Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. 

Government

This map was printed on an electronic plotter directly from digital files. Dimensional calibration may vary between electronic plotters 

and between X and Y directions on the same plotter, and paper may change size due to atmospheric conditions; therefore, scale and 

proportions may not be true on plots of this map.

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225, 1–888–ASK–USGS

Digital files available at https://doi.org/10.3133/ofr20181024

Suggested Citation: Johnson, S.Y., Hartwell, S.R., and Davenport, C.W., 2018, Offshore and onshore geology and geomorphology, 

Offshore of Point Conception map area, California, sheet 9 in Johnson, S.Y., Dartnell, P., Cochrane, G.R., Hartwell, S.R., Golden, N.E., 

Kvitek, R.G., and Davenport, C.W. (S.Y. Johnson and S.A. Cochran, eds.), California State Waters Map Series—Offshore of Point 

Conception, California: U.S. Geological Survey Open-File Report 2018–1024, pamphlet 36 p., 9 sheets, scale 1:24,000, 

https://doi.org/10.3133/ofr20181024.

ISSN 2331-1258 (online)

https://doi.org/10.3133/ofr20181024

120°30' 120° 119°30'

34°

34°30'

Limit of California’s

State Waters

Kilometers 0 5 10

Santa Barbara Channel

Area of

Map

Santa Barbara CALIF.

MAP LOCATION

Anacapa Is.

Santa Cruz Is.

Santa Rosa Is.

San Miguel Is.

1

U.S. Geological Survey;

2

California Geological Survey

Offshore and Onshore Geology and Geomorphology, Offshore of Point Conception Map Area, California

 By

Samuel Y. Johnson,1 Stephen R. Hartwell,1 and Clifton W. Davenport2

2018

ONE MILE = 0.869 NAUTICAL MILES

1 .5 0 1 KILOMETER

1000 0 1000 2000 3000 4000 5000 6000 7000 FEET

1 1/2 0 1 MILE

SCALE 1:24 000

APPROXIMATE MEAN BATHYMETRIC CONTOUR INTERVAL 10 METERS DECLINATION, 2018

MAGNETIC NORTH

12 / ° 1 2

TRUE NORTH

Offshore geology and geomorphology mapped by Samuel Y. 

Johnson and Stephen R. Hartwell, 2016. Onshore geology and 

geomorphology compiled and modified by Clifton W. Davenport, 

2014, from Dibblee (1988a,b). Bathymetric contours by Peter 

Dartnell, 2014

GIS database and digital cartography by Stephen R. Hartwell and 

Peter Dartnell 

Manuscript approved for publication February 13, 2018 

Onshore elevation data from National Oceanic and Atmospheric 

Administration (NOAA) Office for Coastal Management's Digital Coast 

(available at http://www.csc.noaa.gov/digitalcoast/data/coastallidar/) and 

from U.S. Geological Survey’s National Elevation Dataset (available at 

http://ned.usgs.gov/). Offshore shaded relief bathymetry from map on sheet 2, 

this report. California’s State Waters limit from NOAA Office of Coast Survey 

Universal Transverse Mercator projection, Zone 10N

NOT INTENDED FOR NAVIGATIONAL USE

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Jalama Beach

County Park

 Jalama Creek

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Government Point Syncline

Point Conception Anticline

120°25'

120°25'

120°30'

120°30'

34°30'

34°30'

34°25'

34°25'

Tma

Tml

Tm

Qmt

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Kja

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af

af

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Qms

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ass

Tsq

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Qmsc

Tsq

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Tbu

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Qmsd

Qms/Tbu

Tsq

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Qmp

Qms/Tsq

ass

Qas

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Qas

Qas

Qmp

Tsq

Tsq

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Qas

Tbu

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af

Tsq

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Qms/Tsq

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Tsq

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Qms/Tbu

Qas

Qmp

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Tbu

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Qms/Tbu

REFERENCES CITED

Dibblee, T.W., Jr., 1988a, Geologic map of the Lompoc Hills and Point Conception quadrangles, Santa Barbara County, 

California (H.E. Ehrenspeck [1988] and J.A. Minch [2009], eds.): Dibblee Geological Foundation Map DF-18, scale 

1:24,000.

Dibblee, T.W., Jr., 1988b, Geologic map of the Point Arguello and Tranquillon Mountain quadrangles, Santa Barbara County, 

California (H.E. Ehrenspeck [1988] and J.A. Minch [2009], eds.): Dibblee Geological Foundation Map DF-19, scale 

1:24,000.

Draut, A.E., Hart, P.E., Lorenson, T.D., Ryan, H.F., Wong, F.L., Sliter, R.W., and Conrad, J.E., 2009, Late Pleistocene to 

Holocene sedimentation and hydrocarbon seeps on the continental shelf of a steep, tectonically active margin, southern 

California, USA: Marine Geophysical Research, p. 193–206, available at https://doi.org/10.1007/s11001-009-9076-y.

Eichhubl, P., Greene, H.G., and Maher, N., 2002, Physiography of an active transpressive margin basin—High-resolution 

bathymetry of the Santa Barbara basin, southern California continental borderland: Marine Geology, v. 184, p. 95–120.

Golden, N.E., and Cochrane, G.R., 2013, California Seafloor Mapping Program video and photograph portal: U.S. Geological 

Survey, Coastal and Marine Geology Program data portal, available at https://doi.org/10.5066/F7J1015K.

Greene, H.G., Clarke, S.H., Jr., and Kennedy, M.P., 1991, Tectonic evolution of submarine canyons along the California 

continental margin, in Osborne, R.H., ed., From shoreline to abyss: Society for Sedimentary Geology Special Publication 

46, p. 231–248.

Keller, E.A., Duffy, M., Kennett, J.P., and Hill, T., 2007, Tectonic geomorphology and hydrocarbon-induced topography of 

the mid-Channel anticline, Santa Barbara basin, California: Geomorphology, v. 89, p. 274–286.

Kunitomi, D.S., Hopps, T.E., and Galloway, J.M., eds., 1998, Structure and petroleum geology, Santa Barbara Channel, 

California: American Association of Petroleum Geologists, Pacific Section, and Coast Geological Society, Miscellaneous 

Publication 46, 328 p.

Lorenson, T.D, Hostettler, F.D., Rosenbauer, R.J., Peters, K.E., Kvenvolden, K.A., Dougherty, J.A., Gutmacher, C.E., Wong, 

F.L., and Normark, W.R., 2009, Natural offshore seepage and related tarball accumulation on the California coastline, 

Santa Barbara Channel and the southern Santa Maria Basin—Source identification and inventory: U.S. Geological 

Survey Open-File Report 2009–1225 [also released as Minerals Management Service Report 2009–030], 116 p., 

available at http://pubs.usgs.gov/of/2009/1225/. 

Lorenson, T.D., Wong, F.L., Dartnell, P., and Sliter, R.W., 2014, Greenhouse gases generated from the anaerobic 

biodegradation of natural offshore asphalt seepages in southern California: Geo-Marine Letters, v. 34, p. 281–295, 

available at https://doi.org/10.1007/s00367-014-0359-1/.

Monterey Bay Aquarium Research Institute, 2002, Santa Barbara multibeam survey: Monterey Bay Aquarium Research 

Institute Digital Data Series 4, 2 CD-ROMs.

National Geodetic Survey, 2016, NOAA Shoreline Data Explorer: National Oceanic and Atmospheric Administration, 

National Geodetic Survey data viewer and database, accessed May 1, 2016, at http://www.ngs.noaa.gov/NSDE/.

Redin, T., Forman, J., Kamerling, M., and Galloway, J., 2005, Santa Barbara Channel structure and correlation 

sections—CS-32 to CS-42: American Association of Petroleum Geologists, Pacific Section, Publication CS 36, 12 

sheets.

Reid, J.A., Reid, J.M., Jenkins, C.J., Zimmerman, M., Williams, S.J., and Field, M.E., 2006, usSEABED—Pacific Coast 

(California, Oregon, Washington) offshore surficial-sediment data release: U.S. Geological Survey Data Series 182, 

available at http://pubs.usgs.gov/ds/2006/182/.

Rockwell, T.K., Nolan, J., Johnson, D.L., and Patterson, R.H., 1992, Ages and deformation of marine terraces between Point 

Conception and Gaviota, Western Transverse Ranges, California, in Wehmiller, J.F., and Fletcher, C., eds., Quaternary 

coasts of the United States—Marine and lacustrine systems: Society of Economic Paleontologists and Mineralogists, p. 

333–341.

Sorlien, C.C., and Nicholson, C., 2015, Post 1-Ma deformation history of the Pitas Point-North Channel-Red Mountain fault 

system and associated folds in Santa Barbara channel, California: U.S. Geological Survey National Earthquake Hazards 

Reduction Program final report, Award G14AP00012, 24 p., available at https://earthquake.usgs.gov/cfusion/

external_grants/reports/G14AP00012.pdf.

EXPLANATION OF MAP SYMBOLS

Contact—Solid where location is certain or well located, dashed where location is approximate or inferred

Fault—Solid where location is certain, dashed where location is inferred, dotted where location is concealed, 

queried where uncertain 

Folds—Solid where location is certain, dashed where location is inferred, dotted where location is concealed

Anticline

Syncline 

Approximate modern shoreline—From National Oceanic and Atmospheric Administration’s Shoreline Data 

Explorer (National Geodetic Survey, 2016)

3-nautical-mile limit of California’s State Waters

Area of “no data”—Areas beyond 3-nautical-mile limit of California’s State Waters were not mapped as part of 

California Seafloor Mapping Program

DISCUSSION

Marine geology and geomorphology were mapped in the Offshore of Point Conception map area from the shoreline to 

the 3-nautical-mile limit of California’s State Waters. The location of the shoreline, which is from the National Oceanic and 

Atmospheric Administration’s (NOAA’s) Shoreline Data Explorer, is based on their analysis of lidar imagery (National 

Geodetic Survey, 2016). Offshore geologic units were delineated on the basis of integrated analyses of adjacent onshore 

geology with multibeam bathymetry and backscatter imagery (sheets 1, 2, 3), seafloor-sediment and rock samples (Reid and 

others, 2006), digital camera and video imagery (Golden and Cochrane, 2013), and high-resolution seismic-reflection profiles 

(sheet 7). Bathymetric lidar and aerial photographs taken in multiple years were used to map the nearshore area (0 to 10 m 

water depth) and to link the offshore and onshore geology. 

The onshore geology was compiled and modified from Dibblee (1988a,b); unit ages, which are derived from these 

sources, reflect local stratigraphic relations. In addition, some Quaternary units were modified by C.W. Davenport on the 

basis of analysis of 2004 ifSAR and 2009 lidar imagery. 

The offshore part of the map area largely consists of a gently offshore-dipping shelf underlain by Neogene bedrock, as 

well as by Holocene sediments that are derived primarily from relatively small coastal watersheds that drain the Santa Ynez 

Mountains. The dip of the shelf gradually changes from about 1.1° south and east of Point Conception to about 0.7° on the 

broader shelf west of Point Conception. Holocene nearshore and shelf deposits are primarily sand (unit Qms). A distinct field 

(about 1.15 km2) of northeast-trending (about 60° azimuth) low-relief sand ridges (unit Qmsr) is present in the midshelf area 

about 1.5 to 3.0 km south of Point Conception, at water depths of 65 to 80 m; the crests of the sand ridges are as high as 60 

cm and as long as 750 m long, and they are spaced at intervals of about 125 to 200 m.

Coarser grained sediments (units Qmsc, Qmsd) are mapped on the basis of their high backscatter and, in some cases, 

their moderate seafloor relief. Unit Qmsc, which ranges from coarse sand and gravel to possibly boulders, is found as (1) a 

southwest-trending lens about 650 m south of Point Conception, at depths of 15 to 40 m, and (2) along the margins of seafloor 

bedrock outcrops between Point Conception and Point Arguello, at depths of about 30 to 50 m. Unit Qmsd, inferred to 

consist of coarse sand and possibly gravel, is found as single depressions or in groups of depressions interspersed with 

elevated shelf sediments (unit Qms) adjacent to seafloor bedrock outcrops, at water depths of about 15 to 40 m. Areas in 

which unit is found are not likely to change substantially, but the boundaries of unit(s) and locations of individual depressions 

(and intervening flat sheets) likely are ephemeral, changing during significant storm events.

Finer grained sediment—the very fine sand, silt, and clay of unit Qmsf—is mapped between depths of about 80 m and 

the shelf break, which is present only in the southwesternmost part of the map area, at a depth of about 100 m. The boundary 

between units Qms and Qmsf is based on observations and extrapolation from sparse sediment sampling (for example, Reid 

and others, 2006) and camera ground-truth surveying (Golden and Cochrane, 2013). Thus, the boundary between units Qms 

and Qmsf should be considered transitional and approximate and is expected to shift as a result of seasonal- to annual- to 

decadal-scale cycles in wave climate, sediment supply, and sediment transport. 

Fine-grained deposits similar to unit Qmsf also are found below the shelf break on the upper slope at water depths 

greater than 100 m, where they are mapped as a separate unit (unit Qmsl) on the basis of their location and geomorphology. 

Both the shelf break and upper slope are incised by a 600-m-wide, 20- to 30-m-deep, south-facing trough, probably filled 

with sand and mud (unit Qmcr), that is one of the five heads of the informally named Arguello submarine canyon (Greene 

and others, 1991; Eichhubl and others, 2002; Monterey Bay Aquarium Research Institute, 2002). 

Bedrock exposures along the shoreline both north and east of Point Conception primarily consist of marine shale, 

claystone, and diatomite of the upper Miocene and lower Pliocene Sisquoc Formation (unit Tsq). Adjacent Tsq seafloor 

outcrops commonly have a “ribbed” appearance, reflecting the differential erosion of variably resistant interbeds. Unit Tsq 

overlies the Miocene Monterey Formation (Tm), which crops out on the seafloor in the nearshore on the west flank of 

Government Point, as well as in the nearshore to inner shelf areas in the northwestern part of the map area. Because of the 

lack of sampling and their relative lack of distinctive seafloor morphology, some seafloor bedrock outcrops cannot be 

confidently assigned to either unit Tm or unit Tsq; these areas are mapped as the undivided Tertiary bedrock unit (Tbu).

The Santa Barbara Channel region is a mature hydrocarbon province (Kunitomi and others, 1998) that is well known for 

hydrocarbon-induced seafloor topography (Keller and others, 2007). Geomorphic features associated with petroleum seepage 

on the shelf and upper slope, which are prevalent near Point Conception (Draut and others, 2009; Lorenson and others, 2009, 

2014), include fields of dense pockmarks (unit Qmp) and asphalt mounds (unit Qas). In the Offshore of Point Conception 

map area, pockmarks are predominantly grouped or, less commonly, solitary; are circular to elliptical; range in size from 50 to 

150 m along their long axis; typically are 20 to 40 cm deep; and commonly have a central cone as much as 150 cm high. 

Grouped pockmarks cover about 4.2 km2

 of the map area (see table 7–1 in pamphlet). The largest mapped asphalt mounds 

cover 675,856 m2 and 168,950 m2, and they have as much as about 12 m of relief above the seafloor. Draut and others (2009) 

noted that such large mounds likely consist of a mix of tar and sediment, and Lorenson and others (2014) calculated areas and 

volumes of asphalt in the Point Conception area and the larger Santa Barbara Channel region. The asphalt mounds in the 

Offshore of Point Conception map area, which are mainly found on the south flank of the Point Conception Anticline, cover 

about 2.6 km2 (table 7–1 in pamphlet). 

Pipelines through California’s State Waters, which are associated with petroleum platforms located farther offshore in 

federal waters, are mapped as unit af. The remains of two large (about 75 and 60 m long) ships, mapped as unit ass, are 

located about 550 m northeast of Government Point, at a water depth of 10 m, and about 5.8 km east of Government Point, at 

a depth of 22 m.

Neogene strata are deformed in a fold belt that, on a regional scale, is located within a large, east-west-striking, southdipping homocline that extends from the south flank of the Santa Ynez Mountains into the offshore to the south and west. 

Nearby regional cross sections (Redin and others, 2005) and industry seismic-reflection profiles (see fig. 10 on sheet 7; see 

also, Sorlien and Nicholson, 2015) showed that the homocline formed above the blind Pitas Point–North Channel Fault 

system, which in the offshore extends westward for more than 100 km, from Pitas Point (10 km northwest of Ventura) to 

beyond Point Conception. South of Point Conception, the tip of the Pitas Point–North Channel Fault is inferred to be buried 

beneath the slope about 5 to 6 km offshore, to a depth of about 2 to 3 km below sea level. 

In the offshore part of the map area, closely spaced seismic-reflection profiles (see sheet 7) image many shallow, 

west-northwest-striking folds that have variable geometries, lengths, amplitudes, degrees of continuity, and wavelengths. The 

Government Point Syncline, which is the most prominent fold, has been mapped both onshore at Point Conception (Dibblee, 

1988a) and in the offshore both to the west and east; it has a cumulative length of more than 22 km. Local thickening of 

post-LGM sediments along the axis of the Government Point Syncline (see figs. 2, 3, and 4 on sheet 7) could reflect syntectonic sedimentation. Onland at Point Conception, Rockwell and others (1992) also documented active folding of late 

Pleistocene marine terraces in the Government Point Syncline. This regionally extensive syncline and many shorter, 

east-west-striking folds and faults probably are rooted in blind thrust faults and back-thrust faults in the hanging wall above 

the Pitas Point–North Channel Fault system.

LIST OF MAP UNITS

[See Description of Map Units (chapter 7, in pamphlet) for complete map-unit descriptions]

OFFSHORE GEOLOGIC AND GEOMORPHIC UNITS

[Note that composite units (gray-, white-, and black-stippled areas) are designated on map by composite label indicating both 

overlying sediment cover and lower (older) unit, separated by a slash (for example, Qms/Tm indicates that thin sheet of Qms 

overlies Tm)]

Artificial seafloor (late Holocene)—Pipelines associated with offshore oil platforms

Artificially modified seafloor (late Holocene)—Shipwreck(?)

Marine nearshore and shelf deposits (late Holocene)—Mostly sand; ripples common

Coarse-grained marine nearshore and shelf deposits (late Holocene)—Coarse sand and gravel to boulders

Fine-grained marine shelf deposits (late Holocene)—Mostly clay, silt, and very fine sand

Marine shelf scour depressions (Holocene)—Inferred to be coarse sand and gravel, in low-relief scour 

depressions

Marine shelf sand ridges (Holocene)—Field of low-relief (<60 cm) sand ridges and intervening troughs

Marine upper slope deposits (Holocene)—Mostly clay, silt, and very fine sand. Found below shelf break, at 

water depths of more than 100 m

Marine slope canyons and rills (Holocene)—Probably sand and mud; forms incised trough into shelf break and 

outer shelf southwest of Point Conception; one of five heads of informally named Arguello canyon 

Marine pockmarks (Holocene)—Sand and mud, in circular to elliptical pockmarks

Asphalt deposits (Holocene)—Asphalt (tar); weathered and biodegraded oil derived from underlying or nearby 

natural hydrocarbon seeps

Bedrock, undivided (Pliocene and Miocene)—Mainly mudstone and siltstone. Probably consists of the lower 

Pliocene and upper Miocene Sisquoc Formation and the Miocene Monterey Formation

Sisquoc Formation (early Pliocene and late Miocene)—Marine, tan- to white-weathering, diatomaceous 

mudstone and shale, conglomerate, and subordinate dolomite

Monterey Formation (Miocene)—Mainly siliceous and calcareous mudstone and shale 

ONSHORE GEOLOGIC AND GEOMORPHIC UNITS

[Units compiled and modified from Dibblee (1988a,b); unit ages, which are from these sources, reflect local stratigraphic 

relations. In addition, some Quaternary units modified by C.W. Davenport on basis of analysis of 2004 ifSAR and 2009 lidar 

imagery]

Artificial fill (late Holocene)—Engineered and (or) nonengineered material deposited by humans

Beach deposits (late Holocene)—Unconsolidated, fine- to coarse-grained sand, pebbles, and boulders. Mapped in 

coastal band from shoreline to highest elevation of swash zone 

Active stream-channel deposits (late Holocene)—Active stream channels that contain unconsolidated sand, silt, 

and gravel deposits

Dune-sand deposits (late Holocene)—Very well sorted, fine to medium sand; forms active dunes along coast 

Alluvial deposits, undivided (Holocene)—Sand, gravel, and silt deposits, adjacent to or near active stream 

channels 

Alluvial fan deposits (Holocene)—Unconsolidated, heterogeneous layers of sand, silt, and gravel; relatively 

undissected. Internal contacts delineate individual alluvial fans

Colluvium (Holocene)—Loose to firm, unsorted sand, silt, clay, gravel, rock debris, and organic material; 

includes slope wash and valley fill; may contain numerous small landslides and (or) coalesced alluvial fans

Landslide deposits (Holocene and Pleistocene)—Deposits of diverse slope-movement processes; queried where 

identity is uncertain. Internal contacts delineate individual landslide bodies

Alluvial deposits, undivided (Holocene and Pleistocene)—Sand, gravel, and silt deposits. Mapped on gently 

sloping to level surfaces near stream channels 

Alluvial fan deposits (Holocene and Pleistocene)—Poorly consolidated silt, sand, and gravel deposits. Mapped 

either where older age is indicated by greater degree of dissection or where elevations are higher than that of 

adjacent Holocene alluvial fans 

Alluvial fan deposits (Pleistocene)—Discontinuous or highly dissected deposits of semiconsolidated, moderately 

to poorly sorted layers of silty clay, silt, sand, and gravel

Marine-terrace deposits, undivided (Pleistocene)—Semiconsolidated sand and local gravel deposits; on uplifted 

marine-abrasion platforms along coast

Sisquoc Formation (early Pliocene and late Miocene)—Marine shale, claystone, and diatomite; queried where 

identity is uncertain

Monterey Formation, undivided (Miocene)—Marine, predominantly well-bedded, siliceous chert, mudstone, 

shale, diatomite, and conglomerate breccia. Locally divided into three subunits

Chert (Miocene)

Light-gray diatomite (Miocene)

Semisiliceous shale (Miocene)

Tranquillon Volcanics (Miocene)—Rhyolitic tuff breccia

Rincon Shale (early Miocene)—Marine shale or claystone; queried where identity is uncertain 

Vaqueros Formation (late Oligocene)—Marine calcareous sandstone. Includes one subunit

Sandstone and pebble conglomerate (late Oligocene)—Queried where identity is uncertain 

Alegria Formation (Oligocene)—Marine, arkosic sandstone and greenish-gray siltstone; locally fossiliferous 

(Dibblee, 1988a)

Gaviota Formation (Oligocene and Eocene)—Marine arkosic sandstone, locally fossiliferous; includes one 

subunit

Concretionary siltstone and claystone (Oligocene and Eocene) 

Sacate Formation (Eocene)—Marine arkosic sandstone that contains interbeds of micaceous, clayey shale

Cozy Dell Shale (Eocene)—Marine micaceous shale

Matilija Sandstone (Eocene)—Marine arkosic sandstone

Anita Shale (Eocene and Paleocene)—Marine, micaceous, clayey shale; includes foraminiferal claystone 

(informally known as “Poppin shale”); queried where identity is uncertain. Also includes one mappable 

subunit

Sierra Blanca limestone (Eocene and Paleocene)—Algal limestone lens 

Jalama Formation (Late Cretaceous)—Marine arkosic sandstone; includes three subunits 

Siltstone (Late Cretaceous)

Micaceous shale and siltstone (Late Cretaceous)

Arkosic sandstone with interbeds of micaceous shale (Late Cretaceous)

Ts

Tg

Ta

Tv

Tml

Kjsl

Kja

Tan

Tasb

Tma

Tcd

Tm

Qc

Qal

Qyf

Qd

Qsc

Qb

af

Qmt

Qof

Qa

Qls

Qf

Tsq

Tmls

Tr

Kjss

Kjsh

Tt

Tgs

Tmc

Tvsc

Qms

Qmsf

Qmsc

Qmsr

Qmsd

af

Qas

Qmp

Tbu

Qmcr

Tsq

Tm

ass

Qmsl

Tm

Ts

Tan

Ta

Tv

Tcd

ass Qms Qmsc

Qmp

af Qmsf

Tbu

Pliocene

Pleistocene

Miocene

Oligocene

Eocene

Holocene

TERTIARY

QUATERNARY

Paleocene

CRETACEOUS

Tm

Kja

OFFSHORE GEOLOGIC AND GEOMORPHIC UNITS ONSHORE GEOLOGIC AND GEOMORPHIC UNITS

CORRELATION OF MAP UNITS

[See Description of Map Units (chapter 7, in pamphlet) for precise unit ages]

Qb Qsc Qd

Qal

af

Qas

Tsq

Qyf Qc

Qls

Qa Qf

Qof Qmt

Tt

Tr

Tvsc

Tmc

Tml

Tgs

Tg

Tma

Kjsl

Kjss

Kjsh

Qmsd Qmsr

Tmls

Tasb

Tsq

Qmsl Qmcr

 Late

Cretaceous

Open-File Report 2018–1024

Sheet 9 of 9

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey