U.S. Department of the Interior

U.S. Geological Survey

Pamphlet to accompany

Scientific Investigations Map 3312

Surficial Geology and Stratigraphy of Pleistocene Lake 

Manix, San Bernardino County, California
Cover: 1, View to east of playa and distal-fan deposits of unit Qmr (Mojave River formation) near western end of Buwalda Ridge in Cady 

subbasin; 2, view showing Q17 over Qia (vertical cliff) over Qvg (more gullied, steeply sloping) over pink QTcg with white calcic soil at 

top; 3, view to northeast of playa and distal-fan deposits of unit Qp in Afton subbasin; and 4, Units Ql8, Ql7, and Ql6 exposed on south side of 

Mojave River, Afton subbasin, station M11–109.

4

1

3

2
Surficial Geology and Stratigraphy of 

Pleistocene Lake Manix, San Bernardino 

County, California

By Marith C. Reheis, Joanna R. Redwine, Elmira Wan, John P. McGeehin, 

and D. Paco VanSistine

Pamphlet to accompany

Scientific Investigations Map 3312

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Reheis, M.C., Redwine, J.R, Wan, Elmira, McGeehin, J.P., and VanSistine, D.P., 2014, Surficial geology and stratigraphy 

of Pleistocene Lake Manix, San Bernardino County, California: U.S. Geological Survey Scientific Investigations Map 3312, 

46 p., 2 sheets, scale 1:24,000, http://dx.doi.org/10.3133/sim3312.

ISSN 2329-132X (online)
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Physiographic Setting of Lake Manix.........................................................................................................4

A Brief History of Pleistocene Lake Manix................................................................................................4

Rationale for this Map...................................................................................................................................6

Description of Map Units..............................................................................................................................7

Unconsolidated Surficial Deposits ....................................................................................................7

Man-Made Deposits ...................................................................................................................7

Lacustrine Deposits.....................................................................................................................7

Fluvial Deposits ............................................................................................................................9

Alluvial-Fan Deposits.................................................................................................................10

Playa and Distal-Fan Deposits.................................................................................................13

Eolian and Mixed Eolian-Alluvial Deposits............................................................................14

Bedrock Units......................................................................................................................................14

Acknowledgments.......................................................................................................................................15

References Cited..........................................................................................................................................15

Appendix. Captions for Selected Photographs of Pleistocene Lake Manix Map Area................19

Sheets

1. Map of Surficial Geology and Stratigraphy of Pleistocene Lake Manix, 

San Bernardino County, California........................................................................................ link

2. Stratigraphic sections of Pleistocene Lake Manix map area, San Bernardino 

County, California..................................................................................................................... link

 2A. Stratigraphic sections from northern Manix Wash to south of Mojave River

 2B. Stratigraphic sections from western Buwalda Ridge to Dunn

 2C. Stratigraphic sections from Dunn wash and Afton areas

 2D. Stratigraphic sections from north Afton beach ridge in Afton subbasin

Figures

1. Map showing Mojave River drainage basin in southern California.....................................2

2. Index map superimposed on digital orthophoto map showing Pleistocene Lake 

Manix, surficial geologic map area, and boundaries of 7.5’ USGS quadrangles...............3

Tables

1. Radiocarbon ages and site information from Cady and Afton subbasins 

of Lake Manix ..............................................................................................................................25

2. Locations, correlations, age ranges and geochemical compositions 

of tephra layers in map area.....................................................................................................28

3. Site data for Pleistocene Lake Manix surficial map.............................................................29

4. Fault and altitude data for Pleistocene Lake Manix surficial map.....................................38
iv

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F–32)/1.8

Ka, thousand years before present; Ma, million years before present.

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum, or meters above sea 

level (masl) as indicated in the report. 
Surficial Geology and Stratigraphy of Pleistocene Lake 

Manix, San Bernardino County, California

By Marith C. Reheis,1 Joanna R. Redwine,2 Elmira Wan,1 and D. Paco VanSistine1

accurately portrayed in the measured sections that accompany 

the map. Altitudes of many contacts were obtained using differentially corrected Global Positioning System (GPS) or, in 

some cases, lidar (light detection and ranging) data.

Introduction

Pluvial Lake Manix, in the central Mojave Desert of 

California, has been a focus of paleoclimate, surficial processes, and neotectonic studies by the U.S. Geological Survey 

(USGS) since about 2004. From the middle Pleistocene until 

the late Pleistocene, Lake Manix was the primary terminus 

of the Mojave River, which drains northeasterly from the 

San Bernardino Mountains; when in flood, the river currently 

transits Soda Lake playa in the Mojave National Forest and 

terminates in the Silver Lake playa (fig. 1). Southwestern lakes 

are sensitive recorders of precipitation and temperature on millennial to decadal timescales, but there are few detailed studies 

of pluvial lakes in the Mojave Desert region. The stratigraphy, paleontology, and broad lake-level fluctuations of Lake 

Manix were established by Ellsworth (1932; Blackwelder and 

Ellsworth, 1936), Jefferson (2003, and references therein), and 

Meek (1989a, 1989b, 1990, 2000). The U.S. Geological Survey 

initiated paleoclimate studies to improve understanding of the 

shifts in atmospheric circulation that control precipitation in the 

Mojave Desert. The initial focus was on stratigraphic sequences 

of lacustrine and alluvial-fan deposits, and in 2005 a 45-m-long 

core was obtained from the thickest preserved sequence of 

lacustrine deposits for detailed study (fig. 2). Initial conflicts 

between the stratigraphy and sedimentology expressed in the 

core and interpreted from outcrops in previous work led to a 

need to map the exposed sedimentary section in detail.

Lake Manix occupied several subbasins at its maximum 

extent (fig. 2). This report focuses on the extensive exposures 

created by incision of the Mojave River and its tributaries into 

the interbedded lacustrine and alluvial deposits within the central 

(Cady) and northeastern (Afton) subbasins, and extends from the 

head of Afton Canyon to Manix Wash. Deposits west of Manix 

Wash are included in mapping by David M. Miller (USGS, 

unpub. data). Other workers (Dudash, 2006; D.M. Miller, USGS, 

unpub. data) have mapped lacustrine deposits in the northern, 

relatively undissected Coyote Lake subbasin.

1

U.S. Geological Survey

2

U.S. Bureau of Reclamation

Abstract

Pluvial Lake Manix and its surrounding drainage basin, 

in the central Mojave Desert of California, has been a focus 

of paleoclimate, surficial processes, and neotectonic studies 

by the U.S. Geological Survey (USGS) since about 2004. The 

U.S. Geological Survey initiated studies of Lake Manix deposits to improve understanding of the paleoclimatic record and 

the shifts in atmospheric circulation that controlled precipitation in the Mojave Desert. Until approximately 25,000 years 

ago, Lake Manix was the terminus of the Mojave River, which 

drains northeasterly from the San Bernardino Mountains; the 

river currently terminates in the Soda Lake and Silver Lake 

playas. Pleistocene Lake Manix occupied several subbasins at 

its maximum extent. This map focuses on the extensive exposures created by incision of the Mojave River and its tributaries into the interbedded lacustrine and alluvial deposits within 

the central (Cady) and northeastern (Afton) subbasins of Lake 

Manix, and extends from the head of Afton Canyon to Manix 

Wash. The map illuminates the geomorphic development and 

depositional history of the lake and alluvial fans within the 

active tectonic setting of the eastern California shear zone, 

especially interactions with the left-lateral Manix fault.

Lake Manix left an extraordinarily detailed but complex 

record of numerous transgressive-regressive sequences separated by desiccation and deposition of fan, eolian, and fluvial 

deposits, and punctuated by tectonic movements and a catastrophic flood that reconfigured the lake basin. Through careful observation of the intercalated lacustrine and fan sequences 

and by determining the precise elevations of unit contacts, 

this record was decoded to understand the response of the lake 

and river system to the interplay of climatic, geomorphic, and 

tectonic forces. These deposits are exposed in steep badland 

topography. Mapping was carried out mostly at scales of 

1:12,000, although the map is presented at 1:24,000 scale, and 

employs custom unit nomenclature, with multiple subdivided 

lacustrine and alluvial fan units. In addition, many important 

units are very thin and cannot be mapped separately, or are 

covered by thin eolian sand, so these are commonly portrayed 

as stacks of units or combined units. These details are more 
2 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

117°30' 117°00' 116°30' 116°00' 115°30'

35°00'

35°30'

34°30'

Mojave River

Troy Lake

Deep

Creek

West

Fork

Harper

Lake

Coyote

Lake

Cronese

Lakes

Silver Lake

playa

Lake

Manix

Lake Mojave

Soda Lake playa

Kelso

Wash

Barstow

San Bernardino

Baker

Dunn

Yermo

Victorville

San Bernardino

Mountains

Late Pleistocene

Mojave River fan

Victorville

Basin

Area

of 

fig. 2 

San Gabriel

Mountains

Afton

Canyon

Map

area

Overflow to

Death Valley

To Las Vegas

FORT IRWIN

MILITARY RESERVATION

MOJAVE

NATIONAL

PRESERVE

Mojave River fan

CALIFORNIA

NEVADA

To 

Needles

0 10 20 30 KILOMETERS

0 10 20 30 MILES Mojave National Preserve boundary 

modified from the U.S. National Park Service, 

accessed 2014 at http://www.nps.gov/moja/index.htm.

Fort Irwin Military Reservation boundary approximated 

from U.S. Geological Survey topographic maps

EXPLANATION

Dry lake (playa)

Late Pleistocene lake

Late and middle Pleistocene 

 clastic wedges

Mojave River watershed boundary

National military reservation and 

 preserve boundary

Pacific Ocean

CALIFORNIA

NEVADA

ARIZONA

MEXICO

122° 112° 37°

32°

Mojave

River

watershed

MAP LOCATION

15 40

15

Figure 1. Mojave River drainage basin in southern California (modified from Enzel and others, 2003). During historic high-precipitation 

years, most recently in early 2005 and late 2010, storms in the headwaters of the San Bernardino Mountains generated riverflow into 

Silver Lake playa and Cronese Lakes. Red line shows approximate map area.
Figure 2. Index map superimposed on digital orthophoto map showing Pleistocene Lake Manix, surficial geologic map area (red dashed line), and boquadrangles. Green line is the 543-meters above sea level (masl) highstand level that depicts the minimum extent of Lake Manix during the late Pleistonot known due to progradation during highstands and later burial by Mojave River alluvium. Purple line is the 558-m lake limit projected from highest urecognized during mapping (Reheis and Redwine, 2008). CMF, Cave Mountain fault; DLF, Dolores Lake fault; MF, Manix fault; PF, Pisgah fault; TCAF, Tin 

35°07'30"

35°00'

34°52'30"

34°45'

116°52'30" 116°45' 116°37'30" 116°30' 116°22'30"

Coyote

Lake

 playa

Mojave 

River

Troy

 Lake

 playa

Mojave 

River

Manix Wash

Yermo

Newberry

Springs

Dunn

40

15

40

15

FORT IRWIN MILITARY RESERVATION

Harvard

Hill

Buwalda

Ridge

CORE (45-m core in

thickest part of

lacustrine deposits)

CORE (45-m core in

thickest part of

lacustrine deposits)

Approximate

boundary of

mapped area

Afton Canyon

Calico 

Mountains

Alvord

Mountain

Cady Mountains

Cady Mountains

Cave

Mountain

Newberry

 Mountains

Coyote Lake

subbasin

Troy Lake

subbasin

Cady

 subbasin

Afton subbasin

LANE

MOUNTAIN

COYOTE LAKE ALVORD MOUNTAIN WEST ALVORD MOUNTAIN EAST DUNN CAVE MOUNTAIN

HARVARD HILL

NEWBERRY

SPRINGS

TROY HECTOR

LAKE

MANIX HIDDEN VALLEY WEST HIDDEN VALLEY EAST

SLEEPING BEAUTY

YERMO

MINNEOLA

DAGGETT

NEBO

TCAF

CALICO FAULT

CALICO

FAULT

MF

MF

CMF

PF

CADY FAULT

DLF

557 m

543 m

543 m

543 m

543 m

557 m

557 m

557 m

543 m

10 MILES

0 5 10 KILOMETERS

0 5 Base from the U.S. Geological Survey National Elevation dataset, accessed 2012 at http://ned.usgs.gov
4 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

Physiographic Setting of Lake Manix

The Manix basin in south-central California is one of 

a chain of interconnected basins crossed and linked by the 

northeast-flowing Mojave River (fig. 1). Prior to uplift of the 

Transverse Ranges during the Pliocene, regional drainage 

was generally to the south, thus the history of the Mojave 

River has been one of drainage reversal and basin integration 

(Cox and others, 2003). During its evolution, the river has 

integrated several basins that drained internally during the 

late Pliocene and early Pleistocene, including the Victorville, 

Harper, Manix, and Soda Lake basins (Cox and others, 2003; 

Enzel and others, 2003). Each basin contains fluvial and lacustrine sediments indicating the arrival and ponding of the river, 

and a record of paleoclimatic fluctuations when that basin 

served as the terminus (for example, Enzel and others, 2003) 

of the Mojave River. Sediments in the Manix basin contain a 

record of Mojave River discharge and lake fluctuations during 

the middle Pleistocene and most of the late Pleistocene (for 

example, Jefferson, 2003).

Sediments derived from the surrounding mountain ranges 

are abundant in the Pliocene and Pleistocene deposits of the 

Manix basin, and sediment composition sheds light on source 

and tectonic history. The Manix basin is flanked to the south 

by the Cady Mountains (fig. 2), a complex of Tertiary volcanic and sedimentary rocks (Danehy, E.A., and Collier, J.T., 

Southern Pacific Company, unpub. data, 1958; Mosely, 1978; 

Bortugno and Spittler, 1986), with minor Mesozoic granitic 

rocks. Sediments in the Manix basin derived from the south, 

especially fan deposits, are dominated by mafic volcanic 

clasts, but locally also contain foliated granitoids and siliceous 

dike rocks. To the northwest, the Calico Mountains are composed of a wide compositional range of dacitic volcanic and 

volcaniclastic rocks and sedimentary rocks (Dibblee, 1968; 

Singleton and Gans, 2008). Alvord Mountain to the north is 

composed of Paleozoic schist and marble, Mesozoic granitic 

rocks, Tertiary volcanic rocks, and arkosic sandstone and 

lacustrine shale (Byers, 1960; Fillmore, 1993). These rocks 

probably contributed the sediment composing most of the 

Pleistocene fan deposits on the north side of the Mojave River 

(Miller and others, 2011), and likely also the coarse-grained 

fraction of the early Quaternary Mojave River formation 

(informal name; Nagy and Murray, 1991). Finally, Cave 

Mountain to the northeast is a massive complex of mafic and 

felsic Mesozoic plutonic rocks (Danehy, E.A., and Collier, 

J.T., Southern Pacific Company, unpub. data, 1958) and was 

the source of the fanglomerate of Cave Mountain, which 

contains distinctive cobble- to boulder-sized clasts of dark 

iron-rich rock.

Externally sourced deposits of the Mojave River are 

dominated by granitic rocks in the San Bernardino Mountains 

headwaters as well as older basin fill originally derived from 

rocks in the San Bernardino Mountains and rocks exposed 

between Yermo and Victorville (fig. 1). The sand and gravel 

bedload is dominated by granitic grus, with common wellrounded, polished orange quartzite pebbles and lesser amounts 

of volcanic clasts. The silt and clay fraction that constitutes 

Lake Manix sediment deposited in quiet-water settings is commonly grayish olive, olive gray, or greenish-gray in color. These 

sediments are thought to have been derived from the Cretaceous 

Pelona Schist, which is now cut off from the Mojave River 

drainage basin by movement along the San Andreas Fault but 

was a major contributor to late Cenozoic basin fill exposed near 

Victorville (Morton and Miller, 2006).

The Lake Manix basin is composed of several subbasins: 

the northern Coyote Lake subbasin, the central Cady subbasin 

(previously, this was informally referred to as the Manix subbasin), the southern Troy Lake subbasin, and the northeastern 

Afton subbasin (fig. 2). There is no clear boundary or buried 

divide between the Cady and Troy Lake subbasins. The Troy 

Lake area has not been incised and has been almost completely filled by fluvial deposits of the Mojave River during 

and after the late Pleistocene phase of Lake Manix (Reynolds 

and Reynolds, 1985; Meek, 1990). In contrast, the Cady and 

Coyote Lake subbasins are separated by low hills of Tertiary 

rocks and are connected by a relatively high bedrock controlled 

sill at about 540-meters above sea level (masl) through which 

water was transferred between the subbasins when lake level 

was high (Meek, 1990). Fluvial terraces and dated lacustrine 

deposits suggest that occasionally the Mojave River fed the 

Coyote Lake subbasin directly (Meek, 1994, 2004; Miller, 

Dudash, and McGeehin, 2009). The Cady and Afton subbasins 

are not currently separated by a divide, but the sedimentary 

sequences preserved within them indicate that the basins were 

separate in the past. The boundary between them is defined by 

Buwalda Ridge. This ridge, composed of Tertiary fanglomerate, 

is bounded and internally cut by the Manix fault. The Manix 

fault extends eastward and coincides with the former eastern 

threshold of Lake Manix at the head of Afton Canyon. Sheared 

zones in fanglomerate units along this fault probably played a 

significant role in the drainage integration history.

A Brief History of Pleistocene 

Lake Manix

Previous stratigraphic studies of Lake Manix sediments 

have focused on outcrops in the Cady subbasin (Jefferson, 

2003, and citations therein), and other sites mainly in the 

Afton and Coyote subbasins (Meek, 1990). Jefferson (2003) 

conducted stratigraphic and paleontologic studies near the 

confluence of the Mojave River and Manix Wash (fig. 2), and 

interpreted these deposits to represent at least four major lake 

phases or cycles deposited during glacial periods beginning 

about 560 ka (Marine Isotope Stage (MIS) 14; age boundaries 

from Lisiecki and Raymo, 2005). Deposits of the oldest two 

lake cycles are poorly dated; the sediments have normal polarity, and one bone yielded an infinite uranium-thorium (U-Th) 

age of >350 ka (J.L. Bischoff, USGS, cited in Jefferson, 2003). 

Deposits of the third lake cycle interpreted by Jefferson as 

perennial-lake sediments and correlated with MIS 6 (his informal “upper Member C”) are correlative to units Ql7 and Ql6
A Brief History of Pleistocene Lake Manix 5

of this map (photo 1 on sheet 1, and see appendix). (Numbered 

photographs are contained in the appendix that accompanies 

this report. Selections of these photos are presented on the two 

map sheets to illustrate stratigraphic relations.) They contain a 

tephra layer near the base that has an age of 184±4 ka, based 

on chemical correlation with a rhyolite in the Sierra Nevada 

to the northwest recently re-dated using 40Ar/39Ar on sanidine 

by Robert Fleck, USGS (Reheis and others, 2012). Sediments 

representing a sequence of fluctuating lake levels and deltaic 

sands of the prograding Mojave River were correlated with 

MIS 4 and 2 (“Member D,” correlative to unit Ql8 of this 

map) on the basis of several U-Th ages on bone and several 

radiocarbon ages (Jefferson, 2003, p. 48). Numerous beach 

deposits extending to ~543 masl rim the Manix basin. Mollusk 

shells from these deposits were dated by Meek (1989b, 2000) 

and interpreted to indicate multiple lake highstands. Both 

authors correlated the extensive greenish lacustrine muds 

that underlie these beach deposits in the Afton subbasin with 

“upper Member C” of Jefferson (2003). Both also noted the 

apparent absence of older lacustrine deposits in the Afton 

subbasin, with the exception of one section measured by Meek 

(1990), and ascribed this to more extensive erosion along the 

valley axis in that area.

Meek (1989a, 2004) interpreted the geomorphic record 

of overflow that formed the downstream Lake Mojave as 

rapid incision to the base of Lake Manix sediments, followed 

by a second phase of Afton Canyon incision that was slower 

than the initial incision. Reheis and Redwine (2008) generally concurred with this scenario, and provided several more 

radiocarbon ages that indicated multiple lake highstands at or 

near 543 masl prior to final overtopping and incision of the 

threshold not later than about 25 cal ka (calibrated thousand 

years before present). They also identified deposits of one or 

more older lake phases that reached higher lake levels between 

547‒549 and about 558 masl.

The USGS obtained a 45-m-long core of interbedded 

lacustrine and alluvial deposits near the confluence of Manix 

Wash and the Mojave River in 2005 (Reheis and others, 2012). 

We also undertook mapping and stratigraphic investigations 

to improve understanding of the history of Lake Manix and to 

provide geologic context for this core (Miller and McGeehin, 

2007; Reheis and others, 2007; Reheis and Redwine, 2008; 

Reheis and Miller, 2010). These studies have resulted in 

several revisions to the previously established stratigraphy 

and history of Lake Manix.

Interpretation of paleomagnetic data from the Manix 

core suggests that a lake first occupied the area of the core 

site (fig. 2) at about 450 ka during MIS 12 (Reheis and others, 

2012). Eight phases of shallow to deep lakes, numbered from 

oldest to youngest and separated by alluvial-fan deposits or 

soils, are identified from sedimentology (only phases Ql4‒Ql8

are recognized within the map area). However, the youngest two phases in the core, Ql7 and Ql8, indicated generally 

shallow water depth with only brief intervals of deeper water 

at the core site, and that mudflat or alluvial environments 

were common following the deposition of the Manix tephra 

at 184 ka. This interpretation is consistent with outcrop studies 

by Oviatt and others (2007), but differs from that of Jefferson 

(2003), who interpreted a moderate to deep lake during Ql7

time, equivalent to his “upper Member C.” In contrast, correlative deposits in the Afton subbasin, mapped herein as unit Ql7, 

do indicate the presence of a moderately deep lake.

The discrepancies between strata in the Cady and Afton 

subbasins have been resolved by our mapping, which has 

identified a lacustrine unit, Ql6, which was not recognized 

by previous workers. In the Afton subbasin, this unit largely 

consists of bedded sand, but in one critical location (sheet 2C, 

section M07‒159; photo 20) fine-grained strata of Ql6 contain 

the Manix tephra. The Manix tephra is chemically correlated 

to rhyolite in Long Canyon, southern California, which was 

previously dated at ~185 ka by K-Ar on sanidine (Jefferson, 

2003) and recently re-dated by 40Ar/39Ar at 184±4 ka (Reheis 

and others, 2012). The Ql6 unit overlies fluvial sand and 

gravel (unit Qof) that locally includes reworked clasts of green 

lacustrine mud, and in a few localities in the Afton subbasin, 

several meters of chaotically bedded blocks (as much as 

2 m across) of semi-indurated green lake mud, silt, and sand 

mixed with blocks of brown playa mud (photo 35 on sheet 2B, 

section M06‒100; Reheis and others, 2007). The chaotically 

bedded deposits are interpreted as the result of deposition 

caused by a catastrophic failure of a former lake threshold 

on the south side of Buwalda Ridge, astride the Manix fault 

(photo 49 on sheet 1). This event was followed by deposition of sand and gravel by a high-energy stream draining the 

upstream subbasins, and a brief lacustrine period during which 

the Manix tephra was deposited. Thus, this subbasin integration event occurred shortly before 184 ka. After this time, the 

Afton subbasin was the new depocenter of Lake Manix, and 

during much of this period the core site was probably exposed 

or in very shallow water (Reheis and others, 2012).

After the subbasins were integrated, Lake Manix rose at 

least once to a level as much as 10‒15 m higher than its previously recognized highstands at about 543 masl, during or after 

MIS 6 (Reheis and Redwine, 2008). These very high levels 

are represented by eroded beach barriers in both the Cady 

and Afton subbasins (sheet 1, fig. 2) and locally, by fan-delta 

deposits exposed in arroyos (notably, in the informally named 

Field wash and nearby drainages). During this time, the lake 

probably discharged episodically eastward into the Soda Lake 

basin (fig. 1) and may have incised the threshold at the head of 

the present-day Afton Canyon to about 543 masl. During subsequent highstands of MIS 4(?) and 3, the lake repeatedly rose 

to about 543 masl (Meek, 1990, 2000; Reheis and Redwine, 

2008; Reheis and others, 2010), maintained there in part by 

the shallow threshold between the Cady and Coyote Lake subbasins (fig. 2; Meek, 2004). The Afton Canyon threshold failed 

at about 25 cal ka; no recessional shorelines younger than this 

have been recognized, but younger lakes fed by direct inflow 

from the Mojave River episodically occupied the Coyote Lake 

subbasin (Meek, 1994; Dudash, 2006; Miller, Dudash, and 

McGeehin, 2009). Subsequent incision has exposed extensive, 

intricate badlands-type outcrops of interbedded lake and alluvial deposits (photos 1, 3, and 4).
6 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

Rationale for this Map

This surficial-deposits map combines the western portion 

of the surficial map of the Afton Canyon area (J.R. Redwine, 

U.S. Bureau of Reclamation, unpub. data) with mapping carried out by Reheis to refine lake-unit stratigraphy and to extend 

mapping to the mouth of Manix Wash. Some of the subdivisions 

of tributary and alluvial-fan deposits of Redwine (U.S. Bureau 

of Reclamation, unpub. data) were combined in this map, and 

in some cases lacustrine units are emphasized rather than thin 

overlying fan or eolian deposits. The thin sedimentary units are 

commonly exposed in steep badland topography, creating an 

intricate maze not easily depicted. Therefore, mapping was carried out mostly at scales of 1:12,000 and employs custom unit 

nomenclature, with multiple subdivided lacustrine and alluvial 

fan units that are commonly portrayed as stacks of units or 

combined units. Southwest of the Afton Canyon area mapped by 

Redwine, fan and eolian deposits that postdate Lake Manix were 

mapped from aerial photographs with minor field verification. 

Less detailed mapping also characterizes the northeastern corner 

of the map outside the limit of lacustrine deposition. Van Sistine 

produced the topographic and orthographic base maps and the 

GIS database.

Many radiocarbon ages were obtained for Anodonta 

shells that are abundant in the lacustrine gravel, sand, and 

muddy sand (photo 5); analyses were conducted by McGeehin. 

Sample numbers and ages are given in table 1. Several tephra 

layers were also sampled (for example, photos 51 and 58) and 

their correlated ages (table 2), based on chemical analysis of 

glass by Wan in the USGS Tephrochronology Laboratory, help 

constrain ages of older Pleistocene and Pliocene units (see 

Description of Map Units).

Numerous stratigraphic sections were measured at 

varying levels of detail, ranging from centimeter scale using 

a measuring tape, to decimeter scale using an Abney level 

and Jacob’s staff, and to meter scale using estimation. These 

sections illuminate the relations among various lake and 

alluvial-fan units, show buried soils that represent hiatuses 

in deposition, and show the relations between lake histories 

in the Cady and Afton subbasins. Selected sections are shown 

in sheet 2 and are keyed to locations on the map. Locations and altitudes of most of the sections, as well as many 

contacts (see table 3), were obtained using differentially 

corrected GPS; these altitudes are considered accurate to 

within ±1 m. Table 4 contains fault and attitude data for the 

map area.
Description of Map Units 7

DESCRIPTION OF MAP UNITS

[Combined map symbols (for example, Qyao+Qyay) are used where two Quaternary map units are interspersed at such a 

small scale that separating map units was impractical. The first unit listed is considered dominant in the area; the second unit 

must occur in at least 20 percent of the area to be listed. Fractional map symbols (for example, Qia7/Ql7) are used where a 

thin veneer of a younger unit overlies an older unit, especially common for alluvial-fan deposits interbedded with lacustrine 

sediment and for eolian deposits. Unit names are locally queried where identification is uncertain. Ages of alluvial and eolian 

deposits are classified as young, intermediate, or old based on surface micro-topography, pattern and degree of channel dissection of alluvial-fan surfaces, degree of soil development (Soil Survey Staff, 1999), desert pavement development, and intensity 

of rock varnish developed on surface clasts (Miller, Bedford, and others, 2009). Units so classified based on field observations 

are extended into additional areas through interpretation of aerial photographs. Correlations with locally dated deposits provide 

age control for these deposits (Bedford, 2003; Miller and others, 2010). This report follows the currently accepted age of 2.6 Ma 

for the Pliocene-Pleistocene boundary (Geological Society of America, 2012), and thus revises the age of some units such as the 

informal Mojave River formation]

Unconsolidated Surficial Deposits

Man-Made Deposits

d Disturbed areas (modern)—Unconsolidated to loosely compacted rubble composed of silt, sand, and rock. 

Mapped mainly along the interstate highway and railroad beds. Locally includes bulldozed areas

Lacustrine Deposits

Mapped lacustrine units, numbered from oldest (Ql4) to youngest (QL8) are based on correlation with the Manix core, 

located just west of map area on the west side of Manix Wash (fig. 2) (Reheis and others, 2012); units Ql1‒Ql3 represented in 

that core are not recognized within the map area, but may locally interfinger with the upper part of units Qalg and Qvg west of 

Buwalda Ridge. Lake units are typically separated in outcrop by intervening thin (commonly <1 m thick) alluvial-fan deposits 

with buried soils, which are capped by a layer of tufa-coated clasts that mark the base of the next younger lake unit. Those fan 

units older than Ql6, mapped only in the Cady subbasin, are mapped as part of the underlying lake units, but are identified in 

measured sections.

Ql Lacustrine deposits, undivided (late and middle Pleistocene)—Lacustrine gravel, sand, silt, and clay. Mapped in 

only a few places where stratigraphy is confounded by faults and deposits are mostly obscured by colluvium

Ql8 Lacustrine deposits, unit 8 (late Pleistocene)—Primarily lacustrine gravel and sand deposited in nearshore environment (photo 6, sheet 2D). Individual beds moderately sorted. Planar bedded, with finer-grained beds locally 

exhibiting oscillatory wave ripples. Beds horizontal to dipping as much as 20‒25° in nearshore settings. May be 

expressed morphologically as dissected beach barrier or spit. Where deposited in an active alluvial-fan setting, 

beds strongly resemble alluvial clast-supported deposits but are better sorted and bedded (photos 7, sheet 2B; 

and 8, sheet 2C), and commonly exhibit lacustrine tufa or fossils (Reheis and Miller, 2010). In a few locations, 

horizontally bedded deeper-water deposits (photo 9, sheet 2B) of fine sand, silt, and clay are preserved (for 

example, section M07‒11, UTM 11S, easting 551617, northing 3879436 in table 3). Common thin tufa coats on 

clasts, locally overlying weak buried soils, mark lake-level fluctuations. Ostracodes present in finer sediments. 

Numerous radiocarbon dates indicate these deposits range in age from >40,000 to ~25,000 cal yr B.P. (table 1; 

Reheis and Redwine, 2008; Reheis and others, 2010). Unit is correlative with Jefferson’s (2003) “member D.” 

Extends as high as 544 masl. Locally subdivided in Afton subbasin into basal unit Ql8o

Ql8o Lacustrine deposits, older unit 8 (late Pleistocene)—Well-sorted, well-rounded, tufa-coated gravel, commonly just one stone thick, overlying fan gravel (Qia7) that overlies older lake sediments (Ql7). Locally, 

deposits include beach gravel with steeply dipping foreset beds, ~1 m thick, with a tufa-coated cobble line at 

the base. Gravel commonly overlies ~20‒50 cm of poorly sorted green sand and fine gravel with many root 

casts, probably of marsh or lacustrine origin. Mapped only in Afton area south of Mojave River; elsewhere, 

shown as Qia7. Tufa from the gravel yielded a U-Th isochron age of 42±15 ka (table 3, station M06‒62B) 

(J.B. Paces, USGS, written commun., 2010). However, Meek (2000) reported a U-series age of ~80 ka from 

the same unit (dated by James Bischoff, USGS)
8 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

Ql7 Lacustrine deposits, unit 7 (early late Pleistocene and middle Pleistocene)—Lacustrine sediment ranging 

from fan-delta deposits (Reheis and Miller, 2010) to well-sorted, well to moderately well-rounded beach 

gravel to sand, silt, and clay (photos 1, 4, 10, 11, and 16). Sand and gravel beds are locally steeply dipping (as much as 25°). Laminated to bedded with beds from 1 to 10 cm thick. Mud has distinct olive green 

color, and groundwater alteration causes some sandy beds to be bright orange, yellow, or black. Abundant 

ostracodes throughout fine-grained sediment. Basal gravel clasts typically have thick lacustrine tufa coats 

(photos 12 and 13). Preliminary U-Th analyses on tufa from base of unit indicate age range of ~75–170 ka 

(J.B. Paces, USGS, written commun., 2010). In view of stratigraphic position of Ql7 below Ql8 that has ages 

of ~25–≥40 ka, several 14C ages of ~40‒50 ka on Anodonta shells from Ql7 (table 1, M05‒20A, M05‒23C, 

M05‒25J, M05‒26F) are considered minimum ages likely contaminated by younger carbon. In Afton 

subbasin, locally subdivided into older (Ql7a) and younger (Ql7b) units by intervening soil or unconformity. Unit is correlative with upper part of Jefferson’s (2003) “Member C.” Extends as high as 558 masl 

in undeformed areas. Preserved total thickness ranges from less than 1 m to as much as 17 m (sheet 2B, 

DI section) in Afton subbasin; unit is thickest near modern valley axis

Ql7b Lacustrine deposits, unit 7b (early late Pleistocene and late middle Pleistocene)—Upper part of unit Ql7

where locally subdivided in Afton subbasin. Typically dominated by green mud and sandy mud with local 

thin interbeds of sand (photos 10, 11, 14, and 15); locally capped by coarse beach sand. Commonly overlies 

very weak soil formed on older unit Ql7a. Where measured in DI section (sheet 2B), about 10 m thick and 

overlies cross-bedded beach sand instead of soil

Ql7a Lacustrine deposits, unit 7a (middle Pleistocene)—Lower part of unit Ql7 where locally subdivided in Afton 

subbasin. Typically dominated by medium to fine beach sand with lesser green mud, sandy mud, and gravel 

(photos 14, 15, and 16). Commonly overlies very weak soil formed on older unit Qia6. Where measured in 

DI section (sheet 2B), about 7 m thick

Ql6 Lacustrine deposits, unit 6 (middle Pleistocene)—Lacustrine sand, silt, and minor clay. In Afton subbasin, 

well sorted, well to moderately rounded grains; laminated to bedded with beds from 1 to 10 cm thick. Near 

Mojave River, basal sand exhibits long, sweeping, northeast-directed cross-beds (photos 17 and 18) containing rhizoliths that yielded a U-Th age of 173.6±8.7 ka (section M05‒54, sheet 2C; J.B. Paces, USGS, written 

commun., 2010). Sands are locally interbedded with fluvial sand and gravel of unit Qof, and may contain 

rip-up clasts of green lacustrine sediment (photos 19 and 20). In one location north of river (sheet 2C, 

station M07‒159; table 2; photo 20), fine-grained deposits 2.5 m above unit base contain lenses 0.5‒3 cm 

thick of white, fine-grained, reworked Manix tephra, chemically correlated to rhyolite in Long Canyon, 

southern California, dated by 40Ar/39Ar at 184±4 ka (R.J. Fleck, USGS, written commun., 2010). Extends 

as high as ~513 masl. In Cady subbasin, unit commonly contains the Manix tephra west of Manix Wash 

(outside the map area), extends as high as 541 masl, and is usually included for convenience in unit Ql7. 

In some measured sections (for example, sheet 2A, M08‒163, M09‒76, M09‒29) it is less than 1 m thick 

and may contain a bed of fan gravel or coarse sand containing blocks of reworked lake mud (photos 21 and 

22), <25 cm thick, representing sudden draining of lake during Ql6 lake rise (sheet 2A, sections M09‒58, 

M09‒76). As much as 10 m thick in Afton subbasin, mostly sand except in upslope positions

Ql5 Lacustrine deposits, unit 5 (middle Pleistocene)—Lacustrine and alluvial sediment ranging from well-sorted, 

well to moderately well-rounded beach gravel and well-bedded sand and silt to cross-bedded moderately sorted 

sandy gravel (photo 23). Below about 530 masl, unit typically grades upward from alluvial at base to lacustrine 

at top; above 530 masl, sediment in same stratigraphic position is alluvial. Overlain by gravelly alluvial-fan 

deposits less than 1 m thick that are oxidized, locally with Bwk horizon preserved (sheet 2A, section M08‒112). 

Commonly capped by single line of tufa-coated clasts, which locally represent entire unit (sheet 2A, sections M08‒110 and M09‒29). Found only in Cady subbasin. On sheet 2 only. As much as 6 m thick

Ql4 Lacustrine deposits, unit 4 (middle Pleistocene)—Lacustrine sediment ranging from well-sorted, well to moderately well-rounded beach gravel to sand, silt, and clay. Laminated to bedded to massive, with beds 1‒10 cm 

thick (photos 1 and 23). Abundant ostracodes throughout fine-grained sediment. Tufa-coated cobbles commonly mark base of unit. Overlain by alluvial-fan deposits included in lake unit, less than 1.5 m thick, locally 

with weak Bwk horizon preserved (sheet 2A, section M08‒130) and capped by single line of tufa-coated 

clasts (section M09‒29). Correlated with lake phase Ql4 and possibly Ql3 in core (the two phases cannot be 

distinguished with certainty in the map area). Unit Ql4 is found only in Cady subbasin; extends at least as 

high as 532 m. Overlies unit Qalg, and likely interfingers with it. As much as 5 m thick
Rationale for this Map 9

Fluvial Deposits

Qfmr Active channel of the Mojave River (late Holocene)—Arkosic sand and gravel, mostly subrounded to well 

rounded. Clasts larger than pebbles are locally reworked from adjacent alluvial fans. Includes active riverbed 

and adjacent flood-prone overbank areas within the confined channel; equivalent to alluvial-fan deposits 

mapped as Qyay. Extensively modified by eolian processes, creating small fields of active dunes. Thickness 

probably less than 10 m

Qyfmr Mojave River fluvial deposits (Holocene and late Pleistocene)—Include strath, cut-fill, and fill-cut terraces 

and underlying deposits of commonly well-rounded to subrounded, well-sorted, coarse sand to large cobbles 

and small boulders (photos 24 and 25). In Afton area, clast size, rounding, and lithology largely dependent 

on composition of underlying fanglomerate. In Cady subbasin and south of Buwalda Ridge, fluvial deposits 

dominantly arkosic sand and pebble gravel like that of modern river channel. Desert pavement and varnish 

are moderately developed. Soils typically have Av/Bwk1/Bwk2/2Coxk profiles with stage I+ carbonate morphology (Reheis and Redwine, 2008; carbonate stage morphology of Gile and others, 1966). Based on inset 

relations with beach barriers and soil development, these terraces are younger than ~25 ka, the age of the 

youngest highstand of Lake Manix; however, differences in ages of terraces of different heights above stream 

level (ranging from 5 to 50 m) cannot be distinguished using relative age criteria (Reheis and Redwine, 

2008). Based on surface characteristics and soil development, these deposits are probably correlative with 

unit Qyao. Thickness from <10 cm to ~4 m

Qysl Young slackwater deposits (Holocene)—Fine-grained deposits associated with valleys incised into fanglomerate of Cave Mountain (unit QTcg) north of river near the west end of Afton Canyon. Deposits include, from 

bottom to top: (1) sandy alluvium overlain by well-sorted sand interbedded with blocky green mud that is 

locally burrowed and contains abundant secondary gypsum and other soluble salts; (2) thinly interbedded 

green mud and laminated fine to medium sand, (3) thinly interbedded, laminated, and ripple cross-bedded 

sand locally with clay and silt; coarsens upward and intertongues toward adjacent hillslope deposits of coarse 

alluvial-fan sand and gravel; and (4) locally derived fan gravel. Many beds contain lacustrine ostracodes, 

apparently reworked from Lake Manix sediments, because they yielded ages ranging from 27,020±310 to 

31,500±420 14C yr B.P. (table 1, JR04D‒68), in conflict with a luminescence age of about 7,500 yr measured 

using both infrared stimulated and optically stimulated luminescence techniques (Shannon Mahan, USGS, 

written commun., 2005; Reheis and Redwine, 2008). Thickness as much as 5 m

Qyf Young fluvial deposits (Holocene and late Pleistocene)—Unconsolidated sand and gravel, undifferentiated by 

source. Laminated to bedded, with 2‒3 cm-thick beds that are locally cross-bedded; well to moderately well 

sorted sand, silt, and pebble to cobble gravel of mixed lithologies and sources. Mapped only in Afton area. 

Underlies terrace surfaces and includes gravel lags and deposits as much as ~4 m thick

Qyaf Alluvial deposits of paleovalley fill (Holocene and late Pleistocene)—Interbedded tributary and Mojave River 

fluvial deposits, mudflows, and alluvial-fan deposits. Deposits fill a paleochannel incised into Lake Manix 

deposits and unit QTcg (described in Reheis and Redwine, 2008) and lap onto adjacent areas. Eroded with 

no preserved surfaces; inset below Lake Manix deposits. Thickness as much as 25 m in paleochannel fill

Qif Intermediate fluvial deposits (late Pleistocene)—Interbedded clast-supported fluvial and matrix-supported alluvial beds. Fluvial deposits are ~0.75 m thick packages of 2 mm to 1‒7 cm-thick beds, locally cross-stratified; 

well to moderately well-sorted, well to moderately well-rounded, medium to coarse, quartz-rich sand and 

granule to cobble gravel from extra-local sources. Alluvial deposits are 20‒60 cm thick beds, with poorly to 

moderately sorted, mostly angular to subrounded, locally derived coarse sand and gravel. Unit contains many 

buried soils that are mostly reddened and clay rich. Based on soils, these deposits may be more than twice 

the age of nearby beach and fluvial deposits that are ≤25 ka (Reheis and Redwine, 2008). Reworked ostracodes yielded an age of 33,120±710 14C yr B.P. (table 1, JR04CM–87), considered a minimum age. Identified 

only at two locations in eastern map area in eroded remnants perched on canyon rim north of river (photos 26 

and 27), and interpreted to represent discharge from Lake Manix prior to incision of Afton Canyon (Reheis 

and Redwine, 2008). As much as 6 m thick

Qof Older fluvial deposits (middle Pleistocene)—Mostly well-bedded, clast-supported fluvial gravel and sand; 

locally includes chaotically bedded deposits. Thickest outcrops, east of Buwalda Ridge, exposed interbedded 

sand, pebbly sand, and sandy gravel beds, moderately sorted and indurated, as much as 10 m thick 

(sections M07‒117, M07‒144, sheet 2B, photos 28 and 29). Locally, two units separated by a weak buried soil 

are preserved (photo 30). Sands are thinly bedded and locally cross-bedded, with some beds exhibiting dips up 

to 15° northeasterly. Some clasts, especially near base, consist of reworked, indurated blocks of green lake mud 
10 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

(photos 30 and 31). Northeasternmost deposits in Afton subbasin overlie playa deposits and include similar but 

much thinner fluvial gravel (<2 m thick; photos 32 and 33) that overlies several meters of chaotically bedded 

blocks (as much as 2 m across) and clasts of semi-indurated green lake mud, silt, and sand mixed with blocks of 

brown playa mud (sheet 2B, section M06‒100; photos 33, 34, and 35). Unit is interpreted as a result of deposition by high-energy stream flowing into Afton subbasin after drainage integration due to catastrophic failure 

of former lake threshold on south side of Buwalda Ridge. Basal chaotic deposits may have been emplaced as a 

mudflow originating from older lake deposits in the Cady subbasin at least 12 km upstream

Quartz-rich conglomerate (Miocene)—Cobble to boulder conglomerate; locally contains sandy pebble beds. 

Locally well exposed in steep drainage cuts, best viewed just south of map area (photo 36), where unit 

fills north-trending paleovalley cut in Jurassic(?) plutonic rocks (unit Br). Locally cross-bedded, with beds 

suggesting northwest-directed flow. Clasts are mainly well rounded to subrounded; clast size increases and 

rounding decreases toward paleovalley margins. Dominantly composed of flow-banded rhyolite, and granitoids, including meta-diorite, dense gray quartz monzonite (?), and epidotized siliceous dike (?) rocks, with 

lesser amounts of mafic volcanic clasts. South of map area, locally contains beds of limestone with thin wavy 

beds 0.5‒2 cm thick. Limestone beds pinch out laterally within about 100 m and likely represent deposition 

in spring mounds (photo 37). Mapped as conglomerate unit Tcg by Danehy, E.A., and Collier, J.T., Southern 

Pacific Company (unpub. data, 1958); overlain sequentially by rhyolite tuff and andesite flow of unit Tvs

(photo 38). Crops out only south of Manix fault west of Afton Canyon. Unit Tqg is the most likely source of 

similar well-rounded clasts found in basal parts of unit QTvg and fanglomerate of Buwalda Ridge. As much 

as 70 m thick in paleovalley axis; thins to zero along valley margins

Alluvial-Fan Deposits

Alluvial-fan deposits are generally similar in grain size and bedding; the following description applies to each alluvial 

unit described below unless otherwise stated. Gravel, sand, and silt; intermixed and interbedded, moderately sorted to unsorted, 

moderately to poorly stratified. Clasts commonly pebbles to cobbles, but near range fronts, may be larger than 1 m in diameter. 

Beds may be either clast supported (stream-flow deposit) or less commonly, matrix supported (debris-flow deposit). Contain thin 

lenses of sand and silt

Qya Young alluvial-fan deposits, undivided (Holocene and late Pleistocene)—Alluvial fan and wash deposits. 

Includes scattered thin mudflow deposits

Qyay Young alluvial-fan deposits, younger subunit (late Holocene)—Active alluvial fans, washes, and low surfaces 

within washes, <1 m above active channel; prone to flooding in large events. No desert pavement or varnish. 

No to very weak soil development with minor eolian accumulation or weak Av horizons. Includes units Qya1

and Qya2 of Redwine (U.S. Bureau of Reclamation, unpub. data)

Qyao Young alluvial-fan deposits, older subunit (Holocene and late Pleistocene)—Surfaces are mostly abandoned. 

Moderately well-developed desert pavement over ~75 percent of surface and moderately developed varnish on clasts. Fans locally grade to or are inset within lacustrine deposits of the last Lake Manix highstand 

(~25 ka). Includes strath terraces along some tributaries. Soils typically Av/B or Bwk or Btjk/Ck or Av/Btjk/

Ck profiles with stage I or I+ carbonate (Gile and others, 1966). Includes units Qya3 and Qya4 of Redwine 

(U.S. Bureau of Reclamation, unpub. data)

Qia Intermediate alluvial-fan deposits, undivided (early late Pleistocene and middle Pleistocene)—Fan surfaces 

with well-developed desert pavement over ~80 percent of surface and well-developed varnish on clasts. Typical 

soil development: Av/Bwk1/Bwk2/Ck profiles with stage I carbonate (Gile and others, 1966). Depending on 

location, surfaces can be abandoned, rounded, and incised up to tens of meters or can be partially buried (photos 

39 and 40). Where buried, or previously buried and exhumed, deposits are subdivided below on the basis of 

relations with lake units or other fan units; for example, Qia7 underlies deposits of Ql8 and overlies deposits 

of Ql7 (for example, sheet 2D, section M05‒26). Stratigraphy is based on correlation with Manix core, located 

just west of map area, as extrapolated to exposures in Manix Wash; units Qia1‒3 represented in that core are 

not recognized within the map area, but are likely correlative with the upper part of unit Qalg. Units Qia4 and 

Qia5 are not separately mapped but are shown in some stratigraphic sections of sheet 2. In the Afton subbasin, 

intervening fan deposits are sufficiently thick and extensive that they can be mapped, but are usually grouped 

with underlying lake units for convenience (for example, Qia7/Ql7). Separate mapping is often impractical in 

areas where fan deposits are less than 50 cm thick or erosion has removed fan deposits. Fan units older than 

Qia6 in the Cady subbasin are mapped and described together with the underlying lake unit; fan units older 

than Qia6 in the Afton subbasin are mapped as Qia (undivided). Thickness ranges from 25 cm to >5 m
Rationale for this Map 11

Qia7 Alluvial-fan deposits, unit 7 (late Pleistocene)—Surfaces with well-developed desert pavement and varnish. 

West of the Lake Manix threshold, unit was deposited between lacustrine units Ql8 and Ql7 deposits during 

lake regression (photo 6). Locally, clasts in unit Qia7, especially at top, are coated with lacustrine tufa. Qia7

deposits have been buried and subsequently exhumed for varying amounts of time since deposition. As a 

result, surfaces and soils are commonly less developed than would be typical of a fan of equivalent age that 

remained at the surface since deposition

Qia6 Alluvial-fan deposits, unit 6 (middle Pleistocene)—Alluvial fan sediment deposited between units Ql7 and 

Ql6 during lake regression (photo 22). Oxidized at top, locally has weak Bw horizon preserved. Generally 

mapped together with underlying unit Ql6 in Afton subbasin north of the Mojave River. Where unit Ql6 was 

not deposited, generally above 510 m elevation, unit is included with alluvial sequence (Qia) that predates 

arrival of Lake Manix in Afton subbasin. Unit is not separately mapped in Cady subbasin, but interval is 

locally represented there by oxidized fan gravel, sometimes containing reworked lake sediment (for example, 

sheet 2A, sections M09‒58 and M09‒76). Typically <1 m thick, locally represented only by disconformity or 

weathering zone

Qia5 Alluvial-fan deposits, unit 5 (middle Pleistocene)—Alluvial fan sediment deposited between units Ql6 and Ql5

during lake regression. Oxidized at top, locally has weak Bw horizon preserved. Unit occurs only in Cady subbasin but is not separately mapped; locally shown in measured sections (for example, sheet 2A, section M09‒58). 

Typically <1 m thick, locally represented only by disconformity or weathering zone. Sheet 2 only

Qia4 Alluvial-fan deposits, unit 4 (middle Pleistocene)—Alluvial fan sediment deposited between units Ql5 and Ql4

during lake regression. Oxidized at top, locally has weak Bw horizon preserved. Unit occurs only in Cady 

subbasin but is not separately mapped; locally shown in measured sections (for example, sheet 2A, sections M08‒60 and M08‒130). Typically <1 m thick, locally represented only by disconformity or weathering 

zone. Sheet 2 only

Qoa Older alluvial-fan deposits (middle and early Pleistocene)—Alluvial fans with poorly preserved, rounded and 

eroded surfaces. Locally, thick carbonate soils with stage III or greater morphology are exposed. Moderately 

developed and degraded desert pavement and varnish. Age is unknown, but based on poor preservation 

and apparently more developed soils, these deposits are inferred to be older than Qia fans. Mapped only in 

Afton subbasin

Qalg Arkosic-lithic fanglomerate (middle and early Pleistocene)—Pebble to cobble fanglomerate with clasts composed of wide range of plutonic, volcanic, and minor sedimentary rock types; sand fraction dominantly arkosic 

in composition (photos 4, 14, 40, 41, and 42). Unit has many weak to moderate paleosols throughout consisting 

of Bk and Bw or Bt horizons. Weakly to moderately indurated. West and south of Buwalda Ridge, this unit is 

much finer grained than areas to the east, and contains massive silt beds locally interbedded with sandy pebble 

gravel. Near Manix Wash, Nagy and Murray (1991, 1996) mapped unit as upper part of Mojave River formation; however, to the east unit is coarser and overlies unit Qmr on an erosional and locally a slightly angular 

unconformity (photo 42). At one site north of the river, a tuffaceous bed marks an erosional contact with underlying finer-grained deposits of unit Qmr. Sample M10‒94 (table 2) yielded possible correlations with 0.76-Ma 

Bishop ash and 1.2‒0.78-Ma upper Glass Mountain ash beds (Sarna-Wojcicki and others, 2005), suggesting 

that at this site unit may be late Matuyama or early Brunhes polarity chronozones in age as proposed by Pluhar 

and others (1991). In one outcrop on the south side of the river (table 2; sheet 2B, station M10‒90 in sections 

measured at stations M07–128 and M08–55), unit Qmr contains the 2.1-Ma Huckleberry Ridge ash, as also 

reported nearby (Nagy and Murray, 1991; Sarna-Wojcicki and others, 1984, 2005). Above this ash bed, unit 

grades up into gravelly unit Qalg with no unconformity, and this in turn becomes increasingly volcaniclastic 

upward through a 10-m interval to become unit Qvg. Thus, unit Qalg is here considered an alluvial facies of 

upper playa unit Qmr. Generally undeformed except adjacent to faults. Thickness at least 10 m

Qvg Younger volcanic fanglomerate (middle and early Pleistocene)—Coarse fanglomerate derived almost entirely 

from rocks exposed in the Cady Mountains, including a variety of volcanic lithologies, mainly basalt, 

rhyolite, andesite(?), and tuff. Beds mostly 0.5‒2 m thick; clasts rounded to subrounded, locally subangular, 

mostly sand to small cobbles with grayish brown matrix. Unit has weakly to moderately developed paleosols 

throughout consisting of Bk and Bw or Bt horizons. Weakly to moderately indurated. Previously termed the 

“gray conglomerate” by Ellsworth (1932) and Meek (1989b). Widespread on south side of river and directly 

underlies deposits of Lake Manix in both subbasins; also mapped in limited area on north side of river, where 

clasts are derived from Buwalda Ridge. In Afton subbasin, unconformably overlies unit QTcg (photos 43 
12 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

and 44); in Cady subbasin, conformably overlies unit Qmr or Qalg (photo 45) and locally interfingers with 

lacustrine units Ql4 and Ql5. Nagy and Murray (1996) and Meek and Battles (1991) argued that the appearance of Cady Mountain volcanic rocks in fanglomerates marks the time of onset of a compressional tectonic 

regime that caused uplift of the Cady Mountains. Based on magnetostratigraphy within the Cady subbasin, 

this change occurred ~1.1‒0.78 Ma (Nagy and Murray, 1996). However, older volcaniclastic fanglomerate 

(QTvg) underlies unit Qvg in the Afton subbasin and the fanglomerate of Buwalda Ridge (Tbrg) is also 

largely derived from rocks in the Cady Mountains, suggesting earlier uplift. Generally undeformed except 

adjacent to faults. Thickness highly variable, locally as much as 30 m

QTgu Fanglomerate, undifferentiated (early Pleistocene? and Pliocene?)—Fanglomerate. May include deposits 

elsewhere mapped as units QTvg, Qoa, and Tertiary sediment considered by Danehy, E.A., and Collier, J.T., 

Southern Pacific Company (unpub. data, 1958) as possibly equivalent to the informally named Yermo formation. Mapped only south of Mojave River near head of Afton Canyon

QTalg Older arkosic-lithic fanglomerate (early Pleistocene? and Pliocene)—Sandy pebble to cobble fanglomerate 

with clasts composed of wide range of plutonic, volcanic, and minor sedimentary rock types and sand fraction dominantly arkosic in composition. Unit has weak to moderate paleosols throughout consisting of Bk 

and Bw or Bt horizons. Moderately to strongly indurated. Along northeastern margin of Buwalda Ridge, unit 

appears to be conformable on unit Tbrg and contains higher proportion of mafic volcanic clasts than elsewhere. Outcrops generally are tilted from 5‒10° even distant from faults, in contrast to unit Qalg. Considered equivalent to part of south Alvord gravel of Miller and others (2011). Thickness unknown but may be 

more than 100 m

QTcg Fanglomerate of Cave Mountain (early Pleistocene? and Pliocene)—Fanglomerate composed almost entirely 

of felsic and mafic plutonic rocks, commonly with clasts of iron-rich ore. Well cemented, with beds 1‒5 m 

thick; clayey to sandy matrix with angular to subrounded clasts as much as 2 m in diameter. Unit has many 

well-developed buried soils with many, prominent clay films in Bt horizons that can be meters thick, and 

stage V and greater carbonate horizons that can be meters thick and that often create waterfalls in smaller 

drainages. Unit has a pink color from Bt horizons and common felsic granitic rocks. Previously termed 

the “brown conglomerate” by Ellsworth (1932) and Meek (1990). Unit is sourced from Cave Mountain to 

northeast and thins to south, extending slightly south of Mojave River (photos 43 and 44). Unit is faulted 

near the eastern Lake Manix threshold and is not identified farther east. North of river, unit overlain by basal 

Lake Manix deposits (units Ql6 or Ql7). South of river, overlain by unit Qvg. At one locality north of the 

river (table 2, M07‒145) just below contact with unit Ql7, QTcg contains a tephra. Its chemical composition 

matches a range of late Pliocene and Quaternary samples from diverse study areas, but may be most closely 

matched with the 2.4-Ma Ishi Tuff, a member of the Tuscan Formation. Estimated thickness at least 60 m

QTvg Older volcanic fanglomerate (early Pleistocene? and Pliocene?)—Coarse fanglomerate composed almost 

entirely of Cady Mountain lithologies, mainly basalt, andesite, biotite rhyolite, and tuff, but in some beds as 

much as 50 percent granitic clasts. Upper part of exposed section contains clasts similar to unit Tgg, including granite with large pink feldspar phenocrysts, biotite granite, and meta-diorite; middle part contains no 

granitic clasts; and lowest part of section contains as much as 20 percent rounded, gray flow-banded rhyolite, gray quartz monzonite (?), and siliceous dike rocks similar to those in units Tqg and Tbrg (photo 46). 

Compared to unit Qvg, QTvg is generally finer grained (especially the dominantly mafic beds), more thinly 

bedded, and more indurated. Locally contains lenses of reworked eolian sand (photo 47). Well exposed along 

the Manix fault south of river in Afton subbasin, where it is in fault contact with unit Tgg. Commonly tilted, 

with dips up to 45°, and typically underlies unit Qvg with angular unconformity. Unconformably overlies 

unit Tvs (photo 48). Correlative at least in part with unit Tbrg. Total thickness unknown, but at least 75 m

Tbrg Fanglomerate of Buwalda Ridge (Pliocene)—Cobble to boulder fanglomerate composed entirely of Cady 

Mountains lithologies; forms prominent elongate ridge (Buwalda Ridge; fig. 2, photos 1 and 49) separating 

the Cady and Afton subbasins on north side of Mojave River. Bounded on north and south and internally cut 

by strands of the Manix fault. Moderately indurated. Basal part of outcrop resembles a megabreccia composed 

of matrix-supported, angular to well-rounded, cobbles to large boulders, lacking visible bedding, as much as 

35 m thick. Clasts mainly composed of andesite, andesitic tuff, and lesser basalt; as much as 25 percent of 

total mainly composed of granitoids, including meta-diorite, dense gray quartz monzonite (?), and epidotized 

siliceous dike rocks. This breccia may have been deposited as a landslide originating in older alluvial deposits 

partly sourced from plutonic rocks exposed mainly south of map area of unit Tqg. Likely correlative with basal 
Rationale for this Map 13

part of unit QTvg. Upward in section and westward along Buwalda Ridge, grades into coarsely bedded alluvialfan deposits, with clasts generally smaller in caliber, poorly to moderately sorted and rounded, and only a few 

percent granitoid rocks compared to lower part (photo 50). Along the northeastern margin of Buwalda Ridge, 

the unit locally contains finer-grained fan deposits that are intercalated with red, matrix-rich, carbonate-bearing 

paleosols and that appear to grade up into arkosic unit QTalg. In one area on eastern edge of Buwalda Ridge, 

unit grades up into reddish distal-fan and playa deposits of unit Ta. Overlain in angular unconformity by unit 

Qalg. Near top of outcrop on the east end of Buwalda Ridge, contains two lenses of tephra identified as 3.4-Ma 

tuff of Mesquite Springs (table 2, M07‒101A and B; photos 50 and 51). Commonly tilted and strongly sheared 

adjacent to faults. Estimated thickness at least 120 m

Tgg Granitic fanglomerate (Pliocene and late Miocene?)—Pebble to boulder fanglomerate. Clasts are mainly 

composed of granite with large pink feldspar phenocrysts, lesser foliated biotite granite, diorite, andesite, 

rhyolite, and rhyolite tuff; coarsely bedded with sandy matrix and clast sizes ranging from pebbles to boulders. 

Unit lacks paleosols and overall is light gray in color (photo 52). Base of unit, where exposed on western flank 

adjacent to Manix fault, overlies distinctive andesite tuff, pinkish in color, probably part of unit Tvs. Tuff is 

overlain by fanglomerate at least 100 m thick that at base is composed entirely of clasts of same tuff (photo 53), 

and becomes mixed with other volcanic and granitic clasts upward. Basal unit dips vertical adjacent to fault; 

dips decrease upward through section to as low as ~12°. Unit displaced left-laterally at least 7 km along Manix 

fault (Meek, 1990). Total thickness at least 400 m as estimated from topographic map

Playa and Distal-Fan Deposits

Qp Playa and distal-fan deposits (middle Pleistocene)—Mud, silt, sand, and lesser fine gravel in massive, poorly 

sorted, matrix supported beds (photos 34 and 54). Locally includes moderately bedded, poorly sorted alluvial 

deposits 20‒50 cm thick. Deposited by low-gradient streams, playas, and small wetlands in Afton subbasin 

when internally drained, prior to deposition of units Qof and Ql6 that record the influx of Lake Manix 

(sheet 2B, section M06‒70). Interfingers with unit Qalg. Thickness at least 10 m

Qmr Mojave River formation (informal) of Nagy and Murray (1991) (middle and early Pleistocene; previously interpreted as Pliocene)—Mud, silt, sand, and fine gravel; moderately indurated. Described in detail 

by Nagy and Murray (1991). Most of unit is massive to faintly cross-bedded silt and fine sand interbedded with lesser gypsiferous mud and minor thin gravel beds (photo 55). Approximately the upper third of 

unit is dominantly coarse-grained arkosic sand and pebbly sand (in part mapped separately as unit Qalg) 

containing numerous buried soils; this facies varies in thickness depending on distance from basin center. 

Uppermost arkosic deposits are interbedded with, and interpreted to grade upward into, unit Qvg. A tephra 

layer in lower part of unit Qmr was previously correlated with 2.09-Ma Huckleberry Ridge Tuff (photo 

56) and two slightly younger tephra were correlated with the tuff of Emigrant Pass and lower tuffs of Glass 

Mountain (Sarna-Wojcicki and others, 1984, 2005; Nagy and Murray, 1991; Pluhar and others, 1991). At 

one new station, M08‒164B, a tephra layer lies 1.1 m above the Huckleberry Ridge ash (table 2, M08‒164) 

and is correlated with the ~2.0 Ma tuff of Emigrant Pass. Another newly discovered tephra layer (sheet 2B, 

M07‒128, and a sample from station M08‒164, about 2.5 km to the southwest on sheet 1; table 2) lies ~3 m 

below the Huckleberry Ridge ash and is correlated with one of the tuffs of Blind Spring Valley, 2.2‒2.1 Ma 

(photos 57 and 58). Unit is interpreted to represent deposition by low-gradient streams and playas in internally drained basin. Thickness at least 80 m

Ta Playa and distal alluvial-fan deposits (Pliocene)—Massive mud, silt, sand, and fine gravel; strongly indurated. 

Reddish-brown mud beds typically contain single lines of clasts or floating clasts (photo 59). Clast composition grades upward from dominantly mafic volcanic rocks with smaller silicic volcanic component to dominantly arkosic; matrix is reddish, unlike Mojave River formation. Interpreted as playa and distal alluvial fan 

deposits. On eastern margin of Buwalda Ridge, gravelly distal fan deposits overlie reddish carbonate-bearing 

paleosols and matrix-rich debris flows of upper unit Tbrg. Muds are thickest along south side of river (for 

example, sheet 2B, section M07‒144), probably indicating former basin axis. Depositional setting similar to 

that of Mojave River formation, but separate from it in time and space. Mapped only east of Buwalda Ridge 

in vicinity of Manix fault. Likely correlative in part with unit QTalg. Minimum thickness 6 m but probably 

much thicker
14 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

Eolian and Mixed Eolian-Alluvial Deposits

Qye Young eolian deposits (Holocene and late Pleistocene)—Moderately sorted arkosic sand, massive to thinly bedded. Locally contains shell fragments and ostracodes reworked from Lake Manix beds. Eolian deposits forming sand sheets, sand ramps, and dunes. Locally intermixed and interbedded with colluvial deposits. Mapped 

separately only where thickness exceeds ~1 m

Qyea Young mixed eolian and alluvial-fan deposits, undivided (Holocene and late Pleistocene)—Interbedded 

poorly to moderately sorted sand and sandy gravel. Sand beds are arkosic, massive to thinly bedded, and 

interpreted as eolian deposits sourced primarily from the Mojave River. Gravel beds same as in unit Qya. 

Mapped only in Afton area where eolian influence is pervasive. Locally subdivided into:

Qyeay Young mixed eolian and alluvial-fan deposits, younger subunit (late Holocene)—Interbedded poorly to 

moderately sorted sand and sandy gravel. Includes active channels and low surfaces <1 m above active channels; prone to flooding in large events. No desert pavement or varnish. Equivalent to unit Qyay

Qyeao Young mixed eolian and alluvial-fan deposits, older subunit (Holocene and late Pleistocene)—Interbedded 

poorly to moderately sorted sand and sandy gravel. Moderately well-developed desert pavement over 

~75 percent of surface and moderately developed varnish. Fans locally either grade to or are inset within 

lacustrine deposits of the last Lake Manix highstand ~20 14C ka. Equivalent to unit Qyao

Qiea Older mixed eolian and alluvial-fan deposits (late and middle Pleistocene)—Interbedded poorly to moderately sorted sand and sandy gravel (photos 60 and 61). Arkosic sand beds are massive to thinly bedded. 

Gravel beds are generally clast supported with angular to subangular clasts. Interpreted as interbedded eolian, 

reworked eolian, and alluvial-fan deposits. Contain buried soils; weakly to moderately indurated

Bedrock Units

Tvs Volcanic and sedimentary rocks, undivided (Miocene)—Volcanic rocks and volcaniclastic sediments. Unit 

includes basalt, andesite, and dacite flows and intrusive rocks in the southwestern part of the map area 

(Vanderpool, J.S., and Danehy, E.A., Southern Pacific Company Land Dept., unpub. data, 1959). In the 

northeastern part of the area, unit includes rhyolite, rhyolite tuffs, andesite, andesite tuff, pumiceous tuff, 

tuffaceous sandstone, siltstone, and mudstone, basalt, andesitic basalt, and volcaniclastic deposits, interbedded with reddish brown conglomerates and one minor bed of limestone. Mapped by Danehy, E.A., and 

Collier, J.T., Southern Pacific Company (unpub. data, 1958) and Moseley (1978) and defined as Hector 

Formation by Moseley (1978) and Woodburne and others (1974). Age range of Hector Formation 23‒16 Ma 

(MacFadden and others, 1990; Hillhouse and others, 2010)

Br Plutonic rocks (Jurassic?)—Coarse-grained quartz- and orthoclase-rich granitoid rocks, quartz diorite, and 

diorite, as mapped by Danehy, E.A., and Collier, J.T., Southern Pacific Company (unpub. data, 1958). 

Locally sheared and metamorphosed
References Cited 15

Acknowledgments

James B. Paces, USGS, provided the uranium-series ages. 

Norman Meek, California State University, San Bernardino, 

introduced us to Afton basin stratigraphy and his interpretations 

of Lake Manix history. C.G. Oviatt, Kansas State University, 

Manhattan, and D.M. Miller, USGS, made additional stratigraphic observations. The authors would also like to thank 

David M. Miller and Emily M. Taylor (USGS) for their peer 

reviews of this work.

References Cited

Bedford, D.R., 2003, Surficial and bedrock geologic map database of the Kelso 7.5 minute quadrangle, San Bernardino 

County, California: U.S. Geological Survey Open-File 

Report 03‒501, 33 p., scale 1:24,000.

Blackwelder, Eliot, and Ellsworth, E.W., 1936, Pleistocene 

lakes of the Afton basin, California: American Journal of 

Science, v. 231, p. 453‒463.

Bortugno, E.J., and Spittler, T.E., 1986, Geologic map of California, San Bernardino sheet: Department of Conservation, 

California Division of Mines and Geology, scale 1:250,000.

Byers, F.M., Jr. 1960, Geology of the Alvord Mountain quadrangle, San Bernardino County, California: U.S. Geological 

Survey Bulletin 1089‒A, 71 p.

Cox, B.F., Hillhouse, J.W., and Owen, L.A., 2003, Pliocene 

and Pleistocene evolution of the Mojave River, and associated tectonic development of the Transverse Ranges and 

Mojave Desert, based on borehole stratigraphy studies 

and mapping of landforms and sediments near Victorville, 

California, in Enzel, Yehouda, Wells, S.G., and Lancaster, 

Nicholas, eds., Paleoenvironments and paleohydrology of 

the Mojave and southern Great Basin Deserts: Boulder, 

Colo., Geological Society of America Special Paper 368, 

p. 1‒42.

Dibblee, T.W., Jr., 1968, Geology of the Opal Mountain and 

Fremont Peak quadrangles, California: California Division 

of Mines and Geology Bulletin, v. 188, 64 p.

Dudash, S.L., 2006, Preliminary surficial geologic map of 

a Calico Mountains piedmont and part of Coyote Lake, 

Mojave Desert, San Bernardino County, California: 

U.S. Geological Survey Open-File Report 2006‒1090, 

44 p., scale 1:24,000.

Ellsworth, E.W., 1932, Physiographic History of the Afton 

Basin: Stanford, Calif., Ph.D. dissertation, Stanford 

University, 98 p.

Enzel, Yehouda, Wells, S.G., and Lancaster, Nicholas, 2003, 

Late Pleistocene lakes along the Mojave River, southeast 

California, in Enzel, Yehouda, Wells, S.G., and Lancaster, 

Nicholas, eds., Paleoenvironments and paleohydrology of the 

Mojave and southern Great Basin Deserts: Boulder, Colo., 

Geological Society of America Special Paper 368, p. 61‒77.

Fillmore, R.P., 1993, Sedimentation and extensional basin 

evolution in a Miocene metamorphic core complex setting, 

Alvord Mountain, central Mojave Desert, California, USA: 

Sedimentology, v. 40, p. 721‒742.

Geological Society of America, 2012, GSA Geologic time 

scale, ver. 4.0: Boulder, Colo., The Geological Society of 

America, Inc.

Gile, L.H., Peterson, F.F., and Grossman, R.B., 1966, Morphological and genetic sequences of carbonate accumulation in 

desert soils: Soil Science, v. 101, p. 347–360.

Hillhouse, J.W., Miller, D.M ., and Turrin, B.D., 2010, &RU

relation of the Miocene Peach Springs Tuff with the JHR

magnetic polarity time scale, in Reynolds, R.E., and 0LOOHU

D.M., eds., Overboard in the Mojave—20 Million<HDUV

of Lakes and Wetlands, Abstracts of Proceedings: =]\][

Calif., Desert Studies Consortium, California State8QLYHU

sity Fullerton, 2010 Desert Symposium, p. 105‒121, http://

biology.fullerton.edu/facilities/dsc/pdf/2010Overboard.pdf.

Jefferson, G.T., 2003, Stratigraphy and paleontology of 

the middle to late Pleistocene Manix Formation, and 

paleoenvironments of the central Mojave River, southern 

California, in Enzel, Yehouda, Wells, S,G., and Lancaster, 

Nicholas, eds., Paleoenvironments and Paleohydrology of 

the Mojave and Southern Great Basin Deserts: Geological 

Society of America Special Paper 368, p. 43‒60.

Lichvar, R.W., and Finnegan, D.C., 2004, Wetlands Regulatory Assistance Program (WRAP): U.S. Army Corps of 

Engineers.

Lisiecki, L.E., and Raymo, M.E., 2005, A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records: 

Paleoceanography, v. 20, no. PA1003, 17 p.

MacFadden, B.J., Woodburne, M.O., and Opdyke, N.D., 

1990, Paleomagnetism and Neogene clockwise rotation 

of the northern Cady Mountains, Mojave Desert of southern California: Journal of Geophysical Research, v. 95, 

p. 4597‒4608.

Meek, N.C., 1989a, Geomorphic and hydrologic implications of the rapid incision of Afton Canyon, Mojave Desert, 

California: Geology, v. 17, p. 7‒10.

Meek N.C., 1989b, Physiographic history of the Afton basin, 

revisited, in Reynolds, R.E., ed., The west-central Mojave 

Desert—Quaternary studies between Kramer and Afton 

Canyon: Redlands, Calif., San Bernardino County Museum 

Association Special Publication, p.78‒83.
16 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

Meek, N.C., 1990, Late Quaternary geochronology and geomorphology of the Manix basin, San Bernardino County, 

California: Los Angeles, Calif., Ph.D. dissertation, University of California, 212 p.

Meek, N.C., 1994, The stratigraphy and geomorphology of 

Coyote basin, in Reynolds, Jennifer, compiler, Calico, 

Coyote Basin & Lake Havasu Giants: Redlands, Calif., 

San Bernardino County Museum Association Quarterly, 

v. 41, no. 3, p. 5‒13.

Meek, N.C., 2000, The late Wisconsinan history of the Afton 

Canyon area, Mojave Desert, California, in Reynolds, R.E., 

and Reynolds, Jennifer, eds., Empty basins, vanished lakes, 

the year 2000 Desert Symposium Field Guide: Redlands, 

Calif., San Bernardino County Museum Association Quarterly, v. 47, no. 2, p. 32‒34.

Meek, N.C., 2004, Mojave River history from an upstream 

perspective, in Reynolds, R.E., ed., Breaking Up—The 

2004 Desert Symposium Field Trip and Abstracts: Fullerton, 

Calif., California State University Fullerton, Desert Studies 

Consortium, p. 41‒49.

Meek N.C., and Battles, D.A., 1991, Displacement along the 

Manix fault: California Geology, v. 44, p. 33‒38.

Miller, D.M., Bedford, D.R, Hughson, D.L., McDonald, 

E.V., Robinson, S.E., and Schmidt, K.M., 2009, Mapping 

Mojave Desert ecosystem properties with surficial geology, 

in Webb, R.H., Fenstermaker, L.F., Heaton, J.S., Hughson, 

D.L., McDonald, E.V., and Miller, D.M., eds., The Mojave 

Desert—Ecosystem processes and sustainability: Reno, 

Nev., University of Nevada Press, p. 225‒251.

Miller, D.M., Dudash, S.L., and McGeehin, J.P., 2009, Chronology of pluvial Lake Coyote, California, and implications 

for 25,000 to 10,000 cal. yr. B.P. Mojave River paleohydrology [abs.] in Pacific Climate Workshop, Pacific Grove, 

Calif., April 19‒22, 2009: U.S. Department of Agriculture 

Pacific Southwest Research Station, Pacific Climate Workshop (PACLIM) 2009.

Miller, D.M., and McGeehin, J.P., 2007, Depositional environment and radiocarbon chronology of the upper Lake Manix 

deposits, Mojave Desert, California [abs.]: Geological Society of America Abstracts with Programs, v. 39, no. 6, p. 271.

Miller, D.M., Reheis, M.C., Wan, Elmira, Wahl, D.B., and Olson, 

Holly, 2011, Pliocene and early Pleistocene paleography of 

the Coyote Lake and Alvord Mountain area, Mojave Desert, 

California, in Reynolds, R.E., ed., The incredible shrinking Pliocene and Abstracts of Proceedings, the 2011 Desert 

Symposium, April 2011: California State University Fullerton, 

Desert Studies Consortium, p. 53‒67, http://biology.fullerton.

edu/facilites/dsc/pdf/2011shrinkingpliocene.pdf.

Morton, D.M., and Miller, F.K., 2006, Geologic map 

of the San Bernardino and Santa Ana 30' × 60' quadrangles, California: U.S. Geological Survey Open-File 

Report 2006‒1217, scale 1:100,000.

Moseley, C.G., 1978, The geology of a portion of the northern 

Cady Mountains, Mojave Desert, California: Riverside, 

Calif., M.S. thesis, University of California Riverside, 

131 p.

Nagy, E.A. and Murray, Bruce, 1991, Stratigraphy and intrabasin correlation of the Mojave River formation, central 

Mojave Desert, California, in Reynolds, Jennifer, compiler, 

The Mojave River formation, Manix basin, California—

Stratigraphy, correlation, magnetostratigraphy, and rotation, 

Abstracts of Proceedings 1991, Mojave Desert Research 

Symposium: Redlands, Calif., San Bernardino County 

Museum Quarterly, v. 38, no. 2, p. 5‒30.

Nagy, E.A. and Murray, Bruce, 1996, Plio-Pleistocene deposits 

adjacent to the Manix fault—Implications for the history of 

the Mojave River and Transverse Ranges uplift: Sedimentary Geology, v. 103, p. 9‒21.

Oviatt, C.G., Reheis, M.C., Miller, D.M., and Lund, S.P., 

2007, Stratigraphy of Lake Manix beds in the Manix subbasin, Mojave Desert, CA [abs.]: Geological Society of 

America Abstracts with Programs, v. 39, no. 6, p. 271.

Pluhar, C.J., Kirschvink, J.L., and Adams, R.W., 1991, Magnetostratigraphy and clockwise rotation of the Plio-Pleistocene 

Mojave River formation, central Mojave Desert, California, 

in Reynolds, Jennifer, compiler, The Mojave River formation, Manix basin, California—Stratigraphy, correlation, 

magnetostratigraphy, and rotation, Abstracts of Proceedings 1991, Mojave Desert Research Symposium: Redlands, 

Calif., San Bernardino County Museum Quarterly, Redlands, California, v. 38, no. 2, p. 31‒42.

Reheis, M.C., Bright, Jordon, Lund, S.P., Miller, D.M., Skipp, 

Gary, and Fleck, R.J., 2012, A half-million-year record of 

paleoclimate from the Lake Manix Core, Mojave Desert, 

California: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 365‒366, p. 11‒37.

Reheis, M.C., and Miller, D.M., 2010, Environments of nearshore lacustrine deposition in the Pleistocene Lake Manix 

basin, south-central California, in Reynolds, R.E., and 

Miller, D.M., eds., Overboard in the Mojave—20 Million 

Years of Lakes and Wetlands, Abstracts of Proceedings, 

2010 Desert Symposium: Zzyzx, Calif., Desert Studies 

Consortium, California State University Fullerton, 2010 

Desert Symposium, p. 24‒37, http://biology.fullerton.edu/

facilities/dsc/pdf/2010Overboard.pdf.

Reheis, M.C., Miller, D.M., and McGeehin, J.P., 2010, Late 

Pleistocene shoreline fluctuations of Lake Manix, Mojave 

Desert—Paleoclimate implications [abs.]: Geological Society of America Abstracts with Programs, v. 42, no. 4, p. 53.

Reheis, M.C., Miller, D.M., and Redwine, J.R, 2007, 

Quaternary stratigraphy, drainage-basin development, and 

geomorphology of the Lake Manix basin, Mojave Desert—

Guidebook for Fall Field Trip, Friends of the Pleistocene, 

Pacific Cell, October 4‒7, 2007: U.S. Geological Survey 

Open-File Report 2007‒1281, 31 p.
References Cited 17

Reheis, M.C., and Redwine, J.R., 2008, Lake Manix shorelines 

and Afton Canyon terraces—Implications for incision of 

Afton Canyon, in Reheis, M.C., Hershler, R., and Miller, D., 

eds., Late Cenozoic Drainage History of the Southwestern 

Great Basin and Lower Colorado River Region, Geologic 

and Biotic Perspectives: Geological Society of America 

Special Paper 439, p. 227‒259.

Reynolds, R.E., and Reynolds, R.L., 1985, Late Pleistocene 

faunas from Daggett and Yermo, San Bernardino County, 

California, in Reynolds, R.E., ed., Cajon Pass to Manix 

Lake—Geological investigations along Interstate 15: Redlands, Calif., San Bernardino County Museum Association 

Special Publication, p. 175‒191.

Sarna-Wojcicki, A.M., Bowman, H.R., Meyer, C.E., Russell, P.C., 

Woodward, M.J., McCoy, Gail, Rowe, J.J., Jr., Baedecker, P.A., 

Asaro, Frank, and Michael, Helen, 1984, Chemical analyses, 

correlations, and ages of upper Pliocene and Pleistocene ash 

layers of east-central and southern California: U.S. Geological 

Survey Professional Paper 1293, 40 p.

Sarna-Wojcicki, A.M., Reheis, M.C., Pringle, M.S., Fleck, 

R.J., Burbank, Doug, Meyer, C.E., Slate, J.L., Wan, Elmira, 

Budahn, J.R., Troxel, Bennie, and Walker, J.P., 2005, Tephra 

layers of Blind Spring Valley and related upper Pliocene 

and Pleistocene tephra layers, California, Nevada, and 

Utah—Isotopic ages, correlation, and magnetostratigraphy: 

U.S. Geological Survey Professional Paper 1701, 63 p.

Singleton, J.S., and Gans, P.B., 2008, Structural and stratigraphic evolution of the Calico Mountains—Implications 

for early Miocene extension and Neogene transpression 

in the central Mojave Desert, California: Geosphere, v. 4, 

p. 459‒479.

Soil Survey Staff, 1999, Soil taxonomy—A basic system of 

soil classification for making and interpreting soil surveys 

(2d ed.): U.S. Department of Agriculture Handbook 436, 

869 p.

Woodburne, M.O., Tedford, R.H., Stevens, M.S., and Taylor, 

B.E., 1974, Early Miocene mammalian faunas, Mojave Desert, California: Journal of Paleontology, v. 48, p. 65‒76.

Appendix. Captions for Selected Photographs of Pleistocene Lake Manix Map Area 19

Appendix. Captions for Selected Photographs of Pleistocene Lake Manix 

Map Area

Note: Station and photo index numbers are keyed to field notebooks and all stations are not necessarily shown on map.

Photo 1. View northeast from bluffs north of Mojave River looking across Manix Wash to Buwalda Ridge. Interbedded lacustrine and 

alluvial beds of the informally defined Manix formation in foreground. Photo point southeast of The Knob. Qye, eolian and alluvialfan deposits; Qmr, Mojave River formation; Tbrg, fanglomerate of Buwalda Ridge. Photo courtesy of Charles G. Oviatt, Kansas State 

University, 2006 (sheet 1).

Photo 2. Exposure of 184-ka Manix tephra in unit Ql6, Afton subbasin, station M07–159 near Dunn wash (photo index number 07–560).

Photo 3. Panorama looking west from eastern margin of Afton subbasin, showing interbedded lake and alluvial-fan units overlying unit 

QTcg. To right of Shoreline hill, view extends across Mojave River to Manix fault (assembled from photo index numbers 07–306–307).

Photo 4. View northwest of eastern margin of Buwalda Ridge, showing lake beds overlying unit Qalg. Manix fault trace lies just behind the 

crest of the Ql8 outcrop. (photo index number 08–79)

Photo 5. Anodonta and gastropod shells in unit Ql8, northeast side of Manix Wash in Cady subbasin, station M08–113 (table 1; photo 

index number 08–368).

Photo 6. Nearshore sand and gravel of unit Ql8 overlying thin Qia7 and greenish muds of unit Ql7. West side of North Afton beach 

ridge, Afton subbasin, station M05–26 (sheet 2D; photo index number 05–304).

Photo 7. Sand and gravel of unit Ql8 deposited in active alluvial-fan interface setting. Outcrop contains several dated shell beds; 

sample M09–6A (table 1) taken a few cm to right of shovel head. 50-cm shovel for scale. Railroad cut southwest of Dunn, Afton 

subbasin, station M09–6 (sheet 2B; photo index number 09–107).

Photo 8. Sand and gravel of unit Ql8 deposited in active alluvial-fan interface setting. Outcrop contains several beds separated 

by tufa-coated clasts (white streaks) representing lake transgressions and a buried soil (reddish), as well as dated shells (M05–19I, 

table 1). Note backset and foreset beds forming beach barrier in gravel bed above rod top. 1-m rod for scale. Borrow pit in Dunn wash, 

Afton subbasin, station M05–19 (sheet 2C; photo index number 05–117).

Photo 9. Interbedded sand and sandy green mud of unit Ql8. Contains lacustrine ostracodes and a dated gastropod bed at top (sample 

M10–3A, table 1). 50-cm shovel for scale; orange flag at base marks contact with unit Qia7 below. Railroad cut southwest of Dunn, Afton 

subbasin, station M07–62 (sheet 2B, photo index number 07–88).

Photo 10. View to northwest of green muds and thin interbedded sands (marked by steps) of unit Ql7. Dunn “island” outcrop in Afton 

subbasin near Dunn (stations DI1–4, sheet 2B). Total thickness about 17 m; contains abundant ostracodes and fish bones (Reheis and 

others, 2012; photo index number 06–178).

Photo 11. Units Ql8, Ql7, and Ql6 exposed on south side of Mojave River, Afton subbasin, station M11–109. 50-cm shovel for scale with 

head at top of thin Qia6 overlying Ql6, which consists of tan, planar-bedded sand with rip-up clasts of green mud, separated from overlying 

Ql7 by about 60 cm of gravelly sand with tufa-coated clasts (photo index number 11–376).

Photo 12. Layered oncoid tufa coats on clasts at base of unit Ql7, south side of Mojave River, Afton subbasin (photo index 

number 08–106).

Photo 13. Layered oncoid tufa coats on clasts at base of unit Ql7, Dunn wash, Afton subbasin, station M07–19B. Note bumpy stromatolitic 

texture on surface, typical of oncoid coats in Lake Manix deposits (photo index number 05–112).

Photo 14. Units Ql7b (green mud) and Ql7a (tan planar-bedded pebbly sand and silt) overlying pinkish unit Qalg. Section M06–81 

near Field siding, Afton subbasin. Geologist and dog for scale (sheet 2B; photo index number 06–156).
20 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

Photo 15. Units Ql7b (greenish-gray sandy mud) and Ql7a (pink and green interbedded sand and pebble gravel) overlying reddish unit Qiea. 

Weak soil present at top of Ql7a. Ql7a was deposited in a fan-delta setting and thus locally contains packages of fluvial gravel (Reheis and 

Miller, 2010). Section is about 10 m thick. Station M06–160 near Shoreline hill, Afton subbasin (sheet 2C; photo index number 06–522).

Photo 16. Unit Ql7a, deposited in a fan-delta setting. Includes fluvial gravel, beach deposits (backset and foreset beds) and deltaic 

foreset and topset beds. 50-cm shovel for scale. Station M06–135, east side of North Afton beach ridge, Afton subbasin (sheet 2D; photo 

index number 06–471).

Photo 17. Unit Ql6, overlying unit Qia. Fine to medium sand in long sweeping northeast-directed crossbeds; upper part locally 

contains reworked green muds in lenses. Station M05–54, railroad cut northeast of Dunn in Afton subbasin (sheet 2C; photo index 

number 05–370).

Photo 18. Unit Ql6, same station as Photo 17. Well bedded fine sand, weakly cemented by calcium carbonate. Station M05–54, railroad 

cut northeast of Dunn in Afton subbasin (sheet 2C; photo index number 06–118).

Photo 19. Unit Ql6, showing large green rip-up mud clasts embedded in sand matrix. Clasts were derived from erosion of lake deposits 

in Cady subbasin during subbasin integration event. Station M11–109, south side of Mojave River in Afton subbasin (photo index 

number 11–378).

Photo 20. Unit Ql6, showing interbedded medium and fine sand and sandy mud; white lamina is 184-ka Manix tephra. Green bed 

near base of scale consists of reworked rip-up mud clasts. Station M07–159 northeast of Dunn, Afton subbasin (sheet 2C; photo index 

number 07–566).

Photo 21. Unit Ql6, showing rip-up mud clasts and gravel at base of pebbly sand also containing smaller mud rip-ups, and capped 

by a transgressive gravel marking base of Ql7. Station M09–58 south of Mojave River in Cady subbasin (sheet 2A; photo index 

number 09–181).

Photo 22. Interbedded lacustrine and alluvial-fan beds, south of Mojave River in Cady subbasin. Ql7 consists of sandy mud and wellsorted nearshore sand; Ql6 consists of horizontally bedded fine to coarse sand with heavy-mineral laminae. Note white concentration of 

calcium carbonate at base of unit Ql7. Numbers on scale are 10-cm intervals. Station M09–66 (sheet 2A; photo index number 09–234).

Photo 23. Sequence of three lacustrine units overlying unit Qalg, northeast side of Manix Wash, Cady subbasin. About 1 m of muddy 

nearshore sand of unit Ql7 at top is obscured by lag gravel (note daypack for scale). Ql5 consists of an upper interval of nearshore 

sand overlying beach gravel with tufa-coated clasts throughout. Ql4 consists of pale-colored, horizontally bedded arkosic sand. 

Hoodoo of unit Qalg at right capped by cemented sandstone lens. Station M08–110 (sheet 2A; photo index number 08–365).

Photo 24. View to southeast of strath terraces capped by Mojave River gravel (Qyfmr) near the head of Afton Canyon. Straths are 

inset into various units, including unit Tgg forming skyline and plutonic rocks (Br) in middle ground. Also inset below deposits of 

Lake Manix overlying units Qiea and QTcg. Mojave River (Qfmr) and railroad bridge in right middle ground (sheet 1; photo index 

number 06–77).

Photo 25. View to south of strath terraces capped by Mojave River gravel (Qyfmr) south of Buwalda Ridge (foreground). Terraces are 

cut into unit Qvg. Mojave River channel (unit Qfmr; about 0.5 km wide) and active dune sand (Qye and Qyea) in middle ground. Photo 

taken at approximate location of inferred threshold formerly separating Cady and Afton subbasins (photo index 07–205).

Photo 26. View to south of unit Qif, fluvial deposits in middle ground above north rim of Afton Canyon. Foreground is colluvium on 

plutonic rocks (unit Br); background is unit Tgg. Station JR04CM–87 (Reheis and Redwine, 2008; photo index number 04–163).

Photo 27. View to southeast of unit Qif (center middle ground) and thin inset strath terrace of unit Qyfmr to right, overlying bedrock 

above north rim of Afton Canyon. Station JR04CM–87 (Reheis and Redwine, 2008; photo index number 06–512).

Photo 28. View to northeast of unit Qof overlying unit Ta; capped by strath gravel of unit Qyfmr. Exposure is about 17 m high. Qof

consists of interbedded sand and gravel with individual beds 10–60 cm thick. Station M07–144 east of Mojave River in Afton subbasin, 

northeast of Ninemile Well (sheet 2B; photo index number 07–300).

Photo 29. Closeup of part of Qof outcrop in photo 28. Thinly bedded sand and pebbly sand (near base). Note steeply north-dipping 

beds above shovel head (50 cm shovel). Station M07–144 east of Mojave River in Afton subbasin, northeast of Ninemile Well (sheet 2B; 

photo index number 07–302).
Appendix. Captions for Selected Photographs of Pleistocene Lake Manix Map Area 21

Photo 30. Closeup of part of unit Qof outcrop showing reddish, weak buried soil overlain by fluvial sand and gravel containing large 

(about 50 cm across) rip-up clast of green mud (right of shovel head). Near station M08–45, east of Mojave River, northeast of Ninemile 

Well (sheet 2B; photo index number 11–39).

Photo 31. Closeup of unit Qof containing rip-up clasts of green mud in a poorly sorted matrix of gravel, sand, and small mud chips. Qof

overlies buttress unconformity on unit Qalg, sloping about 25° up to left from GPS. Unconformity is inferred to have been cut by flood 

waters during subbasin integration. Station M07–117 on east end of Buwalda Ridge (sheet 2B; photo index number 09–332).

Photo 32. Unit Qof as fluvial terrace cut into unit Qp (brown sandy mud). Geologist for scale. Station M06–68, northwest side of 

Mojave River, Afton subbasin (photo index number 06–126).

Photo 33. Closeup of outcrop in photo 32, showing lenses of green mud rip-ups in fluvial sand and gravel of unit Qof, overlying brown 

playa deposits of unit Qp. Station M06–68, northwest side of Mojave River near Dunn, Afton subbasin (photo index number 06–127).

Photo 34. View south of unit Qof overlying brown playa deposits of unit Qp. Qof consists of about 1 m of fluvial sand and gravel 

overlying several meters of chaotically bedded blocks (as much as 2 m across) and clasts of deformed, semi-indurated green lake 

mud, silt, and sand mixed with blocks of brown playa mud. Station M06–100, northeast side of Mojave River near Dunn, Afton subbasin 

(sheet 2B; photo index number 07–311).

Photo 35. Closeup of rip-up clast of deformed lake sand and mud (left of shovel head) overlying brown rip-up clast of playa sediment at 

station M06–100. 50-cm shovel for scale. Northeast side of Mojave River near Dunn, Afton subbasin (sheet 2B; photo index number 06–196).

Photo 36. Bedding in conglomerate Tqg at map boundary in Afton subbasin, south of Mojave River. Dominantly composed of wellrounded, flow-banded rhyolite and quartz-rich granitoids, with lesser amounts of mafic volcanic clasts. Sandy cemented bed about 

30 cm thick. Station M12–4, just south of map boundary (photo index number 12–46).

Photo 37. Lenticular body of freshwater limestone interbedded with unit Tqg in Afton subbasin, south of Mojave River. Geologist and 

dog for scale. Station M12–3, just south of map boundary (photo index number 12–37).

Photo 38. Orange-stained outcrop of unit Tqg overlain by rhyolite and andesite of unit Tvs. Contact of rhyolite over Tqg continues 

up slope on far right to near top of ridge. Station M12–8 at map boundary in Afton subbasin, south of Mojave River (photo index

number 12–56).

Photo 39. Unit Qia, interbedded poorly sorted alluvial gravel and sand, overlain by units Ql7 and Ql8. West side of North Afton beach 

ridge, Afton subbasin (sheet 2C; photo index number 08–17). 

Photo 40. View to west of the eastern end of Buwalda Ridge. Sequence of lake units Ql8 (tan sand), Ql7 (pale green mud), Qia

(pinkish sand and gravel), and Qalg (pale-colored sand and minor pebble gravel). Qia is less indurated and more gravelly than Qalg, 

but has similar arkosic composition with clasts of varied lithology. Station M07–119, north of Mojave River on western end of Afton 

subbasin (photo index number 07–264).

Photo 41. Unit Qalg on south side of Buwalda Ridge near eastern end. Capped by gravels of unit Qof. Desert tortoise (Gopherus 

agassizii) in foreground for scale (sheet 2A; photo index number 07–259).

Photo 42. View to northwest showing sequence of lacustrine, alluvial, and playa deposits exposed at station M10–86. Manix fault 

runs between Buwalda Ridge on skyline and dissected deposits in front of it. Unit Ql7 overlies thin Ql6 over Qia, resting on erosional 

unconformity. Beneath unconformity is weakly consolidated sand and pebble gravel of unit Qalg, which here rests on a slight angular 

unconformity cut on unit Qmr. At base of unit Qalg are lenses of ashy sediment, analyzed in the next drainage west at station M10–94 

(table 2), thought to be early Pleistocene in age (see map text). Station M10–86 (sheet 1; photo index number 10–198).

Photo 43. View to east showing sequence of lacustrine and alluvial deposits south of Mojave River near Afton Canyon and eastern 

margin of Afton subbasin. Unit Ql7 (green mud) caps right skyline; overlies weakly consolidated alluvial-fan gravel of unit Qia, in turn 

conformably overlying unit Qvg (light brown, forming steep slopes in middle ground). Qvg rests unconformably on pinkish deposits of 

unit QTcg in left middle ground (sheet 1; photo index number 05–84).

Photo 44. Closer view of sequence similar to that in photo 40, showing Ql7 over Qia (vertical cliff) over Qvg (more gullied, steeply 

sloping) over pink QTcg with white calcic soil at top (photo index number 06–496).

Photo 45. Unit Qvg conformably overlying unit Qmr at station M09–48, south side of Mojave River in Cady subbasin, near station 

M08–164 (table 2). Daypack marks bed of 2-Ma Huckleberry Ridge tephra within unit Qmr. The first incursion of volcaniclastic fan gravel 

of unit Qvg is 1.5 m higher, and such beds increase upward through another 2.5 m until they are dominant (photo index number 09–175).
22 Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California

Photo 46. Two facies of unit QTvg separated by a low-angle fault. Footwall is middle part of QTvg that is finer-grained and dominantly 

volcaniclastics; hanging wall is older part of part of QTvg that contains up to 20 percent flow-banded rhyolite and siliceous dike rocks 

(see unit description). Another fault separates QTvg from red-weathering basalt flow (unit Tvs) near skyline. Station M11–50 near map 

boundary south of Mojave River in Afton subbasin (photo index number 11–98).

Photo 47. Reworked eolian sand interbedded with gravels of unit QTvg. Near station M09–196, close to map boundary south of 

Mojave River in Afton subbasin (photo index number 09–287).

Photo 48. View to northwest of lower part of QTvg containing component of rhyolite and siliceous dike rocks (likely reworked from 

Tqg), overlying red-weathering basalt (unit Tvs). Basalt in turn is faulted against middle, dominantly volcaniclastic part of QTvg. Close 

to map boundary south of Mojave River in Afton subbasin (photo index number 11–107).

Photo 49. View west along south margin of Buwalda Ridge showing unit Tbrg cut by inactive strand of Manix fault in photo center. 

Channel of Mojave River on left (unit Qfmr). Near former threshold of Cady and Afton subbasins—see photo number 25 (sheet 1; photo 

index number 07–204).

Photo 50. View northeast near summit of Buwalda Ridge on its eastern end, showing southeast-dipping Tbrg; white streak in upper 

left is tephra layer (3.4-Ma tuff of Mesquite Springs), samples M07–10a and b (table 2). Afton subbasin (photo index number 07–271).

Photo 51. Closer view of two tephra lenses at station M07–101 (table 2, photo 50); both are about 7 cm thick at thickest point. Both 

samples correlated with 3.4-Ma tuff of Mesquite Springs. Afton subbasin (photo index number 07–241).

Photo 52. View to north of north-dipping beds of granitic fanglomerate Tgg. Trucks on highway visible in background. Station M08–98, 

south of Dunn and Mojave River, Afton subbasin (photo index number 08–344).

Photo 53. Base of unit Tgg on its southern flank near Manix fault. Basal part of unit composed mainly of reworked clasts of pink 

andesite tuff (unit Tvs), which underlies Tgg. Near station M08–88 (photo index number 08–475).

Photo 54. View to northeast of playa and distal-fan deposits of unit Qp in Afton subbasin. Most gravel in lower part of image is lagged 

down from a one-clast-thick gravel bed in middle of outcrop. Near station M06–66 northeast of Mojave River near Dunn (photo index 

number 06–123).

Photo 55. View to east of playa and distal-fan deposits of unit Qmr (Mojave River formation) near western end of Buwalda Ridge in 

Cady subbasin. In upper left, resistant pale-colored bed marks approximate contact of overlying unit Qalg as herein mapped (sheet 1; 

photo index number 09–278).

Photo 56. View to southeast of playa deposits of unit Qmr, south of Mojave River near mouth of Manix Wash in Cady subbasin. 

Scraped white area near shovel in foreground is 2-Ma Huckleberry Ridge tephra, as identified by Nagy and Murray (1991) in their

“southern hill section”. White streak partway up mud bluffs is another tephra. Station M09–41 (sheet 2A; photo index number 09–159).

Photo 57. Tephra within unit Qmr identified as one of the ~2.2–2.1-Ma tuffs of Blind Spring Valley (M07–128, table 2, sheet 2A). 50-cm 

shovel for scale. About 3–4 m higher, to left of this view, unit Qmr contains Huckleberry Ridge tephra (M10–90, table 2). Basal part 

of outcrop includes interbedded sand and mudcracked silt and mud layers. Sands display planar cross-beds and climbing ripples 

indicating southwesterly flow. South side of Mojave River in Cady subbasin (photo index number 07–283).

Photo 58. Closeup of tephra in photo 57, station M07–128. Basal ~2 cm of tephra very clean, likely deposited by air-fall on a mudcracked playa surface. Reworked upward and interbedded with silt and very fine sand. South side of Mojave River in Cady subbasin 

(photo index number 07–281).

Photo 59. Playa and distal-fan deposits of unit Ta, near eastern end of Buwalda Ridge near mouth of Field wash. A few hundred 

meters to west, similar deposits interfinger with gravels of unit Tbrg. Station M06–103, northwest of Mojave River in Afton subbasin 

(photo index number 06–206).

Photo 60. Reworked eolian sand and scattered pebble gravel of unit Qiea. Note vertical carbonate root casts in sand beds. 50-cm 

shovel for scale. Station M05–72, east side of North Afton beach ridge, Afton subbasin (photo index number 05–395).

Photo 61. Interbedded reworked eolian sand and gravel beds of unit Qiea, overlain by greenish unit Ql7. Station M06–40, east side of 

North Afton beach ridge, Afton subbasin (sheet 2D; photo index number 06–81).
Tables 23

Tables
 
Table 1. Radiocarbon ages and site information for samples from Afton and Cady subbasins of Pleistocene Lake Manix.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station. m, meters; B.P., years before the present; s.d., standard deviati

Station Lab number1 Altitude (m)3 Samples δ13C4 Age5 (B.P.) 1 s.d. Description

M04‒23 WW4771 539 Anodonta valves n.d. 21,780 70 In-situ whole shells in nearshore sand overlying mud and silt beds; capped 

dune sand. South of Mojave River

M04‒32A/B WW4772 557.8 Anodonta fragments n.d. 20,810 60 Well bedded dune sand containing shell fragments in individual layers. No

M04‒74 WW5279 535 Anodonta valves n.d. 28,170 120 Measured section in station M09‒6 in railroad cut west of Dunn siding. 4 u

Abundant shells in S-dipping foreset sand beds above buried soil; 2.6 m 

M04‒75 WW5357 542 Anodonta valves n.d. 22,470 70 Two lake units; upper unit contains shells 1.25 m below surface; overlies lo

and mottled red and white buried soil. West end of Buwalda Ridge

M05‒07 WW5339 549 Anodonta fragment n.d. 32,690 210 Uppermost limit of probable lake sediment, unit Ql7?; well sorted sand ab

soil. West end of Buwalda Ridge

M05‒19I WW5340 526.0 Anodonta fragments n.d. 34,680 260 Measured section in upper Dunn wash at pipeline crossing. Upper 3 lake u

4th unit Ql7. Sampled shell in second unit from top, 80 cm below surfac

M05‒20A WW5628 527.5 Anodonta,

whole shell

n.d. 49,800 2,000 Shells are from just above oncoid tufa-coated clasts at base of unit Ql7, up

M05‒21 WW5629 535.4 Anodonta fragments n.d. 31,900 200 Shells from 40 cm below surface in second Ql8 unit from top; upper Dunn M05‒22H WW5341 539.4 Anodonta valve n.d. 27,000 120 Measured section on east side of North Afton beach ridge; shells sampled a

M05‒23C WW5342 515 Anodonta,

whole shell

n.d. 40,120 500 Measured section on east side of North Afton beach ridge. Shells from 1 m 

at base of unit Ql7

M05‒25J WW5630 539 Anodonta valves,

weathered

n.d. 45,490 1,200 Measured section on east side of North Afton beach ridge. Shells from 2.8 

clasts at base of unit Ql7

M05‒26F WW5631 521.7 Anodonta,

whole shell

n.d. 40,000 600 Measured section on west side of North Afton beach ridge. Tufa-coated sh

tufa-coated clasts at base of unit Ql7 and 25 cm below Bwk soil formed 

M05‒26G WW5632 532.2 Anodonta fragments n.d. 29,630 190 Measured section on west side of North Afton beach ridge. Sands containin

within unit Ql8, 9.1 m above unit Qia7

M05‒28B WW5343 532.2 Anodonta valves n.d. 26,030 100 Shells lie in greenish lagoonal sediment of unit Ql8, just above tufa-coated 

of pipeline crossing in upper Dunn wash

M05‒62 WW5633 533.8 Anodonta,

whole shell

n.d. 28,440 160 Large, abundant shells in beach sand and gravel of unit Ql8 1 m above uni

Afton beach ridge

M05‒62A WW7485 533.2 Anodonta fragments –3.7 30,600 240 Shell fragment in beach gravel 45 cm above base of unit Ql8, on west side 

M05‒62A‒2 WW7851 533.2 Anodonta fragments –3.7 31,840 270 Re-analysis of sample M05‒62A

M05‒62C WW7486 534.0 Anodonta,

whole shell

–4.9 26,620 150 Whole shell in beach gravel 1.4 m above base of unit Ql8; just below green 

Afton beach ridge

M06‒35A WW5882 526.0 Anodonta

valves

n.d. 47,430 930 Abundant shells in horizontally bedded beach sand just above oncoid tufa-

east side of North Afton beach ridge

M06‒62D WW5885 538.6 Anodonta valve n.d. 21,310 50 Shells in-situ 30 cm below surface of beach gravel, 0.7 m thick; overlies B

of North Afton beach ridge

M06‒89 WW5886 535.3 Anodonta,

whole shell

n.d. 23,130 70 Measured section M09‒6 in railroad cut west of Dunn siding. 4 units withi

uppermost unit, 0.75 m below surface, above buried soil

M06‒116A WW6070 533.1 Anodonta,

whole shell

–1.9 21,140 70 Whole shell in beach sand and gravel, 50 cm above beach cobbles within u

Afton beach ridge

M06‒116B WW6070 533.6 Anodonta valve –4.9 20,510 70 Whole shell in beach sand, 1 m above beach cobbles within unit Ql8; west 

M07‒29 WW6343 522.6 Anodonta valve –7.0 36,040 400 Measured section M07–62. Shell in younger of two subunits of Ql8 near top o

M07‒36A WW6344 533.0 Anodonta,

whole shell

–2.8 27,070 140 Shells in muddy sand and gravel of upper unit Ql8; overlie thin debris flow 

sand and beach gravel forming a spit

M07‒131 WW6346 537.2 Anodonta,

whole shell

–5.3 26,860 140 Whole shell in beach sand and gravel of unit Ql8, about 60 cm above unit Q
Table 1. Radiocarbon ages and site information for samples from Afton and Cady subbasins of Pleistocene Lake Manix.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station. m, meters; B.P., years before the present; s.d., standard deviati

Station Lab number1 Altitude (m)3 Samples δ13C4 Age5 (B.P.) 1 s.d. Description

M07‒151A2 WW6345 539.5 Anodonta valves –3.6 21,580 70 Shells in beach sand and gravel of unit Ql8, 75 cm below surface; lie on tufa-c

formed on older Ql8 sand, in turn unconformably on soil formed on tilted u

M08‒58 WW6986 542.4 Anodonta fragments –4.1 21,450 70 Shell fragments in gravel bed 1 m below surface of beach ridge. Beach gra

overlies unit Qia7. South of Mojave River

M08‒60C1 WW6987 531.3 Anodonta valves –5.0 31,510 230 Measured section on west side of Buwalda Ridge. Five subunits of Ql8 sepa

weak soils overlie truncated soil formed on unit Ql7. Shell layer lies 75 cm 

M08‒60C2 WW6988 531.8 Anodonta valves –4.2 24,400 130 Measured section on west side of Buwalda Ridge. Five subunits of Ql8 sep

weak soils. Shell layer lies 1.35 m above base, in third unit from top

M08‒60C3 WW7616 532.0 Anodonta fragments –3.8 34,970 450 Measured section on west side of Buwalda Ridge. Five subunits of Ql8 sep

weak soils. Shell layer 1.55 m above base in 2nd unit from top

M08‒60C3 resample WW8113 532.0 Anodonta valves –5.2 33,320 210 Measured section on west side of Buwalda Ridge. Five subunits of Ql8 sep

weak soils. Shell layer 1.55 m above base in 2nd unit from top. Resamp

M08‒60C4 WW8114 533.0 Anodonta fragments –5.2 32710 190 Measured section on west side of Buwalda Ridge. Five subunits of Ql8 sep

weak soils. Shell layer 3 m above base in uppermost unit

M08‒76A WW7109 524.0 Anodonta valve –5.9 26,790 230 Shell layer in greenish sand 3 m above tufa-coated clasts marking base of un

ous sand and silt of unit Ql7. Likely separated from outcrop of M08‒76B 

M08‒76B WW7110 529.0 Anodonta fragments –1.8 21,980 120 Shell fragments in tan beach sand, 3.5 m below surface of unit Ql8. Poor o

from outcrop of M08‒76A. South of Mojave River

M08‒108 WW7201 535.7 Anodonta valves –4.7 28,230 190 Shells in beach gravel and sand of unit Ql8. To east, unit overlies buried so

Ql7. Exposed in ditch on N side of railroad service road, upper Manix W

M08‒124A WW7202 531.0 Anodonta valves –5.3 29,090 190 Shells in ripple-laminated beach sand, 40 cm thick, overlain by 3 cm brow

present; sample is from 2nd unit below top. West side of Buwalda Ridge

M08‒124 WW8116 532.6 Anodonta valves –2.6 29,610 130 Shells in thin bedded fine sand, 75 cm thick, coarsens at base; forms 3rd un

buried soil formed on green mud of unit Ql7. West side of Buwalda Rid

M08‒124C WW8117 532.7 Anodonta valves –6.6 27430 130 Shells at base of interbedded sand and pebble gravel, 3 m thick; forms upp

Buwalda Ridge

M08‒141 WW7108 531.5 Anodonta fragments –2.6 34,600 570 Shell fragments in beach sand and gravel of unit Ql8. As much as 1.2 m th

both units apparently faulted. West side of Buwalda Ridge

M08‒172 WW7496 536.7 Anodonta,

whole shell

–3.7 23,120 100 Measured section M08‒172 in unit Ql8 south of Mojave River. Shell layer 1.0 

1.7 m thick, which rests on a weak buried soil and is capped by ~2.5 m poo

M08‒172A WW8041 533.5 Anodonta valves,

weathered

–6.7 27,920 190 Measured section M08‒172 south of Mojave River. Weathered shells in bu

and silt of unit Ql8, overlying thickly tufa-coated boulders of unit Qvg. 

are in third from top

M08‒172C WW8042 534.9 Anodonta,

whole shell

–4 24,400 120 Measured section M08‒172 south of Mojave River. Shell layer in silt and s

weak buried soil. Sample lies 0.9 m above base of second unit from top 

M08‒172D WW8043 536.7 Anodonta valves –3.0 23,200 100 Measured section M08‒172 south of Mojave River. Shell layer 1.0 m abov

thick, which rests on a weak buried soil and is capped by ~2.5 m poorly Resampled to confirm stratigraphic position and age

M09‒5 WW7492 531.3 Anodonta valve –5.2 35,980 450 Measured section M09‒5 in upper Manix Wash. Shell layer in beach sand 

2nd subunit from top; 1.4 m above base of Ql8

M09‒5 (re-analysis) WW7852 531.3 Anodonta valve –5.2 35,130 400 Measured section M09‒5 in upper Manix Wash. Shell layer in beach sand 

2nd subunit from top; 1.4 m above base of Ql8

M09‒6A WW7617 533.0 Anodonta valve –5.7 39,280 770 Measured section M09‒6 at railroad cut west of Dunn siding. 4 units withi

1.6 m above base of outcrop

M09‒6B WW7491 534.4 Anodonta fragments –3.1 27,810 170 Measured section M09‒6 at railroad cut west of Dunn siding. 4 units withi

3.05 m above base of outcrop
Table 1. Radiocarbon ages and site information for samples from Afton and Cady subbasins of Pleistocene Lake Manix.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station. m, meters; B.P., years before the present; s.d., standard deviati

Station Lab number1 Altitude (m)3 Samples δ13C4 Age5 (B.P.) 1 s.d. Description

M10‒3A WW8115 522 Valvata utahensis –6.2 36,410 300 Fine silty sand in unit Ql8 contains abundant snails. Overlies buried soil forme

overlies soil on top of M07‒29 unit, or is equivalent to that unit; lies across at railroad cut west of Dunn siding

J06‒15 WW7112 529.9 Anodonta valves,

weathered

–2.9 33,410 490 Measured section M09‒5 in upper Manix Wash. Weathered shells in green

above stone line marking contact with unit Ql7, in 4th subunit from top

J06‒16 WW7113 530.6 Anodonta valves, 

weathered

–3.9 34,410 580 Measured section M09‒5 in upper Manix Wash. Shell layer lies in ripple-b

12 cm above base of 2nd subunit from top; 1.7 m above base of unit Ql8

J06‒17 WW5850 532.5 Anodonta valves n.d. 31,910 330 Measured section M09‒5 in upper Manix Wash. Shell layer lies in medium 

outcrop, 60 cm above base of 1st subunit; 3.05 m above base of unit Ql8

JR04CM‒87 WW8004 537.7 Limnocythere

bradburyi

n.d. 33,120 710 Reworked ostracodes in fluvial sand of unit Qif, 3.5 m below surface; over

buried soils; north rim of Afton Canyon

JR04D‒1 WW4924 541.0 Anodonta valves n.d. 25,420 120 Shell layer at base of 50-cm-thick beach sand and gravel of unit Ql8; overl

shore of beach ridge in upper Dunn Wash

JR04D‒68 248‒255 WW5384 476 Ostracodes n.d. 27,020 310 Bedded sand containing ostracode coquina; slack-water deposits, unit Qys

JR04D‒68 331‒338 WW5385 476 Ostracodes n.d. 30,540 410 Laminated sand and clay; slack-water deposits, unit Qysl, 331‒338 cm belJR04D‒68B 385‒395 WW4909 476 Ostracodes n.d. 28,020 160 Massive green clay with secondary gypsum and carbonate nodules; slack-w

385‒395 cm below surface. Calgon used to disperse

JR04D‒68A 425‒435 WW4908 476 Ostracodes n.d. 30,180 210 Green silty clay with clay platelets; slack-water deposits, unit Qysl, 425‒4

used to disperse

JR04D‒68B 385‒395 WW5077 476 Ostracodes n.d. 29,280 320 Massive green clay with secondary gypsum and carbonate nodules; slack-w

385‒395 cm below surface; only distilled water used

JR04D‒68A 425‒435 WW5076 476 Ostracodes n.d. 31,500 420 Green silty clay with clay platelets; slack-water deposits, unit Qysl, 425‒4

distilled water used

JR06D‒206A WW5879 536.3 Anodonta valve n.d. 21,830 60 Measured section JR06D‒206 in unit Ql8, south of Mojave River. 5 subun

coated clasts on buried soil formed on unit Qia7, overlying green mud obeach gravel and sand of uppermost subunit, 0.5 m below surface 

JR06D‒206B WW5880 535.3 Anodonta,

whole shell

n.d. 20,940 60 Measured section JR06D‒206 in unit Ql8, south of Mojave River. 5 subun

beach sand at base of uppermost subunit, 1.5 m below surface 

JR06D‒206C1 WW5881 534.3 Anodonta,

whole shell

n.d. 26,620 90 Measured section JR06D‒206 in unit Ql8, south of Mojave River. 5 subun

sand, 4th subunit from top, 2.5 m below surface 

JR06D‒206E WW7483 535.1 Anodonta valve –4.9 23,140 100 Measured section JR06D‒206 in unit Ql8, south of Mojave River. 5 subun

top of 3rd subunit from top, 1.6 m below surface 

JR06D‒206F WW7484 535.3 Anodonta,

whole shell

–3.0 21,780 80 Measured section JR06D‒206 in unit Ql8, south of Mojave River. 5 subun

growth position in beach sand at base of uppermost subunit, 1.5 m below age of sample JR06D‒206B 

1Samples were pretreated at the 14C laboratory of the U.S. Geological Survey in Reston, Virginia (WW designation).2All locations given in UTM units, WGS84 coordinates.3Bold font indicates differentially corrected GPS data; altitudes in normal font estimated from topographic map and handheld GPS; Altitudes calculated for individual sample

datum determinedby GPS or lidar (light detection and ranging). Italics font indicates altitudes from a DEM (Digital elevation Model) created using NASA ATM-III lidar data ac

by the U.S. Army Corps of Engineers, WRAP program, R.W. Lichvar & D.C. Finnegan.

4 δ13C measured on all samples beginning in 2007.5 14C ages were determined at the Center for Accelerator Mass Spectrometry (CAMS), Lawrence Livermore National Laboratory, Livermore, Californa, and at National Scien

Accelerator Mass Spectrometry facility in Tucson, Arizona. Quoted age is in radiocarbon years (B.P.) using Libby half-life of 5,568 yr. 14C age reflects correction for δ13C value
Table 2. Locations, correlations, age ranges, and geochemical compositions* in map area. [Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station. Ma,million years] Station Easting1 Northing Map unit Tephra correlation Tephra age (Ma) SiO Al Fe MgO MnO CaO TiO Na K Total (Raw) 

M07‒101A 545398 3871673 Tbrg Tuffs of Mesquite Springs 3.35‒3.10 78.23 13.42 0.75 0.04 0.08 0.46 0.06 2.76 4.18 94.29 Lower of two tephr

east end Buwaldtion. Lenticular aup to boulder siz

M07‒101B 545398 3871673 Tbrg Tuffs of Mesquite Springs 3.35‒3.10 78.35 13.47 0.74 0.04 0.08 0.46 0.07 2.73 4.07 93.65 Upper of two tephr

east end Buwaldtion. Lenticular aup to boulder siz

M07‒128 544564 3870904 Qmr Tuffs of Blind Spring Valley 2.219 ±0.006 ‒2.135 ±0.02 77.53 13.12 0.58 0.04 0.09 0.34 0.07 4.10 4.14 94.10 Tephra, medium-sa

airfall near base; deposits of Moja

M07‒145 557766 3878699 Tcg Ishi Tuff, correlated age 2.50 78.41 13.45 0.73 0.10 0.05 0.75 0.12 2.73 3.64 93.68 Tephra with carbon

fanglomerate; relain by fan grave

M07‒159B 552769 3879338 Ql6 Manix Basin tephra 0.184 ±0.04 78.04 14.10 0.54 0.03 0.12 0.51 0.04 3.13 3.49 94.64 Between forks of D

tephra about 2 m bedding; tephra silt, and reworkelag gravel M08‒164 542667 3868988 Qmr Huckleberry Ridge ash bed 2.063 ±0.007 76.71 12.67 1.75 0.03 0.04 0.59 0.11 3.80 4.31 94.27 18-cm tephra in Mo

dip 12oSW. Cut 

down to S by 2.5 

M08‒164A 542667 3868988 Qmr Tuffs of Blind Spring Valley 2.219 ±0.006 ‒2.135 ±0.02 76.94 13.05 0.60 0.05 0.08 0.35 0.09 4.35 4.49 93.73 Burrowed white len

altered tephra, 3footwall of fault M08‒164B 542667 3868988 Qmr Tuffs of Emigrant Pass, correlated age <2.063, >1.96 77.30 12.91 0.67 0.02 0.09 0.31 0.07 4.43 4.19 93.05 Lenticular, 0–3 cm 

M08‒164 on han

M10‒90 544673 3871144 Qmr Huckleberry Ridge ash bed 2.063 ±0.007 76.35 12.44 1.74 0.04 0.06 0.60 0.11 3.71 4.95 93.53 ~3 m above tephra 

Thin cemented lplaya-lake faciescoarser-grained, paleosols; mapp

M10‒94 542763 3870995 Qmr Similar to Bishop Tuff, and youngest set of tuffs of Upper Glass 

Mountain

0.759 ±0.0002 

or

1.13 ±019‒0.87

±0.02 

77.41 12.86 0.74 0.06 0.05 0.40 0.06 4.34 4.08 92.93 Tuffaceous marker 

Qmr and lower river. Located nedata of Pluhar antephra lies within (youngest tephra however, micropresemblance to B

*Analyses conducted by U.S. Geological Survey Tephrochronology Laboratory in Menlo Park, Calif. Table provided by Elmira Wan. Chemical compositions of volcanic shards det

analysis. Oxide concentrations are in weight percent oxide recalculated to 100%. Original (raw) oxide totals before recalculations are given to indicate approximate degree of hydratio

1All locations given in UTM units, 11S, WGS 84 coordinates
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station]

Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

M04‒23 11S 542031 3867455 X In-situ whole Anodonta shells in nearshore s

20 cm weak Bt; overlain by dune sand

M04‒29B 11S 551242 3880432 X X Same area as site M03‒12 on barrier crest NW 

west of wash; shells dated 25 ka in probab

M04‒32 11S 558294 3879350 X Well-bedded sands containing broken Anodo

A, sampled in-situ fragments from single 

M04‒75 11S 542357 3871122 X X Ql8 over Ql7 and small fault; upper unit con

capped by debris flow and paleosol. Surfa

75A, 1 m; 75B, 1.3 m; 75C, 2.8 m (lower (upper lake unit) above base of section. 75

M04‒76 11S 542318 3871195 X X Soil pit on upper barrier forming loop bar on 

M04‒77 11 542174 3871175 X Soil pit on lower platform incised into upper M05‒06 542704 3871032 X Unconformity on S side Manix fault. Ql8 ov

above distinctive reddish carbonate soil (d

M05‒07 11S 542650 3871188 X Uppermost limit of probable lake sediment, w

below distinct paleosol

M05‒19 11S 551614 3880174 X X X X Base of Ql7. Top of oncoid “B” layer where 

M05‒20 11S 551506 3880270 X X X Measured section in two lake units (Ql8/Ql7

in section M05‒19. A, ostracodes and she

C, 100 cm above oncoid B layer.

M05‒21 11S 551474 3880398 X X Shells cropping out just below uppermost pa

those already dated ~25 ka at location M0

M05‒22 11S 557663 3878175 X X X Measured section in upper 3 lake units on ea

in-situ shells sampled at very top. A, ostraC, ostracodes, 6.3 m; D-ostracodes, 7.75 m13.5 m; G-ostracodes, 17.2 m; H-shells, 2Revisit 4/2/09: 3 thin beach-gravel units in overlying 3 thicker units, incl. two sand unbeach gravel over Qia7

M05‒23 11S 557825 3877823 X X Shells in base of Ql7a above oncoid tufa lay

D, 3 m above oncoid layer, shells in grow

M05‒25 11S 557859 3878180 X X X X Measured section in lowest 2 of 4 lake units 

beach ridge; connects to section M05‒22. 

8.5 m, A2, 9 m; B, 11.2 m; C, 12.2 m; D, G, 18.5 m; H, 20.8 m; I, tufa, 21.2 m; J, shclasts in same stratum as J

M05‒26 11S 557501 3878054 X X X X Measured section in Ql8/Ql7; 3 units defined 

coid tufa bed at base; B, 9.4 m; and C, 18below tufa B and Bwk; E, seds ~35 cm becoated shells at base of Bwk, 25 cm below bones and snails, just below tufa C

M05‒28 11S 551395 3880292 X X X Uppermost unit of Ql8 above youngest paleo

(M05‒19) on W side Dunn wash where b

M05‒52E, F 11S 552100 3879626 X X Contact of base of Ql8 and underlying beach 

M05‒53 11S 552967 3878677 X Thick sand of Ql6 overlies groundwater tufa 

prelake unit
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued [Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station] Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

M05‒54 11S 552283 3878810 X X Same sequence as M05‒53 in N-facing railro

ceous rhizoliths near base of unit for U-se

M05‒58 11S 549914 3876521 X Local top of indurated paleosol-fan unit, here 

by fluvial sand and gravel dipping north (a

M05‒59 11S 549877 3876657 X Fan gravel on top at M05‒58 here overlain b

rise toward M05‒60 M05‒60 11S 549831 3876767 X 4‒5 m of Ql6 sand overlain by fan gravel wi

sands that grade up to Ql7 with rhythmic 

M05‒61 11S 555389 3877936 X Views of Ql6 deposits (inset bench) underlyi

underlying gravel over paleosol on older u

M05‒62 11S 557377 3878879 X X Large in-situ Anodonta shells above and belo

is 60 cm above the interlacustral fan grave

M05‒62B 11S 555974 3876491 X Tufa bench on Qia8; dated ~80 ka by J. Bisc

analytical data were lost M05‒65 11S 557172 3878279 X X Below Ql7. Fluvial and likely lacustrine dep

granitic fan gravel of Cave Mtn. origin M05‒71 11S 557731 3878737 X X Delta-like deposits (Ql7b over Ql7a?) atop Q

deposits overlying fan gravel with paleoso

M06‒04 11S 552506 3878261 X Base of Ql6 sand atop cemented carbonate la

M06‒05 11S 553482 3878624 X Base of Ql6 sand E of railroad cut and Dunn 

M06‒06 11S 553822 3878492 X Base of lowest Ql6 sand overlying fanglome

M06‒17 11S 554275 3877569 X Ql6. Gray bedded sand, muddy fine sand, an

crossbedding, including sweeping E-direc

M06‒20 11S 555917 3878065 X Ql6. Fluvial sand and gravel overlain by fine 

above slackwater (Qysl) site M06‒35 11S 558394 3878183 X Basal tufa-coated bed of unit Ql7 M06‒44 11S 558972 3877971 X Base of transgressive steep-dipping gravel (Q

dune sand below M06‒48 11S 558467 3877105 X Contact between reddish alluvial seds and so

sand of Ql7b overlying Ql7a(?). Continu

M06‒50 11S 558541 3876690 X Uppermost point on wavecut bench with tufa

overlying gravelly sand of Ql7a (?). Tufa former outlet, and shoreline angle above M06‒51 11S 558647 3876811 X Highest outcrop of greenish sands (Ql7) inte

M06‒59 11S 542851 3871160 X Ql7. Green sand 3 m above base of lake sand 

gravel with tufa coats, then 1.5 m beach g

M06‒62 11S 555809 3876066 X X Shells in-situ 30 cm below surface of Ql8 be

to 543-m highstand; overlies Bwk on dun

M06‒62B 11S 555974 3876491 Tufa bench on Qia8; dated ~80 ka by J. Bisc

analyzed data lost.

M06‒70 11S 551439 3876535 X X Qof/Qp. Complex section of fluvial gravel, s

overlie playa mud and fanglomerates. 2/2pale sands and silts are groundwater dischinto the playa muds to the east
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station]

Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

M06‒74 11S 550833 3876085 X Paleochannel filled with fluvial deposits capp

(Qyfmr). Basal unit is debris flow containOverlying younger gravelly sand mod-wevery sandy; S-directed crossbeds; probabl

M06‒77 11S 550217 3876485 X X Top of fanglomerate overlain by lowest basa

to Ql6 sand and fluvial sand, two units ap

M06‒81 11S 547926 3875054 X Similar stratigraphy as M06‒80 but fluvial d

small-scale crossbedding and shows E-dir

M06‒91 11S 545815 3871520 X Contact of Ql7 lake seds w/thin green mud a

underlain by Qalg unit w/paleosols, S sid

M06‒100 11S 551658 3877284 X X Unit Qof, “mayhem terrane”; large soft-sedim

deformed, transported lake seds beneath b

M06‒104 11S 547217 3872189 X Fill terrace of unit Qof including bedded san

overlies playa deposits (unit Ta)

M06‒116 11S 557305 3879041 X Meek’s dating site on sand+gravel Ql8 “bum

possibly inset? Above beach cobbles, A is and sand, B is 1 m up in sands

M06‒135 11S 557724 3879018 X Point on Qia7 surface. Gilbert-style fan-delta 

including tufa on clasts; overlies old fangloverlain by paleosol, Ql7b, and Qia7

M06‒141 11S 558406 3878483 X E extent of red fanglomerate (QTcg); overla

and Ql7b, separated by weathering zone adelta units fine and thicken eastward

M06‒142 11S 558159 3878188 X Near site M06‒34; point is probably on Qia7

Ql7b overlain by Qia7 and by thin silty s

M06‒143 11S 558406 3878162 X Same as site M06‒35. Basal green mud of Q

into a single tufa line with very thick coatdelta deposits and Qia7

M06‒145 11S 558796 3877707 X Tufa sample at beginning of “tufa ring” (base 

M06‒156 11S 559072 3877340 X Same site as M04‒51A, altitude 554 m. Well

with heavy-mineral laminations interbeddpaleosol separates two units representing h

M06‒161 11S 555007 3878409 X Small outlier of Ql7 (a basal sand) preserved 

in small bump atop main surface

M06‒170 11S 554983 3879960 X Ql7 (adjacent to Afton road). Fines all gone—

by Qia7 equivalent with thin tufa

M06‒184 11S 552914 3879826 X Qia7 at surface overlies Ql7, then tan sand a

bedded and sorted sand and gravel, atop d

M06‒190 11S 551847 3878317 X Ql6 sand S side of railroad tracks and W of p

M07‒11 11S 551617 3879436 X X Thin fan gravel of Qyao with Bwk, base con

overlying Ql8 gravel and sand grading doabout 3 m thick; access road to I-15

M07‒29 11S 548966 3876489 X Contact of Qia7 (w/tufa coats on east end of 

east to muds; contains hiatus and at samplcontains Anodonta; big railroad cut W of D
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued [Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station] Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

M07‒36A 11S 547891 3876226 X 100 m NE of M07‒36, whole Anodonta shel

Ql8 overlying thin debris flow, and gradinthen shoreface gravel M07‒57 11S 547403 3874467 X Same as (obsolete site) M04‒72 (Hole in the 

debris-flow fanglomerate is fluvial sandy fan equivalent of Ql7a? Overlying 4 m of interfingering of Ql7b lake with fan M07‒62 11S 549009 3876519 X X Eastern railroad cut (same cut as M07‒29), s

Qia7. Two units; younger is dated, but no base, only sharp contact with overlying grmore abrupt on N side of cut M07‒66 11S 545742 3874373 X Pale reddish sands, massive to flat bedded, 

tracks; intertongue with alluvial gravel tsand—probable fan-lake margin depositpoint is base of Qia7? Photo is S of trac

M07‒98 11S 546276 3872179 X Complicated. Site in Field wash is pedogenic 

25°NE); terrace displaced about 1 m down overlain by sand and gravel of Qalg, then 

M07‒101 11S 545398 3871673 X Two tephra beds in Tbrg in highest S-facing 

Separated by 2 m of section. Lenticular anto boulder size. A lower than B M07‒117 11S 546716 3871703 X Section in Qof and Ql7 deposits on NW corn

mouth of Field wash. M07‒128 11S 544564 3870904 X X Tephra, med-sand-sized pumice w/biotite; ai

lacustrine-fluvial deposits of Mojave Riveend of outcrop, beds are folded up N65E @ Mojave River channel; smaller faults and 

M07‒131 11S 544793 3870134 X About 2 m of Ql8 is interbedded fine-co sand 

capped by 50 cm regressive gravel; shells 

M07‒134 11S 546498 3869764 X Thick tufa coats on boulders at base of Ql7. F

not preserved here. To SW in flanking outreddish eolian sand capped by thin fan gra

soil; the two are separated by a fault, dow

M07‒144 11S 548436 3872986 X Top of a fill terrace 11 m thick with beds indi

Probably similar at base to site M06‒141‒relatively down here M07‒145 11S 557766 3878699 X Tephra with carbonate cement in groundwate

reworked, fluvial bedded; overlain by fan Ql7a(?)

M07‒147 11S 551913 3877557 X East end of ridge. Section shows flood coupl

deposits are first indication of water flow couplets are then ripped up into flood bloc

M07‒151 11S 541941 3871764 X Tilted older fan unit w/soil (QTalg) overlain 

weak Bwk soil and 1‒2-clast-thick gravel Anodonta (A2), 75 cm beach sand and graby gravel w/thick tufa coats (B)
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station]

Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

M07‒159 11S 552767 3879338 X X Between forks of Dunn wash. Section of Ql6 

above Qia fan gravel with fluvial beddingsilt, and reworked Manix mud, capped by 

M08‒44 11S 548837 3873861 X Northern limit of Qof outcrop along river ch

vco sand and granules, lithic, lots of volc. lies calcic soil on debris-flow deposits, cap

M08‒45 11S 548743 3873771 X ~4 m playa and distal-fan (brown sandy mas

boulders; unit Ta) overlain by 2 fluvial unseparated by debris flow with paleosol; inw/E-directed crossbeds; top 2 m unit Qyfm

M08‒55 11S 544683 3871119 X S side river, northern point. Qmr on W edge 

grade up into Qalg, then that becomes incwith mafic Cady Mtn. clasts (Qvg); all truhere appears to be arkosic facies of upper 

M08‒58 11S 545652 3869849 X Small beach ridge bump (Ql8) S of river surm

thick; has reworked shell frags, sampled abarrier surface

M08‒60C 11S 541287 3871190 X X Shell site in “member D”, E of Manix Wash. 

75 cm above base in unit 2. Redescribed 4shell #3, and new sample #4 in uppermost 

M08‒64 11S 555977 3876486 X Base of Ql8 on Qia7. Abundant small thick t

to clasts. Some rinds look like they have s

M08‒70 543581 3872470 X Fine-pebble surface of Alvord-derived clasts

rounded, fairly well bedded; soil pit

M08‒76 11S 550538 3874023 X X Base of Ql7, overlain by Ql8? Poor outcrop; 

by greenish-tan sand; gravel bench 6‒7 m originally 1/2 shell, 3 m above base of Ql8

M08‒100 544170 3872562 X Fine-pebble surface of Alvord-derived clasts

rounded, fairly well bedded; soil pit

M08‒108 11S 540315 3872581 X Ditch on N side of RR access road. 2 m of in

Ql8, not beachy-looking but has shells in 20 m to east is a paleosol on Qia7 50 cm where shells occur. Later notes indicate sathickens abruptly from paleosol site

M08‒110 11S 540330 3871695 X 25 m S of powerline road E side Manix Wash

m “upper B” (Ql5?), bedded sand over be

“lower C” (Ql4?), pale bedded arkosic sanoxidized fan deposits, possible paleosol 1 

M08‒112 11S 540611 3871782 X Highest outcrop of Ql5 beach sand, with pale

coated clasts, overlain by fining-up sand, 17 cm poorly sorted pebbly vco sand with base of Ql7, underlain by 58 cm mod sortmed-vco sand with some pebble beds; heaColocated with site M09–5.
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued [Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station] Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

M08‒113 11S 540614 3871866 X “Upper C”, actually basal Ql8 in age, has An

notes is actually within “unit D” or Ql8, pfrom below contact, 2 from above M08‒124 11S 540800 3871758 X X Three units of Ql8. New sample 124B is 13 c

lain by 3 cm thick brown mud; underlying Probably same as prev. dated stratum; to nand snails as described before, 50 cm belo

M08‒130 11S 540973 3871581 X Point is base of Ql7 capping outcrop; overlie

fluvial deposits, tufa coats at top, over 130 cobble gravel; overlies 10‒15 cm Bwk imQl4, blocky to thinly bedded. Reverse fauapparently up to S, steepens upward; offsebed 1 m higher by only ~20 cm; Ql7 at to

M08‒141 11S 541141 3871845 X Between sites M08‒140 and ‒131. S side wa

sand of Ql7. N side of wash, Ql7 only 25 Ql8 beach gravel w/Anodonta, same as in

E end, Ql7 is cut out and beach gravel dro

or cut and fill M08‒161 11S 543402 3869953 X Highest butte S of river. Mostly Cady-type v

in bottom 1/3 (poor outcrop of pale carb-clake units: tufa-cemented cobbles overlain cinders); overlain by tufa-cemented cob-bup to green silt/sand and coarse beach santhin tufa and 50 cm well-rdd pebble graveW face near N end M08‒163 11S 542683 3868948 X Qmr is interbedded pale pinkish poorly sorte

groundwater calcrete, overlain by 3 lake utufa coats at base; tufa-coated gravel overgreen mud, indurated and oxidezed near tgravel with thin tufa coats at base, and aga

M08‒164 11S 542667 3868988 X 18-cm tephra (Huckleberry Ridge ash) in Qm

12°SW. Cut by fault striking 70°, vertical, possible tephra on upthrown side just abov2/24/11 to collect other tephra: burrowed wtephra, sample 164A, 3.9 m below HR ash where HR ash caps outcrop. 164B, 1.1 m wall) side of fault

M08‒165 11S 544289 3868293 X NE flank of basalt hill, ca. 2 lake units, mostl

sand. Base to top: carb-indurated cob-bld partly back-dipping indurated beach graveof 1.4 m variably bedded sorted material, into fan gravel; tufa-stone line and 0.75 m 0.5‒0.7 m sorted pebble gravel
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station]

Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

M08‒172 11S 547942 3870478 X X Tufa coated clasts (GPS point) overlain by ~

Ql7? (shell A at top in wxd zone), boulder 

sample B), then 0.9 m silty and med-co saoverlain by 0.6 m similar seds. fining up toverlain by 0.2 m med sand with weak oxtufa coats, then 1.0 m of pale greenish san(original sample plus new shell D), overlapoorly sorted pebbly massive sand 2.5 m 

M09‒5 11S 540611 3871782 X X Measured section at Oviatt’s cone-shaped hil

base of Ql7. Overlies strata of M08‒112. unit 4; J06‒16 near top of unit 3; new samunit 2; J06‒17 at top of unit 1 and of hill. 

M09‒6 11S 547480 3875665 X X Measured section of Ql8 at W railroad cut, si

In unit 5, 1.6 m above base of section.

M09‒25 11S 542193 3867143 X High beach ridge S of Manix Wash. Identica

clast beach ridge that lies to S and several Qia7 fan grades to this ridge

M09‒28 11S 541811 3868823 X 4 lake units on QTcg, GPS at section top? Q

Qyfmr gravel over fluvial/Bwk/debris flow over Bwk/debris flow over E-dipping Ql5W-dipping Ql4? gravelly beach sand

M09‒29 11S 542032 3868809 X Base of Ql4? Fining-up then coarsening-up s

fan gravel with tufa coats (Qia4?)

M09‒58 11S 542194 3868261 X Downslope to N is scarp cut into Qia7/Ql7. 

inter-Ql7 fan, which overlies at least 2 unfan gravel atop blocky green mud, over “n(GPS point). Ql7a over Ql6? With earthqduring Ql6 that remobilized lake-bottom m

M09‒66 11S 542592 3868644 X Qia7/Ql7 sandy mud and beach sand, 2 finin

line over blocky green sandy mud with Msingle line of pebbles overlying poorly sorsand with heavy-mineral laminations (Ql6

M09‒76 11S 544144 3869177 X Ql7/Ql6/Qvg. Ql6 in upper part is coarse, lik

by fan gravel, inversely graded with large includes chunks of green mud—the flood 

M09‒83 11S 541855 3868584 X Contact of thin cap of Ql8, very arkosic vco 

sand)/~6 m vco sand and gravel, with 2 veQl5)/thin fan gravel with Bwk and tufa co

So, here lake sequence is largely all beach 

M09‒127 11S 546709 3871652 X “Mayhem” deposits with lumps and clasts of 

strath of Qof unit, here >3m thick and at bbeds resting on Qalg; 2 cobble beds mark nerby site M07‒117, but here buried by fa

M10‒3A 11S 548886 3876488 X Ql8 unit probably overlies soil on top of M0
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued [Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station] Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

M10‒59 11S 542849 3871108 X Contact of base of 3 lake units over 3 m coar

fanglomerate with 2 buried soils, overlyin

~50 cm thick, granule beach sand, weak s(Ql6?); middle, presumed Ql7, ~6 m thickup, prominent 25° E-dipping beds suggestby mottled red-white soil; upper, Ql8 sand 

M10‒90 11S 544673 3871144 X Near tephra M07‒128 at sharp fold in Qmr. 

up top of escarpment above playa-lake facAbove this ash, little or no gypsum on surarkosic with paleosols like Qalg unit to ea

M10‒94 11S 542763 3870995 X Tuffaceous marker bed at contact with reddis

playa-like Qmr, N side Mojave River M11‒107 11S 553216 3876598 X Near base of Meek’s (1990) “Cady fan” sect

exposed), including rip-up clasts of green overlain by poorly sorted massive to x-beup Ql7 sediments M12‒27 11S 542436 3871072 X 2-cm lenticular pod of white vitric ash, indur

Qmr. Possibly “upper white ash” of Nagy ~8 m above carbonate-impregnated resistawhere beds fold sharply up approaching f

M12‒29 11S 542711 3870939 X Middle white ash of Nagy and Murray (1991

above site M10‒96A that is boundary betwsandier Qmr, or = G1-C1 boundary of Na

DI‒1 11S 550929 3877205 X X Ql7. Basal 2 meters of composite section on 

outcrop of Ql7, 1.6 km SW of Dunn DI‒2 11S 550893 3877186 X X Ql7. Meters 2‒7 of composite section on SE 

of Ql7, 1.5 km SW of Dunn DI‒3 11S 550756 3877214 X X Ql7. Meters 7‒10 of composite section on SE 

of Ql7, 1.5 km SW of Dunn DI‒4 11S 550739 3877169 X X Ql7. Meters 10‒14 of composite section on S

outcrop of Ql7, 1.5 km SW of Dunn JR04D‒1 11S 551349 3880423 X X X Just basinward of the crest of the highstand b

~25 cm-thick foresets and tufa coated cob

JR04D‒68 11S 555946 3877916 X Slackwater site (Qysl) JR04CM‒77 11S 557594 3876469 X Mojave strath terrace (Qyfmr) overlying Qys

JR04CM‒78 11S 557270 3876966 X Mojave strath terrace (Qyfmr); soil descriptiJR04CM‒87 11S 558726 3876339 X X X Highest terrace, paleochannel of Mojave Riv

colluvium. Ostracodes for 14C picked frosurface; also site of OSL age (Reheis and 

JR04CM‒88 11S 558830 3876370 X Highest terrace, paleochannel of Mojave Riv

arroyo to east from JR04CM‒87.

JR04CM‒93 11S 557093 3877862 X Site is just below big cut. Vertical contact bet

(south) which gives way southward to muto gravel sized pieces of green lake sedimalluvial sediments with no green lake-sediunderlain at the south end by strath terrace
Table 3. Site data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple samples taken from the same section or station]

Station UTM Easting1 Northing Section 14C sample Ostracodes U–series Tephra Soil description Descriptio

JR04D‒95 11S 556872 3877730 X Soil description site on highest strath terrace 

partially covered by sand, thus soil develoalso be enhanced from eolian fines.

JR04D‒98 11S 555953 3876602 X X Ql7‒Ql8 lake sediments described and samp

numerous lake level fluctuations

JR04D‒99 11S 555999 3876520 X Tufa on unit Qia7 sampled here, very near N

~80ka (N. Meek, CSU San Bernardino, p

JR04D‒105 11S 552788 3881504 X Soil description site on late Pleistocene highs

Hand dug pit with uppermost 45 cm of pr

JR05D‒107 11S 552766 3881524 X Soil description site on the late Pleistocene h

Afton exit. Exposure on the east side of ththe soil profile described and sampled.

JR05D‒157 11S 555969 3877942 X Soil description site on fan overlying slackw

JR05D‒161 11S 555908 3876567 X X Ql7. On the edge of a vertical cliff beginning 

has infiltrated down through these fracture

JR05D‒162 11S 555907 3876606 X Ql7. Sampled to compare amino-acid racem

location with at least 2.5 meters of overlyinearby site JR04D‒98, with only 1‒1.5 m

JR05D‒168 11S 556323 3876209 X X Section from top of Ql7 lake clays through a

of Meek). Soil description sites (A and B)

JR05D‒194 11S 555088 3877322 X Soil: Av/Bw/Bwk/Btb with stage I+ to II carb

sourced from QTcg and contains some tu

JR05D‒198 11S 556983 3877763 X Soil description: Av/Bwk(Av2?)/Ck profile w

morphology

JR06D‒206A 11S 555095 3876179 X X Ql8. 0.5 m below surface of last-highstand b

JR06D‒206B 11S 555095 3876179 X Ql8. 1.5 m below surface of last-highstand b

JR06D‒206C1 11S 555095 3876179 X Ql8. 2.5 m below surface of last-highstand b

JR06D‒206E 11S 555095 3876179 X Ql8. Top of unit 3, in gravel, nearly intact ha

(below shell B)

JR06D‒206F 11S 555095 3876179 X Ql8. Base of unit 2, in gravel, whole shell in 

surface, redate of sample JR06D‒206B

JR06D‒202 11S 555263 3876780 X Basal oncoid tufa (Ql7) beneath green mud t

Ridge section

JR06D‒220 11S 553315 3876612 X Soil on Qya3 (J.R. Redwine, unpub. data; Q

Av/Bwk.

JR06D‒221 11S 553224 3876562 X Soil on Qya3? (Redwine,unpub. data; Qyao 

8 cm eolian cap/C. Sharp crested levees. B

JR06D‒223 11S 552811 3876896 X Qya4 or 5 (J.R. Redwine, unpub. data; Qyao 

surface, sand covered, poor varnish, weak B cm with a reddish color. Surface looks yinfluence

1All locations given in UTM units, 11S, WGS 84 coordinates
Table 4. Fault and attitude data for Pleistocene Lake Manix surficial map.—Continued [Sample letters (for example, A, B, and so forth) indicate multiple measurements taken from the same section or station. Att, attributed point not on a fault] Station Easting1 Northing Fault strike azimuth Fault dip degrees Bedding strike azimuth Bedding dip degrees Notes M04‒75 542357 3871122 90 85 Two lake units and small fault; upper unit contains shells; overlies lower unit capped by deb

M06‒178 553942 3880341 65 75 N65E @ 75SE on cemented shear plane in poorly sorted sand w/floating pebbles. Capped 2 

abundant tufa coats—base Ql7? 50 m downslope to W, fault plane seems to jump N but S 

sharp increase in tufa lag on N side and subtle step on surface. Jump in fault also coincid

and Ql7 base merge (from here upslope) as seen in gullies just to S where tufa lines mergthem pinch out M06‒182 553290 3880189 65 75 Same fault farther west placing sheared green mud against indurated fan deposits, N65E @ 

of hill has old eolian sand like that @ M06‒178. On W flank of hill, tufa slopes up to 2/3 continuously from Ql7 base. Small remnant of thin tufa on E side of hill near top—Qia7of Ql7 is offset down to north along same fault; appears same is true of capping gravel atexcept there is no tufa M07‒73 544670 3874722 42 65 Upper Midway wash @ road crossing between tracks and I-15. Fault N42E @ 65SE, appare

Qia7 equivalent. Zone of shear about 5 cm wide M07‒78 545240 3871730 90 90 Strand of Manix fault S of Buwalda Ridge crest. Vertical, striking due E–W; apparent displa

beds bend up approaching fault from N M07‒89 546345 3872557 10 85 Fault striking N10E dipping steeply east cuts the tan pre-lake fan gravel (Qalg or upper Tm

M07‒94 546195 3872483 35 85 Western of 2 faults places Ql7 mud on E against older pre-mud Qalg on W; N35E @ 80‒85 

M07‒96 546025 3872274 225 85 Western of two faults on next ridge to west; cross-valley strike is N35E with dip near vertic

M07‒98 546261 3872187 215 85 See new notes p. 120 in March 2008. Thick pedogenic carbonate on Tbrg (dipping 25°NE); 

down to N by fault striking N35E. Soil is overlain by tan distal-fan sediment, unit Qalg M07‒98Att 546265 3872160 290 8 See new notes p. 120 in March 2008. Thick pedogenic carbonate on Tbrg (dipping 25°NE); 

down to N by fault striking N35E. Soil is overlain by tan distal-fan sediment, unit Qalg M07‒106 547190 3872164 5 90 Tbrg is in fault contact with fill terrace @ site M06‒104 (or it is a buttress unconformity). C

faulted. Vertical shear zone lies @ vertical cliff edge; estimate N5W @ 90° M07‒107A 546881 3871999 210 75 Area of M06‒94. At mouth of Field wash, “A” is small fault with normal displacement ~2 m 

green mud (Ql7?) with underlying fan gravel; N30E @ 75NW M07‒107B 546811 3872021 85 90 Area of M06‒94, at mouth of Field wash. “B” is major fault running parallel to wash separaTbrg; N85E @ 90° M07‒120 545264 3871445 265 90 W end of strath terraces where main fault goes into river. Wide shear zone imparts vertical s

same shear zone bounds a block of Qalg (Qmr) that is nearly flat-lying M07‒121 545335 3871369 260 65 Another fault N80E @ 65N farther south, puts Tbrg to N against flat-lying Qalg unit. Proba

shear features and stratigraphy M07‒124 545763 3871557 255 90 Along strike of major fault offsetting youngest Ql8 beach gravels, N75E, vertical. Note how 

beach gravel on N (so apparent offset is down to N) M08‒31A S fault 546453 3872088 40 65 65 5 Faults cutting unit Ta and overlying arkosic fan seds. Primary (southern) fault N40E @ 65S

Several smaller faults between

M08‒31B N fault 546451 3872125 55 58 245 25 Faults cutting unit Ta playa mud and overlying arkosic fan seds (Qalg). Secondary (norther

down to SE, 3 m offset of playa mud over Tbrg, beds of both dipping N65E @ 25NW

M08‒38 545085 3871811 225 5 Highest point of red-matrix (Tbrg) unit. 75 m N, outcrop of QTalg overlies Tbrg, both dipp

buried by young sand-ramp deposits, tan, poor sorting, loose

M08‒39 545418 3871791 60 90 2 faults. Red-matrix unit (facies of Tbrg) to N (relatively up) faulted against S-dipping arko

vertical and strike about N60E. Second fault in Qalg against sand-ramp unit.

M08‒41 545676 3871797 60 90 45 15 Probable fault, vertical shears and fractures, placing Qalg on N against red-matrix unit (fac

strike parallel to gully, about N60E. Qalg dips ~15°SE and Tbrg 20° or more
Table 4. Fault and attitude data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple measurements taken from the same section or station. Att, attributed point not on a fault]

Station Easting1 Northing

Fault

strike

azimuth

Fault

dip

degrees

Bedding

strike

azimuth

Bedding

dip

degrees

Notes

M08‒54 545666 3871520 255 90 Fault contact, Tbrg to S and well rounded beach gravel of Ql8 to N. N of gray humps of bea

Qalg (Qmr?) under beach gravel against Tbrg to N (so up on N). Qalg in middle grades 

downsection, dipping 45SE and vertically fractured; S fault strikes N75E

M08‒54Att 545666 3871535 45 45 Fault contact, Tbrg to S and well rdd beach gravel of Ql8 to N. N of gray humps of beach gra

(Qmr?) under beach gravel against Tbrg to N (so up on N). Qalg in middle grades down indipping 45°SE and vertically fractured; S fault strikes N75E

M08‒79 552437 3873840 270 60 Carbonate-lined small fault in steep cut. Due W @ 60N; N side down about 50 cm; clasts rotated 

M08‒80 552720 3874040 135 20 Fault scarp cut on older fan gravels that dip 20SW; apparent “down” side to S is probably y

M08‒81 552539 3874239 135 20 To north of M08‒80, same gravels dip 50SW; probably another fault. Older fans are capped 

gravel—an unconformity truncating the dipping gravels

M08‒85 551491 3874984 315 90 Fault or fracture, in sandy debris flow deposits, part of younger fan unit? Apparent vertical f

Another probable fault 10 m upvalley in fanglomerate

M08‒86 551812 3875122 270 20 Tgg dips ~20N and is folded and faulted; unconformable younger gravel with arkosic sand-

calcic paleosol or groundwater carbonate bed with fractures feeding it, locally sheared

M08‒87 551868 3874770 290 50 Sandstone beds in Tgg strike 110 @ 50N, approaching main wash and Manix fault

M08‒88 552142 3874551 75 85 270 20 Manix fault. Relatively undeformed QTvg on S against highly sheared pink andesite-tuff fa

Tgg. Fault strikes 75 @ 85S; volc fgl is E–W @ 20N; tuff fanglomerate is vertical and E

M08‒88a 552142 3874551 270 90 Manix fault. Relatively undeformed QTvg on S against highly sheared pink andesite-tuff fa

Tgg. Fault strikes 75 @ 85S; volc fgl is E–W @ 20N; tuff fanglomerate is vertical and E

M08‒89 552285 3874623 80 85 50 m north of Manix fault, vertical beds in andesite-tuff fanglomerate

M08‒90 552395 3874738 290 85 Between M08‒89 and 90, granitic clasts appear in the andesite-tuff fanglomerate and increa

in sandy beds is 110 @ 85N

M08‒92 552483 3874593 270 90 Main Manix fault; abundant clay gouge. Fault strike 270 @ 90

M08‒93 551023 3874250 90 70 Upper limit of tufa coated stones on N side of fault in arroyo; continuous from here to base 

uplifted to SE. Fault across arroyo, 270 @ 70S; apparent offset is reverse up to S

M08‒94 550951 3874187 245 85 Fault in main wash to W, view looking east; fault 65 @ 85N. Matrix-rich reddish arkosic sa

unit on N, latter mostly cut out by younger bedded sand and gravel; strikes upvalley betw

M08‒95 550812 3874342 80 80S Fault, strike 80 @ 80S. Debris flows on both sides. Appears to truncate a line of tufa-coated 

outcrop to S, does not seem to reappear on N side of fault

M08‒97 551635 3875842 230 45 Steep-dipping beds of Tgg? along base of steep cuts and capped by younger gravels bedded 

beds with attitude 50 @ 45NW

M08‒98 551965 3875574 230 25 High in badlands of Tgg, dips appear to decrease upward to ~25°. Pale blocky massive carb

remnants—calcic paleosol?

M08‒99 551780 3876235 240 12 Tgg strikes 60 @ 12N. Carbonate caprock extends down slope toward river. Tgg appears to 

decreasing upward

M08‒128 540759 3871286 60 8 Contact of Ql4 and mod. indurated upper Qalg. Ql4 mostly loose well-bedded sand. Attitud

60 @ 8SE; above this, beds more gravelly and nearly flat-lying. Unconformity?

M08‒130 540973 3871581 90 75 Point is base of Ql7 capping outcrop; overlies 270 cm Ql5, lake-marginal fluvial deposits, tu

x-bedded fluvial sand to cobble gravel; overlies 10‒15 cm Bwk imposed on greenish-brobedded. Reverse fault strike E–W @ 75S near base, apparently up to S, steepens upwardsand bed 1 m higher by only ~20 cm; Ql7 @ top stops @ fault

M08‒131 541168 3871803 90 75 Point is on fault, strat. about 2 m above base of Ql7, but base quite deformed (see photos); a

dip and strike to that @ M08‒130. Two lake units cap Ql7 here; middle one is either cut Ql7 thickens to east incorporating this interval
Table 4. Fault and attitude data for Pleistocene Lake Manix surficial map.—Continued [Sample letters (for example, A, B, and so forth) indicate multiple measurements taken from the same section or station. Att, attributed point not on a fault] Station Easting1 Northing Fault strike azimuth Fault dip degrees Bedding strike azimuth Bedding dip degrees Notes M08‒136 541563 3871338 135 8 To east of M08‒135 up drainage. Attitude ~135 @ 8SW on stratified indurated sand, mud an

mapped to east. 3 m thick above wash, overlain @ angular unconf. and tufa line by ~60 coverlain by ~2 m stratified, mod-weakly sorted sand and gravel. Fault likely @ upstream lower; 25 m farther upstream, Qalg and unconformity both strongly tilted M08‒142 540920 3871142 300 90? 140 15 Manix fault strand. Base of Ql4 marked by sorted gravel with tufa coats at top of Ql5 lake-m

on E–W monoclinal axis; this fault offsets the fold limb. Overlain by well washed arkosi(beach?) of Ql5. Bed attitude S of fault ~40 @ 15NE. M08‒143 540830 3871108 110 22 Folded Qalg 110 @ 22E (08‒410). Slopes to S underlain by a salt-rich muddy unit, poorly expo

M08‒144 541199 3871058 90 90 Main Manix fault?, due E–W, vertical. Many shears in low wash cut place Qalg on N again

then lake sand and mud of Ql4. Qalg 1.5 m thick capped by thickly tufa-coated Buwalda

Ql4 as measured in section M08‒60 just to east. Apparent offset ~2.4 m down to S M08‒150 541841 3871219 240 75 Beds similar to basal ones @ M08‒149, capped by base of Ql4? Adjacent is strongly carbon

exposed in wash bed; some planes indicate 240 @ 75N M08‒150att 541841 3871240 135 30 Beds similar to basal ones @ M08‒149, capped by base of Ql4? Adjacent is strongly carbonexposed in wash bed; some planes indicate 240 @ 75N M08‒159 542702 3870131 230 7 Attitude 140 @ 7NE on thin sandstone interbedded with Qmr muds, N end of outcrop on bu

@ toe of steep slope is Mojave River strath (Qyfmr) M08‒160 542754 3870006 20 2 Attitude 20 @ 2SE on central part of butte. Overlain by ~3 m Mojave River gravel and sand 

Mtn. fan gravel M08‒164 542667 3868988 70 65 18-cm tephra in Qmr, 50 m N of M08‒163. Sediments dip 12°SW. Cut by fault striking 70°

M08‒183 541784 3868355 25 90 Prominent fault outcrop, apparently down to E since Ql7 occurs on that side but on W, Ql8 lies o

Qvg bent strongly up on hanging wall approaching fault; 25° @ vertical (see sketch). Base of 

N across a swale, with no Ql4 present to N but 3‒4 m Ql4 to S M08‒185 541662 3867964 25 90 Fault zone in Qvg resembles the one @ M08‒83: complex set of shears, apparent down to S

M08‒199 552760 3874586 90 90 Manix Fault, volc fgl (QTvg) on S and pink andesite tuff bedrock, another fault with andesi

Fault plane 90 @ vertical, slickenlines plunge 20‒40° E, left-lateral mullion configuratio

M09‒7 542683 3868959 155 East side of hill @ site M08‒164. Fault ~N25W down to W. Tufa line @ base of Ql7 appare

Huckleberry Ridge ash @ top on S side fault faulted down ~4 m M09‒8 542597 3869016 270 Apparent E–W strike on small fault; Huckleberry Ridge ash offset 1 m down to N. Little or 

M09‒9 541720 3868408 80 80 N80E @ 80S on cemented fault zone exposed in wash floor between M08‒182 and 183. Faulted 

Another fault zone ~N70E about 15‒20 m upstream in same unit. No apparent offfset of lake 

M09‒10 541760 3868367 245 65 N65E @ 65 NW, fault in gully just W of M08‒183. Displaces interbedded Qmr‒Qvg unit d

M09‒19 541245 3867475 185 80 GPS point is poor due to slot canyon walls. Fault down to W; drops Qvg against volcs. N5E 

in wash floor; dip is 75‒80°W. Fault in volcanics M09‒19A 541280 3867425 75 75 50 m upcanyon of M09‒19 and 100‒150 m downstream of M09‒18 is another fault in volcs 

drops platy andesite against underlying reddish andesite. N75E @ 75 SE, steeper @ top M09‒20 541419 3867571 15 85 Fault in Qvg, N15E @ 85E. One fanglomerate bed ~4 m below Manix beds is down ~2 m to E

line face to E of fault

M09‒21 541486 3867504 200 80 Fault in Qvg, N20E @ 80W; drag indicates down to W. Cemented shear zone crosses wash 

M09‒22 541579 3867469 0 90 Poorly exposed fault in Qvg. Strikes N about vertical, somewhat exposed on SW-facing slo

M09‒27 541663 3867962 195 80 Fault in Qvg. N15E @ 80W. Wide shear zone in gravels, multiple strands, 2‒3 m wide @ b

M09‒36 541597 3870510 230 80 Fault zone, E side Manix wash nearest river, prominently cuts Qmr. At least 4 offsets along 

and fractures along ~50 m of wash cut. Two northern are down to S, 1-m offsets. Two sousome striae are subhorizontal on all faults. S fault is N50E @ 80NW with curving fault pnorthernmost is N30E @ 75SE. Uppermost Qmr has interfingers of Qalg-type sand and outcrop has Qalg unconformable on Qmr. Souhthernmost fault.
Table 4. Fault and attitude data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple measurements taken from the same section or station. Att, attributed point not on a fault]

Station Easting1 Northing

Fault

strike

azimuth

Fault

dip

degrees

Bedding

strike

azimuth

Bedding

dip

degrees

Notes

M09‒36 541597 3870510 90 55 Fault zone, E side Manix wash nearest river, prominently cuts Qmr. At least 4 offsets along 

and fractures along ~50 m of wash cut. Two northern are down to S, 1-m offsets. Two soustriae are subhorizontal on all faults. S fault is N50E @ 80NW with curving fault plane; nmost is N30E @ 75SE. Uppermost Qmr has interfingers of Qalg-type sand and gravel anQalg unconformable on Qmr. Next fault to North

M09‒36 541597 3870510 30 75 Fault zone, E side Manix wash nearest river, prominently cuts Qmr. At least 4 offsets along m

fractures along ~50 m of wash cut. Two northern are down to S, 1-m offsets. Two southern are subhorizontal on all faults. S fault is N50E @ 80NW with curving fault plane; next N is is N30E @ 75SE. Uppermost Qmr has interfingers of Qalg-type sand and gravel and soils. unconformable on Qmr. Northernmost fault.

M09‒45 542871 3868809 15 75 Pair of faults bound a horst of Qmr, here 2.5 m thick with Huckleberry Ridge ash just abov

N15E @ 75 E, down to E. 2 m of lacustrine sand over Qvg on E side of horst is missing 

and Qvg are truncated by fan gravel of Qia6 overlain by Ql7

M09‒45A 542864 3868815 205 80 Pair of faults bound a horst of Qmr, here 2 m thick with Huckleberry Ridge ash just above wash 

down to W

M09‒46 542944 3868826 30 85 Fault, N30E @ 85SE down to SE, bounding fault of horst block of Qmr, as much as 6 m th

ash ~1.5 m below gradational contact with overlying Qvg; another very thin white ash abexposed, mostly a shear zone in Qmr muds on wash floor

M09‒46A 542917 3868932 220 80 Fault on west side of horst block, N40E @ 78NW, where thickest part of Qmr faulted again

M09‒48 542787 3868968 0 20 Top of Qmr. N @ 20E on bedding in Huckleberry Ridge ash. Qmr interbedded with cobble 

4 m of Qmr-type seds above ash to point where Qvg-type gravel dominates. Suspect faubluff west (M08‒163) because there, Qmr appears flat-lying

M09‒49 543027 3868895 190 80 Fault, N10E @ 80W. Qvg down to west against QmrM09‒50 543095 3868835 15 85 Pair of faults. N15E @ 85E down to E, Qvg against Qmr, minimum 5 m offset

M09‒50A 543079 3868859 190 90 Pair of faults. Approx. N10E, down to W. Top of Qmr under Qvg steps down ~2‒3 mM09‒51 543124 3868785 195 90 Fault up same wash, ~N15E, exposed as shear zone in wash floor but clearly down to W bec

east of fault

M09‒53 543332 3868875 190 75 Fault in Qvg, ~N10E @ 75W, probably down to W, carbonate-cemented. Probably another 

where Qmr pops up again

M09‒62 541880 3868976 235 85 Fault, cuts Qvg, N55E @ 85NW, down to W. Possibly reaches a surface scarp cutting lake u

fluvial; Qyfmr strath gravel lies on top. Strong drag of cobbles along fault in footwall blo

M09‒64 541942 3868764 340 65 Reverse fault, N20W @ 65NE, in Qvg. 3 m up on NE side. Overlying lake beds not offsetM09‒82 542706 3868853 205 Inferred fault, ~N25 E, up to SE. Required, to separate area to SE with Qia7/Ql7/Qvg from 

Ql6/Ql5?/Ql4?/Qmr. Contact of Qia7/Ql7 even seems higher on SE side

M09‒97 541512 3871063 260 75 210 15 Complicated set of 4? faults cutting Ql4 and underlying Qalg, with a faulted fold. See draw

Southern fault is N80E @ 75N. Qalg on both sides ~N45W @ 15SW

M09‒97A 541502 3871066 295 75 Middle fault ~N65W @ 75NE, LL strike-slip. Beds west of scissor ~N30E @ 15 NW; east oM09‒97B 541508 3871079 260 90 Northern fault N80E @ 90, apparently down to N. Beds N of N fault ~N60E @ 15SEM09‒98 541428 3871025 255 75 135 15 Aligned notches trend N75E, to S of prev. fault complex. Fault, N75E @ 75N, apparently dM09‒99 541910 3871091 95 90 Fault, Qalg on both sides. Qalg/Qmr contact about 4 m stratigraphically below this to the S

shears, N85W. Another fault or pair of faults 3 m to N in Qalg; contact with lake deposit

M09‒100 541982 3871096 275 85 2 faults merge to form a 3.5-m-wide shear zone in Qalg. N85W @ 85NM09‒103 542301 3871086 265 75 Southern of two faults, this one @ base of a very steep escarpment and between Qmr to S a

Qalg looks much like a sand ramp, dips steeply SW and is quite fractured. N85E @ 75Nattitude is N45W @ 65N
Table 4. Fault and attitude data for Pleistocene Lake Manix surficial map.—Continued [Sample letters (for example, A, B, and so forth) indicate multiple measurements taken from the same section or station. Att, attributed point not on a fault] Station Easting1 Northing Fault strike azimuth Fault dip degrees Bedding strike azimuth Bedding dip degrees Notes M09‒103att 542280 3871131 315 65 Southern of two faults, this one @ base of a very steep escarpment and between Qmr to S a

Qalg looks much like a sand ramp, dips steeply SW and is quite fractured. N85E @ 75Nattitude is N45W @ 65N M09‒103A 542300 3871111 270 65 Northern of two faults, this near top of escarpment; steep-dipping Qalg on S side and horizo

N side; E–W @ 65N M09‒104 542361 3871011 235 6 Just to S of escarpment, N55E @ 6NW on sandstone bed in Qmr M09‒105 542633 3870937 260 15 N80E @ 15N on bedding in Qmr, south of all faults; no faults exposed here M09‒106 552544 3874610 245 65 Subsidiary fault in andesitic tuff fanglomerate, N of main Manix fault, abundant vertical sli

thick interbeds of eolian sand M09‒108 542924 3871142 90 35 Very close to fault; here, N side of anticline, which was N-dipping, is now steeply S-dipppin

go near vertical in badlands just to N M09‒110 552891 3874586 95 90 Manix fault, sheared gunge of andesitic tuff, against QTvg. N85W @ vertical M09‒112 553060 3874566 255 65 N75W @ 65N on fault separating QTvg? from QTvg with red volcanic gunge dragged into 

M09‒114 553214 3874609 260 70 Fault N80E @ 70N between gunge on N and QTvg on S. Also cuts horizontally bedded Qia 

unconformity. Appears channeled into QTvg and has >1 sandy red calcic soils; likely rewdissection and is more like the age of Qvg M09‒117 553203 3874546 100 S 270 65 Fault bounds S side of red basalt (Tvs) against QTvg, N80W @ 90. To N, QTvg overlies red 

to N, separated from near flat-lying QTvg by fault striking N70W @ 65NE. Section capped 

(M09‒114) M09‒118 553110 3874535 230 45 Crazy unconformities in QTvg. Lower beds N20W @ 35SW, upper beds N20E @ 60NW. 2beds, N5W @ 45W, mafic volcanic gravel with 1‒2% phenocrystic granites. Overlain in (basal QTvg) with abundant very dense med-gray xlline granitoids, with attitude N10W 45 @ N40W. A few meters upstream/downsection, very large rounded boulders of andesiinterbedded with finer-clast mafic beds, some dense gray xlline granitoids too M09‒118Attlo 553102 3874519 175 45 Crazy unconformities in QTvg. Lower beds N20W @ 35SW, upper beds N20E @ 60NW. 2beds, N5W @ 45W, mafic volcanic gravel with 1‒2% phenocrystic granites. Overlain in (basal QTvg) with abundant very dense med-gray xlline granitoids, with attitude N10W 45 @ N40W. A few meters upstream/downsection, very large rounded boulders of andesiinterbedded with finer-clast mafic beds, some dense gray xlline granitoids too M09‒130 546212 3871672 255 90 Another fault in same zone and attitude; N75E near vertical. Ql7 down to N, here against Q

to east M09‒131 546163 3871699 70 90 Fault or steep fold or both. N65–70E. On N side is a cobble lag from Buwalda Ridge that seembase of Ql7 tufa cobbles to N. On S side, beach sand and green mud are dipping gently NE dip of 60°. Likely folded up to a fault contact with Qalg to NW M09‒132 544910 3871709 270 85 245 10 Fault cuts Tbrg here; in spur just to E, cuts old talus dipping 40° and places in probable fau

~10° N or NNW. Fault is E–W @ 85S. Younger inset talus cones don’t appear to be offse

M09‒135 543341 3871287 75 65 Multiple faults overall placing Tbrg against Manix lake units. N fault N75E @ 65SE, faults T

M09‒135Att 543341 3871310 75 15 Multiple faults overall placing Tbrg against Manix lake units. N fault N75E @ 65SE, faults T

M09‒135A 543352 3871276 75 65 Middle fault ~N75E @ 65SE, LL strike-slip. Displaces tufa stone line 2.5 m down to N; sever

dip 15°S. Several stone lines over ~2 m interval tufa-coated. Looks like reworked Qalg wit

M09‒135Att 543352 3871250 255 15 Middle fault ~N75E @ 65SE, LL strike-slip. Displaces tufa stone line 2.5 m down to N; sever

dip 15°S. Several stone lines over ~2 m interval tufa-coated. Looks like reworked Qalg wit
Table 4. Fault and attitude data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple measurements taken from the same section or station. Att, attributed point not on a fault]

Station Easting1 Northing

Fault

strike

azimuth

Fault

dip

degrees

Bedding

strike

azimuth

Bedding

dip

degrees

Notes

M09‒135B 543358 3871229 260 75 S fault, N80E @ 75N. Lake unit overlies a gravelly volcanic-clast-rich version of Qalg—lo

sand interbedded with fan gravel. In fault contact on S with Qmr, attidtude N70E @ 20Nnear the fault; looks like a slight angular unconformity with overlying Qalg unit that intesketch in field notes p. 101

M09‒135B 543358 3871200 250 20 S fault, N80E @ 75N. Lake unit overlies a gravelly volcanic-clast-rich version of Qalg—lo

sand interbedded with fan gravel. In fault contact on S with Qmr, attidtude N70E @ 20Nnear the fault; looks like a slight angular unconformity with overlying Qalg unit that inte

See sketch in field notes p. 101

M10‒13 557518 3874488 290 75 Fault contact of Tgg of this study and fluvial-lacustrine sediment of Tvs unit (QTg and Tu of 

Red clay gouge, 1 m wide shear

M10‒18 557342 3874584 270 75 Fault contact of Tvs to S (Tu of Mosely, 1978) and Tgg to N. Nearly parallel to bedding bu

gouge @ contact. E‒W @ 70‒75 N

M10‒19 557244 3874626 290 70 290 70 Fault contact of Qia (fine-pebble basaltic clasts) on S with Qia derived from Tgg on N. Bel

Tgg on N and Tvs (Tu of Mosely, 1978) on S. Tgg dips 70° N, same as fault; N70W @ 

M10‒20 557113 3874716 90 80 Fault in Tgg, many conjugate shears. Mean zone has shear fabric ~1 m wide. E–W @ 80S. 

plunge on slickenlines. 

M10‒21 557070 3874732 110 80 Fault, N70W @ 70S curving up to near vertical. Contact of gouged olivine-rich basalt on S 

fault of Tvs–Tgg lies a few meters to S so this basalt is faulted into the Tgg. Horizontal 

M10‒22 556783 3874887 110 90 Fault in Tvs unit between Mosely (1978) units Tb3 on S and Ts on N; Ts only 1.5 m thick, i

faults vertical and merge just to east. Striae N70W

M10‒23 556616 3875515 260 85 Fault in Tgg, N80E @ 85N. Close to contact with Tgg and overlying finer-grained darker v

(QTvg?). Some soils in Tgg and here overall much finer grained; fines toward top, QTvg 

M10‒24 556451 3875047 285 77 Fault, N50W @ 77NE cross-valley strike on fault measured by Dave Miller (USGS) in slot 

on NE. Apparent offset is down to NE in upper part, where younger horizontally bedded and is lower to NE, but lower down is opposite. Tvs in turn faulted against green fluvial basalt; that fault strikes E–W @ 77 N

M10‒25 556457 3874866 235 72 Fault, N55E @ 72NW places airfall tuff to NW against Mosely (1978) units Ts4? over Tb3? 

displaced to NE. But to SW, QTvg is down ~75 m to NW against Ts4(?). At least two an“younger” gravel package (QTvg and Qvg?)

M10‒30 555895 3874993 135 25 Main Manix fault puts 20‒25° SW-dipping QTvg, overlain by flat-lying Qvg, to N against T

Springs Tuff) on S. Another fault 15 m north offsets only QTvg, not overlying Qvg

M10‒32 555638 3874928 255 90 Same fault shot back to M10‒31 from west, N75E @ 90. Qvg @ GPS point faulted against 

clasts rotated vertical in fault zone

M10‒36 554747 3874833 90 88 Fault, E–W @ 88S. Tvs faulted against eolian sand (Qiea) 7‒8 m thick. Clay gouge @ faul

some plunge 25°W

M10‒37 554455 3874604 245 75 Fault, N65E @ 75 NW. QTvg on NW against Tvs on SE. Mostly debris flows; to NE, QTv

M10‒38 554307 3874506 245 75 Same fault as M10‒37. Here a fan and eolian (Qia and Qye) unit with strong stage III carbo

S-dipping contact on top of QTvg, here with clasts in sandy matrix, locally well bedded

M10‒56 543067 3870942 205 9 N25E @ 9NW attitude on Qmr bedded silt-sand above massive red-brown playa beds. To wes

and farther west are dipping westward

M10‒57 542979 3871055 0 7 N‒S @ 7E attitude on fluvially bedded distal-fan deposits of Qalg (upper Qmr). 5 m above 

M10‒58 542862 3871099 315 5 N45W @ 5NE on fluvial bed in Qalg, 6 m below contact with strong buried soil on basaltic g
Table 4. Fault and attitude data for Pleistocene Lake Manix surficial map.—Continued [Sample letters (for example, A, B, and so forth) indicate multiple measurements taken from the same section or station. Att, attributed point not on a fault] Station Easting1 Northing Fault strike azimuth Fault dip degrees Bedding strike azimuth Bedding dip degrees Notes M10‒66 542914 3871064 120 5 N60W @ 5SW, attitude on fluvial ss in Qalg near axis of syncline trending N65W. A paralle

then beds turn up abruptly along main fault to dip S. However, lake beds not involved in several m of Qalg; appears to have an angular unconformity within Qalg, marked by soi

sketch). Beds above dip ~SSW @ 15‒20° M10‒67 542937 3871131 285 87 Fault, N75W @ 87N on fault placing older playa Qmr on N, very steeply dipping, against a

which dips ~20°S near fault but approaches horizontal a few meters S; so, apparent drag 

M10‒68 543073 3871187 250 80 Fault, N70E @ 80NW with playa facies Qmr, containing carbonate nodules, dipping 60°SW 

steep-dipping (depositional dip) Buwalda-Ridge derived fan gravel interbedded with probsorted, slightly greenish, @ least 2 beds, multiple sets of opposing crossbeds M10‒70 543139 3871232 90 90 Fault, E–W @ 90. Bedded Buwalda Ridge-derived fan gravel and interbedded eolian sand o

To N is horizontally bedded, to S too sheared up to tell, maybe N-dipping. 2 other paralle

M10‒71 543165 3871225 255 85 Fault, N75E @ 85N. Same interbedded gravel-sand beds down to N against Qmr, arkosic faM10‒77A 548583 3872904 60 90 Same block bounded on SE by probable fault, N60E, strikes directly @ top of Tbrg ridgeto

clayey sand, probably dragged from underlying playa deposits? M10‒82 543154 3871114 120 10 N60W @ 10SW on cemented muddy ss. Break about 1⁄2 way up Qmr between massive salty 

arkosic sand and pebble gravel with less mud. Hard to define on ground; transitional chanunconformity to SW shown in photo? M10‒87 542858 3871066 255 60 ~N60E @ 60N on fault, cuts upper Qmr and cuts off the abrupt clifftop contact with overly

Possibly down to N but loses cemented zone; still grayer above and redder below. To weby color change and cemented bed. 2-m wedge of Buwalda-derived gravel caps Qia @ aturn overlain by several m of lake deposits, @ least 2 units M10‒89 542911 3871110 255 65 Same fault as M10‒87, here N60E @ 65N M10‒101 542252 3871037 225 80 Carbonate associated with a fault zone, here a carbonate-cemented shear, N45E @ 80 NW. Re

fault below red-carb marker bed dip 7°N; beds to N, including red marker, dip as much as 1

M10‒101att 542252 3871000 225 7 Carbonate associated with a fault zone, here a carbonate-cemented shear, N45E @ 80 NW. Re

fault below red-carb marker bed dip 7°N; beds to N, including red marker, dip as much as 1

M11‒13 548647 3873615 280 75 Fault, N80W @ 75N, cuts both Qof units and Ta. Here, 3 m down to S on inter-Qof soil be

reverse fault. Playa unit Ta @ least 5.5 m thick adjacent to fault and upper 2.5 m quite g

M11‒24 544613 3874915 4 Older, pinkish arkosic sediment (QTalg), E bank Field wash, dipping about 4° SE; mostly m

M11‒25 544978 3874650 5 Basal pinkish unit (QTalg) dipping 5° SE makes up half of outcrop. Upper half is bedded sa

Ql7 overlain by ~2 m Qia7 M11‒27 541174 3873503 155 10 On Yermo road. Beds dipping ~10°S55W. Pinkish, stratified gravel and sand, matrix-rich, w

Upper pebble-cobble bed has some rhyolite and quartzite M11‒29 546563 3872339 180 28 North of camp. N‒S @ 28°W on base of sand unit in playa deposits (unit Ta). M11‒31 546525 3872299 250 80 Fault, N70E @ 80N. 2‒3 closely spaced shears place playa-fan deposits (Ta) on N against m

unit on S (Tbrg)

M11‒33 548370 3872962 290 10 N70W @ 10NE on playa beds (Ta) with thin (30‒50 cm) pebble-coarse sand beds. Just to N

top below capping strath (Qyfmr)

M11‒38 544645 3871113 25 82 Fault, N25E @ 82S, down to west (reverse) suggested by small drag on beds @ fault, but big fol

down to east in Qmr @ tight fold, between sites M10‒90 and tephra M07‒128. Last winter flnot seen previously

M11‒40 541934 3871051 235 65 Small fault, N55E @ 65NW, likely down to NW, little displacement. All these little faults near th

to abundant groundwater carbonate cement in this area. About where I thought there might be strike; nothing prominent
Table 4. Fault and attitude data for Pleistocene Lake Manix surficial map.—Continued[Sample letters (for example, A, B, and so forth) indicate multiple measurements taken from the same section or station. Att, attributed point not on a fault]

Station Easting1 Northing

Fault

strike

azimuth

Fault

dip

degrees

Bedding

strike

azimuth

Bedding

dip

degrees

Notes

M11‒47 552590 3874769 340 45 Dip 45°N70E. Largely granitic gravels (Tgg) w/ 5% of dense dark brown aphanitic rocks with 

25% andesite. Just above is pale-colored dominantly sand unit 7‒8 m thick.

M11‒48 552661 3874833 330 45 Top of sand unit in Tgg. Attitude N30W @ 45NE as above. x-bedded but flow direction uncle

to top of Tgg. Sand unit is ~50 m wide along dip direction so....25 m thick?

M11‒52 553468 3874561 10 15 Above basalt (Tvs), steadily upsection through monotonous volcaniclastic gravel, mostly and

no granites (unit QTvg). Attitude N10E @ 15E

M11‒54 553700 3874298 140 10 Big boulder QTvg lies on top of basalt; flow top worked up into base of fanglomerate? Sam

east, lots of granites and flow-banded rhyolite reworked from unit Tqg. This bouldery lag point on ridge to west. In cut below, dip direction S50W @ 10

M11‒57 552867 3873878 200 8 Outcrop of felsic-aphanitic igneous rock: green/pink and strongly foliated. Abutted to E by 

w/very angular clasts: dip direction N70W @ 8°. Fan gravel probably faulted against outup as if rotated in shear near bedrock

M11‒60 552285 3873968 180 11 Qvg containing abundant granite clasts. Dip direction 11°W. Tilt seems to be increasing dow

Rocks are subangular and ~70% or more granitoids

JR05CM‒167 556311 3876335 80 90 Splay of the Manix fault, N80E, dipping near vertical, apparent down to the north offset ~5.

deposits. Qia7 gravels are probably also offset. There is a much thicker package of fan mof the fault

JR05CM‒169 556531 3876305 80 90 Manix fault, 'Lidke splay'? N80E, appears to project through wide shear zone on the north s

does, it cuts the shear zone and the major fault in the shear zone which dips @ 86 degree

M12‒6 554084 3874116 140 25 Sandstone bed in Tqg; attitude S40E @ 25 NE. Crossbeds suggest SW flow

M12‒11 553875 3874237 195 11 QTvg dips 11°S15W. Cut by fault with attitude N10E @ 90. Rake on slickenlines 45°S. Ste

and thus indicate right-lateral motion

M12‒15 553220 3874392 320 42 N40W @ 42SW on QTvg @ approx level where rhyolite and granitoid clasts become scarc

fanglomerate is a basal unit of non-Tqg fangomerate

1All locations given in UTM units, 11S, WGS 84 coordinates
Publishing support provided by:

Denver Publishing Service Center, Denver, Colorado

For more information concerning this publication, contact:

Center Director, USGS Geosciences and Environmental Change Science Center

Box 25046, Mail Stop 980

Denver, CO 80225

(303) 236-5344

Or visit the Geosciences and Environmental Change Science Center Web site at: 

http://gec.cr.usgs.gov/

This publication is available online at:

http://dx.doi.org/10.3133/sim3312
Reheis and others—Surficial Geology and Stratigraphy of Pleistocene Lake Manix, San Bernardino County, California—Scientific Investigations Map 3312

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3312