial deposits of its origin but was not emplaced
by, and commonly does not grade to a present-day stream or drainage
network. Compare - alluvial plain remnant. SW

**palsa** - An elliptical dome-like permafrost mound containing
alternating layers of ice lenses and peat or mineral soil, commonly 3-10
m high and 2-25 m long, occurring in subarctic bogs of the tundra and
often surrounded by water; pl. palsen. [NRC]{.underline}

**parabolic dune** - A sand dune with a long, scoop-shaped form, convex
in the downwind direction so that its horns point upwind, whose ground
plan, when perfectly developed, approximates the form of a parabola.
[GG]{.underline}

**parallel drainage pattern** - A drainage pattern in which the streams
and their tributaries are regularly spaced and flow parallel or
subparallel to one another and tributaries characteristically join the
mainstream at approximately the same angle, over a considerable area. It
is indicative of a region having a pronounced, uniform slope and a
homogeneous lithology and rock structure, such as young coastal plains
and large basalt flows. SW, [GG]{.underline}, [WA]{.underline}

**parent material** - The unconsolidated and more or less chemically
weathered mineral or organic matter from which a soil's solum is
developed by pedogenic processes. GSST

**park** -- (colloquial -- Rocky Mountains, USA; not preferred -- refer
to valley, intermontane basin) (a) An ecological term for a grassy or
shrubby, wide, open valley lying at high elevation and confined between
forested mountain slopes, as in a high meadow; sometimes marshy. Compare
-- glade. (b) (refer to intermontane basin) A level valley between
mountain ranges. [GG]{.underline} & SW

**parna** - A term used, especially in southeast Australia and
southwestern USA, for silt and sand-sized aggregates of eolian clay
occurring as sheets or dunes. Compare - parna dune. SW & GG

**parna dune** - A dune largely composed of silt and sand-sized
aggregates of clay; sometimes called a clay dune or lunette. Compare -
parna. [HP]{.underline}

**partial ballena** - (not preferred) refer to ballena

**patina** - A general term for a colored film or thin outer layer
produced on the surface of a rock or other material by weathering after
long exposure. Compare - rock varnish. [GG]{.underline}

**patterned ground** - A general term for any ground surface exhibiting
a discernibly ordered, more-or-less symmetrical, morphological pattern
of ground and, where present, vegetation. Patterned ground is
characteristic of, but not confined to, permafrost regions or areas
subjected to intense frost action; it also occurs in tropical,
subtropical, and temperate areas. Patterned ground is classified by type
of pattern and presence or absence of sorting and includes nonsorted and
sorted circles, net, polygons, steps and stripes, garlands, and
solifluction features. In permafrost regions, the most common macroform
is the ice-wedge polygon and a common microform is the nonsorted circle.
Stone polygons generally form on slopes of less than 8 percent, while
garlands and stripes occur on slopes of 8 to 15 percent and more than 15
percent, respectively. [NRC]{.underline} and [HP]{.underline}

**pavement karst** -- Areas of bare limestone, usually sculpted by
solution erosion into karren of various types and where soils have been
stripped off, commonly by glaciation in alpine areas (e.g. Rocky
Mountains -- USA) and high latitudes, and by water erosion in arid karst
areas. Compare -- fluviokarst, glaciokarst, sinkhole karst, karst. SW &
WW

**peak** - Sharp or rugged upward extension of a ridge chain, usually at
the junction of two or more ridges; the prominent highest point of a
summit area. HP

**peat** - Unconsolidated soil material consisting largely of
undecomposed, or slightly decomposed, organic matter (i.e. \"fibric\" in
Soil Taxonomy) accumulated under conditions of excessive moisture.
Compare - muck, mucky peat, herbaceous peat. [GSST]{.underline}

**peat plateau** - A generally flat-topped expanse of peat, elevated
above the general surface of a peatland, and containing segregated ice
that may or may not extend downward into the underlying mineral soil.
Controversy exists as to whether peat plateaus and palsen are
morphological variations of the same feature. NRC

**pediment** - A gently sloping erosional surface developed at the foot
of a receding hill or mountain slope, commonly with a slightly
concave-upward profile, that cross-cuts rock or sediment strata that
extend beneath adjacent uplands. The erosion surface may be essentially
bare bedrock (i.e. *rock pediment*), or it may be thinly mantled (e.g. 1
to 3 m) with debris (i.e. *pediment*) such as colluvium, pedisediment,
or alluvium that is ultimately in transit from an upland front to basin
or valley lowland. In hill-footslope terrain the debris mantle (over an
erosional contact) is designated \"pedisediment.\" The term has been
used in several geomorphic contexts: Pediments may be classed with
respect to (a) landscape positions (e.g. intermontane-basin piedmont =
*apron pediment*, or valley-border footslope surfaces ( = *terrace
pediment*); Cooke and Warren, 1973); (b) type of material eroded (e.g.
bedrock = *rock pediment*, or regolith = *pediment*); or (c)
combinations of the above. Compare -- rock pediment, Piedmont slope,
structural bench. SW, [HP]{.underline}, [RR]{.underline}

**pedisediment** - A sediment layer, eroded from the shoulder and
backslope of an erosional slope that lies on and is, or was, being
transported across a pediment. FFP

**pedoturbation** - The mixing of soil materials by natural processes.
Compare - cryoturbation. [BHM]{.underline}

**peneplain** - (not recommended; obsolete) A low nearly featureless,
gently undulating land surface of considerable area, which presumably
has been produced by the processes of long-continued subaerial erosion.
[GG]{.underline}

**peninsula** -- (a) An elongated body or stretch of land nearly
surrounded by water (e.g., on three sides) and connected with a larger
tract of land area, usually by a neck or an isthmus. (b) A relatively
large tract of land jutting out into the water, with or without a
well-defined isthmus; e.g., the Italian peninsula. [GG]{.underline}

**perennial stream** - A stream or reach of a stream that flows
continuously throughout the year and whose surface is generally lower
than the water table adjacent to the region adjoining the stream.
Compare - Ephemeral stream, Intermittent stream. GG

**periglacial** - (adjective) Pertaining to processes, conditions,
areas, climates, and topographic features occurring at the immediate
margins of glaciers and ice sheets, and influenced by cold temperature
of the ice. The term was originally introduced to designate the climate
and related geologic features peripheral to ice sheets of the
Pleistocene. HP

**permafrost** - Ground, soil, or rock that remains at or below 0o C for
at least two years. It is defined on the basis of temperature and is not
necessarily frozen. Compare - continuous permafrost, discontinuous
permafrost, sporadic permafrost, thaw-stable permafrost, thaw sensitive
permafrost. [NRC]{.underline}

**Physiographic Division -** A large portion of a continent of which all
parts are similar in geologic structure and climate at a small scale
(e.g. 1:5,000,000) and which has consequently had a unified geomorphic
history and whose pattern of relief or landforms differ significantly
from that of adjacent areas. Examples: the Laurentian Upland, Rocky
Mountain System, and Interior Highlands of the U.S.A. western U.S.A.
*\[The highest level in the Physiographic Location part of the
Geomorphic Description System\]*. SW & NASIS Data Dictionary

**Physiographic Province** - A region of which all parts are similar in
geologic structure and climate and which has consequently had a unified
geomorphic history; a region whose pattern of relief or landforms differ
significantly from that of adjacent regions**; i.e. a subset within a
Physiographic Division**. Examples: the Valley and Ridge, Blue Ridge,
and Piedmont provinces in the eastern U.S.A., and the Basin and Range,
Rocky Mountains, and Great Plains provinces in the western U.S.A.
***\[The second highest level in the Physiographic Location part of the
Geomorphic Description System\]***. **SW &** **[GG]{.underline}**

**Physiographic Section -** An area which all parts are similar in
geologic structure and climate at a relatively small scale and which has
consequently had a unified geomorphic history, and whose pattern of
relief or landforms differ significantly from that of adjacent areas ( =
Fenneman\'s (1957) \"Section\"); i.e. a subset within a Physiographic
Province). Examples: the Mohawk, Green Mountain, and Floridian Sections
in the eastern U.S.A. and the Sacramento Section, Puget Trough, and
Klamath Mountains in the western U.S.A. *\[The third highest level in
the Physiographic Location part of the Geomorphic Description System\]*.
SW, NASIS Data Dictionary

**piedmont** - (adjective) Lying or formed at the base of a mountain or
mountain range; e.g., a piedmont terrace or a piedmont pediment. (noun)
An area, plain, slope, glacier, or other feature at the base of a
mountain; e.g., a foothill or a bajada. In the United States, the
Piedmont (noun) is a low plateau extending from New Jersey to Alabama
and lying east of the Appalachian Mountains. [GG]{.underline}

**piedmont slope** -- (colloquial -- western USA) The dominant gentle
slope at the foot of a mountain; generally used in terms of
intermontane-basin terrain in arid to subhumid regions. Main components
include: (a) An erosional surface on bedrock adjacent to the receding
mountain front (pediment, rock pediment); (b) A constructional surface
comprising individual alluvial fans and interfan valleys, also near the
mountain front; and (c) A distal complex of coalescent fans (bajada),
and alluvial slopes without fan form. Piedmont slopes grade to
basin-floor depressions with alluvial and temporary lake plains or to
surfaces associated with through drainage (e.g., axial streams). Compare
-- bolson, fan piedmont. [HP]{.underline}

**pillow lava** -- A general term for lava displaying pillow structure
(discontinuous, close-fitting, bun-shaped or ellipsoidal masses,
generally \< 1 m in diameter); considered to have formed in a subaqueous
environment; such lava is usually basaltic or andesitic. Compare --
\`a\`a lava, block lava, pahoehoe lava. SW, GG, & GS

**pillow lava flow** -- A lava flow or body displaying pillow structure
and considered to have formed in a subaqueous environment (underwater);
usually basaltic or andesitic in composition. Compare --\`a\`a lava
flow, block lava flow, pahoehoe lava flow. SW & GS

**pimple mound** - (colloquial: Gulf Coast U.S.A.) Low, flattened,
approximately circular or elliptical features composed of sandy loam
that is coarser than, and distinct from, the surrounding soil; the basal
diameter ranges from 3 m to more than 30 m, and the height from 30 cm to
more than 2 m. Compare - mima mound, patterned ground, shrub-coppice
dune. GG

**pingo** - A large frost mound; especially a relatively large conical
mound of soil-covered ice (commonly 30 to 50 meters high and up to 400
meters in diameter) raised in part by hydrostatic pressure within and
below the permafrost of Arctic regions, and of more than 1 year\'s
duration. [GG]{.underline}

**pinnacle** \[geomorphology\] - A tall, slender, tapering tower or
spire-shaped pillar of rock, either isolated, as on steep slopes or
cliffs formed in karst or other massive rocks, or at the summit of a
hill or mountain. Compare - erosional remnant, hoodoo. SW,
[GG]{.underline}, & WW

**pinnate** **drainage pattern** -- A variation of the dendritic
drainage pattern in which the main stream receives many closely spaced,
subparallel tributaries that join it at slightly acute angles upstream,
resembling in plan a feather. They typically form on steep slopes with
soils that have a high silt content; such as loess landscapes or
fine-textured flood plains. SW, [GG]{.underline}, [WA]{.underline}

**pit and mound topography** -- (not recommended) use tree-tip pit and
mound topography.

**pitted outwash** - Outwash deposits with surficial pits or kettles,
produced by the partial or complete burial of glacial ice by outwash and
the subsequent thaw of the ice and collapse of the surficial materials.
Compare - pitted outwash plain. [GG]{.underline}

**pitted outwash plain** - An outwash plain marked by many irregular
depressions such as kettles, shallow pits, and potholes which formed by
melting of incorporated ice masses; much of the gradient and internal
structures of the original plain remain intact; many are found in WI,
MN, MI, and IN. Compare -- collapsed outwash plain, outwash, pitted
outwash. [GG]{.underline}

**pitted outwash terrace** -- A relict glaciofluvial terrace that
retains its original attitude, composed of undistorted outwash sediments
and depositional structures and whose surface is pock-marked with
numerous potholes or kettle depressions. Compare -- collapsed outwash
plain. SW

**plain** - A general term referring to any flat, lowland area, large or
small, at a low elevation. Specifically, any extensive region of
comparatively smooth and level gently undulating land. A plain has few
or no prominent hills or valleys but sometimes has considerable slope,
and usually occurs at low elevation relative to surrounding areas. Where
dissected, remnants of a plain can form the local uplands. A plain may
be forested or bare of trees and may be formed by deposition or erosion.
Compare - lowland, plateau. [GG]{.underline}

**plateau** - \[geomorphology\] A comparatively flat area of great
extent and elevation; specifically an extensive land region considerably
elevated (more than 100 meters) above adjacent lower-lying terrain, and
is commonly limited on at least one side by an abrupt descent, has a
flat or nearly level surface. A comparatively large part of a plateau
surface is near summit level. Compare - hill, foothill, mountain, mesa,
plain. [GG]{.underline}

**playa** - The usually dry and nearly level lake plain that occupies
the lowest parts of closed depressions, such as those occurring on
intermontane basin floors. Temporary flooding occurs primarily in
response to precipitation-runoff events. Playa deposits are fine grained
and may or may not have high water table and saline conditions.
[HP]{.underline}

**playa dune** -- (colloquial -- Southern High Plains) A linear or
curvilinear ridge of windblown, granular material (generally sand or
parna) removed from the adjacent basin by wind erosion (deflation), and
deposited on the leeward (prevailing downwind) margin of a playa, playa
basin, or salina basin. The dune may be barren or vegetated. Compare --
dune. SW

**playa floor** -- (colloquial -- Southern High Plains) The lowest
extensive, flat to slightly concave surface within a playa basin,
consisting of a dry lake bed or lake plain underlain by stratified clay,
silt or sand, and commonly by soluble salts. Compare -- playa step. SW

**playa lake** - A shallow, intermittent lake in a arid or semi-arid
region, covering or occupying a playa in the wet season but drying up in
summer; an ephemeral lake that upon evaporation leaves or forms a playa.
GG

**playa rim** -- (colloquial -- Southern High Plains) The convex, upper
margin (shoulder) of a playa basin where the playa slope intersects the
surrounding terrain. Compare -- playa slope. SW

**playa slope** -- (colloquial -- Southern High Plains) The generally
concave to slightly convex area within a playa basin that lies between
the relatively level playa floor below (or playa step, if present) and
the convex playa rim above. Overland flow is typically parallel down
slope. Compare -- playa step, playa rim. SW

**playa step** -- (colloquial -- Southern High Plains) The relatively
level or gently inclined "terrace-like" bench or toeslope within a large
playa basin flanking and topographically higher than the playa floor and
below the playa slope; a bench or step-like surface within a playa basin
that breaks the continuity of the playa slope and modified by erosion
and/or deposition. Temporary ponding may occur in response to
precipitation / runoff events. Compare -- playa slope. SW

**playette --** A very small, playa-like, shallow, closed depression
typically with a salt-encrusted surface, little or no vegetation in
semi-arid to arid climates and infrequently subject to ponding from
precipitation events; commonly lacks the component parts of a playa
except for a small *playa floor*. Compare -- playa. SW &
[GHG]{.underline}

**Pleistocene** - The epoch of the Quaternary Period of geologic time
(from about 10 to 12 thousand to 1.6 million years ago), following the
Pliocene Epoch and preceding the Holocene also the corresponding
(time-stratigraphic) \"series\" of earth materials. SW &
[HP]{.underline}

**Pliocene** - The last epoch (from 1.6 to 5.2 million years ago) of the
Tertiary Period of geologic time that follows the Miocene and precedes
the Pleistocene Epoch; also, the corresponding (time-stratigraphic)
\"series\" of earth materials. [HP]{.underline}

**plug** \[volcanic\] -- A consolidated crater-filling of lava, the
surrounding material of which has been largely removed by erosion
leaving an isolated hill or knob. Compare -- neck \[volcanic\]. SW &
[GG]{.underline}

**plug dome** - A volcanic dome characterized by an upheaved,
consolidated conduit filling. GG

**pluton** - A deep-seated igneous intrusion. GG

**plutonic** - Pertaining to igneous rocks formed at great depth, but
also including associated metamorphic rocks. [GG]{.underline}

**pluvial lake** - A lake formed in a period of exceptionally heavy
rainfall; a lake formed in the Pleistocene Epoch during a time of
glacial advance, and now either extinct (relict) or existing as a
remnant (lake); e.g., Lake Bonneville. Compare - glacial lake,
proglacial lake. GG

**pocosin** - (colloquial: southeastern U.S.A.) A large wet area on
broad, commonly a swamp, which occurs on nearly level interfluves in the
Atlantic coastal plain with distinctive, native vegetation relative to
adjacent areas. Soils may be either mineral or organic. A Native
American term for \"swamp on a hill.\" Compare - raised bog.
[RD]{.underline}

**point bar** - One of a series of low, arcuate ridges of sand and
gravel developed on the inside of a growing meander by the slow addition
of individual accretions accompanying migration of the channel toward
the outer bank. Compare - meander scroll. GG

**point bar \[coastal\] -** Low, arcuate, subaerial ridges of sand
developed adjacent to an inlet and formed by the lateral accretion or
movement of the channel. Compare -- sit. SSS

**polje** -- (not preferred) refer to interior valley.

**polygon** - A type of patterned ground consisting of a closed, roughly
equidimensional figure bounded by more or less straight sides; some
sides may be irregular. Refer to patterned ground. Compare - High center
polygon, low center polygon, ice wedge polygon, nonsorted polygon. NRC

**pond** - (a) A natural body of standing fresh water occupying a small
surface depression, usually smaller than a lake and larger than a pool.
(b) A small artificial body of water, used as a source of water.
Compare - salt pond. [GG]{.underline}

**pool** - A small, natural body of standing water, usually fresh; e.g.
a stagnant body of water in a marsh, or a transient puddle in a
depression following a rain. [GG]{.underline}

**porcellanite** - A dense, siliceous rock formed as a indurated or
baked clay or shale with a dull, light-colored, cherty appearance, often
found in the roof or floor of a burned-out coal seam. [GG]{.underline}

**postglacial** - (not preferred) refer to Holocene.

**pothole** - \[geomorphology\] (not preferred) A generic, imprecise
term for any pot-shaped pit or hole. GG

**pothole** -\[glacial geology\] A type of small pit or closed
depression (1 to 15 meters deep), generally circular or elliptical,
occurring in an outwash plain, a recessional moraine, or a till plain.
[GG]{.underline}

**pothole** -\[lake\] - A shallow depression, generally less than 10
hectares in area, occurring on disintegration moraines and commonly
containing an intermittent or seasonal pond or marsh. [GG]{.underline}

**pressure ridge** \[ice\] -- A rugged, irregular wall of broken
floating ice buckled upward by the lateral pressure of wind or current
forcing or squeezing one floe against another, or against a shore; it
may extend for kilometers in length and up to 30 m in height. Along
shores they are lower (\< 10 m tall) and contribute to the temporary or
permanent formation of a beach berm or a rim of boulders and stones. SW
& [GG]{.underline}

**pressure ridge** \[volcanic\] - An elongate uplift of the congealing
crust of a lava flow, probably due to the pressure of the underlying,
still-flowing lava; commonly \< 5 m in height (but range up to 15 m) and
\< 100 m length (but can exceed 500 m). Compare -- tumulus. SW,
[GG]{.underline}, & [GS]{.underline}

**proglacial lake** - A type of glacial lake which formed just beyond
the margin of an advancing or retreating glacier; generally in direct
contact with the ice. Compare - glacial lake, pluvial lake.
[GG]{.underline}

**proglacial lake** \[relict\] - Remnant features of a glacial lake that
is now extinct which formed just beyond the margin of an advancing or
retreating glacier; generally in direct contact with the ice. Compare -
proglacial lake, pluvial lake. SW

**proximal** \[sedimentology\] - (adjective) Said of a sedimentary
deposit consisting of coarse clastics and deposited nearest the source
area. Compare - distal. [GG]{.underline}

**puff** \[gilgai\] -- A surface drape or exposure of up-welled
substratum material forced to the surface and outcropping on a low mound
or rim; the surface exposure of a chimney \[gilgai\]; a type of diapir
composed of earthy material. Compare -- chimney, intermediate position
\[gilgai\], gilgai. SW

**pumice** - (a) \[soils\] Rock fragments \> 2 mm in diameter (i.e.,
retained upon a 2 mm sieve), or coherent rock layers (pumice flow), made
of light-colored, vesicular, glassy rock commonly having the composition
of rhyolite. The material commonly has a specific gravity of \< 1.0 and
is thereby sufficiently buoyant to float on water**.** [SW]{.underline};
pumice-like fragments \< 2 mm in size are called pumiceous ash. ST;
Compare - scoria, tephra; (b) \[geology\] same as (a) but does not
include any size restrictions. [SW]{.underline}.

**pyroclastic** -- (adj.) Pertaining to clastic rock particles produced
by explosive, aerial ejection from a volcanic vent. Such materials may
accumulate on land or under water. Compare - epiclastic, volcaniclastic,
clastic. G. Smith & [HP]{.underline}

**pyroclastic flow** -- A fast density current of pyroclastic material,
usually very hot, composed of a mixture of gasses and a variety of
pyroclastic particles (ash, pumice, scoria, lava fragments, etc.);
produced by the explosive disintegration of viscous lava in a volcanic
crater or by the explosive emission of gas-charged ash from a fissure
and which tends to follow topographic lows (e.g. valleys) as it moves;
used in a more general sense than *ash flow*. Compare --pyroclastic
surge, ash flow, nueé ardente, lahar. SW, [SN]{.underline},
[GG]{.underline}

**pyroclastic surge** -- A low density, dilute, turbulent *pyroclastic
flow*, usually very hot, composed of a generally unsorted mixture of
gases, ash, pumice and dense rock fragments that travels across the
ground at high speed and less constrained by topography than a
pyroclastic flow; several types of pyroclastic surges can be specified
(e.g. base surge, ash-cloud-surge). Compare - pyroclastic flow. SW,
[SN]{.underline}, [GG]{.underline}

**quarry** -- Excavation areas, open to the sky, usually for the
extraction of stone. [GG]{.underline}

**Quaternary** - The period of the Cenozoic Era of geologic time,
extending from the end of the Tertiary Period (about 1.6 million years
ago) to the present and comprising two epochs, the Pleistocene (Ice Age)
and Holocene (Recent); also, the corresponding (time-stratigraphic)
\"series\" of earth materials. [GG]{.underline}

**radial drainage pattern** - A drainage pattern in which consequent
streams radiate or diverge outward, like the spokes of a wheel from a
high central area.; a major collector stream is usually found in a
curvilinear alignment around the bottom of the elevated topographic
feature. It is best developed on the slopes of a young domal structure,
a volcanic cone, or isolated hills (erosional remnant). SW,
[GG]{.underline}, [WA]{.underline}

**railroad bed** -- The trace or track of a railroad route, commonly
constructed slightly above the adjacent land, and composed mostly of
earthy materials (gravel, rock fragments, etc.). Abandoned or reclaimed
beds may no longer be topographically or visually distinct, but the
materials used to construct them may still be a significant portion of
the soil zone. SW

**raised beach** - An ancient (relict) beach occurring above the present
shoreline and separated from the present beach, having been elevated
above the high-water mark either by local crustal movements (uplift) or
by lowering of sea or lake level, and which may be bounded by inland
cliffs. [GG]{.underline}

**raised bog** - An area of acid, peaty soil especially that developed
from moss, in which the center is higher than the margins. Compare -
pocosin, Carolina Bay, moss peat. \[Note: raised peat bog (not
preferred) - refer to highmoor bog\]. SW & [GG 87]{.underline}

**ravine** - A small stream channel; narrow, steep-sided, commonly
V-shaped in cross section and larger than a gully, cut in unconsolidated
materials. General synonym (not preferred) - gulch. Compare -- arroyo,
draw, gully. [HP]{.underline}

**recessional moraine** - An end or lateral moraine, built during a
temporary but significant halt in the final retreat of a glacier. Also,
a moraine built during a minor readvance of the ice front during a
period of general recession. Compare - end moraine, ground moraine,
terminal moraine. GG

**reclaimed land** -- a) A land area composed of earthy fill material
that has been placed and shaped to approximate natural contours,
commonly part of land-reclamation efforts after mining operations; b) A
land area, commonly submerged in its native state, that has been
protected by artificial structures (e.g. dikes) and drained for
agricultural or other purposes (e.g. polder). SW

**rectangular drainage pattern** -- A drainage pattern in which the
tributaries join the main streams at right-angles, and exhibit sections
of approximately the same length which form rectangular shapes; it is
indicative of streams following prominent bedrock fault, joint, or
foliation systems that break the rocks into rectangular blocks. It is
more irregular than the trellis drainage pattern, as the side streams
are not perfectly parallel and not necessarily as conspicuously
elongated, and secondary tributaries need not be present. The stronger
or more harsh the pattern, the thinner the soil cover. These patterns
commonly form in slate, schist, and gneiss, in resistive sandstone in
arid climates, or in sandstone in humid climates if little soil has
developed. SW, [GG]{.underline}, [WA]{.underline}

**reef** - (a) A ridge-like or mound-like structure, layered or massive,
built by sedentary calcareous organisms, especially corals, and
consisting mostly of their remains; it is wave-resistant and stands
above the surrounding contemporaneously deposited sediment. Reefs can
also include a mass or ridge of rocks, especially coral and sometimes
sand, gravel, or shells, rising above the surrounding estuary, sea or
lake bottom to or nearly to the surface. SSS, SW & [GG]{.underline}

**regolith** - All unconsolidated earth materials above the solid
bedrock. It includes material weathered in place from all kinds of
bedrock and alluvial, glacial, eolian, lacustrine, and pyroclastic
deposits. Soil scientists regard as soil only that part of the regolith
that is modified by organisms and soil-forming processes. Most engineers
describe the whole regolith, even to a great depth, as \"soil.\"
Compare - residuum, bedrock. HP

**relict** - (adjective) Pertaining to surface landscape features e.g.,
landforms, geomorphic surfaces, and paleosols that have never been
buried and yet are predominantly products of past environments.
Compare - exhumed, buried, ground soil. [HP]{.underline}

**relict-tidal inlet** - A channel remnant of a former tidal inlet. The
channel was cutoff or abandoned by infilling from migrating shore
sediments. Compare -- inlet, tidal inlet. SSS

**relief** - The relative difference in elevation between the upland
summits and the lowlands or valleys of a given region. Compare - local
relief. [GG]{.underline}

**remnant** - (not preferred) refer to erosion remnant.

**residuum** - (residual soil material) Unconsolidated, weathered, or
partly weathered mineral material that accumulates by disintegration of
bedrock in place. Compare - colluvium, regolith, saprolite.
[HP]{.underline}

**reworked lake plain** -- The bottom of a shallow, extinct glacial lake
composed of thin (e.g., \< 2 m thick), fine-textured, reworked
lacustrine sediments that overlie outwash or till; original lacustrine
sediments have been subsequently redistributed primarily by wave action
(eroded and / or moved a short distance). A distinctive lake plain
topography is not always present. It may include subdued, till-capped
topographic highs, ringed by shores or strandlines that were once
emergent islands. Common to MI, OH. Compare -- till-floored lake plain.
SW

**rhythmite** - An individual unit of a succession of beds developed by
rhythmic sedimentation; e.g. a cyclothem. The term implies no limit as
to bedding thickness or complexity and denotes no time or seasonal
connotation. Compare - varves, cyclothem. [GG]{.underline}

**rib** -- A small, high angle, tertiary spur ridge or mini-interfluve
that is a constituent part of rib & groove topography; (slopes generally
20 - 90 %, ); common on the mid and lower hillslopes of well dissected
uplands. Compare -- finger ridge, groove, rib and groove topography. SW

**rib and groove topography** -- A local scale topography composed of
repeating, small, high-angle (slopes generally 20 - 90 %), tertiary spur
ridges or mini-interfluves (ribs) separated by small, natural, narrow
drainageways (grooves); the overall effect is a corrugated transverse
surface, common on the mid and lower slopes of well dissected uplands in
semi-arid to humid environments (e.g. Basin and Range, Ozarks, etc.).
Micro-elevational differences generally range from \< 3 to \< 15 m. SW

**ribbed fen** - A nutrient-rich wetland with a surface pattern of
ridges and depressions.

**rice paddy -** An anthropogenic, nearly level impoundment that is
inundated for long periods typically for wetland rice production. It is
applied to areas that have been used in this fashion for a long enough
period of time to significantly change the original soil morphology
(especially redoximorphic features). SW

**ridge** - A long, narrow elevation of the land surface, usually sharp
crested with steep sides and forming an extended upland between valleys.
The term is used in areas of both hill and mountain relief. HP

**rift valley** -- A valley that has developed along a long, narrow
continental trough that has down-dropped and is bounded by normal
faults; a graben of regional size. It marks part of a zone along which
the entire thickness of the lithosphere has ruptured under crustal
extension. SW & [GG]{.underline}

**rill -** A very small channel with steep sides caused by erosion and
cut in unconsolidated materials by concentrated but intermittent flow of
water, usually during and immediately following moderate rains or after
ice / snow melt. Generally, a rill is [not]{.underline} an obstacle to
wheeled vehicles and is shallow enough (e.g., \< 0.5 m) to be
obliterated by ordinary tillage. Compare - gully. SW &
[GSST]{.underline}

**rim** - The border, margin, edge, or face of a landform, such as the
curved brim surrounding the top part of a crater or caldera;
specifically the rimrock of a plateau or canyon. GG

**ripple mark** - An undulating surface of alternating, subparallel,
small-scale ridges and depressions, commonly composed of loose sand. It
is produced on land by wind and under water by the agitation of water by
currents or wave action, and generally tends at right angles or
obliquely to the direction of flow of the moving fluid. Compare - giant
ripple mark. [GG]{.underline}

**rise** - (refer to lake plain) (a) A imprecise term for a slight
increase in slope and elevation of the land surface, usually with a
broad summit and gently sloping sides. [GG]{.underline} (b) \[soil
survey\] same as (a) but the term is restricted to microfeatures in
areas of very low relief such as lake plains or coastal plains. SW

**rise** \[geomorphology\] **-** A geomorphic component of flat plains
(e.g., lake plain, low coastal plain, low-gradient till plain)
consisting of a slightly elevated but low, broad area with low slope
gradients (e.g. 1-3 % slopes); typically a microfeature but can be
fairly extensive. Commonly soils on a rise are better drained than those
on the surrounding talf. Compare - talf. SW

**riser** \[geomorphology\] **-** A geomorphic component of
terraces**,** flood-plain steps, and other stepped landforms consisting
of the vertical or steep side slope (e.g. escarpment) typically of
minimal aerial extent. Commonly a recurring part of a series of natural,
step-like landforms such as successive stream terraces. Its
characteristic shape and alluvial sediment composition are derived from
the cut and fill processes of a fluvial system. Compare - tread. SW

**river** \[streams\] -- (a) A general term for a natural, freshwater
surface stream of considerable volume and generally with a permanent
base flow, moving in a defined channel toward a larger river, lake, or
sea. (b) (not recommended: colloquial - New England, USA) A small
watercourse which elsewhere in the USA is known as a *creek*. Compare --
stream. [GG]{.underline}

**river valley** - an elongate depression of the Earth\'s surface carved
by a river during the course of its development. Compare - valley side,
valley floor. GG

**road bed** -- The trace or track of a wheeled vehicle route that may
or may not be raised slightly above the adjacent land, and composed of
earthy fill material (gravel, rock fragments, etc.) or local soil
material. Traffic can alter various soil properties primarily by
compaction. Abandoned or reclaimed beds may no longer be topographically
or visually distinct. However, materials used to construct beds or
changes in soil properties may continue to have a significant impact on
soil management or plant growth. SW

**road cut --** A common anthropogenic feature, typically a
microfeature, consisting of the sloping, cut surface flanking a road bed
on one or both sides, that remains after local topography is minimized
by cutting an elongated depression through higher ground during road
construction; a type of cutbank. Compare -- cut, cutbank. SW

**roche moutonnée** - A small elongate protruding knob or hillock of
bedrock, so sculptured by a large glacier as to have its long axis
oriented in the direction of ice movement, an upstream (stoss or scour)
side that is gently inclined, smoothly rounded, and striated, and a
downstream (lee or pluck) side that is steep and rough. It is usually a
few meters in height, length, and breadth. GG

**rockfall** \[mass movement\] -- The process, associated sediments
(rockfall deposit) or resultant landform characterized by a very rapid
type of *fall* dominated by downslope movement of detached rock bodies
which fall freely through the air or by leaps and bounds (lacks an
underlying slip face)**;** also spelled *rock fall*. Compare -- debris
fall, soil fall, landslide. SW

**rockfall avalanche** \[mass movement\] - The process, associated
sediments (rockfall avalanche deposit) or resultant landform
characterized by an extremely rapid, large type of *rock-fragment flow*
(a type of landslide) that starts as a rockfall but turns into a flow
and characteristically deposits rock-dominated debris long distances
from the failure face (such as 10 -- 20 times the fall height); occurs
only when huge rockfalls and rockslides involving millions of metric
tons of material attain extremely rapid speeds; most common in a rugged
mountainous area; ex. the 1903 Franks, Alberta, Canada avalanche.
Sometimes loosely referred to as a long run-out landslide. Compare --
rock fragment flow, flow, landslide. SW

**rock glacier** - A mass of poorly sorted angular boulders and fine
material, with interstitial ice a meter or so below the surface
(ice-cemented) or containing a buried ice glacier (ice-cored). It occurs
in a permafrost area, and is derived from a cirque wall or other steep
cliff. Rock glaciers have the general appearance and slow movement of
small valley glaciers, ranging from a few hundred meters to several
kilometers in length, and having a distal area marked by a series of
transverse, arcuate ridges. [GG]{.underline}

**rock pediment** -- An erosion surface of low relief, cut directly into
and across bedrock and composed of either bare rock or thinly veneered
pedisediment or residuum (e.g. \< 1.5 m) over bedrock; it occurs along
the flanks of mountain fronts, or at the base of mountains or high
hills. Its surface grades to the backwearing mountain slopes or
hillslopes above, and generally grades down to and merges with a
lower-lying alluvial plain, piedmont slope or valley floor below. SW &
[FFP]{.underline}

**rock spread** \[mass movement\] -- The process, associated sediments
(rock spread deposit) or resultant landforms characterized by a very
rapid type of *spread* dominated by lateral movement in a rock mass
resulting from liquefaction or plastic flow of underlying materials that
may be extruded out between intact units; rock bodies predominate.
Compare -- debris spread, earth spread, landslide. SW & [DV]{.underline}

**rock topple** \[mass movement\] -- The process, associated sediments
(rock topple deposit) or resultant landform characterized by a
localized, very rapid type of fall in which large blocks of rock
material literally fall over, rotating outward over a low pivot point;
rock bodies predominate (little fine earth). Portions of the original
material may remain intact, although reoriented, within the resulting
deposit. Compare -- earth topple, debris topple, landslide. SW

**rock varnish -** A thin, dark, shiny film or coating, composed of iron
oxide accompanied by traces of manganese oxide and silica, formed on the
surfaces of pebbles, boulders, and other rock fragments, commonly on
rock outcrops in arid regions. It is believed to be caused by exudation
of mineralized solutions from within and deposition by evaporation on
the surface. [GG]{.underline}

**rotational debris slide** -- \[mass movement\] -- The process,
associated sediments (rotational debris slide deposit) or resultant
landform characterized by an extremely slow to moderately rapid type of
slide, composed of comparatively dry and largely unconsolidated earthy
material, portions of which remain largely intact and in which movement
occurs along a well-defined, concave shear surface and resulting in a
backward rotation of the displaced mass; sediments have substantial
proportions of both fine earth and coarse fragments. The landform may be
single, successive (repeated up and down slope), or multiple (as the
number of slide components increase). Compare -- rotational earth slide,
rotational rock slide, translational slide, lateral spread, landslide.
SW & [DV]{.underline}

**rotational earth slide** -- \[mass movement\] -- The process,
associated sediments (rotational earth slide deposit) or resultant
landform characterized by an extremely slow to moderately rapid type of
slide, composed of comparatively dry and largely unconsolidated earthy
material, portions of which remain largely intact and in which movement
occurs along a well-defined, concave shear surface and resulting in a
backward rotation of the displaced mass; sediments predominantly fine
earth (\< 2 mm). The landform may be single, successive (repeated up and
down slope), or multiple (as the number of slide components increase).
Compare -- rotational debris slide, rotational rock slide, translational
slide, lateral spread, landslide. SW & [DV]{.underline}

**rotational landslide** -- (not preferred) use rotational slide.

**rotational rock slide** -- \[mass movement\] -- The process,
associated sediments (rotational rock slide deposit) or resultant
landform characterized by an extremely slow to moderately rapid type of
slide, composed of comparatively dry and largely consolidated rock
bodies, portions of which remain largely intact but reoriented, and in
which movement occurs along a well-defined, concave shear surface and
resulting in a backward rotation of the displaced mass. The landform may
be single, successive (repeated up and down slope), or multiple (as the
number of slide components increase). Compare -- rotational debris
slide, rotational earth slide, translational slide, lateral spread,
landslide. SW & [DV]{.underline}

**rotational slide** \[mass movement\] -- The process, associated
sediments (rotational landslide deposit) or resultant landform**s**
characterized by an extremely slow to moderately rapid type of slide,
composed of comparatively dry and largely soil-rock materials, portions
of which remain largely intact and in which movement occurs along a
well-defined, concave shear surface and resulting in a backward rotation
of the displaced mass. The landform may be single, successive (repeated
up and down slope), or multiple (as the number of slide components
increase). Compare -- rotational debris slide, rotational earth slide,
rotational rock slide, translational slide, lateral spread, landslide.
SW & [DV]{.underline}

**rotational slump** - (not recommended) use rotational slide.

**rubble** - An accumulation of loose angular rock fragments, commonly
overlying outcropping rock; the unconsolidated equivalent of a breccia.
Compare - scree, talus. [GG]{.underline}

**saddle** - A low point on a ridge or interfluve, generally a divide
(pass, col) between the heads of streams flowing in opposite directions.
Compare - summit, crest. HP

**sag** -- A small, partially or completely closed depression formed by
movement along a strike-slip fault, or by mass movement (i.e.,
landslide) that may or may not temporarily pond water from impounded
drainage or surface runoff. For example, a closed depression formed
between a scarp or headwall and an adjacent rotated slump block of a
landslide. SW

**sag pond -** A small, permanent body of water in a semi-closed or
closed depression formed by movement along a strike-slip fault or by
mass movement (i.e., landslide) that ponds water from impounded drainage
or surface runoff. Also spelled sagpond. SW & [GG]{.underline}

**salt marsh** - Flat, poorly drained area that is subject to periodic
or occasional overflow by salt water, containing water that is brackish
to strongly saline, and usually covered with a thick mat of grassy
halophytic plants; e.g., a coastal marsh periodically flooded by the
sea, or an inland marsh, (or salina) in an arid region and subject to
intermittent overflow by salty water. Compare - tidal marsh, mud flat.
GG

**salt pond** - A large or small body of salt water in a marsh or swamp
along the seacoast. GG

**sand boil** - An accumulation of sand commonly in the form of a low
mound, produced by the expulsion of liquefied sand to the ground
surface; sometimes called sand volcanoes (not preferred). Examples are
found on top of some landslide deposits (i.e. spreads) or on the upper
surface of highly contorted layers of laminated sediments. SW &
[GG]{.underline}

**sand dune -** see dune

**sandur --** (not preferred -- use *outwash plain*).

**sand flow** \[mass movement\] -- a) A flow of wet sand, as along banks
of noncohesive clean sand that is subject to scour and to repeated
fluctuations in pore-water pressure due to rise and fall of the tide. b)
A flow of loose, dry sand, as along the slip face of a sand dune;
typically a microfeature. SW, CV & [GG]{.underline}

**sandhills** - A region of semi-stabilized sand dunes or sandy hills,
either covered with vegetation or bare, as in north-central Nebraska and
the midlands of the Carolinas. [GG]{.underline}

**sand pit** -- A depression, ditch or pit excavated to furnish sand for
roads or other construction purposes off-site; a type of borrow pit. SW

**sand plain** -- (a ) \[geomorphology\] A sand-covered plain, which may
originate by deflation of sand dunes, and whose lower limit of erosion
is governed by the water table. Also spelled *sandplain*.
[GG]{.underline} (b) \[glacial geology\] (not preferred -- refer to
*sandy* outwash plain) A small outwash plain composed chiefly of sand
deposited by meltwater streams flowing from a glacier. [GG]{.underline}

**sand ramp** -- A sand sheet blown up onto the lower slopes of a
bedrock hill or mountain and forming an inclined plane, sometimes
filling small mountain-side valleys and even crossing low passes.
Compare -- climbing dune, sand sheet. [FFP]{.underline} & SW

**sand ridge** - (a) (not preferred) An imprecise, generic name for any
low ridge of sand, formed at some distance from shore, e.g. submerged
(longshore bar) or emergent (barrier beach). (b) One of a series of
long, wide, extremely low, parallel ridges believed to represent the
eroded stumps of former longitudinal sand dunes, as in western Zimbabwe.
[GG]{.underline}

**sand sheet** - A large, irregularly shaped, commonly thin, surficial
mantle of eolian sand, lacking the discernible slip faces that are
common on dunes. [GG]{.underline}

**sand volcano** -- (not preferred) use sand boil.

**sand wedge** - (not preferred) refer to ice wedge cast.

**sandstone** - Sedimentary rock containing dominantly sand-size clastic
particles. HP

**sanitary landfill** -- A land area where municipal solid waste is
buried in a manner engineered to minimize environmental degradation.
Commonly the waste is compacted and ultimately covered with soil or
other earthy material. Compare -- dump. [GG]{.underline}

**saprolite** - Soft, friable, isovolumetrically weathered bedrock that
retains the fabric and structure of the parent rock ([Colman and
Dethier, 1986]{.underline}) and exhibiting extensive inter-crystal and
intra-crystal weathering. In pedology, saprolite was formerly applied to
any unconsolidated residual material underlying the soil and grading to
hard bedrock below. Compare - grus, residuum. SW & [HP]{.underline}

**scabland** - An elevated, flat-lying, basalt-floored area, with little
if any soil cover, sparse vegetation, and usually deep, dry channels
scoured into the surface, especially by glacial meltwaters such as the
Channeled Scablands of eastern Washington. Compare - coulee.
[GG]{.underline}

**scalped area** -- a) A modified slope, feature, or land area where
much or all of the natural soil has been mechanically removed (e.g.
scraped off) due to construction or other management practices. Compare
-- truncated soil. b) A forest soil area where the ground vegetation and
root mat has been removed to expose mineral soil in preparation for
planting or seeding. Compare -- truncated soil. SW

**scarp** - An escarpment, cliff, or steep slope of some extent along
the margin of a plateau, mesa, terrace, or structural bench. A scarp may
be of any height. Compare - escarpment. [GG]{.underline}

**scarp slope** - The relatively steeper face of a cuesta, facing in a
direction opposite to the dip of the strata. Compare - dip slope.
[GG]{.underline}

**scoria** - (a) \[soils\] Vesicular, rock fragments \> 2 mm in at least
one dimension and a specific gravity \> 2.0, or a cindery crust of such
material on the surface of andesitic or basaltic lava; the vesicular
nature is due to the escape of volcanic gases before solidification; it
is usually heavier, darker, and more crystalline than pumice. Compare -
cinder, pumice, tephra; (b) \[geology\] The same as (a) except no size
restrictions are applied. [SW]{.underline}

**scour** \[geomorphology\] - (a) The powerful and concentrated clearing
and digging action of flowing air, water, or ice, especially the
downward erosion by stream water in sweeping away mud and silt on the
outside curve of a bend, or during the time of a flood; a process. (b) A
place in a stream bed swept (scoured) by running water, generally
leaving a gravel bottom. [GG]{.underline}

**scour and fill** \[geomorphology\] -- A *process* of alternate
excavation and refilling of a channel, as by a stream or the tides;
especially such a process occurring in time of flood, when the discharge
and velocity of an aggrading stream are suddenly increased, causing the
digging of new channels that become filled with sediment when the flood
subsides. Compare - cut and fill. [GG]{.underline}

**scree** - A collective term for an accumulation of coarse rock debris
or a sheet of coarse debris mantling a slope. Scree is not a synonym of
talus, as scree includes loose, coarse fragment material on slopes
without cliffs. Compare - talus, colluvium, mass movement.
[HP]{.underline}

**scree slope** -- A portion of a hillside or mountainslope mantled by
scree and lacking an up-slope rockfall source (i.e. cliff). Compare --
talus slope, scree, talus. SW

**scroll** - (not preferred) refer to meander scroll.

**sea** - a) A large inland body of salt water (e.g. the Sultan Sea,
CA). b) A geographic subdivision of an ocean (e.g. the South China Sea).
Compare -- gulf, ocean, salt pond. [GG]{.underline}

**sea cliff** \[coastal\] - A cliff or slope produced by wave erosion,
situated at the seaward edge of the coast or the landward side of the
wave-cut platform. It may vary from an inconspicuous slope to a high,
steep escarpment. GG

**sediment** - Material, both mineral and organic, that is in
suspension, is being transported, or has been moved from its site of
origin by water, wind, ice or mass-wasting and has come to rest on the
earth\'s surface either above or below sea level. Sediment in a broad
sense also includes materials precipitated from solution or emplaced by
explosive volcanism, as well as organic remains; e.g., peat that has not
been subject to appreciable transport. HP

**sedimentary peat** \[Soil Taxonomy\] - An accumulation of organic
material that is predominantly the remains of floating aquatic plants
(e.g. algae) and the remains and fecal material of aquatic animals,
including coprogenous earth. Compare - herbaceous peat, moss peat, woody
peat, peat, muck, and mucky peat. SSM

**sedimentary rock** - A consolidated deposit of clastic particles,
chemical precipitates, or organic remains accumulated at or near the
surface of the earth under \"normal\" low temperature and pressure
conditions. Sedimentary rocks include consolidated equivalents of
alluvium, colluvium, drift, and eolian, lacustrine, marine deposits;
e.g., sandstone, siltstone, mudstone, clay-stone, shale, conglomerate,
limestone, dolomite, coal, etc. Compare - sediment. HP

**seep** - (noun) An area, generally small, where water outflows slowly
at the land surface. Flow rates for seeps are too small to be considered
as springs, but reflow and / or lateral subsurface flow keeps the
surface or near soil saturated during dry periods. SW & [GG]{.underline}

**seif dune** - A large, sharp-crested, elongated, longitudinal (linear)
dune or chain of sand dunes, oriented parallel, rather than transverse
(perpendicular), to the prevailing wind. If unmodified, the crest, in
profile, commonly consists of a succession of curved slip faces produced
by strong, but infrequent cross winds. A seif dune may be as much as 200
m high and from 400 m to more than 100 km long. Compare -- longitudinal
dune. [GG]{.underline} and [HP]{.underline}

**semi-bolson** - (colloquial: western USA) A wide desert basin or
valley that is drained by an intermittent stream, an externally drained
(open) intermontane basin. Compare - bolson [GG]{.underline}

**semi-open depression** -- A topographically enclosed basin that
generally functions as a closed depression and lacks a defined exit
channel. Surface water loss may occur via overland flow through a
topographic low area or gap in response to large storm events. Semi-open
depressions commonly contain small lakes, ponds, or wet meadows
dominated by hydric soils (e.g. in karst valleys, or in low areas on
marine terraces with \< 1 % slopes). SW

**sewage lagoon** -- Any artificial pond or other water-filled
excavation for the natural oxidation of sewage or disposal of animal
manure. [GG]{.underline}

**shale** - Sedimentary rock formed by induration of a clay, silty clay,
or silty clay loam deposit and having the tendency to split into thin
layers, i.e., fissility. HP

**sheep tracks** - (not recommended) use terracettes.

**shield volcano** - A volcano having the shape of a very broad, gently
sloping dome, built by flows of very fluid basaltic lava or rhyolitic
ash flows. Compare - stratovolcano. [GG]{.underline} & [MA]{.underline}

**shoal** - (noun) (a) A relatively shallow place in a stream, lake,
sea, or other body of water; a shallows. (b) A natural, subaqueous
ridge, bank, or bar consisting of, or covered by, sand or other
unconsolidated material, rising from the bed of a body of water (e.g.
estuarine floor) to near the surface. It may be exposed at low water.
Compare - reef. SSS & [GG]{.underline}

**shoal** (relict) - A surficial ridge, bank, or bar consisting of sand
or other subaqueous deposit that has become permanently exposed by the
retreat or lowering of a proglacial lake or other body of water.
Compare - longshore bar \[relict\]. [GG]{.underline}

**shore** -- The narrow strip of land immediately bordering any body of
water, esp. the sea or a large lake; specifically the zone over which
the ground is alternately exposed and covered by tides or waves, or the
zone between high water and low water. GG

**shore complex** -- Generally a narrow, elongate area that parallels a
coastline, commonly cutting across diverse inland landforms, and
dominated by landforms derived from active coastal processes which give
rise to beach ridges, washover fans, beaches, dunes, wave-cut platforms,
barrier islands, cliffs, etc. SW

**shoreline** - The intersection of a specified plane of water with the
beach; it migrates with changes of the tide or of the water level.
Compare - shore complex, beach, swash zone. [GG]{.underline}

**shoulder** - The hillslope profile position that forms the convex,
erosional surface near the top of a hillslope. If present, it comprises
the transition zone from summit to backslope. Compare - summit, crest,
backslope, footslope, and toeslope. SW & [HP]{.underline}

**shrub-coppice dune** - A small, streamlined dune that forms around
brush and clump vegetation. [GG]{.underline}

**side slope** \[geomorphology\] - A geomorphic component of hills
consisting of a laterally planar area of a hillside, resulting in
predominantly parallel overland water flow (e.g., sheet wash); contour
lines generally form straight lines. Side slopes are dominated by
colluvium and slope wash sediments. Slope complexity (downslope shape)
can range from simple to complex. Compare - head slope, nose slope, free
face, interfluve, crest, base slope. SW; The slope bounding a
drainageway and lying between the drainageway and the adjacent
interfluve. It is generally linear along the slope width.
[RR]{.underline}

**sidewall** -- (not preferred) refer to glacial-valley wall.

**sill** \[intrusive rocks\] - A tabular, igneous intrusion that
parallels the bedding or foliation of the surrounding sedimentary or
metamorphic rock. Compare - dike. [GG]{.underline}

**siltite -** A compact, weakly metamorphosed rock formed by alteration
of siltstone, mudstone or silty shale. Siltite is more indurated than
mudstone or shale and lacks either shale fissility or slate-like
cleavage. Siltite differs from argillite in that silt-size grains (0.002
to 0.062 mm) dominate the matrix rather than clay-size particles
(\<0.002 mm). Siltite differs from siltstone, mudstone, or shale in that
it exhibits very low to low grade metamorphic or diagenetic layer
silicate and feldspar alteration to sericite, chlorite, and albite
(subgreenschist to greenschist metamorphic facies) (Maxwell, 1973;
Kidder, 1987). SW

**siltstone** - An indurated silt having the texture and composition of
shale but lacking its fine lamination or fissility; a massive mudstone
in which silt predominates over clay. GG.

**sinkhole** - A closed, circular or elliptical depression, commonly
funnel-shaped, characterized by subsurface drainage and formed either by
dissolution of the surface of underlying bedrock (e.g., limestone,
gypsum, salt) (*solution sinkhole*) or by collapse of underlying caves
within bedrock (*collapse sinkhole*); diameters range from a few meters
to as much as 1000 m. Complexes of sinkholes in carbonate-rock terrain
are the main components of karst topography. Synonym (not preferred) -
doline. Compare -- karst valley, interior valley, cockpit. SW & WW

**sinkhole karst** -- A landscape dominated by subsurface drainage and
sinkholes (dolines) that range widely in sizes and density; the most
common type of karst in **upland areas of** temperate regions (e.g.
Highland Rim of TN, northern FL, southwestern MO, etc.); also called
doline karst (not preferred). Compare -- fluviokarst, pavement karst,
glaciokarst, karst. SW, WW, & [GG]{.underline}

**skid trail** -- Irregularly spaced, roughly linear to radial
depressions or small mounds associated with shallow to deep soil
disturbance caused by dragging logs across a slope from where they were
cut down to a central processing area such as a log landing during
timber harvest operations. SW

**slick rock** - (colloquial: southwestern U.S.A.) A barren, highly
smoothed and subrounded bedrock pavement with considerable, irregular
topography sculpted primarily by wind in an arid climate; a type of rock
outcrop common on the top of massive sandstone bedrock (e.g. Navajo,
Windgate, or Kayenta Formations), especially on summits of ridges and
near the leading edge of plateaus, mesas and cuestas. Compare --
pavement karst. SW

**slackwater** - A quiet part of, or a still body of water in a stream.
Compare - backswamp. [GG]{.underline}

**slickensides \[pedogenic\]** - Shrink-swell produced slip faces on
pedo-structure faces (e.g. wedges, bowls); grooves, striations, glossy
sheen. Most evident in **(but not limited to)** Vertisols. Compare --
slickensides \[geogenic\]. SW

**slickensides \[geogenic\]** - Vertical or oblique, roughly planar slip
face produced by external forces such as tectonics (e.g. fault), or mass
movement (e.g. large slump blocks; grooves, striations on slip face).
Compare -- slickensides \[pedogenic\]. SW

**slide** \[mass movement\] - (a) - A category of mass movement
processes, associated sediments (slide deposit) or resultant landforms
(e.g., rotational slide, translational slide, and snowslide)
characterized by a failure of earth, snow, or rock under shear stress
along one or several surfaces that are either visible or may reasonably
be inferred. The moving mass may or may not be greatly deformed, and
movement may be rotational (rotational slide) or planar (translational
slide). A slide can result from lateral erosion, lateral pressure,
weight of overlying material, accumulation of moisture, earthquakes,
expansion owing to freeze-thaw of water in cracks, regional tilting,
undermining, fire, and human agencies. Compare - fall, topple, lateral
spread, flow, complex landslide. SW & [DV]{.underline} (b) The track of
bare rock or furrowed earth left by a slide. (c) The mass of material
moved in or deposited by a slide. Compare - fall, flow, complex
landslide, landslide. SW & [GG]{.underline}

**slip face** - The steeply sloping surface on the lee side of a dune,
standing at or near the angle of repose of loose sand, and advancing
downwind by a succession of slides wherever that angle is exceeded. GG

**slip surface** -- A landslide displacement surface, often slickensided
and striated, or brecciated, and subplanar. It is best exhibited in
argillaceous materials and in those materials which are highly
susceptible to clay alteration when granulated; also called shear
surface (not preferred). Compare -- main scarp, landslide, escarpment.
[GG]{.underline}

**slope** - (also called slope gradient or gradient) The inclination of
the land surface from the horizontal. Percent slope is the vertical
distance divided by the horizontal distance, then multiplied by 100. SW

**slope alluvium** - Sediment gradually transported down mountain or
hill slopes primarily by non-channel alluvial processes (i.e., slope
wash processes) and characterized by particle sorting. Lateral particle
sorting is evident on long slopes. In a profile sequence, sediments may
be distinguished by differences in size and/or specific gravity of
coarse fragments and may be separated by stone lines. Sorting of rounded
or subrounded pebbles or cobbles and burnished peds distinguish these
materials from unsorted colluvial deposits. Compare -- colluvium, slope
wash. SW & [HP]{.underline}

**slope wash** -- A collective term for non-fluvial, incipient alluvial
*processes* (e.g. overland flow, minor rills) that detach, transport,
and deposit sediments down hill and mountain slopes. Related sediments
(*slope alluvium*) exhibit nominal sorting or rounding of particles,
peds, etc., and lateral sorting downslope on long slopes; stratification
is crude and intermittent and readily destroyed by pedoturbation and
frost action. Also called *slope wash processes*. Compare -- slope
alluvium, colluvium, valley-side alluvium. SW

**slot canyon** -- A long, narrow, deep and tortuous channel or
drainageway with sheer rock walls eroded into sandstone or other
sedimentary rocks, especially in the semi-arid western USA (e.g.
Colorado Plateau); subject to flash flood events; depth to width ratios
exceed 10:1 over most of its length and can approach 100:1; commonly
containing unique ecological communities distinct from the adjacent,
drier uplands. SW

**slough** - (a) A small marsh, especially a marshy area lying in a
local, shallow, closed depression on a piece of dry land, as on the
prairie of the Midwestern U.S.A. (b) A term used, especially in the
Mississippi Valley, for a creek or sluggish body of water in a tidal
flat, flood plain, or coastal marshland. Compare - bayou, oxbow. (c) A
sluggish channel of water, such as a side channel of a river, in which
water flows slowly through low, swampy ground, as along the Columbia
River, or a section of an abandoned river channel which may contain
stagnant water and occurs in a flood plain or delta. (d) (not preferred)
An area of soft, miry, muddy or waterlogged ground, a place of deep mud.
[GG]{.underline}

**sloughed till** - (not recommended) use flow till.

**slump** \[mass movement\] - (a) (not preferred- refer to rotational
slide) A generic, obsolete term for various types of landslides,
especially rotational landslide; the process, associated sediments, or
resultant landform characterized by a slide involving a shearing and
rotary movement of a generally independent mass of rock or earth along a
curved slip surface (concave upward) and about an axis parallel to the
slope from which it descends, and by backward tilting of the mass with
respect to that slope so that the slump surface often exhibits a
reversed slope facing uphill. Compare - rotational slide, slide,
landslide. SW, [GG]{.underline}, & [DV]{.underline}. (b) (not
recommended) refer to rotational slide. An informal term for the
landform or mass of material slipped down during, or produced by a
landslide. [GG]{.underline} & DV

**slump block** - A mass of material torn away as a coherent unit during
a landslide; a largely intact but displaced and commonly reoriented body
of rock or soil. SW & [GG]{.underline}

**slump till** - not recommended; see \"flowtill\"

**snowfield** -- a) A broad expanse of terrain covered with snow,
relatively smooth and uniform in appearance, occurring usually at high
latitudes or in mountainous regions above the snowline and persisting
throughout year. b) A region of permanent snow cover, as at the head of
a glacier; the accumulation area of a glacier. Compare - glacier. GG

**soil creep** - (not preferred) refer to creep.

**soil fall** \[mass movement\] -- The process, associated sediments
(soil fall deposit) or resultant landform characterized by a rapid type
of *fall* involving the relatively free, downslope movement or collapse
of detached, unconsolidated soil material which falls freely through the
air (lacks an underlying slip face); sediments predominantly fine earth
(\< 2 mm); common along undercut stream banks. Also called earth fall,
and (not recommended) debris fall. Compare -- rock fall, debris fall,
topple, landslide. SW

**soil ripples** - (not recommended) use terracettes.

**solifluction** - Slow, viscous downslope flow of water-saturated
regolith. Rates of flow vary widely. The presence of frozen substrate or
even freezing and thawing is not implied in the original definition.
However, one component of solifluction can be creep of frozen ground.
The term is commonly applied to processes operating in both seasonal
frost and permafrost areas. Compare - creep. [NRC]{.underline}

**solifluction deposit** -- A deposit of non-sorted, water-saturated,
earthy material locally derived that is moving or has moved down slope
en masse, caused by the melting of seasonal frost or permafrost. SW

**solifluction lobe** - An isolated tongue-shaped feature up to 25 m
wide and 150 m or more long, formed by rapid solifluction on certain
sections of a slope showing variations in gradient. This feature
commonly has a steep (e.g. 15o - 60o) front and a relatively smooth
upper surface. [NRC]{.underline}

**solifluction sheet** - A broad deposit of nonsorted, water-saturated,
locally derived material that is moving or has moved downslope, en
masse. Stripes are commonly associated with solifluction sheets. Compare
-- stripe. NRC

**solifluction terrace** - A low step with a straight or lobate front,
the latter reflecting local differences in rate of flow. A solifluction
terrace may have bare mineral soil on the upslope part and \'folded
under\' organic matter in both the seasonally thawed and the frozen
soil. NRC

**solution chimney** -- Small diameter (e.g. 1-5 m), irregular, hollow,
vertical shaft 5-10+ m deep on karst landscapes, typically covered with
a thin layer of soil or plant debris that can collapse and expose the
shaft to the surface; represents a significant safety hazard. Locally
called "stove-pipe sinkholes in Florida (not recommended). Compare --
solution pipe. SW

**solution corridor** -- A straight, open trench about 3 to 10 m wide in
a karst area, formed by vertical and lateral solution zones developed
along bedrock fractures; also called (not preferred) bogaz, zanjon
(Puerto Rico). Compare -- cutter, solution fissure, karst valley. SW &
[GG]{.underline}

**solution fissure** -- One of a series of vertical open cracks commonly
\< 0.5 m wide dissolved along joints or fractures, separating limestone
pavement (pavement karst) into blocks (clints); also called kluftkarren
(not preferred). Compare -- cutter, solution corridor, karren. SW,
[GG]{.underline}, & WW

**solution pipe** -- A subsurface, vertical, cylindrical or cone-shaped
hole, formed by dissolution in soluble bedrock (e.g. limestone) and
often without surface expression, that is filled with detrital material
(e.g. soil) and which serves as a bypass route for internal water flow.
SW & GG

**solution platform** -- A broad, nearly horizontal intertidal surface
(modern or relict) formed across carbonate rocks, produced primarily by
solution with contributions by intertidal weathering and biological
erosion and deposition, not by abrasion. Compare -- wave-cut platform.
SW & [GG]{.underline}

**solution sinkhole** -- The most common type of sinkhole, caused by
dissolution that forms fissures or a chimney and a depression in the
bedrock surface which grows when closely spaced fissures underneath it
enlarge and coalesce. Compare -- collapse sinkhole. SW, WW, &
[GG]{.underline}

**solution valley** -- (not preferred) use karst valley.

**sorted circle** - A type of patterned ground whose mesh (shape) is
largely circular and has a sorted appearance commonly due to a border of
coarse fragments surrounding finer material, occurring either singly or
in groups. Diameters range from a few centimeters to more than 10
meters. The coarse fragment border may be 35 cm high and 8 to 12 cm
wide. Compare - patterned ground. [GG]{.underline} and [NRC]{.underline}

**sorted polygon** - refer to patterned ground.

**sound** \[coast\] - a) A relatively long, narrow waterway connecting
two larger bodies of water (as a sea or lake with the ocean or another
sea) or two parts of the same water body, or an arm of the sea forming a
channel between the mainland and an island (e.g. Puget Sound, WA); it is
generally wider and more extensive than a strait \[coast\]. b) A long,
large, rather broad inlet of the ocean, generally extending parallel to
the coast (e.g. Long Island Sound, NY). C) A lagoon along the southeast
coast of the US (e.g. Pamlico Sound, NC). d) A long bay or arm of a
lake; a stretch of water between the mainland and a long island in a
lake. Compare -- sound, lagoon, gulf, ocean. [GG]{.underline}

**spatter cone** - A small, steep-sided cone (e.g., 3 -- 15 m high, or
more) built up on a lava flow, usually pahoehoe, composed of clots of
lava ejected with escaping gases from a vent or fissure which spatters
and congeals as it hits the ground to form a small cone; rougher lava
clots than a spiracle. Compare -- spiracle. SW

**specific gravity -** The ratio of a material's density to that of
water \[ material weight in air ÷ (weight in air - weight in water)\].
Used to differentiate different kinds of volcaniclastics and other
materials. SW

**spiracle** \[volcanic\] -- A small tubular opening or chimney formed
by fluid lava congealing and mounding around a fumarolic vent in a
basaltic lava flow, usually about 1 m in diameter and up to 5 m high,
although in the northwestern USA where spiracles are common they
generally are 10 m in diameter and 12 m high or more; formed by a
gaseous explosion in lava that is still fluid, probably due to steam
generated from underlying wet material; smoother lava clots and drapes
than a spatter cone. Compare -- spatter cone. SW, [GS]{.underline}, &
[GG]{.underline}

**spit** - (a) A small point or low tongue or narrow embankment of land,
commonly consisting of sand or gravel deposited by longshore transport
and having one end attached to the mainland and the other terminating in
open water, usually the sea; a finger-like extension of the beach. (b) A
relatively long, narrow shoal or reef extending from the shore into a
body of water. GG

**splay** - (not preferred) refer to flood-plain splay.

**spoil bank** - **A** bank, mound, or other artificial accumulation of
rock debris and earthy dump deposits removed from ditches, strip mines,
or other excavations. Compare -- dredge spoil bank. SW

**spoil pile** -- (a) A bank, mound, or other artificial accumulation
composed of spoil; e.g., an embankment of earthy material removed from a
ditch and deposited alongside it. Compare -- dredge spoil bank. (b) A
pile of refuse material from an excavation or mining operation; e.g., a
pile of dirt removed from, and stacked at the surface of a mine in a
conical heap or in layers. SW & [GG]{.underline}

**sporadic permafrost** - The area near the southern boundary of
discontinuous permafrost where permafrost occurs in isolated patches or
islands. Compare - continuous permafrost, discontinuous permafrost.
[NRC]{.underline}

**spread** -- see lateral spread

**spur** \[geomorphology\] - A subordinate ridge or lesser elevation
that projects sharply from the crest or side of a hill, mountain, or
other prominent range of hills or mountains. GG

**spur ridge** - (not recommended) use spur.

**stack** \[coast\] -- An isolated pillar-like rocky island or mass near
a cliffy shore, detached from a headland by wave erosion assisted by
weathering; especially one showing columnar structure with horizontal
stratification. Examples occur along the Oregon coast and the Lake
Superior shore. SW & [GG]{.underline}

**stack** \[geom\] -- A steep-sided mass of rock rising above its
surroundings on all sides from a slope or hill. Compare -- knob. GG

**stagnant ice** - (a) Glacial ice that is not flowing forward and is
not receiving material from an accumulation area; (b) Detached blocks of
ice left behind by a retreating glacier, usually buried in a moraine and
melting very slowly. [GG]{.underline}

**star dune** -- A large, isolated sand dune whose base, in plan view,
resembles a star, with sharp-crested ridges converging from basal points
to a central peak that may be as high as 100 m above the surrounding
plain. It tends to remain fixed for centuries in an area where the wind
blows from all directions. Compare -- dune. [GG]{.underline}

**State Physiographic Area -** An area of relatively local extent and
whose parts are similar in geologic structure and climate and which has
consequently had a unified geomorphic history, and whose pattern of
relief or landforms differ significantly from that of adjacent areas;
i.e. a subset within a Physiographic Section. *\[ The fourth highest
level in the Physiographic Location part of the Geomorphic Description
System\].* SW & NASIS Data Dictionary

**steptoe** - An island-like area of older rock surrounded by a lava
flow. Compare - kipuka. [HP]{.underline}

**stock** -- A relatively small, concordant and / or discordant plutonic
rock body exposed at the land surface, with an aerial extent \< 40 sq.
mi. (100 km^2^) and no known bottom. Compare -- batholith.
[GG]{.underline}

**stone line** - In vertical cross-section, a line formed by scattered
fragments or a discrete layer of angular and subangular rock fragments,
commonly a gravel- or cobble-sized lag concentration that drape across a
former topographic surface and later buried by additional sediments. A
stone line generally caps material that was subject to weathering, soil
formation, and erosion before burial. Many stone lines seem to be buried
erosion pavements, originally formed by sheet and rill erosion across
the land surface. It can best be observed as outcrops in natural and
artificial cuts. Also called a carpedolith. Compare - erosional
pavement, desert pavement. SW & RR

**stone net** - (not preferred) refer to patterned ground. Synonym -
sorted polygon, stone polygon.

**storm surge** - An abnormal, sudden rise of sea level along an open
coast during a storm, caused primarily by onshore-wind stresses, or less
frequently by atmospheric pressure reduction, resulting in water piled
up against the coast. It is most severe when accompanied by a high tide.
GG

**strait** \[coast\] -- A relatively narrow waterway connecting two
larger bodies of water, as the Straits of Mackinac linking Lake Michigan
and Lake Huron; a large channel. Compare -- sound. [GG]{.underline}

**strandline** - (a) The shoreline, especially a former (relict)
shoreline now elevated above the present water level, that commonly
appears as a bench or line wrapping around the landscape at a common
elevation. SW (b) A beach, especially one raised above the present sea
or lake level. [GG]{.underline}

**strand plain** - A prograded shore built seaward by waves and
currents, and continuous for some distance along the coast. It is
characterized by subparallel beach ridges and swales, in places with
associated dunes. GG

**strath terrace** - A type of stream terrace, formed as an erosional
surface cut on bedrock and thinly mantled (e.g. \< 3 m) with stream
deposits (alluvium), commonly with a gravel lag deposit immediately
above the bedrock. SW & [GG]{.underline}

**stratified** - (adjective) Formed, arranged, or laid down in layers.
The term refers to geologic deposits. Layers in soils that result from
the processes of soil formation are called horizons; those inherited
from the parent material are called strata. [HP]{.underline}

**stratigraphy** - The branch of geology that deals with the definition
and interpretation of layered earth materials; the conditions of their
formation; their character, arrangement, sequence, age, and
distribution; and especially their correlation by the use of fossils and
other means. The term is applied both to the sum of the characteristics
listed and a study of these characteristics. [HP]{.underline}

**stratovolcano** - A volcano that is constructed of alternating layers
of lava and pyroclastic deposits, along with abundant dikes and sills.
Viscous, acidic lava may flow from fissures radiating from a central
vent, from which pyroclastics are ejected. Compare - shield volcano. GG

**stream** - (a) Any body of running water that moves under gravity to
progressively lower levels, in a relatively narrow but clearly defined
channel on the ground surface, in a subterranean cavern, or beneath or
in a glacier. It is a mixture of water and dissolved, suspended, or
entrained matter. (b) A term used in quantitative geomorphology
interchangeably with channel. Compare - river. [GG]{.underline}

**stream channel** - (not preferred) refer to channel.

**stream order** - An integer system applied to tributaries (stream
segments) that documents their relative position within a drainage basin
network as determined by the pattern of its confluences. The order of
the drainage basin is determined by the highest integer. Several systems
exist. In the Strahler system, the smallest unbranched tributaries are
designated order 1; the confluence of two first-order streams produces a
stream segment of order 2; the junction of two second-order streams
produces a stream segment of order 3, etc. [GG]{.underline}

**stream terrace** - One, or a series of flat-topped landforms in a
stream valley that flank and are parallel to the stream channel,
originally formed by a previous stream level, and representing remnants
of an abandoned flood plain, stream bed, or valley floor produced during
a past state of fluvial erosion or deposition (i.e., currently very
rarely or never flooded; inactive cut and fill and/or scour and fill
processes). Erosional surfaces cut into bedrock and thinly mantled with
stream deposits (alluvium) are called \"strath terraces.\" Remnants of
constructional valley floors thickly mantled with alluvium are called
alluvial terraces. Compare - alluvial terrace, flood-plain step, strath
terrace, terrace. [HP]{.underline} & SW

**strike** \[structural geol.\] -- The compass direction or trend taken
by a structural surface (e.g. a bed or fault plane) as it intersects the
horizontal; used in combination with "dip" to describe the orientation
of bedrock strata. SW & GG

**strike valle**y -- A subsequent valley eroded in, and developed
parallel to the strike of, underlying weak strata, such as a cuesta; a
valley that commonly, but not necessarily contains a stream valley. SW &
[GG]{.underline}

**string bog** - A peatland with rough**ly** parallel**,** narrow ridges
of peat dominated by peat vegetation interspersed with slight
depressions, many of which contain shallow pools. The ridges are at
right angles to low (\< 2o) slopes. They are typically 1 to 3 m wide, up
to 1 m high and may be over 1 km long. The ridges are slightly elevated
and are better drained allowing shrubs and trees to grow. They are best
developed in areas of discontinuous permafrost. [NRC]{.underline}

**stripe** - A type of patterned ground; one of the alternating bands of
fine and coarse surface material, or of rock or soil and
vegetation-covered ground, commonly found on steeper slopes. It is
usually straight, but may be sinuous or branching. Compare - patterned
ground. [GG]{.underline}

**stoss** -- (adj.) Said of the side of the hill or knob that faces the
direction from which an advancing glacier or ice-sheet moved; facing the
upstream ("up-ice") side of a glacier, and most exposed to its abrasive
action. Compare -- lee, stoss and lee, crag and tail. [GG]{.underline}

**stoss and lee** -- An arrangement of small hills or prominent rocks,
in a strongly glaciated area, having gentle slopes on the stoss
("up-ice") side and somewhat steeper, plucked slopes on the lee
("down-ice") side. This arrangement is the opposite of crag and tail.
Compare -- crag and tail, drumlin, drumlinoid ridge, flute.
[GG]{.underline}

**structural back slope** - (not recommended) use dip slope.

**structural bench** - A platform-like, nearly level to gently inclined
erosional surface developed on resistant strata in areas where valleys
are cut in alternating strong and weak layers with an essentially
horizontal attitude. Structural benches are bedrock controlled, and in
contrast to stream terraces, have no geomorphic implication of former,
partial erosion cycles and base-level controls, nor do they represent a
stage of flood-plain development following an episode of valley
trenching. Compare - pediment, ledge; see scarp. [HP]{.underline}

**subaerial** - (adjective) Said of conditions and processes, such as
erosion, that exist or operate in the open air on or immediately
adjacent to the land surface; or of features and materials, such as
eolian deposits, that are formed or situated on the land surface.
Compare -- subaqueous. [GG]{.underline}

**subaqueous** -- (adjective) Said of conditions and processes, features
or deposits, that exist or operate in or under water. Compare --
subaerial. SSS & [GG]{.underline}

**subaqueous landscapes** - Permanently submerged areas that are
fundamentally the same as subaerial (terrestrial) systems in that they
have a discernable topography composed of mappable, subaqueous
landforms. SSS

**subaqueous soils** - Soils that form in sediment found in shallow,
permanently flooded environments. Excluded from the definition of these
soils are any areas "permanently covered by water too deep (typically
greater than 2.5 m) for the growth of rooted plants". SSS

**subglacial** - (a) Formed or accumulated in or by the bottom parts of
a glacier or ice sheet; said of meltwater streams, till, moraine, etc.
(b) Pertaining to the area immediately beneath a glacier, as subglacial
eruption or subglacial drainage. GG

**subglacial melt-out till** - (not preferred) refer to till.

**subglacial till** -- Till deposited in or by the bottom parts of a
glacier or ice sheet; types include lodgment till, subglacial flow till;
synonym (not preferred; obsolete): basal till. SW & GM

**submerged-upland tidal marsh** -- An extensive nearly level,
intertidal landform composed of unconsolidated sediments (clays, silts,
and/or sand and organic materials), a resistant root mat, vegetated
dominantly by hydrophytic (water loving) plants. The mineral sediments
largely retain pedogenic horizonation and morphology (e.g. argillic
horizons) developed under subaerial conditions prior to submergence due
to sea level rise; a type of tidal marsh. Compare -- tidal marsh. SW

> **submerged back-barrier beach** - A permanently submerged extension
> of the back-barrier beach that generally parallels the boundary
> between estuary and the barrier island. Compare -- submerged mainland
> beach, barrier beach. SSS
>
> **submerged mainland beach** - A permanently submerged extension of
> the mainland beach that generally parallels the boundary between an
> estuary or lagoon and the mainland. Compare -- submerged back-barrier
> beach, barrier beach. SSS
>
> **submerged point bar** \[coastal\] - The submerged extension of an
> exposed (subaerial) point bar. SSS
>
> **submerged wave-built terrace** - A subaqueous, relict depositional
> landform originally constructed by river or longshore sediment
> deposits along the outer edge of a wave-cut platform and later
> submerged by rising sea level or subsiding land surface. Compare wave
> -- built terrace, wave-cut platform. [GG]{.underline}

**submerged wave-cut platform** - A subaqueous, relict erosional
landform that originally formed as a wave-cut bench and abrasion
platform from coastal wave erosion and later submerged by rising sea
level or subsiding land surface. Compare -- wave-built terrace, wave-cut
platform. [GG]{.underline}

**subtidal - (adjective)** -- Continuous submergence of substrate in an
estuarine or marine ecosystem; these areas are below the mean low tide.
Compare -- intertidal. SSS & [CC]{.underline}

**subtidal wetlands -** Permanently inundated areas within estuaries
dominated by subaqueous soils and submerged aquatic vegetation. SSS

**summit** - (a) The topographically highest position of a hillslope
profile with a nearly level (planar or only slightly convex) surface.
Compare - shoulder, backslope, footslope, and toeslope, crest. (b) A
general term for the top, or highest area of a landform such as a hill,
mountain, or tableland. It usually refers to a high interfluve area of
relatively gentle slope that is flanked by steeper slopes, e.g.,
mountain fronts or tableland escarpments. [HP]{.underline}

**superglacial** - (not recommended) refer to supraglacial.

**supraglacial** - Carried upon, deposited from, or pertaining to the
top surface of a glacier or ice sheet; said of meltwater streams, till,
drift, etc. GG

**supraglacial debris-flow sediment** - (not preferred) refer to
\"till\"

**supraglacial melt-out till** - (not preferred) refer to \"till\"

**supraglacial till** - (not preferred) refer to ablation till.

**surface mine -** A depression, open to the sky, resulting from the
surface extraction of earthy material (e.g. soil / fill) or bedrock
material (e.g. coal). Compare -- borrow pit, openpit mine, quarry. SW

**swale** - (a) A shallow, open depression in unconsolidated materials
which lacks a defined channel but can funnel overland or subsurface flow
into a drainageway. Soils in swales tend to be moister and thicker
(cumulic) compared to surrounding soils. SW (b) A small, shallow,
typically closed depression in an undulating ground moraine formed by
uneven glacial deposition; Compare - swell-and-swale topography. (c)
(not preferred; refer to interdune) A long, narrow, generally shallow,
trough-like depression between two beach ridges, and aligned roughly
parallel to the coastline. [GG]{.underline}

**swallow hole -** A closed depression or doline into which all or part
of a stream disappears underground. GG

**swamp** - An area of low, saturated ground, intermittently or
permanently covered with water, and predominantly vegetated by shrubs
and trees, with or without the accumulation of peat. Compare - marsh,
bog, fen. [GG]{.underline}

**swash zone** - The sloping part of the beach that is alternately
covered and uncovered by the uprush of waves, and where longshore
movement of water occurs in a zigzag (upslope-downslope) manner. Compare
-- shoreline. GG

**swell** - (not recommended) refer to swell-and-swale topography.

**swell and swale topography** -- A local scale topography composed of
small, well-rounded hillocks and shallow, closed depressions irregularly
spaced across low-relief ground moraine (slopes generally 2 -- 6%); the
effect is a subdued, irregularly undulating surface that is common on
ground moraines. Micro-elevational differences generally range from \< 1
to \< 5 m. SW

**syncline -** (a) \[landform\] A unit of folded strata that is concave
upward whose core contains the stratigraphically younger rocks, and
occurs at the earth's surface. In a single syncline, beds forming the
opposing limbs of the fold dip toward its axial plane. Compare -
monocline, syncline, fold. SW & [HP]{.underline} (b) \[structural
geology\] A fold, at any depth, generally concave upward whose core
contains the stratigraphically younger rocks. [GG]{.underline}

**tableland** - A general term for a broad upland mass with nearly level
or undulating summit area of large extent and steep side slopes
descending to surrounding lowlands (e.g. a large plateau). Compare -
plateau, mesa, cuesta. [HP]{.underline}

**talf** \[geomorphology\] - A geomorphic component of flat plains
(e.g., lake plain, low coastal plain, low-gradient till plain)
consisting of an essentially flat (e.g. 0-1 % slopes) and broad area
dominated by closed depressions and a non-integrated or poorly
integrated drainage system. Precipitation tends to pond locally and
lateral transport is slow both above and below ground, which favors the
accumulation of soil organic matter and a retention of fine earth
sediments; better drained soils are commonly adjacent to drainageways.
Compare - rise. SW

**talus** - Rock fragments of any size or shape (usually coarse and
angular) derived from and lying at the base of a cliff or very steep
rock slope. The accumulated mass of such loose broken rock formed
chiefly by falling, rolling, or sliding. Compare - talus slope,
colluvium, mass movement, scree. [GG]{.underline}

**talus cone** -- A steep (e.g. 30 - 40º), cone-shaped landform at the
base of a cliff or escarpment that heads in a relatively small declivity
or ravine, and composed of poorly sorted rock and soil debris that has
accumulated primarily by episodic rockfall or, to a lesser degree, by
slope wash. Finest material tends to be concentrated at the apex of the
cone. Not to be confused with an *alluvial cone*; a similar feature but
of fluvial origin, composed of better stratified and more sorted
material, and that tapers up into a more extensive drainageway. Compare
-- alluvial cone, beveled base, talus slope. SW

**talus slope** -- a portion of a hillslope or mountainslope mantled by
talus and lying below a rockfall source (e.g. cliff). Compare -- scree
slope, scree, talus. Compare -- beveled base. SW

**tank** - (colloquial: southwestern USA) A natural depression or cavity
in impervious rocks in which water collects and remains for the greater
part of the year. [GG]{.underline}

**tarn** -- A relatively deep, steep-banked lake or pool occupying an
ice-gouged rock basin amid glaciated mountains. A cirque lake.
[GG]{.underline}

**tephra** - A collective, general term for any and all clastic
materials, regardless of size or composition, ejected from a vent during
a volcanic eruption and transported through the air; including ash
\[volcanic; **\<** 2 mm\], blocks \[volcanic; \> 64 mm\], cinders
\[volcanic; 2 -- 64 mm\], lapilli \[2 - 76 mm & specific gravity \>
2.0\], pumice \[\> 2 mm & specific gravity \< 1.0\], and scoria \[\> 2
mm & specific gravity \< 2.0\]. Tephra, unlike many volcaniclastic
terms, does not denote properties of composition, vesicularity, or grain
size. SW

**terminal moraine** - An end moraine that marks the farthest advance of
a glacier and usually has the form of a massive arcuate or concentric
ridge, or complex of ridges, underlain by till and other drift types.
Compare - end moraine, recessional moraine, ground moraine.
[HP]{.underline} and [GG]{.underline}

**terrace** \[geomorphology\] - A step-like surface, bordering a valley
floor or shoreline, that represents the former position of a flood
plain, or lake or sea shore. The term is usually applied to both the
relatively flat summit surface (tread), cut or built by stream or wave
action, and the steeper descending slope (scarp, riser), graded to a
lower base level of erosion. Compare - stream terrace, flood-plain step.
HP. \[ soil survey\] Practically, terraces are considered to be
generally flat alluvial areas above the 100 yr. flood stage. SW

**terrace slope** - not recommended, use riser

**terracettes** - Small, irregular step-like forms on steep hillslopes,
especially in pasture, formed by creep or erosion of surficial materials
that may be induced or enhanced by trampling of livestock such as sheep
or cattle. Synonyms (not preferred) - catstep, sheep or cattle track.
[HP]{.underline}

**terrain** - A generic name for a tract or region of the Earth\'s
surface considered as a physical feature, an ecological environment, or
a site of some planned human activity. [GG]{.underline}

**Tertiary** - A period of the Cenozoic Era of geologic time (from 65 to
1.6 million years ago). The Tertiary epoch/series subdivisions comprise,
by increasing age, the Pliocene, Miocene, Oligocene, Eocene, and
Paleocene. HP

**thalweg** \[geomorphology\] - The line of continuous, maximum descent
from any point on a land surface; e.g., the line connecting the lowest
points along the bed of a stream, or the line crossing all contour lines
at right angles. [GG]{.underline}

**thaw-sensitive permafrost** - Perennially frozen ground which, upon
thawing, will experience significant thaw settlement and suffer loss of
strength to a value significantly lower than that for similar material
in an unfrozen condition. Compare - thaw-stable permafrost. NRC

**thaw-stable permafrost** - Perennially frozen ground which, upon
thawing, will not experience either significant thaw settlement or loss
of strength. Compare - thaw-sensitive permafrost. NRC

**thermokarst** - Karst-like topographic features produced in a
permafrost region by local melting of ground ice and subsequent settling
of the ground. GG

**thermokarst depression** - A hollow in the ground resulting from
subsidence following the local melting of ground ice in a permafrost
region. [GG]{.underline}

**thermokarst** **drainage pattern** -- Drainage patterns that form
polygonal and hexagonal shapes with streams that may connect rounded
depressions, exhibiting a beaded appearance; developed in poorly
drained, fine-grained sediments and in organic materials in regions of
permafrost. Freezing causes many cracks to develop; thawing causes
slumping, settlement, and depressions. This type of drainage pattern
with its associated hexagons and beaded ponds indicates the existence or
previous presence of permafrost conditions. SW, [WA]{.underline}

**thermokarst lake** - Lake or pond produced in a permafrost region by
melting of ground ice. HP

**tidal flat** - An extensive, nearly horizontal, barren or sparsely
vegetated tract of land that is alternately covered and uncovered by the
tide, and consists of unconsolidated sediment (mostly clays, silts
and/or sands and organic materials). Compare -- tidal marsh**,**
wind-tidal flat. [GG]{.underline}

**tidal inlet** - Any inlet through which water alternately floods
landward with the rising tide and ebbs seaward with the falling tide.
Compare -- inlet, relict tidal inlet. [GG]{.underline}

**tidal marsh** -- An extensive, nearly level marsh bordering a coast
(as in a shallow lagoon, sheltered bay or estuary) and regularly
inundated by high tides; formed mostly of unconsolidated sediments (e.g.
clays, silts, and/or sands and organic materials), and the resistant
root mat of salt tolerant plants; a marshy tidal flat. Compare -- tidal
flat. SW & [GG]{.underline}

**till** \[glacial\] - Dominantly unsorted and unstratified drift,
generally unconsolidated and deposited directly by a glacier without
subsequent reworking by meltwater, and consisting of a heterogeneous
mixture of clay, silt, sand, gravel, stones, and boulders; rock
fragments of various lithologies are imbedded within a finer matrix that
can range from clay to sandy loam. Compare - ablation till, basal till,
flowtill, lodgment till, drift, moraine. SW & [GG]{.underline}

**till-floored lake plain** -- \[soil survey\] The floor of an extinct
glacial lake where a thin (e.g. \< 2 m), often discontinuous veneer of
lacustrine sediments overlies till. Commonly its topography reflects the
underlying, irregular or undulating till surface rather than a
distinctive, flat, lake plain surface. It may include subdued,
till-capped topographic highs, ringed by shore deposits or strandlines,
which were once emergent islands. Compare -- reworked lake plain. SW

**till plain** -- An extensive, flat to gently undulating area underlain
predominantly by till and bounded on the distal end by subordinate
recessional or end moraines. Compare -- till, ground moraine. SW

**tilted fault block** - A fault block that has become tilted, perhaps
by rotation on a hinge line (fault). Compare - fault-line scarp. GG

**toe** \[mass movement\] -- The lowest, usually curved margin of
displaced material of a landslide, most distant from the main scarp.
Commonly it has an irregular surface that has ripples and may be
breached by radial cracks or gaps. Compare -- main scarp, minor scarp.
[CV]{.underline} & SW

**toeslope** - The hillslope position that forms the gently inclined
surface at the base of a hillslope. Toeslopes in profile are commonly
gentle and linear, and are constructional surfaces forming the lower
part of a hill-slope continuum that grades to valley or
closed-depression floors. Compare - summit, shoulder, backslope,
footslope, valley floor. [HP]{.underline}

**tombolo** - A sand or gravel bar or barrier that connects an island
with the mainland or with another island. GG

**topography** - The relative position and elevations of the natural or
manmade features of an area that describe the configuration of its
surface. HP

**topple** \[mass movement\] -- A category of processes, associated
sediments (topple deposit) or resultant landforms characterized by a
localized, very rapid type of fall in which large blocks of soil or rock
literally fall over, rotating outward over a low pivot point. Portions
of the original material may remain intact, although reoriented, within
the resulting debris pile. Types of topples can be specified based on
the dominant particle size of sediments (i.e. debris topple, soil
topple, rock topple. Compare -- fall, flow, slide, spread, complex
landslide, landslide. SW & [DV]{.underline}

**tor** - A high, isolated pinnacle, or rocky peak; or a pile of rocks,
much-jointed and usually granitic, exposed to intense weathering, and
often assuming peculiar or fantastic shapes. GG

**Toreva block** -- A slump block consisting of a single large mass of
unjostled material which, during descent, has undergone a backward
rotation toward the parent cliff along a horizontal axis that roughly
parallels it; a type of rotational landslide. The unit forms a crude,
elongated rectangular block rather than a bowl shape or chaotic mass;
typically associated with horizontal to gently dipping, interbedded
bedrock (e.g. Black Mesa area, NM). SW, [GG]{.underline}, &
[RF]{.underline}

**tower k**ar**st --** (a) A type of tropical karst topography
characterized by isolated, steep-sided, residual limestone hills or
ridges with vertical or near-vertical walls, and may be relatively
flat-topped; commonly surrounded by a flat alluvial plain or lagoons.
(Also called *fenglin*). (b) A cluster of peaks or ridges with vertical
or near-vertical walls, and convex upper side slopes where towers rise
from a common base and are separated by deep, rugged ravines or large
sinkholes. (Also called fengcong, turmkarst). Compare -- karst tower,
cockpit karst, cone karst, fluviokarst, kegel karst, sinkhole karst. SW
& [GG]{.underline}

**translational debris slide** \[mass movement\] -- The process,
associated sediments (translational debris slide deposit) or resultant
landform characterized by an extremely slow to moderately rapid type of
slide, composed of comparatively dry and largely unconsolidated earthy
material, portions or blocks of which remain largely intact and in which
movement occurs along a well-defined, planar slip face roughly parallel
to the ground surface and resulting in lateral displacement but no
rotation of the displaced mass; sediments have substantial proportions
of both fine earth and coarse fragments. The landform may be single,
successive (repeated up and down slope), or multiple (as the number of
slide components increase). Compare -- translational earth slide,
translational rock slide, rotational slide lateral spread, landslide. SW
& [DV]{.underline}

**translational earth slide** \[mass movement\] -- The process,
associated sediments (translational earth slide deposit) or resultant
landform characterized by an extremely slow to moderately rapid type of
slide, composed of comparatively dry and largely unconsolidated earthy
material, portions or blocks of which remain largely intact and in which
movement occurs along a well-defined, planar slip face roughly parallel
to the ground surface and resulting in lateral displacement but no
rotation of the displaced mass; sediments predominantly fine earth (\< 2
mm). The landform may be single, successive (repeated up and down
slope), or multiple (as the number of slide components increase).
Compare translational debris slide, translational rock slide, rotational
slide, lateral spread, landslide. SW & [DV]{.underline}

**translational rock slide** \[mass movement\] -- The process,
associated sediments (translational rock slide deposit) or resultant
landform characterized by an extremely slow to moderately rapid type of
slide, composed of comparatively dry and largely consolidated rock
bodies, portions or blocks of which remain largely intact and in which
movement occurs along a well-defined, planar slip face roughly parallel
to the ground surface and resulting in lateral displacement but no
rotation of the displaced mass; sediments predominantly fine earth (\< 2
mm). The landform may be single, successive (repeated up and down
slope), or multiple (as the number of slide components increase).
Compare translational debris slide, translational earth slide,
rotational slide, lateral spread, landslide. SW & [DV]{.underline}

**translational slide** **-** A category of mass movement processes,
associated sediments (translational slide deposit) or resultant
landforms characterized by the extremely slow to moderately rapid
downslope displacement of comparatively dry soil-rock material on a
surface (slip face) that is roughly parallel to the general ground
surface, in contrast to falls, topples, and rotational slides. The term
includes such diverse *slide* types as translational debris slides,
translational earth slide, translational rock slide, block glides, and
slab or flake slides. . Compare - rotational slide, slide, landslide.
SW, [DV,]{.underline} [GG]{.underline}

**transverse dune** - A very asymmetric sand dune elongated
perpendicular to the prevailing wind direction, having a gentle windward
slope and a steep leeward slope standing at or near the angle of repose
of sand; it generally forms in areas of sparse vegetation. Compare --
longitudinal dune. [GG]{.underline}

**tread** \[geomorphology\] - A geomorphic component of terraces,
flood-plain steps, and other stepped landforms consisting of the flat to
gently sloping, topmost and laterally extensive slope. Commonly a
recurring part of a series of natural, step-like landforms such as
successive stream terraces. It's characteristic shape and alluvial
sediment composition is derived from the cut and fill processes of a
fluvial system. Compare - riser. SW

**tree-throw** -- (not preferred) see tree-tip, tree-tip mound, tree-tip
pit.

**tree-tip** -- The process of uprooting and tipping over of trees by
strong winds, commonly resulting in a small depression from which the
root-ball is displaced and an adjacent mound from the sediments
subsequently sloughed from the root ball. Most prevalent in shallow
forested soils over a restrictive layer (e.g. bedrock); also called
tree-throw, windthrow. Compare -- tree-tip mound, tree-tip pit. SW

**tree-tip mound** - The small mound of debris sloughed from the root
plate (root ball) of a tipped-over tree. Sometimes called a cradle knoll
(not recommended). Local soil horizons are commonly obliterated and
result in heterogeneous strata. Compare - tree-tip pit. SW &
[BHM]{.underline}.

**tree-tip pit** - The small pit or depression resulting from an area
vacated by the root plate (ball) resulting from tree-tip
(\"tree-throw\"). Such pits are commonly adjacent to small mounds
composed of the displaced material. Subsequent infilling commonly
results in a heterogeneous soil matrix that may or may not include a
stone line that lines the depression. Compare - tree-tip mound. SW &
[BHM]{.underline}.

**tree-tip pit and mound topography** -- A local-scale topography
composed of irregularly spaced, small, closed depressions and adjacent
mounds caused by the displacement of root balls from trees knocked down
by wind (i.e., tree-tip; also called tree-throw). The result is a
subdued, irregularly pock-marked or undulating surface; most common in
forested areas overlying shallow rooting conditions (e.g., lithic
contact, water table, etc). Micro-elevational differences generally
range from 0.5 to \< 2 m. Sometimes also referred to as (not preferred:)
*cradle and knoll*, or *pit and mound* topography. Compare -- tree-tip
mound, tree-tip pit. SW

**trellis** **drainage pattern** -- A drainage pattern characterized by
parallel main streams intersected at, or nearly at, right angles by
their tributaries, which in turn are fed by elongated secondary
tributaries and short gullies parallel to the main streams, resembling,
in plan view, the stems of a vine on a trellis. This pattern indicates
marked bedrock structural control rather than a type of bedrock and
usually indicates in which the main parallel channels follow the strike
of the beds. It is commonly developed where the beveled edges of
alternating hard and soft rocks outcrop in parallel belts, as in titled,
interbedded sedimentary rocks in a rejuvenated folded-mountain region or
in a maturely dissected belted coastal plain of tilted strata. SW,
[GG]{.underline}, [WA]{.underline}

**tripoli** -- A light-colored, porous, friable, siliceous (largely
chalcedonic) sedimentary rock, which occurs in powdery or earthy masses
that result from the weathering of siliceous limestone. It has a harsh,
rough feel and is used to polish metals and stones. [GG]{.underline}

**trough** \[geomorphology\] - (a) Any long, narrow depression in the
earth\'s surface, such as one between hills or with no surface outlet
for drainage. (b) (not preferred -- see U-shaped valley, mountain
valley) A broad, elongate U-shaped valley, such as a glacial trough.
Compare - U-shaped valley. [GG]{.underline}

**trough bottom** -- (not preferred) refer to glacial-valley floor.

**trough end** - (not recommended - refer to cirque, cove). The steep,
semicircular rock wall forming the abrupt head or end of a U-shaped
valley. Compare - headwall. [GG]{.underline}

**trough valley** - (not preferred) refer to U-shaped valley.

**trough wall** - (not preferred) refer to glacial-valley wall.

**truncated soil** -- Soil that has had part or all of the upper soil
horizon(s) removed by erosion, excavation, etc. Compare -- scalped area.
SW & [GSST]{.underline}

**tuff** - A generic term for any consolidated or cemented deposit that
is **≥** 50 percent volcanic ash (\< 2 mm); various types of tuff can be
recognized based on composition: acidic tuff is predominantly composed
of acidic particles; basic tuff is predominantly composed of basic
particles. SW

**tumulus** (pl. tumuli) -- A small dome or mound on the surface of a
lava flow formed by the buckling of the congealing crust near the edge
of a flow caused by differences in flow rates of the cooler crust above
and the hotter, more fluid lava below. Dimensions commonly range from \<
1 m to 5 m in height, 3 to 10 m in width and 30 to 40 m in length. Some
tumuli are hollow. Compare -- pressure ridge \[volcanic\]. SW,
[GG]{.underline}, and [GS]{.underline}

**tunnel valley** - A relatively shallow trench or depression cut into
drift and other loose material, or in bedrock, by a subglacial stream
not loaded with coarse sediment that may or may not be part of the
present day drainage pattern. [GG]{.underline}

**tunnel-valley lake** -- A glacial lake occupying a portion of a tunnel
valley. [GG]{.underline}

**turf hummock** - A hummock consisting of vegetation and organic matter
with or without a core of mineral soil or stones. Compare - earth
hummock, non-sorted circle, patterned ground. NRC

**unconformity** - A substantial break or gap in the geologic record
where a unit is overlain by another that is not in stratigraphic
succession. Compare -- conformity, discontinuity. GG

**underfit stream** - A stream that appears to be too small to have
eroded the valley in which it flows; a stream whose volume is greatly
reduced or whose meanders show a pronounced shrinkage in radius. It is a
common result of drainage changes effected by capture, glaciers, or
climatic variations. GG

**upland** \[geomorphology\] - An informal, general term for (a) the
higher ground of a region, in contrast with a low-lying, adjacent land
such as a valley or plain. (b) Land at a higher elevation than the flood
plain or low stream terrace; land above the footslope zone of the
hillslope continuum. Compare - lowland. [HP]{.underline} &
[GG]{.underline}

**uplift** \[tectonic\] - A structurally high area in the earth\'s
crust, produced by positive movements that raise or upthrust the rocks,
as in a dome or arch. GG

**upthrust** - (a) An upheaval of rock; said preferably of a violent
upheaval. (b) A high angle gravity or thrust fault in which the
relatively upthrown side was the active (moving) element. HP

**U-shaped valley** - A valley having a pronounced parabolic cross
profile suggesting the form of a broad letter \"U\", with steep walls
and a broad, nearly flat floor; specifically a valley carved by glacial
erosion.\
Compare - V-shaped valley. GG

**uvala** -- (not preferred) refer to karst valley.

**valley** - An elongate, relatively large, externally drained
depression of the Earth\'s surface that is primarily developed by stream
erosion or glacial activity. Compare - basin. HP

**valley-border surfaces** - A general grouping of valley-side
geomorphic surfaces of relatively large extent that occur in a stepped
sequence graded to successively lower stream base levels, produced by
episodic valley entrenchment; for example, multiple stream terrace
levels, each with assemblages of constituent landforms (e.g.
interfluves, hillslopes, fans, etc.) that dominate the margins of large
river valleys. SW & [HP]{.underline}

**valley fill** - The unconsolidated sediment deposited by any agent
(water, wind, ice, mass wasting) so as to fill or partly fill a valley.
HP

**valley flat** -- A generic term for the low or relatively level ground
lying between valley walls and bordering a stream channel; especially
the small plain at the bottom of a narrow, steep-sided valley. The term
can be generally applied noncommittally to a flat surface that cannot be
identified with certainty as a floodplain or terrace. Compare --
backswamp, meander belt. [GG]{.underline}

**valley floor** - A general term for the nearly level to gently
sloping, lowest surface of a valley. Landforms include axial stream
channels, the flood plain, flood-plain steps, and, in some areas, low
terrace surfaces. Compare - flood-plain landforms, meander, braided
channel, valley side. [HP]{.underline}

**valley floor remnant -** Hills that are now erosion remnants of a
former valley or basin floor, composed mostly of unconsolidated valley /
basin fill sediments (e.g. alluvium) and typically lie well above the
modern valley floor and flood plain. Former basin floor surfaces have
become dissected and irregular and consist of hillslope positions
(shoulder, backslope, etc.) and hill components (interfluve, headslope,
etc.); common in large valleys of the western US. SW

**valley side** - The sloping to very steep surfaces between the valley
floor and summits of adjacent uplands. Well-defined, steep valley sides
have been termed valley walls (not recommended). Note: Scale, relief,
and perspective may require use of closely related terms such as hill
slope or mountain slope. [HP]{.underline}

**valley-side alluvium** - A concave \"slope wash\" deposit at the base
of a hill slope, mountain slope, terrace escarpment, etc., that may or
may not include the alluvial toe slope. Compare -- base slope, slope
alluvium. HP

**valley train** - A long narrow body of outwash confined within a
valley beyond a glacier; it may, or may not, emerge from the valley and
join an outwash plain. [GG]{.underline}

**valley wall** - (not recommended) use valley side.

**varve** - A sedimentary layer, lamina, or sequence of laminae,
deposited in a body of still water within 1 year; specifically, a thin
pair of graded glaciolacustrine layers seasonally deposited, usually by
meltwater streams, in a glacial lake or other body of still water in
front of a glacier. Compare - rhythmite. [GG]{.underline}

**ventifact** - A stone or pebble that has been shaped, worn, faceted,
cut, or polished by the abrasive action of windblown sand, usually under
arid conditions. When the pebble is at the ground surface, as in a
desert pavement, the upper part is polished while the lower or below
ground part is angular or subangular. [GG]{.underline} &
[HP]{.underline}

vernal pool -- A natural, seasonal pond in a small closed depression
(micro-low) which supports a semi-aquatic or aquatic ecosystem adapted
to annual cycles of standing water in the springtime followed by drying
in the summer / autumn; commonly recognized in CA. SW

**vitric** - Pyroclastic material that is more than 75% glass. GG

**volcanic** - (adjective) Pertaining to (a) the deep seated (igneous)
processes by which magma and associated gases rise through the crust and
are extruded onto the earth\'s surface and into the atmosphere, and (b)
The structures, rocks, and landforms produced. Compare - extrusive,
volcaniclastic. HP

**volcanic breccia** -- A volcaniclastic rock composed mostly of angular
rock fragments greater than 2 mm in size. The name volcanic breccia is
not synonymous with pyroclastic breccia (volcanic breccia forms in
different ways). [GG]{.underline}

**volcanic cone** - A conical hill of lava and/or pyroclastics that is
built up around a volcanic vent. GG

**volcanic dome** - A steep-sided, rounded extrusion of highly viscous
lava squeezed out from a volcano, and forming a dome-shaped or bulbous
mass of congealed lava above and around the volcanic vent.
[GG]{.underline}

volcanic field -- A more or less well defined area that is covered with
volcanic rocks of much more diverse lithology and distribution than a
lava field, or that is so modified by age and erosion that it's original
topographic configuration, composition and extent is uncertain. Compare
-- lava field, lava plain. SW

**volcaniclastic** - Pertaining to the entire spectrum of fragmental
materials with a preponderance of clasts of volcanic origin. The term
includes not only pyroclastic materials but also epiclastic deposits
derived from volcanic source areas by normal processes of mass movement
and stream erosion. Examples: welded tuff, volcanic breccia.
[HP]{.underline}

**volcanic plug** - (not recommended) use plug.

**volcano** - (a) A vent in the surface of the Earth through which magma
and associated gases and ash erupt; also, the form or structure, usually
conical, that is produced by the ejected material. (b) Any eruption of
material, e.g. mud, sand, etc. that resembles a magmatic volcano. GG

**V-shaped valley** - A valley having a pronounced cross profile
suggesting the form of the letter \"V\", characterized by steep sides
and short tributaries; specifically a narrow valley resulting from
downcutting by a stream. The \"V\" becomes broader as the downcutting
progresses. Compare - U-shaped valley. [GG]{.underline}

**wash** (dry wash) - (colloquial: western U.S.A.) The broad,
flat-floored channel of an ephemeral stream, commonly with very steep to
vertical banks cut in alluvium. Note: When channels reach intersect
zones of ground-water discharge they are more properly classed as
\"intermittent stream\" channels. Synonym - arroyo. Compare - gully. HP

**washover fan** - A fan-like deposit of sand washed over a barrier
island or spit during a storm and deposited on the landward side.
Washover fans can be small to medium sized and completely subaerial, or
they can be quite large and include subaqueous margins extending into
adjacent lagoons or estuaries. Large fans can be subdivided into
sequential parts: ephemeral washover channel (microfeature) cut through
dunes or beach ridges, back-barrier flats, (subaqueous) washover-fan
flat, (subaqueous) washover-fan slope. Subaerial portions can range from
barren to completely vegetated.. SSS

**washover-fan apron** -- (not preferred) use washover-fan flat.

**washover-fan flat** - A gently sloping, fan-like, subaqueous landform
created by overwash from storm surges that transports sediment from the
seaward side to the landward side of a barrier island (GG). Sediment is
carried through temporary overwash channels that cut through the dune
complex on the barrier spit (Fisher and Simpson, 1979; Boothroyd et al.,
1985; Davis, 1994) and spill out onto the lagoon-side platform where
they coalesce to form a broad belt. Also called storm-surge platform
flat (Boothroyd et al., 1985) and washover fan apron (GG). Compare --
washover fan slope. SSS

**washover-fan slope** - A subaqueous extension of a washover-fan flat
that slopes toward deeper water of a lagoon or estuary and away from the
washover-fan flat. Compare -- washover-fan flat. SSS

water \[soil survey\] - A generic map unit for any permanent, open body
of water (pond, lake, reservoir, etc.) that does not support rooted
plants. SW

**waterway** - (a) A general term for a way or channel, either natural
(as a river) or artificial (as a canal), for conducting the flow of
water. (b) A navigable body or stretch of water available for passage; a
watercourse. Compare - drainageway. [GG]{.underline}

**wave-built terrace** - A gently sloping coastal feature at the seaward
or lakeward edge of a wave-cut platform, constructed by sediment brought
by rivers or drifted along the shore or across the platform and
deposited in the deeper water beyond. Compare -- submerged wave-built
terrace, beach plain, strand plain. **[GG]{.underline}**

**wave-cut platform** - A gently sloping surface produced by wave
erosion, extending into the sea or lake from the base of the wave-cut
cliff. This feature represents both the wave-cut bench and the abrasion
platform. Compare -- submerged wave-cut platform. [GG]{.underline}

**wave-cut terrace** - (not recommended) use wave-built terrace.

**weathering** - All physical disintegration, chemical decomposition,
and biologically induced changes in rocks or other deposits at or near
the earth\'s surface by atmospheric or biologic agents or circulating
surface waters with essentially no transport of the altered material.
These changes result in disintegration and decomposition of the
material. Compare - regolith, residuum, saprolite. [HP]{.underline}

**welded soil** **--** (not preferred -- use overprinted soil).

**welded tuff** - A glass-rich, pyroclastic rock composed of volcanic
ash indurated at the time of deposition by the welding together of its
glass shards under the combined action of the heat retained by
particles, the weight of overlying material, and hot gasses. It is
generally composed of silica pyroclasts and appears banded or streaked.
[GG]{.underline}

**welding** - (a) Consolidation of sediments (especially of clays) by
pressure resulting from the weight of superincumbent material or from
earth movement, characterized by cohering particles brought within the
limits of mutual molecular attraction as water is squeezed out of the
sediments. (b) the diagenetic process whereby discrete crystals and/or
grains become attached to each other during compaction, often involving
pressure solution and pressure transfer. GG

**wind gap** - A former water gap now abandoned by the stream that
formed it, suggesting stream piracy or stream diversion. HP

**window** \[tectonic**\]** - An eroded area of a thrust sheet, commonly
a basin or valley floor, that exposes the incongruous bedrock
stratigraphy beneath the thrust-sheet; a particular structural or
stratigraphic relationship is implied, rather than a particular
topographic form. Common in the Appalachian and Rocky Mountain margins.
Synonym: *fenster*. [GG]{.underline}, [WT]{.underline}, SW

**windthrow** -- (not preferred) see tree-tip.

**wind-tidal flat** -- A broad, low-lying, nearly-level sand flat that
is alternately inundated by ponded rainwater or by wind-driven bay or
estuarine water from storm surges or seiche. Frequent salinity
fluctuations and prolonged periods of subaerial exposure preclude
establishment of most types of vegetation except for mats of filamentous
blue-green algae. Compare -- tidal flat. SSS & [HF]{.underline}

**woody organic materials -** see organic materials

**woody peat** \[Soil Taxonomy\] - An accumulation of organic material
that is predominantly composed of trees, shrubs, and other woody plants.
Compare herbaceous peat, moss peat, sedimentary peat, peat, muck, and
mucky peat. SSM

**yardang -** (a) A microfeature in the form of a long, irregular,
sharp-crested, undercut ridge between two round-bottomed troughs, carved
on a plateau or unsheltered plain in a desert region by wind erosion,
and cut into soft but coherent deposits (such as clayey sand); it lies
in the direction of the dominant wind, and may be up to 6 m high and 40
m wide. (b) A landform produced in a region of limestone or sandstone by
infrequent rains combined with wind action, and characterized by "a
surface bristling with a fine lacework of sharp ridges pitted by
corrosion". Compare -- pavement karst. [GG]{.underline}

**yardang trough -** A long, shallow, round-bottomed groove, furrow,
trough, or corridor excavated in the desert floor by wind abrasion, and
separating two yardangs. Compare -- yardang. GG

**zibar** -- A small, low-relief sand dune that lacks discernible slip
faces and commonly occurs on sand sheets, in interdune areas, or in
corridors between larger dunes. Zibar spacing can range from 50 -- 400 m
with local relief \< 10 m. Unlike coppice dunes, zibars are not related
to deposition around vegetation. Generally dominated by coarser sands.
Compare -- dune, coppice dune. SW, [GG]{.underline}, [NL]{.underline},
[CW]{.underline}.

## 629.03 References. {#references. .600.00}

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## (b) Classic references. {#b-classic-references. .TOC-Heading-(a)}

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> (now *Buol, Southard, Graham, and McDaniel 2003*)

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> *(see Birkeland, 1999)*

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Inc., New York, NY; 1295 p.

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Magraw-Hill Co., New York, NY; 534p.

Fenneman, N.M. 1938. Physiography of the eastern United States.
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Fenneman, N.M. 1946. (reprinted 1957). Physical divisions of the United
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Flint, R.F. 1971. Glacial and Quaternary geology. John Wiley and Sons,
Inc., New York, NY; 892 p.

Freeze, A.L. and Cherry, J.A. 1979. Groundwater. Prentice-Hall, Inc.,
Englewood Cliffs, NJ.; 604 p.

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Jackson, 1987).

Green, J., and Short, N.M. 1971. Volcanic landforms and surface
features: A photographic atlas and glossary. Springer-Verlag, New York,
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## Exhibit 629-1 Lists of Landscape, Landform, Microfeature, and Anthropogenic Feature Terms defined in the Glossary {#exhibit-629-1-lists-of-landscape-landform-microfeature-and-anthropogenic-feature-terms-defined-in-the-glossary .600.00}

> (comprehensive alphabetical and subset lists arranged by Geomorphic
> Process or Setting)**.** Geomorphic Process is a framework for the
> *Geomorphic Description System* (Schoeneberger and Wysocki, 2002).

\[Note: Codes follow some entries: **NR** - indicates terms that are NOT
recommended (should not be used); **NP** - indicates terms that are not
preferred (have been used, but better alternatives exist). Also
following terms are italicized letters for the corresponding shorthand
code (e.g., *BA*); a dash (\--) indicates that no shorthand code has
been assigned.\]

**I) Alphabetical Lists** (Landscapes, Landforms, Microfeatures,
Anthropogenic Features).

### A) LANDSCAPES (broad or unique groups or clusters of natural, spatially associated features).

> alluvial plain \--
>
> alluvial plain remnant \--
>
> badlands *BA*
>
> bajada (also Landform) *BJ*
>
> basin *BS*
>
> basin floor (also Landform) *\--*
>
> batholith \--
>
> bay \[coast\] (water body; also Landform) \--
>
> bolson *BO*
>
> barrier island (also Landform) \--
>
> breaks *BK*
>
> canyonlands \--
>
> coastal plain (also Landform) *CP*
>
> cockpit karst \--
>
> cone karst \--
>
> continental glacier \--
>
> delta plain (also Landform) \--
>
> drumlin field \--
>
> dune field \--
>
> estuary (water body; also Landform) \--everglades \--
>
> fan piedmont (also Landform) *FP*
>
> fault-block mountains \--
>
> fluviokarst \--
>
> fluviomarine terrace (also Landform) \--
>
> foothills *FH*
>
> glaciokarst \--
>
> gulf \[coast\] (water body; also Landform) \--
>
> hills (singular = Landform) *HI*
>
> ice-margin complex \--
>
> intermontane basin (also Landform) *IB*
>
> island (also Landform) \--
>
> karst *KP*
>
> kegel karst \--
>
> lagoon \[coast\] (water body; also Landform)

lake plain (also Landform) \--

lava field (also Landform) \--

lava plain (also Landform) \--

lava plateau (also Landform) *LL*

lowland \--

marine terrace (also Landform) \--

meander belt *MB*

mountain range \--

mountains (singular = Landform) *MO*

mountain system \--

ocean (water body) \--

outwash plain (also Landform) \--

peninsula \--

piedmont *PI*

piedmont slope \--

plains (also Landform) *PL*

plateau (also Landform) *PT*

rift valley \--

river valley (also Landform) *RV*

sandhills *SH*

sand plain \--

scabland *SC*

sea (water body; also Landform) \--

semi-bolson *SB*

shore complex \--

sinkhole karst \--

sound (water body; also Landform) \--

strait (water body; also Landform) \--

tableland *TB*

thermokarst *TK*

till plain (also Landform) *TP*

tower karst \--

upland *UP*

valley (also Landform) *VA*

volcanic field (also Landform) \--

> **B) LANDFORMS** (natural, individual, earth-surface features mappable
> at common survey scales)

\`a\`a lava flow **\--**

alas *AA*

alluvial cone \--

alluvial fan *AF*

alluvial flat *AP*

alpine glacier \--

anticline *AN*

arete *AR*

arroyo *AY*

ash flow *AS*

atoll *AT*

avalanche chute *AL*

axial stream \--

back-barrier beach \--

back-barrier flat \--

backshore *AZ*

backswamp *BS*

bajada (also Landscape) *BJ*

ballena *BL*

ballon *BV*

bar *BR*

barchan dune *BQ*

barrier beach *BB*

barrier cove \--

barrier flat *BP*

barrier island (also Landscape) *BI*

basin floor (also Landscape) *BC*

basin-floor remnant *BD*

bay \[coast\] (water body; also Landscape) *WB*

bay \[geom.\] \--

bay bottom *\--*

bayou (water body) *WC*

beach *BE*

beach plain *BP*

beach ridge *BG*

beach terrace *BT*

berm *BM*

beveled base \--

blind valley *VB*

block field *BW*

block glide \--

block lava flow \--

block stream *BX*

blowout *BY*

bluff *BN*

bog *BO*

box canyon \--

braided stream *BZ*

broad interstream divide \--

butte *BU*

caldera *CD*

canyon *CA*

canyon bench \--

Carolina Bay *CB*

channel (also Microfeature) *CC*

chenier *CG*

chenier plain *CH*

cinder cone *CI*

cirque *CQ*

cirque floor \--

cirque headwall \--

cirque platform \--

cliff *CJ*

climbing dune \--

closed depression (also Microfeature) \--

coastal plain (also Landscape) *CP*

cockpit \--

col *CL*

collapsed ice-floored lakebed *CK*

collapsed ice-walled lakebed *CN*

collapsed lake plain *CS*

collapsed outwash plain *CT*

collapse sinkhole \--

colluvial apron \--

complex landslide \--

coral island \--

coulee *CE*

cove \[coast\] (water body) *\--*

cove \[geom\] *CO*

crag and tail \--

crater \[volcanic\] *CR*

creep \--

crevasse filling *CF*

cuesta *CU*

cuesta valley *\--*

cutoff *CV*

debris avalanche *DA*

debris fall \--

debris flow *DF*

debris slide \--

debris spread \--

debris topple \--

deflation basin *DB*

deflation flat \--

delta *DE*

delta plain (also Landscape) *DC*

depression *DP*

diapir *DD*

diatreme \--

dike *DK*

dipslope *DL*

disintegration moraine *DM*

divide *DN*

dome *DO*

drainageway *DQ*

drainhead complex -

draw *DW*

drumlin *DR*

drumlinoid ridge \--

dune *DU*

dune field (also Landscape) *\--*

dune lake (water body) \--

dune slack (also Microfeature) \--

earth flow *EF*

earth spread \--

earth topple \--

end moraine *EM*

ephemeral stream (also Microfeature) \--

eroded fan remnant \--

eroded fan-remnant sideslope \--

erosion remnant *ER*

escarpment *ES*

esker *EK*

estuary (water body; also Landscape) *WD*

faceted spur *FS*

fall *FB*

falling dune \--

fan *FC*

fan apron *FA*

fan collar \--

fanhead trench *FF*

fan piedmont (also Landscape) *FG*

fan remnant *FH*

fan skirt *FI*

fault-block \--

fault-line scarp *FK*

fault zone \--

fen *FN*

fissure vent \--

fjord (water body) *FJ*

flat *FL*

flatwoods \--

flood plain *FP*

flood-plain playa *FY*

flood-plain splay *FM*

flood-plain step *FO*

flood-tidal delta \--

flood-tidal delta flat \--

flood-tidal delta slope \--

flow \--

flute (also Microfeature) *FU*

fluviomarine bottom \--

fluviomarine terrace (also Landscape) \--

fold *FQ*

foredune *FD*

fosse *FV*

free face (also Geom. Comp. -- Hills,

Mountains) *FW*

fringe-tidal marsh \--

gap *GA*

geyser \--

geyser basin \--

geyser cone \--

giant ripple *GC*

glacial drainage channel *GD*

glacial lake (water body) *WE*

glacial lake \[relict\] *GL*

glacial-valley floor \--

glacial-valley wall \--

glacier \--

gorge *GO*

graben *GR*

ground moraine *GM*

gulch *GT*

gulf \[coast\] (water body; also Landscape) *\--*

gut \[stream\]; (water body) *WH*

gut (valley) *GV*

half graben \--

hanging valley *HV*

headland *HE*

head-of-outwash \--

headwall *HW*

high hill \--

highmoor bog *HB*

hill *HI*

hillslope \--

hogback *HO*

homoclinal ridge \--

horn *HR*

horst *HT*

hot spring \--

ice-contact slope \--

ice-marginal steam \--

ice-pushed ridge \--

inlet \--

inselberg *IN*

inset fan *IF*

interdrumlin \--

interdune (also Microfeature) *ID*

interfluve (also Geom. Component - Hills) *IV*

interior valley \--

intermittent stream (also Microfeature) \--

intermontane basin (also Landscape) *IB*

island (also Landscape) \--

kame *KA*

kame moraine *KM*

kame terrace *KT*

karst cone \--

karst tower \--

karst valley \--

kettle *KE*

kipuka \--

knob *KN*

knoll *KL*

lagoon \[coast\] (water body; also Landscape)*WI*

lagoon bottom \--

lagoon channel \--

lahar *LA*

lake (water body) *WJ*

lakebed \[relict\] *LB*

lake plain (also Landscape) *LP*

lakeshore *LF*

lake terrace *LT*

landslide *LK*

lateral moraine *LM*

lateral spread \--

lava field (also Landscape) \--

lava flow *LC*

lava flow unit (also Microfeature) \--

lava plain (also Landscape) *LN*

lava plateau (also Landscape) *LL*

lava trench (also Microfeature) \--

lava tube \--

ledge *LE*

levee \[stream\] *LV*

loess bluff *LO*

loess hill *LQ*

longitudinal dune \--

longshore bar \[relict\] *LR*

louderback *LU*

low hill \--

lowmoor bog *LX*

maar \--

mainland cove \--

main scarp (also Microfeature) \--

mangrove swamp \--

marine lake (water body) \--

marine terrace (also Landscape) *MT*

marsh *MA*

mawae \--

meander *MB*

meandering channel *MC*

meander scar *MS*

meander scroll *MG*

medial moraine *MH*

mesa *ME*

meteorite crater \--

mogote \--

monadnock *MD*

monocline *MJ*

moraine *MU*

mountain (plural **=** Landscape) *MM*

mountain slope *MN*

mountain valley *MV*

mud flat *MF*

mudflow *MW*

mud pot \--

muskeg *MX*

natural levee *NL*

neck \[volcanic\] \--

notch *NO*

nunatak *NU*

open depression (also Microfeature) \--

outwash delta \--

outwash fan *OF*

outwash plain (also Landscape) *OP*

outwash terrace *OT*

overflow stream channel \--

oxbow *OX*

oxbow lake (water body) *WK*

oxbow lake (ephemeral) *OL*

paha *PA*

pahoehoe lava flow \--

paleoterrace \--

parabolic dune *PB*

parna dune *PD*

partial ballena *PF*

patterned ground *PG*

pavement karst \--

peak *PK*

peat plateau *PJ*

pediment *PE*

perennial stream (water body) \--

pillow lava flow \--

pingo *PI*

pinnacle \--

pitted outwash plain *PM*

pitted outwash terrace \--

plain (also Landscape) *PN*

plateau (also Landscape) *PT*

playa *PL*

playa dune (also Microfeature) \--

playa floor (also Microfeature) \--

playa lake (water body) *WL*

playa rim (also Microfeature) \--

playa slope (also Microfeature) \--

playa step (also Microfeature) \--

plug \[volcanic\] \--

plug dome *PP*

pluvial lake (water body) *WM*

pluvial lake (relict) *PQ*

pocosin *PO*

point bar *PR*

point bar \[coastal\] \--

pothole (also Microfeature) *PH*

pothole lake (water body) *WN*

pressure ridge \[ice\] \--

pressure ridge \[volcanic\]; also Micro.) *PU*

proglacial lake (water body) *WO*

proglacial lake \[relict\] \--

pyroclastic flow \--

pyroclastic surge \--

raised beach *RA*

raised bog *RB*

ravine *RV*

recessional moraine *RM*

reef *RF*

relict-tidal inlet (water body) \--

reworked lake plain \--

ribbed fen *RG*

ridge *RI*

rim *RJ*

river (water body) \--

river valley (also Landscape) \--

roche moutonnée (also Microfeature) *RN*

rock fall (also Microfeature) \--

rock avalanche \--

rock glacier *RO*

rock pediment \--

rock spread \--

rock topple \--

rotational debris slide \--

rotational earth slide \--

rotational rock slide \--

rotational slide *RP*

saddle *SA*

sag (also Microfeature) \--

sag pond (water body, also Microfeature) \--

salt marsh *SM*

salt pond (water body also Microfeature) *WQ*

sand flow *RW*

sand ramp \--

sand sheet *RX*

scarp *RY*

scarp slope *RS*

scree slope \--

sea (water body; also Landscape) \--

sea cliff *RZ*

seif dune *SD*

semi-open depression \--

shield volcano \--

shoal (water body) *WR*

shoal (relict) *SE*

shore \--

sill *RT*

sinkhole *SH*

slackwater (water body) *WS*

slick rock (also Microfeature) \--

slide *SJ*

slot canyon \--

slough (ephemeral water) *SL*

slough (permanent water) *WU*

slump *SK*

slump block *SN*

snowfield \--

soil fall \--

solution platform \--

solution sinkhole \--

sound (water body; also Landscape) *\--*

spit *SP*

spur *SQ*

stack \[coast\] *\--*

stack \[geom\] *SR*

star dune \--

steptoe *ST*

stock \--

stoss and lee \--

strait (water body; also Landscape) *\--*

strand plain *SS*

strath terrace *SU*

stratovolcano *SV*

stream (water body) \--

stream terrace *SX*

strike valley \--

string bog *SY*

structural bench *SB*

submerged back-barrier beach \--

submerged mainland beach \--

submerged point bar \[coastal\] \--

submerged-upland tidal marsh \--

submerged wave-built terrace \--

submerged wave-cut platform \--

swale (also Microfeature) *SC*

swallow hole *TB*

swamp *SW*

syncline *SZ*

talus cone \--

talus slope \--

tarn (water body; also Microfeature) \--

terminal moraine *TA*

terrace *TE*

thermokarst depression *TK*

thermokarst lake (water body) *WV*

tidal flat *TF*

tidal inlet \--

tidal marsh \--

till-floored lake plain \--

till plain (also Landscape) *TP*

toe (also Microfeature) \--

tombolo *TO*

topple \--

tor *TQ*

Toreva block \--

translational debris slide \--

translational earth slide \--

translational rock slide \--

translational slide *TS*

transverse dune *TD*

trough *TR*

tunnel valley *TV*

tunnel-valley lake (water body) \--

U-shaped valley *UV*

valley *VA*

valley-border surfaces \--

valley flat *VF*

valley floor *VL*

valley floor remnant \--

valley side *VS*

valley train *VT*

volcanic cone *VC*

volcanic dome *VD*

volcanic field (also Landscape) \--

volcano *VO*

V-shaped valley *VV*

wash *WA*

washover fan *WF*

washover-fan flat \--

washover-fan slope \--

wave-built terrace *WT*

wave-cut platform *WP*

wind gap *WG*

window \--

wind-tidal flat \--

yardang (also Microfeature) \--

yardang trough (also Microfeature) \--

**C) MICROFEATURES** (discrete, natural, earth-surface features too
small to delineate at survey scales).

bar \--

channel (also Landform) \--

closed depression (also Landform) \--

corda \--

cutter \--

dune slack (also Landform) \--

dune traces \--

earth pillar \--

ephemeral stream (also Landform) \--

finger ridge \--

flute (also Landform) \--

frost boil \--

glacial groove \--

groove \--

gully \--

hillock \--

hoodoo \--

interdune (also Landform) \--

intermittent stream (water body; also Landform)

karren \--

lava flow unit (also Landform) --

lava trench (also Landform) \--

main scarp (also Landform) \--

minor scarp \--

mound *M*

nivation hollow \--

open depression (also Landform) \--

patterned ground *(see below) PG*

Patterned ground microfeatures (used in association with the landform
"patterned ground" or *PG*):

*(a) **Periglacial*** patterned ground microfeatures:

> circle \--
>
> earth hummocks \--
>
> high-center polygons \--
>
> ice wedge polygons \--
>
> low-center polygons \--
>
> non-sorted circles \--
>
> palsa, palsen \--\
> (= peat hummocks) \--
>
> polygons \--
>
> sorted circles \--
>
> stripes \--
>
> turf hummocks \--

*(b) **Other ***patterned ground microfeatures:

> bar and channel \--
>
> circular gilgai \--
>
> elliptical gilgai \--
>
> linear gilgai \--
>
> gilgai *G*
>
> hummocks \--
>
> intermediate position \[gilgai\] \--
>
> mima mounds \--
>
> pimple mounds \--

perennial stream (water body; also Landform) \--

pinnacle \--

playa dune (also Landform) \--

playa floor (also Landform) \--

playa rim (also Landform) \--

playa slope (also Landform) \--

playa step (also Landform) \--

playette \--

pond (water body) \--

pool (water body) \--

pothole (also Landform) \--

pressure ridge \[volcanic\] \--

rib \--

rill \--

ripple mark \--

roche moutonnée (also Landform) \--

rockfall (also Landform) **\--**

sag (also Landform) \--

sag pond (water body; also Landform) \--

sand boil \--

scour (mark) \--

shoreline \--

shrub-coppice dune \--

slick rock (also Landform) \--

slip face \--

solifluction lobe \--

solifluction sheet \--

solifluction terrace \--

solution chimney \--

solution corridor \--

solution fissure \--

solution pipe \--

spatter cone \--

spiracle \--

strandline \--

swale (also Landform) \--

swash zone \--

tank (water body) \--

tarn (water body; also Landform) \--

terracettes *T*

toe \[mass move.\] (also Landform) \--

tree-tip mound \--

tree-tip pit \--

tumulus (tumuli = plural) \--

vernal pool (seasonal water body) \--

yardang (also Landform) \--

yardang trough (also Landform) \--

zibar \--

**D) Anthropogenic Features** \[discrete, human-made or modified,
earth-surface features\]*.*

artificial collapsed depression *G*

artificial levee *A*

beveled cut \--

borrow pit \--

burial mound *B*

cut *(road, railroad)* \--

cutbank \--

ditch \--

dredged channel \--

dredge-deposit shoal \--

dredge spoil bank \--

dump \--

fill \--

filled marshland \--

floodway \--

gravel pit \--

impact crater \--

landfill (*see sanitary landfill***)**

leveled land \--

log landing \--

midden *H*

openpit mine \--

pond *(human-made)* \--

quarry \--

railroad bed *D*

reclaimed land \--

rice paddy *E*

road bed *I*

road cut \--

sand pit \--

sanitary landfill \--

scalped area

sewage lagoon \--

skid trail \--

spoil bank \--

spoil pile \--

surface mine \--

tillage features *(below)* F

> *Tillage / Management* *features (common types)* :
>
> conservation terrace *(modern)* \--
>
> double-bedding mound \--
>
> drainage ditch \--
>
> furrow \--
>
> hillslope terrace *(e.g., archeological features)*
>
> inter-furrow \--

truncated soil \--

urban land \--

**II) GEOMORPHIC ENVIRONMENTS AND OTHER GROUPINGS** (Landscape,
Landform, and Microfeature terms grouped by geomorphic process (e.g.
Fluvial) or setting e.g. Water Bodies). These lists are not mutually
exclusive; some features occur in more than one environment or setting.)

> **1. COASTAL MARINE and ESTUARINE** (wave or tidal control or
> near-shore / shallow marine).

***Landscapes:***

bay \[coast\] (water body; also Landform) \--

coastal plain (also Landform) *CP*

barrier island (also Landform) \--

estuary (water body; also Landform) --

fluviomarine terrace (also Landform) \--

gulf \[coast\] (water body; also Landform) \--

island (also Landform) \--

lagoon \[coast\] (water body; also Landform) \--

lowland \--

marine terrace (also Landform) \--

ocean (water body; also Landform) \--

peninsula \--

sea (water body; also Landform) \--

shore complex \--

sound (water body; also Landform) \--

strait (water body; also Landform) \--

***Landforms:***

atoll *AT*

back-barrier beach \--

back-barrier flat \--

backshore *AZ*

bar *BR*

barrier beach *BB*

barrier cove \--

barrier flat *BF*

barrier island (also Landscape) *BI*

bay \[coast\] (water body; also Landscape) *WB*

bay bottom \--

beach *BE*

beach plain *BP*

beach ridge *BG*

beach terrace *BT*

berm *BM*

bluff *BN*

chenier *CG*

chenier plain *CH*

coastal plain *CP*

coral island \--

delta *DE*

delta plain (also Landscape) *DC*

drainhead complex -

flat *FL*

flatwoods \--

fluviomarine terrace (also Landscape) \--

foredune *FD*

fringe-tidal marsh \--

gulf \[coast\] (water body; also Landscape) \--headland *HE*

island (also Landscape) \--

lagoon \[relict\] *WI*

lagoon (water body) \--

longshore bar \[relict\] *LR*

mangrove swamp \--

marine lake (water body) \--

marine terrace (also Landscape) *MT*

mud flat *MF*

point bar \[coastal\] \--

raised beach *RA*

reef *RF*

salt marsh *SM*

sea (water body; also Landscape) \--

sea cliff *RZ*

semi-open depression \--

shoal (relict) *SE*

shore \--

sound (water body; also Landscape) \--

spit *SP*

stack \[coast\] *\--*

strait (water body; also Landscape) \--

strand plain *SS*

tidal flat *TF*

tidal marsh \--

tombolo *TO*

washover fan *WF*

wave-built terrace *WT*

wave-cut platform *WP*

wind-tidal flat \--

***Microfeatures:***

ripple mark *\--*

shoreline \--

swash zone \--

> **2. LACUSTRINE** (related to inland water bodies).

***Landscapes:***

island (also Landform) \--

lake plain (also Landform) \--

peninsula **\--**

shore complex \--

***Landforms:***

backshore *AZ*

bar *BR*

barrier beach *BB*

barrier flat *BF*

barrier island *BI*

beach *BE*

beach plain *BP*

beach ridge *BG*

beach terrace *BT*

berm *BM*

bluff *BN*

delta *DE*

delta plain (also Landscape) *DC*

flat *FL*

flood-plain playa *FY*

foredune *FD*

headland *HE*

island (also Landscape) \--

lagoon \[relict\] *WI*

lakebed \[relict\] *LB*

lakebed (water body) *LB*

lake plain (also Landscape) *LP*

lake terrace *LT*

longshore bar \[relict\] *LR*

mud flat *MF*

oxbow lake (ephemeral) *OL*

playa *PL*

playa floor (also Microfeature) \--

playa rim (also Microfeature) \--

playa slope (also Microfeature) \--

playa step (also Microfeature) \--

pluvial lake (relict) *PQ*

raised beach *RA*

reworked lake plain \--

salt marsh *SM*

shoal (relict) *SE*

shore \--

spit *SP*

stack \[coast\] *\--*

strand plain *SS*

till-floored lake plain \--

tombolo *TO*

wave-built terrace *WT*

wave-cut platform *WP*

***Microfeatures:***

## bar \--

playa floor (also Landform) \--

playa rim (also Landform) \--

playa slope (also Landform) \--

playa step (also Landform) \--

playette \--

ripple mark *\--*

shoreline \--

strandline \--

swash zone \--

vernal pool \--

> **3. FLUVIAL** (dominantly related to concentrated water flow (channel
> flow); includes erosional and depositional features, but excluding
> glaciofluvial landforms (see Glacial), and permanent water features
> (see Water Bodies).

***Landscapes:***

alluvial plain \--

alluvial plain remnant \--

badlands *BA*

bajada *BJ*

breaks *BK*

canyonlands \--

delta plain \--

fan piedmont *FP*

meander belt *MB*

river valley \--

scabland *SC*

***Landforms:***

alluvial cone \--

alluvial fan *AF*

alluvial flat *AP*

arroyo *AY*

axial stream (water body) \--

backswamp *BS*

bajada *BJ*

bar *BR*

basin-floor remnant *BD*

block stream *BX*

braided stream *BZ*

box canyon \--

canyon *CA*

channel *CC*

coulee *CE*

cutoff *CV*

delta *DE*

delta plain (also Landscape) *DC*

drainageway *DQ*

drainhead complex -

draw *DW*

ephemeral stream (also Microfeature) \--

fan apron \--

fan collar \--

fanhead trench *FF*

fan remnant \--

fan skirt *FI*

flood plain *FP*

flood-plain playa *FY*

flood-plain splay *FM*

flood-plain step *FO*

giant ripple *GC*

gorge *GO*

gulch *GT*

gut (valley) *GV*

inset fan *IF*

intermittent stream (also Microfeature) \--

levee \[streams\] *LV*

meander scar *MS*

meander scroll *MG*

natural levee *NL*

overflow stream channel \--

oxbow *OX*

oxbow lake (ephemeral) *OL*

paleoterrace \--

point bar *PR*

ravine *RV*

river valley (also Landscape) \--

semi-open depression \--

slot canyon \--

strath terrace *SU*

stream terrace *SX*

valley border surfaces \--

valley flat \--

valley floor remnant \--

wash *WA*

wind gap *WG*

***Microfeatures:***

bar \--

bar & channel \--

channel \--

ephemeral stream (also Landform) \--

groove \--

gully \--

intermittent stream (also Landform) \--

ripple mark *\--*

swash zone \--

> **4. SOLUTION** (dominated by dissolution, and commonly, subsurface
> drainage).

***Landscapes:***

cockpit karst \--

cone karst \--

fluviokarst \--

glaciokarst \--

karst *KP*

kegel karst \--

sinkhole karst \--

thermokarst *TK*

tower karst \--

***Landforms:***

blind valley *VB*

cockpit \--

collapse sinkhole \--

interior valley \--

karst cone \--

karst tower \--

karst valley \--

mogote \--

pavement karst \--

pinnacle \--

sinkhole *SH*

solution platform \--

solution sinkhole \--

swallow hole *TB*

thermokarst depression (also

Microfeature) *TK*

yardang (also

Microfeature) \--

yardang trough (also

Microfeature) *TK*

***Microfeatures:***

cutter *\--*

karren \--

solution chimney \--

solution corridor \--

solution fissure \--

solution pipe \--

thermokarst depression (also Landform) \--

yardang (also Landform) \--

yardang trough (also Landform) \--

> **5. EOLIAN** (dominantly wind related, erosional or depositional).

***Landscapes:***

dune field \--

sandhills *SH*

sand plain \--

***Landforms:***

barchan dune *BQ*

blowout *BY*

climbing dune \--

deflation basin *DB*

dune *DU*

dune field (also Landscape) *\--*

dune lake (water body) \--

dune slack (also Microfeature) \--

falling dune \--

foredune *FD*

interdune *ID*

loess bluff *LO*

loess hill *LQ*

longitudinal dune \--

paha *PA*

parabolic dune *PB*

parna dune *PD*

playa dune (also Microfeature) \--

sand ramp \--

sand sheet *RX*

seif dune *SD*

slick rock (also Microfeature) \--

star dune \--

transverse dune *TD*

yardang (also Microfeature) \--

yardang trough (also Microfeature) \--

***Microfeatures:***

dune slack (also Landform) \--

dune traces \--

interdune (also Landform) \--

playa dune (also Landform) \--

playette \--

shrub-coppice dune \--

slick rock (also Landform) \--

slip face \--

yardang (also Landform) \--

yardang trough (also Landform) \--

zibar **\--**

> **6. GLACIAL** ( includes ice contact, glaciofluvial,
> glaciolacustrine, glaciomarine, and outwash features).

***Landscapes:***

continental glacier \--

## drumlin field \--

glaciokarst \--

hills *HI*

ice-margin complex \--

outwash plain (also Landform) \--

till plain (also Landform) *TP*

***Landforms:***

# **alpine glacier \--**

arete *AR*

cirque *CQ*

cirque floor \--

cirque headwall \--

cirque platform \--

col *CL*

collapsed ice-floored lakebed *CK*

collapsed ice-walled lakebed *CN*

collapsed lake plain *CS*

collapsed outwash plain *CT*

crag and tail \--

crevasse filling *CF*

disintegration moraine *DM*

drumlin *DR*

drumlinoid ridge \--

end moraine *EM*

esker *EK*

fjord (water body) *FJ*

flute (also Microfeature) *FU*

fosse *FV*

giant ripple *GC*

glacial drainage channel *GD*

glacial lake \[relict\] *GL*

glacial lake (water body) *\--*

glacial-valley floor \--

glacial-valley wall \--

glacier \--

ground moraine *GM*

hanging valley *HV*

head-of-outwash \--

ice-contact slope \--

ice-marginal stream \--

ice-pushed ridge \--

interdrumlin \--

kame *KA*

kame moraine *KM*

kame terrace *KT*

kettle *KE*

lateral moraine *LM*

medial moraine *MH*

moraine *MU*

nunatak *NU*

outwash delta \--

outwash fan *OF*

outwash plain (also Landscape) *OP*

outwash terrace *OT*

paha *PA*

pitted outwash plain *PM*

pitted outwash terrace \--

pothole (also Microfeature) *PH*

pressure ridge \[ice\] \--

proglacial lake \[relict\] \--

proglacial lake (water body) \--

recessional moraine *RM*

reworked lake plain \--

roche moutonnée (also Microfeature) *RN*

rock glacier *RO*

snowfield \--

stoss and lee \--

tarn (water body; also Microfeature) \--

terminal moraine *TA*

till-floored lake plain \--

till plain (also Landscape) *TP*

tunnel valley *TV*

tunnel-valley lake (water body) \--

underfit stream \--

valley train *VT*

U - shaped valley *UV*

***Microfeatures:***

flute (also Landform) *\--*

glacial groove \--

ice wedge \--

ice wedge cast \--

nivation hollow \--

pothole \[glacial\] \--

roche moutonnée (also Landform) *\--*

swale (also Landform) \--

tarn (water body; also "Landform") \--

> **7. PERIGLACIAL** \[related to non-glacial, cold climate (modern or
> relict), including periglacial forms of patterned ground. Note:
> consider \"patterned ground\" as a Landform, but treat specific types
> of patterned ground, singular or plural, as Microfeatures. \]

***Landscapes:***

coastal plain (*e.g. North Slope, AK*) *CP*

hills *H*

*I*

plains *PL*

thermokarst *TK*

***Landforms:***

alas *AA*

block field *BW*

muskeg *MX*

patterned ground (see

*Microfeatures* for types) *PG*

peat plateau *PJ*

pingo *PI*

rock glacier *RO*

string bog *SY*

thermokarst depression *TK*

thermokarst lake (water body) \--

***Microfeatures:***

circle *\--*

earth hummocks \--

frost boil \--

high-center polygons \--

ice wedge polygons \--

low-center polygons \--

nivation hollow \--

non-sorted circles \--

palsa (palsen = *plural*;

= peat hummocks) \--

polygon \--

solifluction lobe \--

solifluction sheet \--

solifluction terrace \--

sorted circles \--

stripes \--

turf hummocks \--

> **8. MASS MOVEMENT** (**MASS WASTING**) (dominated by gravity,
> including creep forms).

***Landscapes:*** (these generic Landscapes are not Mass Movement
features per say, but are commonly modified by, and include localized
areas of, Mass Movement).

foothills *FH*

hills *HI*

mountain range \--

mountains *MO*

***Landforms:***

ash flow *AS*

avalanche chute *AL*

block glide \--

block stream *BX*

colluvial apron \--

complex landslide \--

creep \--

debris avalanche \--

debris fall \--

debris flow *DF*

debris slide \--

debris spread \--

debris topple \--

earth flow *EF*

earth spread \--

earth topple \--

fall *FB*

flow \--

lahar *LA*

landslide *LK*

lateral spread \--

main scarp (also Microfeature) \--

mudflow *MW*

rock fall (also Microfeature) \--

rockfall avalanche \--

rock spread \--

rock topple \--

rotational debris slide \--

rotational earth slide \--

rotational rock slide \--

rotational slide *RP*

sag (also Microfeature) \--

sag pond (water body; also Micro.) \--

sand flow *RW*

scree slope \--

slide *SJ*

slump *SK*

slump block *SN*

soil fall \--

talus cone \--

talus slope \--

toe \[mass move.\] (also Micro.) \--

topple \--

Toreva block \--

translational debris slide \--

translational earth slide \--

translational rock slide \--

translational slide *TS*

***Microfeatures:***

main scarp (also Landform) *\--*

minor scarp \--

rockfall (also Landform) \--

sag (also Landform) \--

sag pond (also Landform) \--

sand boil **\--**

solifluction lobe \--

solifluction sheet \--

solifluction terrace \--

terracettes *T*

toe \[mass move.\] (also Landform) \--

> **9. VOLCANIC and HYDROTHERMAL**

***Landscapes:***

foothills *FH*

hills *HI*

lava field (also Landform) \--

lava plain (also Landform) \--

lava plateau (also Landform) \--

mountains *MO*

volcanic field (also Landform) \--

***Landforms:***

\`a\`a lava flow \--

ash flow *AS*

block lava flow \--

caldera *CD*

cinder cone *CI*

crater \[volcanic\] *CR*

diatreme \--

fissure vent \--

geyser \--

geyser basin \--

geyser cone \--

hot spring \--

kipuka \--

lahar *LA*

lava field (also Landscape) \--

lava flow-unit (also Microfeature) **\--**

lava flow *LC*

lava plain (also Landscape) *LN*

lava plateau (also Landscape) *LL*

lava trench (also Microfeature) \--

lava tube \--

louderback *LU*

maar \--

mawae \--

mud pot \--

neck \[volcanic\] \--

pahoehoe lava flow \--

pillow lava flow \--

plug \[volcanic\] \--

plug dome *PP*

pressure ridge \[volcanic\] (also Micro.) *PU*

pyroclastic flow \--

pyroclastic surge \--

shield volcano \--

steptoe *ST*

stratovolcano *SV*

volcanic cone *VC*

volcanic dome *VD*

volcanic field (also Landscape) \--

***Microfeatures:***

corda *\--*

lava flow unit (also Landform) \--

lava trench (also Landform) \--

pressure ridge \[volc.\] (also Landform) \--

spatter cone \--

spiracle \--

tumulus (tumuli = plural) \--

> **10. TECTONIC and STRUCTURAL** (related to regional or local bedrock
> structures, or crustal movement. In Soil Survey, tectonic and
> structural features are only recognized if they have some expression
> at or near the land surface).

***Landscapes:***

batholith \--

bolson *BO*

fault-block mountains \--

foothills *FH*

hills *HI*

intermontane basin *IB*

mountain range \--

mountains *MO*

mountain system \--

plateau *PT*

rift valley \--

semi-bolson *SB*

tableland *TB*

valley *VA*

***Landforms:***

anticline *AN*

canyon bench \--

cuesta *CU*

cuesta valley \--

diapir *DD*

dike *DK*

dipslope *DL*

dome *DO*

fault-line scarp *FK*

fault-block \--

fault zone \--

fold *FQ*

graben *GR*

half graben \--

hogback *HO*

homoclinal ridge \--

horst *HT*

louderback

*LU*

meteorite crater \--

monocline *MJ*

scarp slope *RS*

sill *RT*

stock \--

strike valley \--

structural bench *SB*

syncline *SZ*

window \--

***Microfeatures:***

sand boil \--

> **11. SLOPE** - generic terms or those that describe slope form,
> geometry, or arrangement of land features, rather than any particular
> genesis or process.

***Landscapes:***

badlands *BA*

breaks *BK*

canyonlands \--

foothills *FH*

hills *HI*

mountain range \--

mountains *MO*

mountain system \--

piedmont *PI*

piedmont slope \--

plateau (also Landscape) *PT*

tableland *TB*

upland *UP*

***Landforms:***

beveled base \--

block stream *BX*

bluff *BN*

broad interstream divide \--

butte *BU*

canyon bench \--

cliff *CJ*

colluvial apron \--

cuesta *CU*

dome *DO*

escarpment *ES*

faceted spur *FS*

fault-line scarp *FK*

free face (also Geom Component -- Hills,

Mountains.) *FW*

gap *GA*

headwall *HW*

high hill \--

hill (plural = Landscape) *HI*

hillslope \--

hogback *HO*

interfluve (also Geom. Component - Hills) *IV*

knob *KN*

knoll *KL*

ledge *LE*

low hill \--

mesa *ME*

mountain (plural = Landscape) *MM*

mountain slope *MN*

mountain valley *MV*

notch *NO*

paha *PA*

peak *PK*

pediment *PE*

plain (plural = Landscape) *PN*

plateau (also Landscape) *PT*

ridge *RI*

rim *RJ*

rock pediment \--

scarp *RY*

scarp slope \--

scree slope \--

slick rock (also Microfeature) \--

spur *SQ*

stack \[geom\] *SR*

talus cone \--

talus slope \--

tor *TQ*

valley *VA*

valley floor remnant \--

wind gap *WG*

***Microfeatures:***

finger ridge \--

mound *M*

rib \--

rill \--

slick rock (also Landform) \--

> **12. EROSIONAL** -- related dominantly to water erosion but excluding
> perennial, channel flow (i.e. fluvial, glaciofluvial), or eolian
> erosion.

***Landscapes:***

badlands *BA*

breaks *BK*

canyonlands \--

foothills *FH*

hills *HI*

mountain range \--

mountains *MO*

piedmont *PI*

piedmont slope \--

plateau (also Landscape) *PT*

tableland *TB*

***Landforms:***

ballena *BL*

ballon *BV*

basin floor remnant *BD*

beveled base \--

canyon bench \--

col *CL*

colluvial apron \--

cuesta *CU*

cuesta valley *\--*

eroded fan remnant \--

eroded fan-remnant sideslope \--

erosion remnant *ER*

free face (also Geom. Comp. -- Hills,

Mountains) *FW*

gap *GA*

hogback *HO*

inselberg *IN*

monadnock *MD*

notch *NO*

paha *PA*

partial ballena *PF*

peak *PK*

pediment *PE*

plateau (also Landscape) *PT*

rock pediment \--

saddle *SA*

scarp slope *RS*

slick rock (also Microfeature) \--

stack \[geom\] *SR*

strike valley \--

structural bench *SB*

tor *TQ*

valley border surfaces \--

valley floor remnant \--

wind gap *WG*

window \--

***Microfeatures:***

earth pillar \--

finger ridge \--

groove \--

gully \--

hoodoo \--

pinnacle \--

rib \--

rill \--

slick rock (also Landform) \--

swale \--

> **13. DEPRESSIONAL** ( low area or declivity features, excluding
> permanent water bodies ).

***Landscapes:***

basin *BS*

basin floor (also Landform) *\--*

bolson *BO*

semi-bolson *SB*

valley *VA*

***Landforms:***

alluvial flat *AP*

basin floor (also Landscape) *BC*

basin floor remnant *BD*

box canyon \--

canyon *CA*

closed depression (also Microfeature) *\--*

col *CL*

coulee *CE*

cove \[geom.\] *CO*

cuesta valley *\--*

depression *DP*

drainageway *DQ*

drainhead complex -

gap *GA*

gorge *GO*

gulch *GT*

gut (valley) *GV*

intermontane basin *IB*

kettle *KE*

mountain valley *MV*

open depression (also Microfeature) \--

playa *PL*

playa floor (also Microfeature) \--

playa rim (also Microfeature) \--

playa slope (also Microfeature) \--

playa step (also Microfeature) \--

pothole (intermittent water; also Microfeature) *PH*

ravine *RV*

saddle \--

sag (also Microfeature) \--

semi-open depression \--

slot canyon \--

strike valley \--

swale (also Microfeature) *SC*

trough *TR*

U-shaped valley *UV*

valley *VA*

valley floor *VL*

V-shaped valley *VV*

***Microfeatures:***

closed depression (also Landform) *\--*

open depression (also Landform) \--

playa floor (also Landform) \--

playa rim (also Landform) \--

playa slope (also Landform \--

playa step (also Landform) \--

pothole (intermittent water; also Landform) \--

swale (also Landform) \--

tree-tip pit \--

> **14. WETLANDS** - \[ Related to vegetated and / or shallow wet areas,
> and wet soils. Provisional list: conventional, geologic definitions;
> not legalistic or regulatory usage \].

***Landscapes:***

estuary (also Landform) \--

everglades \--

***\[ generally, there is no appropriate Landscape term for wetlands; by
default, choose the most appropriate Landscape term from another Process
Environment or Other Grouping \]***

***Landforms:***

alas *AA*

backswamp *BS*

bog *BO*

Carolina Bay *CB*

# dune slack (also Microfeature) \--

ephemeral stream (also Microfeature) \--

estuary (also Landscape) *WD*

fen *FN*

flood-plain playa *FY*

fringe tidal marsh \--

highmoor bog *HB*

intermittent stream (also Microfeature) \--

lowmoor bog *LX*

mangrove swamp \--

marsh *MA*

mud flat *MF*

muskeg *MX*

oxbow lake (ephemeral water) *OL*

peat plateau *PJ*

playa (intermittent water) *PL*

pocosin *PO*

pothole (intermittent water; also Micro.) *PH*

raised bog *RB*

ribbed fen *RG*

salt marsh *SM*

slough (intermittent water) *SL*

string bog *SY*

swamp *SW*

tidal flat *TF*

tidal marsh \--

***Microfeatures:***

dune slack (also Landform) \--

ephemeral stream (also Landform) \--

intermittent stream (also Landform) \--

playette \--

pothole (intermittent water; also Landform)\--

vernal pool (seasonal water) \--

> **15. WATER BODIES** - Discrete "surface water" features, primarily
> permanent open water, which in Soil Survey Reports are commonly
> treated as the generic map unit "water" (e.g. lake), or as a spot /
> line symbol (e.g., perennial stream).

***Landscapes:***

bay \[coast\] (water body; also Landform) \--

estuary (water body; also Landform) \--

lagoon \[coast\] (water body; also Landform) \--

***Landforms:***

axial stream \--

bay \[coast\] *WB*

bayou *WC*

cove \[coast\] \--

dune lake \--

estuary *WD*

fjord *FJ*

glacial lake *WE*

gulf \[coast\] \--

gut \[stream\] *WH*

ice-marginal stream \--

inlet \--

lagoon (water body; also Landscape) *WI*

lagoon channel \--

lake *WJ*

marine lake (water body) \--

ocean \--

oxbow lake *WK*

perennial stream (also Microfeature) \--

playa lake *WL*

pluvial lake *WM*

pothole (lake) (also Micro.) *WN*

proglacial lake *WO*

relict-tidal inlet (water body) --

river \--

sag pond (also Microfeature) \--

salt pond (also Microfeature) *WQ*

sea \--

shoal *WR*

slackwater *WS*

slough (permanent water) *WU*

sound \--

strait \--

stream (permanent water) \--

tarn (also Microfeature) \--

thermokarst lake *WV*

tidal inlet \--

tunnel-valley lake \--

***Microfeatures:***

channel (permanent water) \--

perennial stream (also Landform) \--

pond \--

pool \--

pothole (permanent water; also Landform) \--

sag pond (also Landform) \--

salt pond (also Landform) \--

tank \--

tarn (also Landform) \--

> **16. SUBAQUEOUS FEATURES** \[ Discrete, relatively shallow underwater
> features that commonly can support rooted plants, and adjacent
> features, ordinarily found below permanent open water. Historically,
> in Soil Survey Reports these underwater features have been included in
> the generic map unit \"water\" \]. Subaqueous "Landscape" terms are
> obviously not terrestrial, but are Earth surface features.

***Landscapes:***

> bay \[coast\] (water body; also Landform) \--
>
> *gulf \[coast\] (water body) \--*
>
> estuary (water body; also Landform) \--
>
> lagoon \[coast\] (water body; also Landform) --
>
> *ocean (water body) \--*
>
> *sea (water body)* \--
>
> *sound (water body)* \--
>
> *strait (water body)* \--

***Landforms:***

> barrier cove \--
>
> bay \[coast\] (water body; also Landscape) *\--*
>
> bay bottom \--
>
> cove \[coast\] \-- dredged channel *(Anthropogenic Feature)*\--
>
> dredge-deposit shoal *(Anthro. Feature)* \--
>
> estuary (water body; also Landscape)*WD*
>
> flood-tidal delta \--
>
> flood-tidal delta flat \--
>
> flood-tidal delta slope \--
>
> fluviomarine bottom \--
>
> inlet \--
>
> lagoon \[coast\] (water body; also Landscape) *WI*
>
> lagoon bottom \--
>
> lagoon channel \--
>
> ? lake *WJ*
>
> mainland cove \--
>
> marine lake \--
>
> reef *RF*
>
> relict-tidal inlet \--
>
> shoal \--
>
> submerged back-barrier beach \--
>
> submerged mainland beach \--
>
> submerged point bar \[coastal\] \--
>
> submerged wave-built terrace \--
>
> submerged wave-cut platform \--
>
> tidal inlet \--
>
> washover-fan flat \--
>
> washover-fan slope \--

***Microfeatures:***

> channel (permanent water) \--

[]{#__RefHeading___Toc164067419 .anchor}**Exhibit 629-2 List of
Materials or Material-Related, Structure, or Morphological-Feature Terms
Contained in the Glossary.**

> (**NR** - terms that are NOT recommended; **NP** - terms that are not
> preferred)

\`a\`a lava

ablation till

alluvium

anticline

aquiclude

aquifer

aquitard

ash

ash flow

backswamp deposit

basal till

beach sands

bed

bedded

bedding plane

bedrock

block

block lava

block field

block glide deposit

block stream

blue rock \[volcanic\]

bombs \[volcanic\]

boulder field - NR

bowl

breccia

buried soil

caliche

caprock

chert

chimney

cinders

clast

clastic

coastal marl

colluvium

complex landslide deposit

conglomerate

continuous permafrost

coprogenous earth

coprogenous material

country rock

craton

creep deposit

cross-bedding

cross-lamination

cross-stratification

cryptogamic crust

cryoturbate

cyclothem

dead-ice - NR

debris

debris avalanche deposit

debris flow deposit

debris slide deposit

deposit

desert pavement

desert varnish - NP

detritus (geology)

diamictite

diamicton

diatomaceous earth

dike

dip

discontinuity

discontinuous permafrost

dropstone

dolomite (mineral)

dolomite (rock)

dolostone - NR

dome

dredge spoils

drift (glacial geology)

earthflow deposit

eolian deposit

epiclastic

erosional pavement

erratic

estuarine deposit

facies (stratigraphy)

fanglomerate

felsenmeer - NP

felsic rock

fill

fly ash

flowtill

fluviomarine deposit

fold

formation (stratigraphy)

freshwater marl

glacial drift - NR

glacial outwash - NR

glacial till - NR

glaciofluvial deposits

glaciolacustrine deposits

glaciomarine deposits

glauconite pellets

graben

greensands

ground soil

grus

herbaceous peat

horst

ice-pushed ridge

ice wedge

ice wedge cast

igneous rock

interbedded

intrusive

lacustrine deposit

lagoonal deposit

lahar

lamella

lamina

lamination - NR

lapilli

lateral spread deposit

lava flow

limestone

lithologic

lodgment till

loess

louderback

mafic rock

marine deposit

marl

melt-out till

metamorphic rock

metasediment

microbiotic crust

mine spoil, coal extraction

mine spoil, metal-ore extraction

mine spoil or earthy fill

moraine

moss peat

muck

mucky peat

mudstone

mudflow deposit

novaculite

nueé ardente

outcrop

outwash

overbank deposit

overburden

overthrust

paleosol

pahoehoe lava

parna

peat

pedisediment

permafrost

pillow lava

pitted outwash

pluton

plutonic

porcellanite

puff \[gilgai\]

pumice

pyroclastic

regolith

relict soil

residuum

rhythmite

rockfall deposit

rockfall avalanche deposit

rockfall landslide deposit

rock varnish

rotational landslide deposit

rubble

sand sheet

sandstone

saprolite

scoria

scree

sediment

sedimentary peat

sedimentary rock

shale

siltstone

sill

siltite

slide

slip face

slip surface

slope alluvium

sloughed till - NR

slump - NR

slump block

slump till

soil fall deposit

solifluction sheet

spoil bank

spoil pile

sporadic permafrost

stagnant ice

stone line

strandline

subglacial till

subglacial melt-out till

supraglacial till

supraglacial debris-flow sediment - NP

supraglacial melt-out till - NP

supraglacial till - NP

syncline

talus

tephra

thaw-sensitive permafrost

thaw-stable permafrost

till (glacial)

tombolo

topple deposit

tor

tuff

valley fill

valley side alluvium

varve

ventifact

vitric

volcanic breccia

volcaniclastic

welded soil

welded tuff

woody peat

##   {#section .600.00 .unnumbered}

## Exhibit 629-3 Genesis - Process Terms and Geologic Time Terms Contained in the Glossary. {#exhibit-629-3-genesis---process-terms-and-geologic-time-terms-contained-in-the-glossary. .600.00}

> (**NR** - terms that are NOT recommended; **NP** - terms that are not
> preferred).

aeolian - NR

accretion

active layer

active slope - NR

aggradation

alluvial

angle of repose

avalanche

avulsion

backwearing

block glide

buried

bypassed

cat clay - NR

colluvial

competence

complex landslide

conformity

congelifraction - NP

congeliturbation - NR

constructional (geomorphology)

corrosion

creep

cryoplanation

cryoturbation

cut and fill

debris avalanche

debris flow (mudflow)

debris slide

deflation

degradation

deposition

destructional (geomorphology)

dip \[structural geol.\]

discontinuity

distal

earthflow

Eocene

eolian

erosion

erosional (geomorphology)

exfoliation

exhumed

extramorainic - NP

extramorainal

extrusive

fall

flow

fluvial

frost bursting - NR

frost churning - NR

frost riving - NR

frost shattering

frost splitting - NR

frost stirring - NR

frost weathering - NR

frost wedging - NR

geomorphology

gelifraction - NR

gelivation - NR

glacial

glacial epoch

glacial marine sedimentation

glacial outburst flood (see *jokulhlaup*)

glaciation

Holocene

ice age - NR

ice-rafting

ice segregation

intramorainal

joint

knickpoint

landslide

lateral spread

lithification

mass movement

mass wasting -- NP

metastable slope - NR

Miocene

mudflow

nivation

Oligocene

Paleocene

pedoturbation

periglacial

Pleistocene

Pliocene

postglacial - NP

proximal

Quaternary

recent

relict

rockfall

rockfall avalanche

rotational landslide

sand flow

scour

scour and fill

slide

slope wash

slump - NP

soil creep - NP

soil fall

solifluction

strike \[structural geol.\]

subaerial

subaqueous

storm surge

stratified

stratigraphy

stream order

subaerial

subglacial

superglacial - NP

Tertiary

topple

translation slide

volcanic

weathering

welding

##   {#section-1 .600.00 .unnumbered}

## Exhibit 629-4 North American Glacial Episodes and General Geologic Time Scale. {#exhibit-629-4-north-american-glacial-episodes-and-general-geologic-time-scale. .600.00}

(Schoeneberger, et al, 2002; After Morrison; [In]{.underline}: Sibrava,
et al., 1986; and Harland, et al., 1990)

+-----------------+---------------+--------------+-------+----------+
| **Geologic      | **Geologic    | **Su         | **O   | *        |
| Period**        | Epoch**       | b-Division** | Is    | *Years** |
|                 |               |              | otope |          |
|                 |               |              | Stage | **(BP)** |
|                 |               |              | *^    |          |
|                 |               |              | 2^*** |          |
+-----------------+---------------+--------------+-------+----------+
|                 | **Holocene**  |              | \(1\) | 0 to     |
|                 |               |              |       | 10-12    |
|                 |               |              |       | ka\*     |
+-----------------+---------------+--------------+-------+----------+
|                 |               | Late         | \(2\) | 10-12 to |
|                 |               |              |       | 28 ka    |
|                 |               | Wisconsin    |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 |               | Middle       | (3,   | 28 to 71 |
|                 |               |              | 4)    | ka       |
|                 |               | Wisconsin    |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 | *Late         | Early        | (5a - | 71 to    |
|                 | Pleistocene*  |              | 5d)   | 115 ka   |
|                 |               | Wisconsin    |       |          |
|                 |               |              |       |          |
|                 |               | *Late        |       |          |
|                 |               | Sangamon*    |       |          |
+-----------------+---------------+--------------+-------+----------+
| *               |               | Sangamon     | (5e)  | 115      |
| **QUATERNARY*** |               |              |       | to128 ka |
+-----------------+---------------+--------------+-------+----------+
|                 | **            | Late --      | (6 -  | 128 to   |
|                 | Pleistocene** |              | 8)    | 300 ka   |
|                 |               | Mid          |       |          |
|                 |               | Pleistocene  |       |          |
|                 |               |              |       |          |
|                 |               | *            |       |          |
|                 |               | (Illinoian)* |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 | *Middle       | Middle --    | (9 -  | 300 to   |
|                 | Pleistocene*  |              | 15)   | 620 ka   |
|                 |               | Mid          |       |          |
|                 |               | Pleistocene  |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 |               | Early --     | (16 - | 620 to   |
|                 |               |              | 19)   | 770 ka   |
|                 |               | Mid          |       |          |
|                 |               | Pleistocene  |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 | ##### Earl    |              |       | 770 ka   |
|                 | y Pleistocene |              |       | to\      |
|                 |               |              |       | 1.64     |
|                 |               |              |       | Ma\*\*   |
+-----------------+---------------+--------------+-------+----------+
|                 | **Pliocene**  |              |       |          |
|                 | 1.64 to 5.2   |              |       |          |
|                 | Ma            |              |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 | **Miocene**   |              |       |          |
|                 | 5.2 to 23.3   |              |       |          |
|                 | Ma            |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***TERTIARY***  | **Oligocene** |              |       |          |
|                 | 23.3 to 35.4  |              |       |          |
|                 | Ma            |              |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 | **Eocene**    |              |       |          |
|                 | 35.4 to 56.5  |              |       |          |
|                 | Ma            |              |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 | **Paleocene** |              |       |          |
|                 | 56.5 to 65.0  |              |       |          |
|                 | Ma            |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| *               | *Late         |              |       |          |
| **CRETACEOUS*** | Cretaceous*   |              |       |          |
|                 | 65.0 to 97.0  |              |       |          |
|                 | Ma            |              |       |          |
+-----------------+---------------+--------------+-------+----------+
|                 | *Early        |              |       |          |
|                 | Cretaceous*   |              |       |          |
|                 | 97.0 to 145.6 |              |       |          |
|                 | Ma            |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***JURASSIC***  |               |              |       |          |
| 145.6 to 208.8  |               |              |       |          |
| Ma              |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***TRIASSIC***  |               |              |       |          |
| 208.8 to ≈      |               |              |       |          |
| 243.0 Ma        |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***PERMIAN*** ≈ |               |              |       |          |
| 243.0 to 290.0  |               |              |       |          |
| Ma              |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***P            |               |              |       |          |
| ENNSYLVANIAN*** |               |              |       |          |
| 290.0 Ma to     |               |              |       |          |
| 322.8 Ma        |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***M            |               |              |       |          |
| ISSISSIPPIAN*** |               |              |       |          |
| 322.8 to 362.5  |               |              |       |          |
| Ma              |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***DEVONIAN***  |               |              |       |          |
| 362.5 to 408.5  |               |              |       |          |
| Ma              |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***SILURIAN***  |               |              |       |          |
| 408.5 to 439.0  |               |              |       |          |
| Ma              |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| *               |               |              |       |          |
| **ORDIVICIAN*** |               |              |       |          |
| 439.0 to 510.0  |               |              |       |          |
| Ma              |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| ***CAMBRIAN***  |               |              |       |          |
| 510.0 to ≈      |               |              |       |          |
| 570.0 Ma        |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+
| **              |               |              |       |          |
| *PRECAMBRIAN*** |               |              |       |          |
| \> ≈ 570.0 Ma   |               |              |       |          |
+-----------------+---------------+--------------+-------+----------+

> \* ka = x 1,000; \*\* Ma = x 1,000,000

≈ = "approximately"

> *^1^* Modified from Morrison, 1991; Sibrava, et al., 1986; and
> Harland, et al., 1990.
>
> *^2^* Oxygen isotope.

REFERENCES

Harland, W.B., R.L. Armstrong, L.E. Craig, A.G. Smith, and D.G. Smith.
1990. A geologic time scale. Press Syndicate of University of Cambridge,
Cambridge, UK. 1 sheet.

Morrison, R.B. (ed.). 1991. Quaternary nonglacial geology: conterminous
United States. Geological Society of America, Decade of North American
Geology, Geology of North America, Vol. K-2. 672 p.

Schoeneberger, P.J., Wysocki, D.A., Benham, E.C., and Broderson, W.D.
2002. Field book for describing and sampling soils, version 2.0. Natural
Resource Conservation Service, USDA, National Soil Survey Center,
Lincoln, NE.

Sibrava, V., D.Q. Bowen, and D.Q. Richmond (eds.). 1986. Quaternary
glaciations in the Northern Hemisphere: final report of the
International Geological Correlation Programme, Project 24. Quaternary
Science Reviews, Vol. 5, Pergamon Press, Oxford. 514 p.

## Exhibit 629-5 Till Terms. {#exhibit-629-5-till-terms. .600.00}

TILL TERMS

Genetic classification and relationships of till terms commonly used in
soil survey. (Schoeneberger, et al., 2002; adapted from Goldthwaite and
Matsch, 1988.)

+--------------------------+----------------------+-------------------+
| **Location**             | **Till Types**       |                   |
+--------------------------+----------------------+-------------------+
| **(Facies of tills       | **Terrestrial**      | **Waterlaid**     |
| grouped by position at   |                      |                   |
| deposition)**            |                      |                   |
+--------------------------+----------------------+-------------------+
| **Proglacial Till**      | proglacial flowtill  | waterlaid         |
|                          |                      | flowtill          |
| (at the front of,        |                      |                   |
|                          |                      |                   |
| or in front of **a       |                      |                   |
| glacier**)               |                      |                   |
+--------------------------+----------------------+-------------------+
| **Supraglacial Till**    | supraglacial         | \-\-\-\-\-        |
|                          | flowtill *^1,\ 3^*   | \-\-\-\-\-\-\-\-- |
| (on top of,              |                      |                   |
|                          | supraglacial         |                   |
| or within upper part of  | melt-out till *^1^*  |                   |
|                          |                      |                   |
| a glacier)               | (ablation till - NP) |                   |
|                          | *^1^*                |                   |
|                          |                      |                   |
|                          | (lowered till - NP)  |                   |
|                          | *^2^*                |                   |
|                          |                      |                   |
|                          | (sublimation till -  |                   |
|                          | NP) *^2^*            |                   |
+--------------------------+----------------------+-------------------+
| **Subglacial Till**      | lodgment till *^1^*  | waterlaid         |
|                          |                      | melt-out till     |
| (within the lower part   | subglacial melt-out  |                   |
| of,                      | till                 | waterlaid         |
|                          |                      | flowtill          |
| or beneath a glacier)    | subglacial flowtill  |                   |
|                          |                      | iceberg till      |
|                          | (= "squeeze till"    |                   |
|                          | *^2,\ 3^*)           | ( = "ice-rafted") |
|                          |                      |                   |
|                          | (basal till - NP)    |                   |
|                          | *^1^*                |                   |
|                          |                      |                   |
|                          | (deformation till -  |                   |
|                          | NP) *^2^*            |                   |
|                          |                      |                   |
|                          | (gravity flowtill -  |                   |
|                          | NP) *^2^*            |                   |
+--------------------------+----------------------+-------------------+

*^1^ Ablation till* and *basal till,* generic terms that only describe
"relative position" of deposition, have been widely replaced by
multiple, more specific terms that convey both relative position and
process. *Ablation till* (any comparatively permeable, non-sorted debris
deposited within or above stagnant ice) is replaced by *supraglacial
melt-out till*, *supraglacial flowtill*, etc. *Basal till* (any dense,
non-sorted, subglacial till) is replaced by *lodgement till*,
*subglacial melt-out till*, *subglacial flowtill*, etc.

*^2^* Additional (proposed) till terms that have not gained wide
acceptance, and are therefore considered to be *Not Preferred*, and
should [not]{.underline} be used (shown for completeness).

*^3^* Also called *gravity flowtill* (Not Preferred).

REFERENCES

Goldthwaite, R.P. and Matsch, C.L. (eds.). 1988. Genetic classification
of glacigenic deposits: final report of the commission on genesis and
lithology of glacial quaternary deposits of the International Union for
Quaternary Research (INQUA). A.A. Balkema, Rotterdam. 294 p.

Jackson, J.A. (ed.). 1997. Glossary of geology, 4th Ed. American
Geological Institute, Alexandria, VA. 769 p.

Schoeneberger, P.J., Wysocki, D.A., Benham, E.C., and Broderson, W.D.
2002. Field book for describing and sampling soils, ver. 2.0. Natural
Resource Conservation Service, USDA, National Soil Survey Center,
Lincoln, NE.

## Exhibit 629-6 Pyroclastic Terms. {#exhibit-629-6-pyroclastic-terms. .600.00}

***PYROCLASTIC TERMS***: Size and compositional relationships of
pyroclastic terms commonly used in soil survey. (Schoeneberger, et al.,
2002; adapted from Fisher, 1989.)

+----------+--------------+-----------------+-------------------------+
| **Py     |              |                 |                         |
| roclasts |              |                 |                         |
| and      |              |                 |                         |
| Pyr      |              |                 |                         |
| oclastic |              |                 |                         |
| Deposits |              |                 |                         |
| (U       |              |                 |                         |
| nconsoli |              |                 |                         |
| dated)** |              |                 |                         |
+----------+--------------+-----------------+-------------------------+
| Size     |              |                 |                         |
|          |              |                 |                         |
| Scale:   |              |                 |                         |
| 0.062 mm |              |                 |                         |
| *^1^* 2  |              |                 |                         |
| mm 64 mm |              |                 |                         |
| *^1^*    |              |                 |                         |
+----------+--------------+-----------------+-------------------------+
|          |              |                 |                         |
+----------+--------------+-----------------+-------------------------+
| \<−−−−   |              |                 |                         |
| −−−−−−−− |              |                 |                         |
| −−−−−−−− |              |                 |                         |
| **       |              |                 |                         |
| tephra** |              |                 |                         |
| −−−−−−−  |              |                 |                         |
| −−−−−−−− |              |                 |                         |
| −−−−−−\> |              |                 |                         |
|          |              |                 |                         |
| (*all    |              |                 |                         |
| ejecta*) |              |                 |                         |
+----------+--------------+-----------------+-------------------------+
|          |              |                 |                         |
+----------+--------------+-----------------+-------------------------+
| \<−−−−−− |              | \<− **cinders   | \<−− **bombs**          |
| **ash**  |              | *^2^*** −\>     | ***^2^*** −−\>          |
| −−−−−−\> |              |                 |                         |
|          |              | (*specific      | (*fluid-shaped coarse   |
|          |              | gravity\        | fragments*)             |
|          |              | \> 1.0 & \<     |                         |
|          |              | 2.0*)           |                         |
+----------+--------------+-----------------+-------------------------+
| \        | \<−−−−−−−\>  |                 |                         |
| <−−−−−\> |              |                 |                         |
|          | **coarse     |                 |                         |
| **fine   | ash**        |                 |                         |
| ash**    |              |                 |                         |
+----------+--------------+-----------------+-------------------------+
|          |              | \<−−            | \<−− **blocks**         |
|          |              | **lapilli**     | ***^2^*** −−\>          |
|          |              | ***^2^*** −\>   |                         |
|          |              |                 | (*angular-shaped coarse |
|          |              | (*specific      | fragments*)             |
|          |              | gravity         |                         |
|          |              | \> 2.0*)        |                         |
+----------+--------------+-----------------+-------------------------+
|          |              | \<−−−−−−−−−−−   |                         |
|          |              | **scoria        |                         |
|          |              | *^2^***         |                         |
|          |              | −−−−−−−−−\>     |                         |
|          |              |                 |                         |
|          |              | (*slightly to   |                         |
|          |              | moderately      |                         |
|          |              | vesicular;\     |                         |
|          |              | specific        |                         |
|          |              | gravity \>      |                         |
|          |              | 2.0*)           |                         |
+----------+--------------+-----------------+-------------------------+
|          | \<−−−−−−−\>  | \<−−−−−−−−−     |                         |
|          |              | **pumice        |                         |
|          | **pumiceous  | *^2^***         |                         |
|          | ash *^3^***  | −−−−−−−−\>      |                         |
|          |              |                 |                         |
|          |              | (*highly        |                         |
|          |              | vesicular;      |                         |
|          |              | specific        |                         |
|          |              | gravity*        |                         |
|          |              |                 |                         |
|          |              | *\< 1.0*)       |                         |
+----------+--------------+-----------------+-------------------------+
| **As     |              |                 |                         |
| sociated |              |                 |                         |
| L        |              |                 |                         |
| ithified |              |                 |                         |
| (Conso   |              |                 |                         |
| lidated) |              |                 |                         |
| Rock     |              |                 |                         |
| Types**  |              |                 |                         |
+----------+--------------+-----------------+-------------------------+
| \        | \<−−−−−−−\>  | \<              | \< --**pyroclastic      |
| <−−−−−\> |              | *               | breccia**--\>           |
|          | **coarse     | *lapillistone** |                         |
| **fine   | tuff** *^1^* | *^1^* \>        |                         |
| tuff**   |              |                 |                         |
| *^1^*    |              | (*sp. gr. \>    |                         |
|          |              | 2.0*)           |                         |
+----------+--------------+-----------------+-------------------------+
| \<−−     |              | \<−−−−−−−−−     |                         |
| **welded |              | **agglomerate** |                         |
| tuff**   |              | −−−−−−−−−\>     |                         |
| −−\>     |              |                 |                         |
|          |              | (*[rounde       |                         |
|          |              | d]{.underline}, |                         |
|          |              | volcanic coarse |                         |
|          |              | fragments*)     |                         |
+----------+--------------+-----------------+-------------------------+
| \<−−     |              | \<−−−−−−−−      |                         |
| **igni   |              | **volcanic      |                         |
| mbrite** |              | breccia**       |                         |
| −−−\>    |              | −−−−−−−−\>      |                         |
|          |              |                 |                         |
| (**      |              | (*[angula       |                         |
| *ash-dom |              | r]{.underline}, |                         |
| inated** |              | volcanic coarse |                         |
| flows    |              | fragments*)     |                         |
| and nuee |              |                 |                         |
| a        |              |                 |                         |
| rdentes* |              |                 |                         |
| )        |              |                 |                         |
+----------+--------------+-----------------+-------------------------+

*^1^* These size breaks are taken from geologic literature (Fisher,
1989) and based on the modified Wentworth scale. The 0.062 mm break is
very close to the USDA's 0.05 mm break between *coarse silt* and *very
fine sand* (Soil Survey Staff, 1993). The 64 mm "geologic" break is
relatively close to the USDA's 76 mm break between *coarse gravel* and
*cobbles*. (See the chart "Comparison of Particle Size Classes in
Different Systems" in the "Profile / Pedon Description Section" under
"Soil Texture" in the Field Book for Describing and Sampling Soils
(Schoeneberger, et al., 2002).

*^2^* A minimum size limit of 2 mm is required in Soil Taxonomy (Soil
Survey Staff, 1994; p. 54), but is [not]{.underline} required in
geologic usage (Fisher, 1989).

*^3^* The descriptor for pumice smaller than 2 mm, as used in Soil
Taxonomy (Soil Survey Staff, 1999). Geologic usage is based solely upon
composition and does [not]{.underline} include any size restrictions;.

REFERENCES

Fisher, R.V. 1989. Pyroclastic sediments and rocks. AGI Data Sheet 25.2.
[In]{.underline}: Dutro, J.T., Dietrich, R.V., and Foose, R.M. 1989. AGI
data sheets for geology in the field, laboratory, and office, 3rd
edition. American Geological Institute, Washington, D.C.

Jackson, J.A. (ed.). 1997. Glossary of geology, 4th Ed. American
Geological Institute, Alexandria, VA. 769 p.

Schoeneberger, P.J., Wysocki, D.A., Benham, E.C., and Broderson, W.D.
2002. Field book for describing and sampling soils, ver. 2.0. Natural
Resource Conservation Service, USDA, National Soil Survey Center,
Lincoln, NE.

Soil Survey Staff. 1994. Keys to Soil Taxonomy, 6th Ed. USDA - Natural
Resources Conservation Service.

Soil Survey Staff. 1998. Keys to Soil Taxonomy, 8th Ed. USDA - Natural
Resources Conservation Service, Pocahantas Press, Inc., Blacksburg, VA.
524 pp.

Soil Survey Staff. 1999. Soil Taxonomy, 2^nd^ Ed. A basic system of soil
classification for making and interpreting soil surveys. USDA - Soil
Conservation Service, Agricultural Handbook #436, U.S. Government
Printing Office, Washington, DC, 869p.