U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2007–1281

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
Cover photo: A modern restoration of Lake Manix at the 543-m highstand level. View to the northwest from above the Cady Mountains. Clockwise from left center are 

the Troy Lake subbasin, Newberry Mountains, Mojave River, Calico Mountains, Coyote Lake subbasin, Tiefort Mountains (right skyline), and Afton subbasin. Modern-day 

Afton Canyon lies at the easternmost point of the Afton subbasin in this image. Eolian sand sheets east of the lake would have been less extensive prior to draining of 

Lake Manix. Visualization created in Visual Nature Studio (v. 2.53, 3D Nature Co.) by Paco Van Sistine (USGS) using 30-m DEMs and 1-m NAIP orthophotos.
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

By Marith C. Reheis, David M. Miller, and Joanna L. Redwine

Principal Trip Leaders: Marith Reheis, Dave Miller, Joanna Redwine, Stephanie 

Dudash, and Jack Oviatt

Open-File Report 2007–1281

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director 

U.S. Geological Survey, Reston, Virginia: 2007

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U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Reheis, M.C., Miller, D.M., and Redwine, J.L., 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: U.S. Geological Survey Open-File Report

2007–1281, 31 p. 
iii

Contents

List of Annual Trips, Pacific Cell, Friends of the Pleistocene .................................................................2

General Field Trip Information .....................................................................................................................4

Introduction to Lake Manix Basin...............................................................................................................4

Pre-Trip Day (Optional): Early Incision of Lake Manix Threshold and Flooding of 

Afton Subbasin..................................................................................................................................9

Walking Tour of Lake Manix Overflow Point and Highstands .....................................................10

Stop 1 ...........................................................................................................................................10

Stop 2 ...........................................................................................................................................11

Stop 3A.........................................................................................................................................12

Stop 3B.........................................................................................................................................14

Day 1: Afton Subbasin of Lake Manix and History of Afton Canyon ..................................................15

Stop 1A..................................................................................................................................................17

Stop 1B..................................................................................................................................................17

Stop 2 ....................................................................................................................................................19

Inset Strath Terraces West of Lake Manix Threshold.........................................................19

“Slack Water” Deposits............................................................................................................19

Stop 3 ....................................................................................................................................................20

Stop 4 ....................................................................................................................................................21

Day 2: Manix Subbasin of Lake Manix and Tectonic Disruptions........................................................21

Stop 1 ....................................................................................................................................................22

Stop 2 ....................................................................................................................................................23

Stop 3 ....................................................................................................................................................24

Optional Stop 4 ....................................................................................................................................25

Day 3: Coyote Lake Subbasin of Lake Manix and Post-Lake Manix Lake and River History .........25

Stop 1 ....................................................................................................................................................25

Stop 2 ....................................................................................................................................................27

References Cited..........................................................................................................................................30

Figures

1. Mojave River drainage basin in southern California (modified from Enzel and 

others, 2003)...................................................................................................................................4

2. Map of principal Quaternary faults in the Lake Manix region ..............................................6

3. Geographic features of the Lake Manix basin.........................................................................7

4. Preliminary correlation of lake and fan units...........................................................................8

5. Sedimentology and stratigraphy of measured sections along the Mojave 

Road ..............................................................................................................................................13

6. Map of Afton Canyon campground and area of Stop 3B, Pre-Trip Day.............................14

7. Stratigraphy of deposits at Stop 1B, Day 1.............................................................................18

8. Sketch of geology at intersection of the Dolores Lake and Manix faults 

near Harvard Hill (Day 2, Stop 3)..............................................................................................24

9. Map of the southeast Coyote Lake beach (Day 3, Stop 1)...................................................26
iv

10. Map of hillshade derived from 1-m LiDAR, southwestern Coyote Lake 

basin..............................................................................................................................................28

Table

1. Tentative correlation of Redwine’s units (U.S. Geological Survey, 

 unpublished mapping) to ongoing mapping and interpretation of 

 Lake Manix stratigraphy...........................................................................................................10
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

By Marith C. Reheis,1 David M. Miller,2 and Joanna L. Redwine3

Principal Trip Leaders: Marith Reheis, Dave Miller, Joanna Redwine, Stephanie Dudash, and Jack Oviatt

1

U.S. Geological Survey, MS-980, Federal Center, Box 25046, Denver, CO 80225.

2

U.S. Geological Survey, MS-975, 345 Middlefield Road, Menlo Park, CA 80225.

3

Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512.
List of Annual Trips, Pacific Cell, Friends of the Pleistocene

[This section (or cell) was organized by Steve Porter with Linc Washburn, assisted by Eastern “Friends” and students of Dick Flint, in 1965 at 

the conclusion of INQUA Field Conference A in Bellingham, Washington. Due to growth and mitosis, the Pacific NW Cell was spawned in 

1993]

Trip 

no.

Year Date Area or title and leaders

1 1966 Sept. 24–25 Glaciomarine environments and the Fraser glaciation in northwest Washington: Don Easterbrook

2 1967 Sept. 23–24 Pleistocene geology and palynology, Searles Valley, Calif.: George Smith, Estella Leopold, and E.L. Davis

1968 No trip conducted

3 1969 Sept. 27–28 Pleistocene geology of the east-central Cascade Range, Wash.: Steve Porter

4 1970 Oct. 9–10 Cape Blanco sediments and terraces, Oreg.: Dick Janda

5 1971 Sept. 11–12 Glacial and Pleistocene history of the Mammoth Lakes Sierra: Bob Curry

6 1972 Oct. 6–8 Progress report on the USGS Quaternary studies in the San Francisco Bay area: Dave Adams, Dennis Burke, 

Jon Cummings, and others

7 1973 Sept. 8–9 Mount St. Helens, Wash., stratigraphy and eruptive history: D. Rocky Crandell, Don Mullineaux, and 

Jack Hyde

1974 No trip conducted

8 1975 Nov. 21–22 San Diego coastal area, Calif.: Jeff Bada, George Carter, Dennis Nettleton, and George Borst

9 1976 Oct. 30–31 Archeology and tectonics, China Lake, Calif.: Stan Berryman, Wendell Duffield, Glenn Roquemore, and 

William Page

1977 No trip conducted

10 1978 Nov. 10–12 Pluvial lake history of Searles, Panamint, and Death Valleys, Calif.: George Smith, Roger Smith, and Roger 

Hooke

11 1979 Aug. 22–26 Relative dating methods applied to glacial deposits, eastern Sierra Nevada, Calif.: R.M. “Bud” Burke, Pete 

Birkeland, and Jim Yount

12 1980 Sept. 18–20 Ice-sheet flooding in a portion of Columbia River Valley, Wash.: Richard Waitt, Jr.

13 1981 Quaternary tectonic deformation of Transverse Ranges, Calif.: Ed Keller, Tom Rockwell, 

George Dembroff, Andrei Sarna-Wojcicki, Ken Lajoie, Bob Yerkes, Malcolm Clark, and Don Johnson

14 1982 Aug. 5–8 Northern California coast, Humboldt basin, late Cenozoic deformation and stratigraphy: Debbie Harden, 

Donna Marron, and Anne McDonald

15 1983 Aug. 26–28 Glacial Lake Columbia basin, Wash. and McCall area, Idaho (joint trip with Rocky Mountain section): 

Brian Atwater, Richard Waitt, Steve Colman, Ken Pierce, and Maynard Fosberg

16 1984 Oct. 12–14 Holocene paleoclimatology and tephrochronology east and west of the central Sierran crest: Scott Stine, 

Spencer Wood, Kerry Sieh, and Dan Miller

17 1985 Oct. 25–27 Quaternary lakes of the eastern Mojave Desert, Calif.: G. Robert Hale, Steve Wells, John Ritter, and 

John Dohrenwend

18 1986 Oct. 31–Nov. 2 Quaternary tectonics of southern Death Valley: Roland Brady, III, Paul Butler, and Bennie Troxel

19 1987 Sept. 18–20 Pleistocene geology of northwestern Lake Lahontan, Nev.: Jonathan Davis and Rob Negrini

20 1988 Sept. 8–10 Central Oregon High Cascades: Willie Scott, Cynthia Gardner, and Andrei Sarna-Wojcicki

21 1989 April 7–9 Quaternary stratigraphy, soil geomorphology, chronology, and tectonics, western Transverse Ranges, Calif.: 

Ed Keller, Don Johnson, D.M. Laduzinsky, Tom Rockwell, D.B. Seaver, Rick Zepeda, and X. Zhao

2 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
Trip 

no.

Year Date Area or title and leaders

22 1990 January Western Salton trough—Soils and neotectonics: Tom Rockwell, Robert Crisman, Jonathan Goodmacher, 

Ralph Klinger, Scott Lindvall, Andy Thomas, and others

23 1990 Sept. 21–23 Neotectonics of south-central coastal California: Bill Lettis, Kathryn Hanson, Keith Kelson, John Wesling, 

Michael Angell, Doug Clark, Tim Hall, Anthony Orme, and Tom Rockwell

24 1991 May 31–June 2 Fish Lake Valley, Calif.-Nev.: Marith Reheis, Janet Slate, Tom Sawyer, Andrei Sarna-Wojcicki, 

Jennifer Harden, Elise Pendall, Alan Gillespie, and Doug Burbank

25 1992 June 5–7 Northern coastal California—A look at the southern end of the Cascadia subduction zone and the Mendocino 

triple junction: Bud Burke, Gary Carver, Dorothy Merritts, Oliver Chadwick, and Ken Aalto

26 1993 April 23–25 The paleoseismic record of subsidence, tsunamis, liquefaction, and landslides from the northern Oregon coast: 

Evidence of subduction zone seismicity in the central Cascadia margin: Curt D. Peterson

27 1994 Sept. 30–Oct. 2

Transpressional deformation in the San Francisco Bay region: William Lettis, Kevin Clahan, N. Timothy Hall, 

Christopher Hitchcock, Keith Kelson, Jay Noller, David Schwartz, Gary Simpson, Janet Sowers, and Jerry 

Weber

28 1995 Oct. 6–9

Quaternary geology along the boundary between the Modoc Plateau, southern Cascade Mountains, and 

northern Sierra Nevada: Bill Page, Jeff Bachhuber, Duane Champion, Mike Clynn, Julie Donnelly-Nolan, 

Wendy Gerstel, Fraser Goff, Jim Humphrey, Keith Kelson, Marcia McLaren, Paul Renne, Tom Sawyer, 

Gary Simpson, Janet Sowers, Jeff Unruh, John Wakabayashi, and Jim Yount

29 1996 Sept. 27–29

Quaternary history, isostatic rebound, and active faulting in the Lake Lahontan basin, Nevada and California: 

Ken Adams, Marith Reheis, Steve Wesnousky, Nick Lancaster, Kurt Cupp, Steve Wells, Adrian Harvey, and 

Bruce Bills

30 1997 Sept. 26–28 Owens Valley, Calif.: Doug LaFarge, Fred Berman, Bud Burke, Paul Bierman, Malcolm Clark, Alan Gillespie, 

Liz Hearn, Marith Reheis, George Smith, and Paul Zehfuss

31 1998 Oct. 9–11

Quaternary geology of the Yucca Mountain area, southern Nevada: Emily Taylor, Ralph Klinger, 

Larry Anderson, Brian Andraski, John Bell, Jeff Coe, Pat Glancy, Scott Lundstrom, Shannon Mahan, 

Chis Menges, Silvio Pezzopane, Chris Potter, Alan Ramelli, Marith Reheis, Daniel Soeder, and Tim Sullivan

32 1999 Sept. 24–26 Quaternary geology of the northern Quinn River and Alvord Valleys, southeastern Oregon: Charlie Narwold, 

Dave Lindberg, Mark Hemphill-Haley, Marith Reheis, Silvio Pezzopane, Tom Sawyer, and Ken Adams

33 2001 Feb. 17–19 Quaternary and late Pliocene geology of the Death Valley region: Recent observations on tectonics, stratigraphy, and lake cycles: Ralph Klinger, Mike Machette, Jeff Knott, and Andrei Sarna-Wojcicki

34 2001 Oct. 12–14 Northern Walker Lane and northeast Sierra Nevada: Ken Adams, Rich Briggs, Bill Bull, Jim Brune, Darryl 

Granger, Alan Ramelli, Clifford Riebe, Tom Sawyer, John Wakabayashi, and Chris Wills

35 2002 Sept. 20–22 Historical faulting, chronostratigraphy, and paleoseismicity of the central Nevada seismic belt: John Caskey, 

John Bell, Alan Ramelli, Ken Adams, and Marith Reheis

36 2003 Oct. 3–5

Tectonics, climate change, and landscape evolution in the southern Sierra Nevada, California—Sequoia and 

Kings Canyon: Greg Stock, Bill Bull, Gary Weismann, Anthony Caprio, Nate Stephenson, John

Wakabayashi, Bud Burke, and John Tinsley

37 2004 Santa Barbara fold belt: Larry Gurrola, Ed Keller, and others

38 2005 Oct. 8–10

Geomorphology and tectonics at the intersection of Silurian and Death valleys: Dave Miller, Chris Menges, 

Matt McMackin, Kirk Anderson, Jordon Bright, Richard Hereford, Heather Lackey, Shannon Mahan, 

Jennifer Mendonca, Joanna Redwine, Kevin Schmidt, Roger Smith, and Jonathan Stock

39 2006 Oct. 6–9

Signatures of Quaternary crustal deformation and landscape evolution in the Mendocino deformation zone, 

northwestern California: Mark Hemphill Haley, Tom Leroy, Bob McPherson, Jay Patton, Jay Stallman, 

Diane Sutherland, and Todd Williams, and many guidebook contributors

40 2007 Oct. 4–7

Quaternary stratigraphy, drainage-basin development, and geomorphology of the Lake Manix basin, Mojave 

Desert: Marith Reheis, Dave Miller, Joanna Redwine, Stephanie Dudash, Jack Oviatt, Darrell Kaufman, and 

Jordon Bright

List of Annual Trips 3
General Field Trip Information

The Friends of Calico Early Man Site have graciously 

offered the Early Man Site facilities as our base of operations 

and campground for the entire trip, beginning Wednesday 

night (for those arriving early for the optional Pre-Trip Day) to 

Sunday morning. Please treat the facilities, both buildings and 

archaeology, with respect. The only power on-site is provided 

by a gasoline generator, and all water must be hauled in, so 

please provide your own water and power needs. We will have 

several portable toilets available for our use—please use them 

and not the BLM outhouse (permanent building). There is 

a small visitor center with artifacts on display, and the main 

staffer, Chris Christianson, can answer your questions about 

the site as well as sell you T-shirts and coffee cups (their main 

source of revenue, so please consider buying!). Chris will be at 

the camp during the day, so your belongings will be somewhat 

safe while you are out “FOPping.”

To get there from I-15: Three exits north of Barstow, 

take Minneola Road exit. Turn north and follow the paved 

road past a few businesses. At about 0.1 mi from the exit, take 

a left on a graded road marked with “Calico Early Man Site,” 

and follow signs to a right turn that leads you to the site. 

To get there from I-40: Two exits west of Barstow, take 

Daggett exit. Turn north and 

follow the paved road through 

Daggett to Yermo, enter I-15 

north, and proceed two exits. 

Refer to directions for I-15 

above. 

Camping is permitted in 

many places. Immediately after 

entering the site, some established camp sites are located 

on the left side of the road. 

Others (particularly those with 

campers) can use undesignated 

sites in the parking area beyond 

the buildings or continue 

farther around the loop road 

to bulldozed areas suitable for 

camping east of the buildings. 

Still others can walk north from 

the buildings to walk-in sites. 

Please ask if you are uncertain 

about sites. The group fire will 

be in the meeting area next to 

the two buildings. You can also 

build fires in the fire rings that 

already exist at some sites, but 

the staff has asked us not to build 

additional new fire rings or pits at 

the site.

If you prefer not to camp, 

motels and restaurants are 

available in Barstow and as close as the Yermo exit. Barstow 

is also the nearest source of significant supplies. Gas stations 

at several exits (Yermo, Minneola, and Harvard Road) also 

carry a few food items; no gas is available east of Harvard 

Road until Baker. Consult the road log for daily start times and 

rendezvous points.

Introduction to Lake Manix Basin

The following brief description and introduction to the 

literature is summarized from reviews in Enzel and others 

(2003) and Reheis and Redwine (in press). The Mojave River 

originates in the San Bernardino Mountains and in high-water 

years flows north and east to its terminus in Silver Lake playa 

north of Baker, Calif. Along this course, the river passes 

through or near several basins that were internally drained 

prior to integration by the Mojave River, including the Victorville, Harper, Manix, and Soda Lake basins (fig. 1; Cox and 

others, 2003; Enzel and others, 2003). Each of these basins 

contains a partial sedimentary record of integration, including fluvial and lacustrine sediments, indicating the arrival 

and ponding of the river and a record of climatic fluctuations 

Transverse Ranges

I-15

I-40

I-15

HARPER

LAKE

LAKE MANIX

LAKE

MOJAVE

Overflow to

Death Valley to Las

Vegas

to 

Needles

117o30'

35o00'

116o15' 35o00'

0 15 30 km

EXPLANATION

Dry lake (playa)

Late Pleistocene lake

Late and middle Pleistocene

 clastic wedges

San Bernardino

Victorville

Barstow

Baker

TROY

LAKE

COYOTE

LAKE

CRONESE

LAKES

SILVER

LAKE

SODA

LAKE

late Pleistocene

Mojave River fan

Mojave River fan

Mojave River

West Fork Deep

Creek

Afton

Canyon

Victorville

basin

area of 

Figs. 2 and 3

N

Kelso

Wash

Pacific

Ocean

California Nevada

Arizona

Mexico

122o 112o

37o

32o

Mojave River

watershed

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, the river 

flows into Silver Lake playa. In late Pleistocene time, after breaching of the Lake Manix 

basin, Lake Mojave episodically discharged northward into Death Valley. Dashed box is area 

of figures 2 and 3.

4 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
during the periods when a particular basin served as the river 

terminus. Sediments in the Lake Manix basin record Mojave 

River discharge and lake fluctuations that began during the 

middle Pleistocene and continued through most of the late 

Pleistocene (Jefferson, 2003). 

The Lake Manix basin lies within a broad zone of faulting and folding that accommodates 20 percent or more of 

the Pacific-North American plate motion (termed the Eastern 

California shear zone by Dokka and Travis, 1990). Deformation within this zone has influenced basin geometry over the 

past 3 million years; Coyote Lake basin has lowered and the 

Alvord Mountains have risen since a distinctive Pliocene 

fluvial deposit was laid across their northern margins (Miller 

and Yount, 2002). This deposit is warped into steep dips 

adjacent to both the basin and the mountain, suggesting that 

much of today’s topography is youthful. The informal Mojave 

River formation of Nagy and Murray (1991) is significantly 

deformed adjacent to the Manix fault. Faults that are known to 

cut Quaternary deposits of the Manix area are shown in 

figure 2; of these, we consider the Calico, Camp Rock, Dolores Lake, Pisgah, and Manix faults to have strong evidence for 

Holocene rupture.

All workers in the Lake Manix basin have noted that it 

currently consists of several subbasins. We use the following 

names (fig. 3) for these subbasins: Coyote Lake, Troy Lake, 

Manix, and Afton. As the lake evolved, fluvial and deltaic 

sediments were deposited progressively eastward into the lake, 

modifying the geometry of the subbasins and total lake volume. As a result, the current configuration may not accurately 

reflect the configuration of the early lake.

Jefferson (2003, and citations therein) conducted stratigraphic and paleontologic studies of the Pleistocene Manix 

Formation in the Manix subbasin near the confluence of the 

Mojave River and Manix Wash (fig. 3). He interpreted these 

deposits to represent at least four major lake cycles (fig. 4). 

Deposits of the oldest two lake cycles are poorly dated; the 

sediments have normal polarity, and one bone yielded an 

infinite uranium (U)-series age of >350 ka (J.L. Bischoff, U.S. 

Geological Survey, cited in Jefferson, 2003). Deposits that Jefferson interpreted as perennial-lake sediments and correlated 

with OIS 6 (his informal “upper Member C”) contain a tephra 

layer near the base that has an assigned age of about 185 ka, 

based on a tentative chemical correlation with a rhyolite in 

the Sierra Nevada to the northwest; this tephra is overlain by 

a bed bearing a bone fragment that yielded a U-series age of 

about 184 ka (J.L. Bischoff, U.S. Geological Survey, cited 

in Jefferson, 2003). Sediments representing a sequence of 

fluctuating lake levels were correlated with OIS 4 (lower part 

of “Member D”) on the basis of several U-series ages on bone 

ranging from about 74 to 50 ka and several mostly infinite 

radiocarbon ages, but several ages of both methods were not in 

stratigraphic order (Jefferson, 2003, p. 48). The youngest lake 

deposits at this site (upper part of “Member D”), coeval with 

OIS 2, consist mainly of sands interpreted as a delta that was 

deposited as the Mojave River prograded eastward. Numerous 

beach deposits at ~543 masl (meters above sea level) rim the 

basin and were taken by Jefferson (2003) and Meek (1990) as 

indicating multiple lake highstands.

Meek (1989, 1990) initially interpreted the geomorphic 

record of Lake Manix overflow and incision of Afton Canyon to have occurred rapidly at about 18 ka (~21.5 cal ka), 

but noted the presence of inset fluvial terraces suggesting 

the canyon was not all cut at once (Meek, 1990). Later, he 

(Meek, 2004) clarified his interpretation as inferring a 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. From stratigraphic records of Lake 

Mojave downstream, Wells and others (2003, and references 

therein) and Enzel and others (2003) strongly disagreed and 

argued for slower initial and later incision of Afton Canyon 

and integration of the Soda and Silver Lake basins to form 

Lake Mojave over a period of perhaps several thousand years, 

beginning >22 ka (~26.5 cal ka). An accurate understanding of 

the timing of these integration events is needed to reconstruct 

paleoenvironmental conditions during the late Pleistocene, 

because interpretations of past temperature and precipitation in 

the Mojave River drainage basin depend heavily on knowing 

the sizes of water bodies that may have been simultaneously 

maintained by the river (Enzel and others, 2003). Furthermore, 

the thick well-preserved sections of lake deposits in the Lake 

Manix basin offer the opportunity to develop a detailed record 

of paleoclimate variations prior to the latest Pleistocene; such 

records are rare in the Mojave Desert, with the exception of 

the Death Valley core (Lowenstein and others, 1999; Forester 

and others, 2005). 

The principal trip leaders undertook mapping and stratigraphic investigations to improve understanding of the history 

of Lake Manix and to provide geologic context for a 45-mlong core obtained from the section preserved at the confluence of the Mojave River and Manix Wash. This field trip is 

intended to provide an introduction to the outcrop record of 

interbedded lake, alluvial-fan, and alluvial deposits, and to our 

interpretations of lake history based on this outcrop record and 

our new mapping, dating, and preliminary interpretations from 

the core. Significant revisions to the previously established 

stratigraphy include the following: 

1. A subbasin integration event. For much of its history 

during the middle Pleistocene, Lake Manix was confined 

to the Manix, Troy Lake, and probably Coyote Lake subbasins to the west of Buwalda Ridge (fig. 3); the Afton 

subbasin during this time was an internally drained basin 

separate from the lake. At about the time of deposition of 

the Manix ash bed, thought to be about 185 ka (Jefferson, 

2003), this lake overtopped a threshold located near the 

east end of Buwalda Ridge and entered the Afton subbasin in a catastrophic flood event. This event has profound 

implications for the interpretation of younger sediments 

deposited in the Afton and Manix subbasins. 

2. After the subbasins were integrated, Lake Manix rose to 

a level as much as 10–15 m higher than its previously 

recognized highstands at about 543 masl, likely during 

Introduction to Lake Manix Basin 5
FOP camp

Figure 2. Map of principal Quaternary faults in the Lake Manix region, based on unpublished mapping of J.L. Redwine, D.M. Miller, and D.J. LGeological Survey) and Phelps and others (in press). Dashed faults are poorly exposed or covered. Field trip stops where faults will be discussBackground image is from Landsat 7.
Figure 3. A. Geographic features of the Lake Manix basin, showing subbasins, playas (dotted), the Mojave River fluvial fan between Yermo and 

and major faults (from Reheis and Redwine, in press). Field trip stops are also shown. Medium-weight line is the 543-masl highstand level that deminimum extent of Lake Manix during the late Pleistocene; western margin is not known due to progradation during highstands and later burial bRiver alluvium. Thin line is the 557-masl lake limit projected from highest shoreline features recognized in this study. Study sites (dots) shown whnot included on other figures. Note east-west streaks of eolian sand (es), derived from Mojave River and lake sediment, blanketing slopes of the Mountains, Cady Mountains, and Cave Mountain. B. Inset showing lacustrine features and study sites in upper Dunn Wash. Barrier crests and wscarp lie at 543 masl.

Coyote

 Lake

Coyote

 Lake

 playa

Troy Lake playa

Alvord

Mtns.

Cav

Calico Mtns.

Cady Mtns. Cady Mtns.

Newberry

 Mtns.

N

Mtn

s.

e

w

b

erry

Harvard

Hill

Buwalda

Ridge

North Afton

beach ridge

Yermo

depot

Mojave

River

Mojave R.

116°45'

35°00'

34°45

116°30'

Afton

Can

543 m

543 m

543 m

543 m

557 m

543 m

557 m

557 m

557 m

Afton subbasin

Manix

 subbasin

Coyote Lake

subbasin

Troy Lake

subbasin

Troy Lake

Manix 

Wash

10 km

Modern playa

543-m highstand, dashed where buried; hachures show island

Projected 557-m lake level, dashed where buried;  hachures show island

Principal Quaternary fault

es

es

es

es

es

es

es

area of B 

(inset)

Ba

N

JR

JR04D-1

M04-29B

M04-29A

M05-19

M05-20

M05-28

M05-21

M04-29C

Dunn

wash

B

wavecut scarp

barrier

crest

lacumud

D1-S1

D2-S4

D2-S3

D2-S2

D3-S2

D3-S1 D1-S2 D1-S3 D1-S1

PD-S3a PD-S3b

PD-S1,2

D1-S4

D2-S1

Field trip stop  (day 1, stop 1) 

FOP camp and

Calico Early Man site
B

D

D

C

UC

LC

UB

LB

B

C

OIS H I L

Lake

Levels

Members

EXPLANATION

Lithology

conglomerate

H - Periods of relatively 

 high lake level

I - Periods of intermediate

 lake level

L - Periods of low lake level

oncoid-coated clasts

sandstone

siltstone

claystone

silty sandstone

ash tuff

mollusc shell

19 ka 14C

>35 ka, >47 ka 14C

60 ka U/Th 

74 ka U/Th 

51 ka, 48 ka U/Th 

68 ka U/Th 

184 ka U/Th 

350+ ka U/Th 

185 ka tephra

OIS - Inferred oxygen isotope stage

Base of major lake

 transgression

14

13

12

11

10

9

8

7

6

5

4

?

?

?

?

?

?

?

?

North Afton Beach Ridge

Dunn Island sections

Section M06-77

Section M07-147

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

42

44

Bwk?

Possible foresets

Beach gravel and sand

Beach gravel

 and sand

Beach sand

 and gravel

Beach gravel

 and sand

OSL

OSL

OSL

OSL

OSL

OSL

OSL

By/Bk, st II CaCO3

Bwk, st I CaCO3

Delta or beach?

Bt/Bk st II CaCO3

Sand

Sand

Green laminated silt 

 and clay, sand lenses

TEPHRA

Fish bones

Fish bone

EARTHQUAKE

(affects sediment

down to ~23 m)

Oxidized sandy mud

Fish bones

Fault cuts core

Possible fault

Foreset beds

Btk/Bk; st. 1 CaCO3 Btk/Bk; st. 2 CaCO3

 Bk, st. I CaCO3

Lithoid tufa 4 cm thick

 at top; locally to 15 cm

Bk, st. II CaCO3

Bk, st. II CaCO3

Manix core 

rough log

Composite sections from Afton subbasin

FAULTING

EVENT

(affects sediment

down to ~30 m)

EARTHQUAKE

(affects sediment

down to ~17.5 m)

Manix reference section

of Jefferson (2003)

silt and clay

fine sand, siltmed-co sand

gravel

Fluvial X-bedded gravel 

 and sand; upper 3 m is 

 gravel channel fill containing 

 reworked Manix mud clasts

Gravel and sand; 

dominantly volcanics

Playa mud and 

 thin distal fan 

 gravel, indurated

To east contains

 large deformed

 blocks of Manix 

 mud overlying

 sand and mud 

 flood couplets 

LAKE 8c

LAKE 8b

LAKE 8a

LAKE 7a

LAKE 7a

LAKE 7b

LAKE 7b

FAN 8

FAN 8

LAKE 8

LAKE 1

LAKE 2

LAKE 3

LAKE 4

LAKE 5

FAN 1

FAN 2

FAN 3

LAKE 6

LAKE 7b

LAKE 7a

R6

R6

R6

LAKE 6

LAKE 6

LAKE 6

FAN 1-6

U-Th range 

71-138 ka (laminated tufa)

Moderately

 deep lake

Shallow lake

Fluvial and deltaic

Mudflat

Alluvial fan

Buried soil

Afton and Manix

 core explanation

Deposits of shallow lakes, mudflats,

 and moderately deep lakes

Buried soil v = vertisol;

 gw = groundwater carbonate

Schematic composite 

section of Manix 

subbasin (Oviatt)

Fluvial and deltaic

Tufa-coated gravel

Gravel

Sand

Mud

Alluvial fan

?

gw

v

v

v

v

v

A

Tufa coats

throughout

interval

Strat. position

of ~2.5-Ma tephra

at site M07-145

“Interlacustral gravel” of

Meek (1990)

Minimum-limiting age 

range 39.9-49.8 14C ka in Afton subbasin

(several ages)

Age range 31.9-34.7 14C ka in Afton subbasin (two ages)

Age range 25.4-29.6 14C ka in Afton subbasin (several ages)

Age range 20.5-23.1 14C ka in Afton subbasin (several ages)

Meters

26 14C ka 

40 14C ka 

fluvial

cap

several ages

Fan-delta 

deposits at

site M06-135

8 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
Figure 4. Preliminary correlation of lake and fan units; level 

of uncertainty is expressed by solid lines vs. dashed lines and 

queries. Three columns on the left are from the Manix subbasin; 

four columns on the right are from the Afton subbasin. From 

left to right, the first column is from Jefferson (2003), showing 

informal members of the Manix Formation and tentative 

assignments to oxygen-isotope stages (OIS). The second 

column is from unpublished mapping of C.G. Oviatt (Kansas 

State University, written commun., 2007), showing correlations 

to units of Jefferson (2003); UC is upper part of member C, 

and so forth. The third column is a condensed stratigraphic 

section from descriptions of a 45-m-long core acquired by the 

U.S. Geological Survey near the intersection of Manix Wash 

and the Mojave River (fig. 3). The four columns on the right are 

composite and individual measured sections (see Reheis and 

Redwine, in press, and this guidebook, fig. 5). Note that the five 

oldest lake units in the Manix subbasin are absent from the 

Afton subbasin.

and (or) after OIS 6, and probably discharged episodically 

eastward into the Soda Lake basin. During these discharges, the threshold at the head of the present-day Afton 

Canyon was gradually incised to about 543 masl. 

3. During subsequent highstands of OIS 4(?), 3, and 2, the 

lake repeatedly rose to about 543 masl (Meek, 1990, 

2000; Reheis and Redwine, in press), maintained there in 

part by an internal shallow threshold between the Manix 

and Coyote Lake subbasins (Meek, 2004) and perhaps in 

part by the eastern threshold at the head of Afton Canyon. 

4. This eastern threshold failed sometime after about 21 14C 

ka and Afton Canyon was cut quickly enough that ages 

of soils on inset terraces are not distinguishable (Reheis 

and Redwine, in press); no recessional shorelines younger 

than this have been recognized.

Because the stratigraphic records preserved in the Manix 

and Afton subbasins are dissimilar due to the integration event 

(no. 1 above), we have developed a new preliminary system 

of nomenclature for the interbedded lake and fan deposits that 

differs from that of Jefferson (2003). This preliminary stratigraphic system may need to be modified in the future should 

more numerical dating show that our current correlations are 

incorrect. In the interim, the sequences are simply numbered 

upward as follows: L indicates lake deposits, F indicates fan 

deposits, and R indicates river or fluvial deposits. F1 is the 

oldest fan unit in the Manix subbasin and is equivalent to 

Jefferson’s (2003) informal “Member A” of the Manix Formation; L1 is the oldest lake unit. L1 through L5 and the underlying and interbedded fan units (locally marked only by soils 

or unconformities) are exposed only west of Buwalda Ridge 

in the main Manix subbasin. L6 was the first lake to enter 

the Afton subbasin, and the fluvial deposits that locally mark 

the incursion of flood water from upstream are referred to as 

R6. In some places, these units are subdivided with subscript 

letters, for example, L7a (older) and L7b (younger). Figure 4

shows a very preliminary suggested correlation between the 

two subbasins and Jefferson’s informal member designations of the Manix Formation. By this scheme, the youngest 

lake event is L8c, which is the OIS 2 lake for this basin. For 

those who wish to compare these units with those of regional 

surficial-map units used by Redwine (U.S. Geological Survey, 

unpublished mapping) in her map of the Afton Canyon area, 

see table 1.

In the following road log and field trip guide, we provide 

GPS locations for all stops in UTM units, NAD83 coordinate 

system. Altitudes are in meters above sea level (masl); most 

have been differentially corrected.

Pre-Trip Day (Optional): Early Incision 

of Lake Manix Threshold and Flooding 

of Afton Subbasin

YOU MUST RIDE IN A 4WD VEHICLE FOR THIS 

DAY!!! PLEASE CARPOOL!! Only undertake this if you 

are reasonably fit and accustomed to hiking in rough, rocky, 

sometimes steep terrain. We will start from Calico Early Man 

Site at 8 A.M., or if you prefer, you can meet us on the southeast side of the Afton (Dunn) exit at 8:30 A.M. The round-trip 

drive is about 65 miles. Follow the road log for Day 1 to Mile 

26.0, at the north edge of the north Afton beach ridge. Continue straight ahead. The back (east) side of the beach ridge is 

in view to the southwest.

26.4 F653 route sign. Ridge to the right and bouldery hillslopes to left are composed of Tertiary(?) fanglomerate.

26.5 Greenish-tan sands to left in arroyo cut contain shell 

fragments that yielded a 14C age of 20,810±130 yr B.P. Yet the 

sands lie at an altitude of 558 m, 15 m higher than well-preserved beach barriers that yielded similar ages. We interpret 

these as eolian sands and shell fragments reworked from the 

youngest highstand of Lake Manix, part of extensive sheets 

and ramps of sand in the Mojave River sand-transport corridor. 

26.7 Road crosses over the fanglomerate ridge; wavecut 

terraces on Shoreline Butte are obvious at 1:00. Varnished 

surfaces in the middle ground and sloping toward north Afton 

beach ridge are the Afton F7 unit (F7 is the “interlacustral 

gravel” of Meek, 1990).

27.3 TURN RIGHT at fork and prepare to cross sandy wash. 

Engage 4WD before descending into the wash—we don’t 

want to waste time digging or pulling your vehicle out! On 

the other side, bear right along the mountain front, and right 

again past tailings pile on an indistinct track heading for 

Shoreline Hill. STAY IN 4WD!

Pre-Trip Day (Optional): Early Incision of Lake Manix Threshold and Flooding of Afton Subbasin 9
Table 1. Tentative correlation of J.L. Redwine’s units (U.S. Geological Survey, unpublished mapping) to ongoing mapping 

and interpretation of Lake Manix stratigraphy.

Approximate OIS assignments based on radiocarbon ages (this 

guidebook), U-series ages reported by Meek (2000) and preliminary ages of J.B. Paces (U.S. Geological Survey, written commun., 2007), surficial mapping, and soil development

Nomenclature used in surficial geological map of Afton Canyon (Redwine, 

U.S. Geological Survey, unpublished 

mapping)

Nomenclature used 

in this guidebook

~OIS 2 Qya (Qya4 through Qya1) Not discussed

OIS 2 to OIS 3 Qylg and Qylb

Lake 8a

Lake 8b

Lake 8c

OIS 3 to OIS 4? Qia1 Not discussed

OIS 4(?) Qilg1 Lake 8a?

OIS 4(?) to OIS 5(?) Qia2 Fan 8

~OIS 5 and 6

~OIS 6 and 7(?) Qilf2 Lake 7Lake 6

27.9 Road dead-ends on a sandy surface with old timbers 

scattered about. Park anywhere and prepare for a minimum

4-hour hike; take plenty of water and lunch or major snacks.

Walking Tour of Lake Manix Overflow Point and 

Highstands

Cross the wash headed southwest toward the left edge of 

Shoreline Hill; follow the remains of the jeep trail at first. In 

~150 m, pause on a sand ramp for overview of stratigraphy 

and a panoramic view from Shoreline Hill to the north Afton 

beach ridge. Downslope are extensive varnished surfaces 

of F7 overlying greenish deposits of L6, which locally have 

thick tufa coats on clasts at the base, especially near Shoreline 

Hill where tufa cementation is so extensive it has formed an 

exhumed surface that is one of the apparent shorelines on the 

hill. These deposits overlie a reddish zone that is F7, which in 

turn overlies fan-delta deposits of L6; we will see these better 

on Day 1, Stop 1B. This same sequence can be found in the 

north Afton beach ridge, except that there are three subunits 

of L8 that overlie F7. L8 deposits are scarce to absent east of 

the beach ridge. F7 passes beneath the beach ridge forming 

a continuous planar surface coextensive with the one we see 

below us; these relations imply that the beach ridge was built 

entirely during L8 time.

Move east toward Shoreline Hill, dipping in and out of 

the nearshore sands of L7. Ascend to a saddle on the east side 

of the hill, composed of varnished pavement (with remnants of 

bar and swale morphology) that is probably a relict F8 surface. 

Follow this surface down to the southwest. Here the fan gravel 

overlies two sand units.

Stop 1 

At site M06-156 (559072 E, 3877340 N), two units of fan 

gravel separated by a buried soil form the top ~1 m of the outcrop. These are underlain in sequence by 1.5 m of pale, wellbedded medium sand with interbedded minor gravel; 1.5 m 

of poorly exposed angular fan gravel; ~3 m of interbedded, 

moderately sorted sand and gravel fining down to mostly wellbedded, oxidized sand, locally with steep northeast dip; and 

bouldery angular fan gravel that pinches out upslope against 

bedrock. The basal sand unit locally has ripple cross-bedding 

with heavy-mineral laminae. A differentially corrected GPS 

altitude at the top of the upper sand unit is 551.2 masl. These 

two sand units are inferred to be two units of L7 nearshore 

sands representing a lake level as much as 8 m higher than the 

well-known 543-m barrier beach deposits. The multicolored 

badland-type hill due west consists of L7/F7/L6 (fan-delta 

deposits)/F1-6 with prominent paleosols. The extreme badland 

topography to the west-southwest is Tertiary(?) fanglomerate 

exposed along the trace of the Manix fault.

Take the sheep trail west down to the arroyo floor, then 

climb to the top of the steep mountain face due north. Once on 

top, catch your breath and look at the view. The upper part of 

the south wall of Afton Canyon runs from east to southwest. 

In the foreground, an inactive fault parallel to and north of the 

Manix fault strikes northeast through this valley (Redwine, 

U.S. Geological Survey, unpublished mapping). To the west, 

on the south side of the Mojave River, green beds of L7 are 

prominent. Near the river, they overlie (in sequence) a thin 

gravelly facies of L6, the fanglomerate of Cady Mountains 

(gray fanglomerate of Ellsworth, 1932, but it looks more 

brown), and the fanglomerate of Cave Mountain (brown fanglomerate of Ellsworth, 1932, but it looks reddish). Strath terraces are visible along the river to the west. To the northwest 

10 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
stretches the back (east) side of the north Afton beach ridge. 

Cave Mountain looms to the northeast.

Descend in a southerly direction into the valley and climb 

the red ridge ahead. Bear right along the ridge crest, and then 

take aim on two small bumps on a gentle ridge below and 

east of a rounded hill, bearing S25°W. A steep arroyo cut in 

bedrock bounds the east side of this ridge. Once down the hill 

partway, you can use a sheep trail that leads directly to the 

little bumps.

Stop 2

The two small bumps consist of interbedded alluvial-fan, 

colluvial, and fluvial deposits overlying metamorphic rocks; 

the following is summarized from detailed descriptions in 

Reheis and Redwine (in press) and Redwine (U.S. Geological Survey, unpublished mapping). Site JR04CM-87 (558726 

E, 3876135 N) on the west side, at an altitude of 537.7 masl, 

about 130 m above the present river channel, exposes nearly 

6 m of locally derived alluvial-fan deposits and contains an 

interval of fluvial gravel, including well-rounded volcanic and 

igneous clasts and quartz-rich sand (fig. 14 of Reheis and Redwine, in press). The outcrop comprises 18 depositional layers 

divided into 13 units that are separated and defined by buried 

soils (b1, b2, and so forth; table 2 of Reheis and Redwine, in 

press) overlying bedrock. Reworked fluvial deposits of unit 

5 contain lacustrine ostracodes (R. Forester, U.S. Geological Survey, written commun., 2005) typical of those found 

throughout Manix Formation sediments (Steinmetz, 1987); 

thus, it is probable that these fluvial deposits originated by 

discharge from Lake Manix. A similar but thinner stratigraphic 

sequence is preserved at site JR04CM-88 on the east side.

We estimate the age of the fluvial deposits by summing 

the normalized profile development index (PDI) values of the 

overlying soils (surface soils and soils b1-b5, tables 2 and 3 

of Reheis and Redwine, in press). This yields a value of 0.24, 

much larger than the PDI values of 0.01–0.05 that are typical of soils formed on last-highstand Lake Manix barriers 

(L8 deposits); however, these soils and PDI values are difficult to compare due to the vastly different parent materials, 

deposit thicknesses, and effects of ground water. In addition, a 

summed PDI value of 0.04 for soils b6–b9 that formed on the 

four fluvial units implies a lengthy period of fluvial aggradation with short episodes of stability. Cumulatively, these soils 

and the complex sequence of deposits represent a significant 

period of intermittent deposition, during which the surrounding landscape must have been stable with no rapid incision 

forming an adjacent Afton Canyon. The presence of four 

fluvial units separated by weak buried soils implies a stable, 

slightly aggrading river at this time. A sample from the fluvial 

deposits (fig. 14 of Reheis and Redwine, in press) yielded ages 

of 19.9±2.2 ka (IRSL, infrared stimulated luminescence on 

feldspar) and 15.0±1.5 ka (OSL, blue-light optically stimulated luminescence on quartz; S. Mahan, U.S. Geological Survey, written commun., 2006). The complex soil-stratigraphic 

sequence above the sampled unit, the large PDI values, and the 

poor preservation of the entire deposit suggest these luminescence ages are much too young. We suspect that disequilibrium in the dose rate caused by fluctuating ground water 

has affected the OSL ages. Comparison of the summed PDI 

value (0.24) to those of dated soils elsewhere and to those of 

older shorelines in the Lake Manix basin suggest these fluvial 

deposits represent discharge from Lake 7 (OIS 6–5?) or the 

earliest phase of Lake 8 (OIS 4?–3).

Inset below the 538-m fluvial and alluvial-fan deposits 

are two nested strath terraces sloping gently and stepping 

down toward the canyon rim. These terraces are similar in 

appearance and preservation to the straths below the canyon 

rim, and bear a similar suite of rounded clasts. The lower 

terrace slopes down from about 510 masl to about 490 masl 

at the rim (site JR04CM-84). A shallow pit excavated on 

the best-preserved surface exhibited weak soil development, 

similar to soils developed on the lower terraces. We interpret 

these high strath terraces to represent initial incision of the 

Lake Manix threshold at ca. 25 cal ka (Reheis and Redwine, in 

press).

Cross to the eastern ridge to descend to these lower strath 

terraces and a spectacular view of Afton Canyon. From here 

you can return to the cars the way we came, or you can take a 

different route if you are interested in seeing more evidence of 

shorelines higher than 543 m. However, please do not attempt 

this route if you are not agile or if you are prone to vertigo!

To continue the loop, backtrack upslope on the west ridge 

of fluvial deposits, then veer sharp left (southwest) along the 

flank of the dark hill, angling uphill (no need to go to the top, 

however). Cross a small gully to a rugged small red knob 

and regroup. Note that from here, looking southeast, the high 

fluvial remnants are visible, and to the northwest, just 25 m 

away, is a somewhat lower bench than the ridge we stand on. 

That bench is just above the easternmost remnant of Lake 

Manix deposits and represents a higher level, when the lake 

was at times discharging through the outlet whose deposits we 

just examined, long before Afton Canyon was cut. Thus, we 

are standing just above what was probably the lake threshold. 

Descend to that little bench (note the many bighorn sheep bedding places around here), and if you wish, very carefully (due 

to the steep outcrop and exposure) look at the small outcrop 

of probable beach sands exposed just below it (site M06-159, 

558537 E, 3876617 N), at an altitude of 544.1 masl. We are 

looking down on a tufa-coated terrace (site M06-50; 558541 

E, 3876690 N) at 530.7 masl. Preliminary U-series ages from 

tufa coats at this site are about 220 to 150 ka (J. Paces, U.S. 

Geological Survey, written commun., 2007) and thus may 

represent lake phase L6 and perhaps L7. Carefully descend to 

that terrace on a steep treacherous sheep path, then intersect a 

sheep highway that runs from here all the way back to Shoreline Hill.

Halfway to the next bench, look ahead at two wave-cut 

terraces. The lower, at a level below the trail on which we 

stand, has tufa-coated clasts at the base overlain by 3–4 m of 

lake sand banked against a steep riser or shoreline angle cut in 

bedrock. A higher shoreline angle and bench, above the sheep 

Pre-Trip Day (Optional): Early Incision of Lake Manix Threshold and Flooding of Afton Subbasin 11
trail on which we stand, has a thin mantle, ~1 m thick, of possible lake sand buried by colluvium. The altitude of the bench 

descending from the lower shoreline angle is 530.7 masl; the 

highest outcrop of greenish sand on the upper bench is 544.6 

masl. The sheep trail crosses the bedrock gulch ahead by 

climbing above the higher bench.

Cross the next gully and climb to the next lake bench. 

Here the sheep trail forks. The high trail climbs gradually, then 

eventually drops back to the arroyo floor just below Stop 1. 

The low trail drops northwest into a small valley, then climbs 

up through deposits of F7 and L7 (the little green-capped hill 

visible from here), then up a rocky arroyo and back to Stop 1.

From the saddle east of Shoreline Hill, either return to the 

cars via the up-and-down route we used in the morning, or for 

more lake stratigraphy and less scrambling, descend an arroyo 

to the northwest, then back up a northeasterly trending fork to 

the vehicles.

If you have seen enough for one day, retrace route back 

to camp via I-15. If you would like to continue to the sites at 

Stop 3A to see evidence for a very large flood that emanated 

from Lake Manix when it was confined west of Buwalda 

Ridge and filled the Afton subbasin with water for the first 

time, we will drive the Mojave Road (the dry riverbed)—4WD 

also required. Alternatively, those interested can take a look at 

soil development on two more fluvial terraces inset into Afton 

Canyon near the Afton Canyon campground (Stop 3B).

To go to Stops 3A or 3B, retrace route to Afton Canyon Road.

29.8 TURN LEFT (south) on Afton Canyon Road. For geology along this stretch, see notes in road log for Day 1 between 

Stops 1 and 2, Mile 27.1 to 27.8.

30.8 TURN RIGHT AND ENGAGE 4WD at fork near railroad bridge (BLM road sign) to go to Stop 3A. BEAR LEFT 

on main road to Afton Canyon campground for Stop 3B. 

Directions To Stop 3A:

30.9 Pass under the railroad bridge and continue straight 

through a gate on F726 (last car please close gate). At 31.0, 

cross a shallow-water muddy wetland (it has a fairly firm 

sandy bottom) and continue straight. Perennial spring discharge exists at the head of Afton Canyon because the sands 

of the Mojave River aquifer terminate here against indurated 

Tertiary fanglomerate and bedrock, forcing the ground water 

to the surface locally.

31.5 The bluff on the left (9:00; site M06-17) exposes, from 

bottom to top, reddish fanglomerate of Cave Mountain; 15 m 

of tan to gray fanglomerate of Cady Mountains capped by a 

buried soil (Bwk horizon); 1.4 m of gray, moderately bedded, 

sandy cobble granitic gravel; 2.3 m of well-bedded pebble 

gravel interbedded with coarse, medium, and muddy fine sand 

that displays long sweeping east-directed crossbeds; and 0.9 m 

of carbonate-cemented coarser gravel capped by brown Cady 

Mountains-derived fan gravel. Greenish well-bedded sand 

and muddy sand underlie the capping fan gravel to the south. 

These deposits are interpreted to be derived from the influx of 

water from Lake Manix upstream. 

We are now passing onto the dry sandy bed of the Mojave 

River. If you have not driven on loose sand before, keep your 

speed steady, do not drive too slowly, and stay on the tracked 

part of the sand—rude surprises await the unwary driver 

in the loose sand on either side! To accelerate from a stop, 

apply power gradually and smoothly to avoid digging in your 

wheels. Finally, never make a sharp turn in loose sand; turn 

gradually.

31.7 Strath terraces postdating the draining of Lake Manix on 

the left, and on the right at 2:00 near the railroad.

32.4 Mojave Road follows main channel traversing toward 

the north side of the valley floor. 

32.9 Active sand dunes blanket the north valley wall on the 

right. The gravel-capped reddish bluffs straight ahead are the 

location of Stop 3A. 

33.0 Veer to the right onto the gravel bars, just another 

0.1 mi. Park in this area; do not attempt to drive close to the 

bluffs! The gravel bars here provide a stable surface and an 

easy place to turn around. Take water; the main deposits of 

interest are within a few hundred meters.

Stop 3A

The bluffs are underlain by a cliff-forming unit, about 10 

m thick, of brown playa deposits composed of poorly sorted 

sandy mud and interbedded thin fan-gravel lenses. Above this 

is an abrupt change to a gentler slope. This slope is underlain 

by a section (fig. 5; site M07-147; 551913 E, 3877557 N, 

463.0 masl) of horizontally bedded flood couplets composed 

of medium sand overlain by well-sorted, laminated silt and 

then clay (lacking sand grains, unlike the playa muds below). 

The uppermost mud displays soft-sediment deformation. This 

in turn is overlain by similar sand, silt, and clay layers, but 

they are dipping as much as 20° eastward. The deposits are 

capped by interbedded coarse sand and pebble-cobble beds 

dipping 10° eastward. The clasts are dominantly volcanic 

rocks similar to those exposed in Buwalda Ridge (the dark 

hump on the western horizon). 

Moving to the west along the same outcrop (site M07-

148; 551889 E, 3877524 N, 464.7 masl), the flood couplets 

and the steeply dipping sand, silt, and clay unit are still present, but the latter are dipping less steeply, and the overlying 

gravel contains a rip-up clast of green Lake Manix mud. Yet 

farther west, the dipping unit is replaced by a contorted zone 

of green sand, silt, and mud (site M06-66, 551871 E, 3877498 

N, 463.9 masl). 

We interpret the flood couplets to represent initial discharge from an overflowing Lake Manix that, at the time, was 

12 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
Figure 5. Sedimentology and stratigraphy of measured sections along the Mojave Road. Sites M07-147 and M06-100 will be visited at Stop 3A on 

Site M05-54 will be visited at Stop 3 on Day 1.

500

495

490

485

480

475470465

460455450

MASL

WEST 

Transect, North side Mojave River west from Dunn Wash

(sections are hung from topography; altitude and thicknesses at same scale)

Site M06-77

(SW of Dunn; S-facing river bluff) 

(Abney level and tape)

Well bedded and sorted beach sandIndurated fanglomerate with calcic paleosols; thickness not measured

Pebble-cobble gravel fining upward to crossbedded fluvial sand; volcanic clastsRipple X-bedded to flat-bedded well sorted med-fi sand and greenish muddy sand

Interbedded X-bedded pebble-cobble gravel and pebbly sand; channeled into sand below as much as  1-2 m; contains clasts of green Manix mud

Largely covered; locally buried by slumped green muds from cliffs above; in places well bedded lake sand and mud are exposed

Angular-subangular fan gravel; Alvord Mtn. lithologies; bears weak soil

Contiguous upward with Dunn Island section; ~14 m interbedded green mud and lacustrine sand

Site M06-74

(SSW of Dunn; W-facing river bluff) 

(Abney level and tape)

Crossbedded coarse gravel (to boulders), fine gravel, and sand; volcanic clasts

Crossbedded pebble gravel grading up to sand; erosional basal contact; volcanic clasts Inset young strath terrace

Pale tan fi-med sand; ripple X-bedded at base; poorly sorted w/ carb. nodules at top Reddish sand, weakly bedded

Weakly indurated, moderately sorted, interbedded pebble-cobble gravel and sand; rounded cobble bed at base; lithologies similar to fanglomerate below

Indurated, reddish NW-dipping fanglomerate with calcic paleosols

Site M06-70

(due south of Dunn; S-facing river bluff) 

(Abney level and tape)

Crossbedded coarse gravel (to boulders), fine gravel, and sand; volcanic clasts

Crossbedded pebble gravel and sand; volcanic clasts and rip-up clasts of brown mud

Upward-fining fine sand to massive pale silt to brown mud w/carb. nodules

Non-calc. white fi-med sand;  soft-sed. deformation

Tan massive sand; carb. nodules

2 fining-upward gravel to sand beds

Approx. 10 m of indurated playa and distal-fan deposits

Site M06-100

(south of Dunn; upslope in tributary wash) 

(estimated)

Interbedded vco sand and gravel; abundant volcanic clasts; contains rip-up clasts of green Manix mudPlaya/distal fan: Indurated, brown sandy mud interbedded with thin  sand and gravel

Flood couplets?

Approximately 3 kilometers west to east

Sites M05-54 a

(east of Dunn; S 

(tape measure an

Arkosic med-c

sweeping pla

abundant car

Poorly sorted  atop disconf

Horizontally be

locally with th

Thinly bedded f

capped by cem

 bed; locally co

Poorly sorted p

Site M07-147

(southeast of Dunn; river bluff) 

(tape measure)

Interbedded vco sand and grave abundant volcanic clasts; beds  dip 10o E; cut into unit below; lo

contains clasts of green Manix 

Interbedded blocky mud, sand and silt, dipping 20oE; rip-up blo

6 flood couplets: each couplet g up from arkosic fi-co sand to si

Playa/distal fan: Indurated, brown sandy mud interbedded with thin  sand or gravel

LAKE 7

LAKE 6

R6

R6

R6

R6

R6

FAN 1-6

FAN 7

“Mayhem terrane”: chaotic mix of Manix-derived bedded sand, silt,  and green mud, and brown blocky mud (from flood couplets?)
confined to the area west of Buwalda Ridge; this discharge 

was transporting sediment eroded from the playa floor of the 

Afton subbasin. The deformed green sediments and the steeply 

dipping beds represent blocks of the Lake Manix deposits 

transported as much as 8 km, as well as more locally derived 

flood-couplet deposits, largely intact, brought down by flood 

water when the barrier at Buwalda Ridge failed catastrophically. The overlying coarse sand and gravel (R6) represents 

the establishment of through-flowing drainage emanating from 

the Manix subbasin upstream (in other words, a proto-Mojave 

River). This fluvial deposit elsewhere grades up into well-bedded lacustrine sand and silt of L6, the first lake in the Afton 

subbasin (Stop 3, Day 1; fig. 5). In the last outcrop 

we will examine, ~250 m to the west (site M06-100; 

551658 E, 3877284 N, 466.8 masl), a similar stratigraphy is well exposed (after much shovel work). 

This outcrop displays a distorted assemblage of large, 

semi-intact, highly deformed, beach sand, green 

mud, and blobs of brown clay. These blobs are either 

paleosols formed on Manix muds or the early flooding 

clays, distinguishable from the underlying playa mud 

because the paleosols and (or) flooding clays are well 

sorted with no sand grains.

We will not go west of this outcrop, but if you 

wish to see more outcrops on your own someday, 

they are easily accessible along the Mojave Road. 

The unit of flood couplets gradually thickens and 

coarsens over a distance of 2 km (fig. 5) to become an 

entirely fluvial section of sand and pebble gravel with 

crossbedding indicating eastward flow; the overlying 

coarse sand and cobble gravel unit continues and 

locally contains rip-up clasts of green mud. Locally, 

however, the upper portion of the finer-grained 

fluvial beds is truncated by an inset strath terrace. In 

the westernmost outcrops (site M06-77; 550217E, 

3876485N, 473.0 masl), the coarse sand and cobble 

unit is directly overlain by well-bedded and wellsorted granitic sand representing the L6 deposits in 

the Afton subbasin (we will see these at Day 1, Stop 

3). This sand locally contains one or more wedges 

of fan gravel thickening to the north, and is overlain 

by a similar thin fan gravel, locally bearing a weak 

soil (Bwk horizon). This final fan gravel is directly 

overlain by beach sand and thick deposits of green 

muds representing L7 in the Afton subbasin (fig. 3).

Directions to Stop 3B:

Return to the directions from Stop 2 to Stop 3 of Optional 

Pre-Trip Day at Mile 30.8. 

30.8 CONTINUE STRAIGHT for approximately 0.8 

mi on the main road which leads to the Afton Canyon 

campground and park. This stop will likely take an hour or 

two at most and involves light to moderate walking (see 

map, fig. 6). 

Stop 3B

The fluvial terrace sites near the Afton Canyon campground are the upper and lower terraces within a flight of 

about 10. These surfaces include an intermediate level of 

canyon incision (site JR04CM-95; 556872 E, 3877730 N, 

~463 masl) and one of the lowest terrace remnants within 

Afton Canyon (site JR04CM-78; 557270 E, 3876966 N, 

~439 masl). Soil development differences between these locations and the uppermost fluvial terrace seen at Stop 2 (site 

JR04CM-84) are minimal, do not correspond with elevation 

differences, and likely represent the natural variability of soil 

development within fluvial deposits of similar ages. These 

deposits and soils are discussed in Reheis and Redwine (in 

press; see figs. 8, 9, and 11 therein).

Walk to the northeast end of the developed campground 

along the dirt road with campsites. Head past the farthest 

campsite and through the bushes for ~0.25 mi towards a 

narrow V-shaped canyon, bearing ~N60°E. Here, at the 

upstream end of this flight of fluvial terraces, strath terraces 

inset below basal Lake Manix sediments track incision to 

Figure 6. Map of Afton Canyon campground and area of Stop 3B, 

Pre-Trip Day.

14 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
within about 12 m of the modern Mojave River. Overlying 

these strath terraces are 20–25 m of fluvial deposits, 

mudflows, and alluvium. We will climb up this deposit and 

glance at the soil development of the overlying Qya4 fan 

at site JR05D-198 (fig. 6; 556983 E, 3877763 N); this soil 

has an Av/Bwk/Ck profile with maximum stage I carbonate 

morphology and postdates much of the canyon incision 

(fig. 11 of Reheis and Redwine, in press). 

We will then walk to the uppermost strath terrace within 

this terrace flight (fig. 6; site JR04CM-95; 556872 E, 3877730 

N; figs. 8, 9, and 11 of Reheis and Redwine, in press) and 

examine the soil profile. Next we will proceed to a nearby site 

where Shannon Mahan and David Miller (U.S. Geological 

Survey) sampled a sand sheet that overlies a channel-shaped 

gap just southeast of site JR04D-95 (Miller site M05SM-004; 

556939 E, 3877684 N) for luminescence analyses. The age 

of the OSL analysis on quartz is 12.6±1.2 ka and ages from 

IRSL on feldspars are 13.1±0.71 and 13.6±0.94 ka (S. Mahan, 

U.S. Geological Survey, written commun., 2006). This eolian 

deposit represents burial after the cutting and filling of this 

channel and likely pre-dates subsequent piracy and abandonment of these surfaces. 

We will then walk about 0.5 mi to the southeast, down the 

flight of terraces, and look at the soil development in one of 

the lowest fluvial terraces inset into the canyon (site JR04CM78; 557270 E, 3876966 N; figs. 8, 9, and 11 of Reheis and 

Redwine, in press). We will discuss what these soils, flights of 

terraces, and luminescence ages may mean in terms of timing 

and rate of incision of Afton Canyon. 

Retrace route down the Mojave Road to the Afton Canyon Road (from Stop 3A) or upstream from the campground 

(Stop 3B) and return to camp via I-15.

Day 1: Afton Subbasin of Lake Manix 

and History of Afton Canyon

We will start from Calico Early Man Site at 7:30 A.M. 

(this will be the longest day); if you have not checked in and 

paid the previous night, please plan to arrive a half-hour early 

to pay the field trip fee and pick up a guidebook. The drive 

this day is about 60 miles round trip. Access to the first stop 

requires a high-clearance vehicle and parking space is limited. 

Please carpool as closely packed as possible from Calico Early 

Man Site, and be aware that at least 10 miles of the driving 

today will be on gravel and sand of lightly graded roads; leave 

the sedans behind!

0.0 Exit the gate at the Calico Site; set mileage to 0. We are 

driving across Holocene fan deposits, all derived from the 

nearby Yermo Hills. To the south, in the middle distance, the 

fluvial plain of the Mojave River forms a broad expanse. The 

Mojave River itself is marked by dunes of eolian sand derived 

from the river bed.

0.5 Cross riblets of Pleistocene fan deposits, marked by dark 

varnish, desert pavements, and a flat surface.

0.6 Left turn (south).

1.5 Fan merges with the Mojave River fluvial plain.

1.7 Right turn onto a paved road. Pass gas stations and the 

Minneola Store.

2.2 Cross I-15 freeway. The hills on the south side of the 

freeway are composed of folded gravels of the Mojave River 

(Reynolds and Kenney, 2004) that we will visit on Day 2. The 

hills mark an uplift at a restraining bend in the Calico fault 

(Dibblee, 1992).

2.3 Turn left to enter the freeway eastbound. Reset odometer 

to 0.

0.0 Eastbound freeway entrance. Much of the drive for the 

next dozen miles will be along the very flat Mojave River 

fluvial plain of latest Pleistocene age. Dated charcoal from 

fine-grained sediment (also bearing shells and bones) from 

excavations a few kilometers west of here yielded ages from 

12.8±0.9 to 9.05±0.35 14C ka (Reynolds and Reynolds, 1985).

0.3 The Toomey Hills are visible at 10:00. The light-colored 

Miocene Barstow Formation contains a record of large lakes in 

this region (Reynolds and others, 2003; Reynolds and Woodburne, 2002), which were probably the aftermath of widespread extensional tectonism (for example, see Glazner and 

others, 1994). The linear front of the Toomey Hills is probably 

caused by faulting and uplift along the approximately eaststriking Manix fault, a structure that played an important role 

in the evolution of Lake Manix.

3.0 Road cut on your left displays a spectacular exposure of 

the Manix(?) fault and associated folds. The main fault lies 

south of the white beds of the Barstow Formation. Faulted 

onto the Barstow Formation are gravels of unknown age, on 

top of which lie fluvial gravel of the Mojave River (Reynolds and Kenney, 2004). All of the gravels are folded and the 

Mojave River gravels lie well above the surrounding plain, 

indicating at least 8 m of uplift locally.

3.5 At 1:00 to 2:00 is Harvard Hill. It is composed of Miocene gravels and the Barstow Formation. Along its east and 

southwest sides, Mojave River gravels and gravels of Lake 

Manix form gentle slopes. We will visit some of the Lake 

Manix exposures on Day 2.

5.5 Ground on both sides of the freeway rises to the east, 

approximately where the Dolores Lake fault of Meek (1994) 

lies. Displacement along this fault apparently uplifts both 

Mojave River gravels and underlying Miocene strata, and 

Day 1: Afton Subbasin of Lake Manix and History of Afton Canyon 15
therefore its latest offset may be Holocene in age. On the 

left is Dolores Lake, an example of a common perversion of 

deserts. The waterpark has never been seen in operation by us; 

rumors circulate of a new housing development at the lake.

7.5 Harvard Road exit. We will exit here for Days 2 and 3.

8.7 Miocene(?) gravel and fine-grained sediment in hills on 

the left are generally similar to those in the Toomey Hills, suggesting that the hills represent uplift along an unknown fault.

10.0 At 8:00 to 9:00 on the left is the broad divide between 

the Manix subbasin, in which we are driving, and the Coyote 

Lake subbasin to the northwest. Notice how flat the divide is. 

Much of the divide is underlain by a thin mantle of Mojave 

River fluvial sediment on Miocene deposits (Meek, 1994). At 

9:00 to 10:00 lie the Alvord Mountains, which expose Mesozoic granitoids on the left with a prominent white streak of 

Paleozoic marble (Miller and Walker, 2002), and dark volcanic 

rocks on the right. The white rim of gravels in the distance on 

the right side of the mountains is Pliocene in age (Miller and 

Yount, 2002), and nicely marks vertical tectonics of the area 

since Pliocene time; it is domed up on the north side of the 

Alvord Mountains but sags down into the Coyote Lake basin 

on the west side of the Alvord Mountains.

11.0 Manix Wash overpass. Lake Manix muds and sands are 

exposed widely to the south.

13.6 At 2:30 is Buwalda Ridge, the west end of which we 

will visit on Day 3; it is informally named for J.P. Buwalda 

(1914), a paleontologist who first recognized the lake beds. 

The divide between the Manix and Afton subbasins in Lake 

Manix is located on the far side of the ridge, in an area now 

occupied by the Mojave River. Buwalda Ridge is an uplifted 

ridge of Pliocene fanglomerate that is intensely faulted on 

the south by shear along multiple strands of the Manix fault 

(McGill and others, 1988). During its earlier history, Lake 

Manix was apparently confined to the area upstream (west) of 

Buwalda Ridge, that is, the Manix, Troy Lake, and probably 

Coyote Lake subbasins. The lake entered the Afton subbasin 

downstream (east) by overtopping or by sapping through the 

divide, abetted by sheared zones along the fault. Later today 

(Stop 3) we will see evidence for the first lake in the Afton 

subbasin, which followed a catastrophic flood originating from 

the vicinity of Buwalda Ridge (Pre-Trip Day, Stop 3A). 

15.0 Field Road exit. Pliocene(?) gravels are deformed into 

a broad fold and are exposed in freeway road cuts as eastdipping strata. These gravels differ from those on Alvord 

Mountain by having a different clast assemblage. On the 

north side of the hills we are driving across, a linear front is 

interpreted as fault-controlled by Phelps and others (in press), 

and that inferred fault is co-extensive with the Cave Mountain 

fault cutting Lake Manix sediment in the Afton subbasin 

(fig. 2), suggesting that the fault system has been active in the 

Quaternary.

16.0 At 2:30, dark blocks at the low point in the valley are 

cuts along the south side of the Mojave River channel, exposing pre-Lake Manix deposits. From here to Afton Canyon, the 

river has incised through the Manix lake beds into underlying 

valley-fill deposits. The Cady Mountains lie in the distance to 

the south.

17.4 We are crossing a bridge over an arroyo that cuts into 

the uppermost, youngest lake deposits in the Afton subbasin.

18.7 Rest area exit. Potable water is available here at spigots 

next to the handicapped parking spaces. A beach deposit is 

preserved above the rest area on the north side of the freeway.

19.5 The mountain on the left has faults in old gravels near 

its southern base; these faults may have Quaternary offset 

because they align with others that cut Lake Manix deposits.

19.8 At 2:30, prominent green outcrops across the railroad 

tracks on the right are the “Dunn Island” area. They consist 

of sands and muds of L7, the second lake phase in the Afton 

subbasin (fig. 4). Beach and nearshore sands in the middle of 

the outcrop grade shoreward into fan deposits bearing a weak 

buried soil, indicating a notable fluctuation in lake level during 

the time represented by this outcrop. Sediment analyses by 

Jordon Bright (Northern Arizona University, written commun., 2007) suggest that the lower subunit commonly contains 

gypsum crystals but no fish bones and thus probably represents more saline lake water, whereas the upper subunit lacks 

gypsum and has many fish bones, and thus represents fresher 

water.

22.3 Cross the informally named Dunn Wash, where thick 

L7 green mud is capped by varnished F8 surfaces (Fan 8, 

exhumed) overlain by L8 sand and mud.

22.9 Take the Afton exit, which climbs to the L8 (late Pleistocene) highstand barrier beach.

23.2 TURN RIGHT (south) on the barrier beach crest. Cuts 

along the freeway and in drainage channels show that lagoonal 

deposits capped by weak soils are overlain by beach gravels, 

illustrating multiple lake occupations at this level. Drive south 

along the barrier, which is 543 masl (1,780 ft on the Dunn 7.5’ 

quadrangle).

23.6 The strike-slip Cave Mountain fault cuts the barrier 

beach at this position, although exposures have been destroyed 

by human bioturbation.

23.8 Holocene fan deposits, shed from the hill to the left, lie 

on F8 exhumed gravels (the varnished surfaces downslope) 

that once lay between L8 and L7 deposits. This relation is 

16 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
common in the Afton subbasin, where L8 fines are widely 

stripped away and subjacent alluvial fans are exposed; these 

were deposited atop L7 deposits during a lengthy hiatus and 

possibly lake desiccation. Ellsworth (1932), Blackwelder and 

Ellsworth (1936), and Meek (1990) refer to this fan as the 

“Interlacustral Gravel;” here we refer to it as “Fan 8” (fig. 4).

24.6 The fan surface to the right, past the power lines, bears 

scattered tufa coats on clasts that mark the transgressive base 

of L7; the rest of L7 and younger deposits have been removed.

24.8 Continue past the power line road (graded gravel); prepare to turn left.

24.9 TURN LEFT on the 4WD track. Only high clearance, 

not 4WD, is required as far as Stop 1; 2WD pickups will be 

fine. Leave smaller cars at the parking spot on the right after 

turning onto the road. We are again driving over very thin, 

young fan deposits and occasional patches of L8 gravels overlying F8 and L7 deposits.

25.4 On the right at about 2:00, the whole sweep of the 2-kmlong north Afton beach ridge is visible. We will walk onto that 

ridge for Stop 1A. Green muds exposed across the valley on 

the south side of the Mojave River represent L7. Cave Mountain is visible at 11:00.

25.8 On the left are eroded Tertiary(?) gravels with huge 

boulders of granitoids. At 3:00 is Shoreline Hill; wavecut terraces formed on bedrock are visible.

26.0 Park on the pavement surface to the right of the road, 

OR take a right fork onto a fainter road; it parallels the main 

track and rejoins it to make a one-way parking loop. We will 

take a long walk, so carry water for two to three hours. Walk 

about 0.8 km southward on the linear beach ridge (to GPS 

coordinates 557525 E, 3878741 N) for this overview stop.

Stop 1A

Here we will discuss the general setting and review the 

lake-basin geography, tectonics, stratigraphic scheme, and 

lake-basin history (see Introduction to Lake Manix basin). 

Moving clockwise beginning due east of this point, a palegreen ridge, capped by a thin gravel remnant, consists of 

F8/L7/L6 (fig. 4); we will see this stratigraphy at Stop 1B. 

To the southeast, the same sequence is visible, but the L6 

deposits lie atop a steeply dipping unconformity on older F1-6 

beds (reddish due to buried soils; this is the fanglomerate of 

Cave Mountain). Next is Shoreline Hill, visited yesterday in 

the optional Pre-Trip Day (as if any day on an FOP field trip 

is ever mandatory...), and beyond that hill on the right is the 

overflow point and former threshold of Lake Manix. To the 

south is the Manix fault. To the south and southwest, across 

the river, are green L7 beds over thin L6 fan-delta deposits 

and two fanglomerate units. The upper “gray” fanglomerate, with abundant volcanic clasts, was sourced from the 

Cady Mountains to the south (Ellsworth, 1932; Meek, 1990). 

The lower “brown” fanglomerate, with red and white calcic 

paleosols and a granitic composition, was sourced from Cave 

Mountain to the north. To the west of the beach ridge, most 

of the surfaces are either F7 or F8 fan gravels exhumed from 

beneath younger deposits by erosion, but the perspective from 

here makes discrimination of these gravels difficult.

From the ridge we will drop down eastward through a 

depositional sequence of L8 (three subunits)/F8/L7/L6 fandelta deposits; the main wash at the bottom lies atop, and is 

locally incised into, the Cave Mountain fanglomerate (F1-6). 

We will not examine the details of this section; a similar one, 

but in a fluvial-nearshore setting, will be the focus of Stop 4 

today. Briefly, the L8 deposits seen here include, from top to 

bottom: L8c, ~1.5 m of beach pebbles; L8b, ~2 m of interbedded sand and pebble layers capped by a poorly sorted, 

indurated sand layer that represents a drop in lake level, and 

marked at the base by a gravel layer with thin tufa coats indicating a transgression over the next lower unit; and L8a, ~4–5 

m of mostly medium sand at the top, slightly oxidized, grading 

downward and eastward into greenish fine sand and a few thin 

blocky muds (lagoonal?), underlain by 2–3 m of interbedded 

sand and gravel. This entire sequence rests atop fan deposits of 

F8 and a few meters of nearshore deposits of L7.

At the main wash (GPS point 557700 E, 3878740 N), 

go straight across and up a side wash leading north to see a 

spectacular section of fan-delta deposits of L6 overlain by 

finer-grained L7 deposits (site M06-135; GPS point lies on 

the capping F8 gravels at the top of the exposure, 557724 E, 

3879018 N, 539.0 masl).

Stop 1B

Most of this outcrop (fig. 7) consists of sandy gravel and 

gravelly sand. Although at first glance, these deposits might 

appear to be of fluvial origin, most of them have bedding 

features that indicate they were deposited as an alluvial fanlake interface; we interpret this section as fan-delta deposits 

of lake 6 (L6), the first phase of Lake Manix to fill the Afton 

subbasin. L6 deposits are nearly 7 m thick and are capped by 

0.6 m of alluvial-fan deposits (F7) bearing a weak soil; 2.7 m 

of pale-colored bedded lacustrine silt and sand of unit L7, and 

0.6 m of F8 fan gravel. Gravel clasts in the basal ~1.5 m of L6 

commonly have tufa coats. L6 deposits can be traced up this 

drainage to a ~10–15° dipping line of large boulders, locally 

tufa-coated, that define the transgressive base of L6.

Return to the cars over the top of the fans, or walk back 

to the main wash and follow it upstream back to the cars.

Return to Afton Canyon Road.

27.1 TURN LEFT on main gravel road (Afton Canyon 

Road). We are driving on the interlacustral gravel (F8).

Day 1: Afton Subbasin of Lake Manix and History of Afton Canyon 17
fluvial sand and

gravel with tufa coats

Figure 7. Stratigraphy of deposits at Stop 1B, Day 1. The panoramic view is a composite of nine original photographs. This arroyo cut exposes sedfan gravel of F8 caps the top of the ridge. The top of the underlying fanglomerate of Cave Mountain emerges from the arroyo floor a few tens of meteis not visible in the panorama. Most of this outcrop consists of sandy gravel and gravelly sand. Most of these deposits have bedding features that inan alluvial fan-lake interface, and they are interpreted as fan-delta deposits of Lake 6, the first phase of Lake Manix to fill Afton subbasin. L6 depositand are capped by 0.6 m of alluvial-fan deposits (F7) bearing a weak soil, 2.7 m of pale-colored bedded lacustrine silt and sand of unit L7, and 0.6 m oclasts in the basal ~1.5 m of L6 commonly have tufa coats.
27.4 Road steepens as we drive down the scarp across F8 

gravel and across L7 greenish mud and sand to the base of L7 

deposits, marked by tufa-coated cobbles.

27.7 Road steepens again, cutting below the lake deposits 

into Tertiary(?) Cave Mountain fanglomerate (F1-6) bearing 

many soils. As you start to descend, sight downhill (south) 

along the surface marked by tufa-coated cobbles at the base of 

L7 to see a flat surface that intersects it. This surface, on both 

sides of the river, is a thin fan gravel (F7) that overlies sand 

and thin green mud of L6, the first lake phase to occupy the 

Afton subbasin.

27.8 Straight ahead, the upper 2–3 m of the canyon wall are 

greenish sands of L6.

28.3 On the left are strath gravels overlain by steeply dipping 

beds of sands and gravels, all deposited by the Mojave River 

as it incised below the former base of Lake Manix after Afton 

Canyon formed and the lake drained. Drive onto a flat fluvial 

terrace.

28.4 Drive up the back edge scarp of the next terrace. From 

this surface we can see the North Afton beach ridge at 12:00 

(Stop 1, walking tour), composed of light-colored sediments 

weathering in badland forms. Drive down the back edge of the 

fluvial terrace. High fluvial straths are visible at 1:00 on the 

north rim of the canyon as you top the fluvial terrace (visited 

yesterday on the optional day hike). At 3:00 on the south side 

of the river, you can see the contact of the tan and red Cave 

Mountain fanglomerate with the overlying gray-brown Cady 

Mountain fanglomerate, both of which are overlain by green 

lacustrine muds of L7. The lower fanglomerate contains strong 

calcic soils, while the upper has very few.

28.6 Reverse fault is exposed in road cut on the right (N. 

Meek, Calif. State Univ. San Bernardino, oral commun., 

2006).

29.0 TURN LEFT into Afton Canyon campground, where pit 

toilets are available. We’ll eat lunch here and then take a short, 

strenuous hike to STOP 2.

Stop 2

See the detailed description and measured sections in 

the appended draft copy of Reheis and Redwine (in press; 

their figs. 3 and 14) and additional materials in Redwine (U.S. 

Geological Survey, unpublished mapping); the following is 

summarized from these reports. 

Inset Strath Terraces West of Lake Manix 

Threshold

Fluvial deposits inset below Lake Manix deposits, west 

of the lake threshold, include strath terraces with both a 

veneer of gravel and much thicker alluvial fills that are variably re-incised. Terrace surfaces lie between 12 and 36 m 

above the modern channel and commonly exhibit meander 

scars. The terraces are almost entirely cut into the indurated, 

matrix-supported Cave Mountain fanglomerate. In contrast, 

the fluvial deposits overlying the strath surfaces are loose, 

clast-supported deposits, 1–4 m thick, of rounded to wellrounded gravel of primarily Cave Mountain lithologies with 

rare clasts of reworked, green lacustrine mud. The gravels are 

interbedded with quartz-rich sand and rare, thin, discontinuous beds of green clay and silt. In some deposits there are also 

well-rounded volcanic lithologies, mainly basalt and rhyolite, 

likely sourced from the Cady Mountains south of the Mojave 

River. Soils developed into the fluvial deposits typically have 

Av/Bwk/Ck or Av/Btk/Coxk horizon sequences. Normalized 

PDI values for these terrace soils range from 0.02 to 0.07, 

similar to values for soils on the 543-masl beach ridges in the 

eastern Afton subbasin (tables 2 and 3 of Reheis and Redwine, 

in press). Soil differences are not consistent relative to elevation above the river, and likely reflect a range of natural soil 

variation among soils that are similar in age. These terraces 

and their soil development show incremental incision of the 

canyon at a rate faster than can be recorded by differences in 

pedogenesis.

“Slack Water” Deposits

Fine-grained deposits are associated with valleys incised 

into the fanglomerate of Cave Mountain on the north side 

of Afton Canyon, west of the lake threshold (JR04D-68 and 

-70, fig. 3 of Reheis and Redwine, in press). Ellsworth (1932) 

inferred these deposits to represent the presence of a lake that 

formed after much or all of the canyon incision had produced 

the modern dendritic topography. However, Ellsworth (1932) 

and Blackwelder and Ellsworth (1936) were confounded by 

the absence of evidence for any damming of the canyon to 

the east by fan aggradation, fault movement, or landslides, 

which would be required to produce such a lake. Meek (1989, 

1990) interpreted some of the deposits to represent slumping 

or reworking of overlying lacustrine clays when they were still 

present nearby (lake deposits are eroded far back from these 

sites today), and suggested that the thickest deposits represent 

side-canyon ponding or “slack water” deposits formed during 

floods that were transporting eroded lacustrine sediment.

Our study of these fine-grained deposits, concentrated 

in the largest and most complete exposure (JR04D-68), has 

yielded more data, yet the interpretation of their origin and age 

is still difficult. More than 5 m of deposits rest unconformably 

on pre-lake fanglomerate at and below about 478 masl. These 

deposits include, from bottom to top (fig. 10 of Reheis and 

Day 1: Afton Subbasin of Lake Manix and History of Afton Canyon 19
Redwine, in press): (1) sandy alluvium overlain by well-sorted 

sand; (2) blocky green mud, locally burrowed, with abundant 

secondary gypsum and other soluble salts, overlain by 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 with coarse fan sand and gravel; and 

(4) locally derived fan gravel.

Many beds in units 1 and 2 contain abundant to rare 

lacustrine ostracodes, abraded and winnowed near the base but 

including a coquina-like ‘death bed.’ The ostracode assemblages and their changes with stratigraphy appear to represent 

life assemblages in a perennial lake; the species represented 

are identical to those found in Lake Manix lake beds (R. 

Forester, U.S. Geological Survey, written commun., 2005; 

Steinmetz, 1987). Analyses of ostracodes from four strata in 

units 1 and 2 yielded ages in approximate, but overlapping, 

stratigraphic order from 31,500±420 to 27,020±10 14C yr B.P. 

In direct conflict with these 14C ages is a luminescence age of 

8.05±0.25 ka using OSL on quartz and a similar result using 

IRSL on feldspar (S. Mahan, U.S. Geological Survey, written 

commun., 2006); the surface soil properties of the capping 

fan gravel are consistent with such a younger age (Reheis and 

Redwine, in press).

The majority of our new evidence supports a fluvial 

origin for the “slack water” deposits at site JR04D-68, as first 

suggested by Meek (1989, 1990), rather than a shallow young 

lake as posited by Blackwelder and Ellsworth (1936). In 

support of the lake hypothesis, the stratigraphy, 14C ages, and 

life-like ostracode assemblages appear to indicate deposition 

in a perennial but short-lived lake that occupied a valley that 

had been incised below the bottom of Lake Manix, but significantly before the last highstand of the lake (about 22,000 

14C yr B.P. in this study). However, no other stratigraphic or 

geomorphic data support such a hypothesis; the ~8-ka luminescence ages are in conflict, and no remnants of a damming 

mechanism once Afton Canyon was partially or completely 

incised have been identified. In addition, the calibrated 14C 

ages overlap and do not show a consistent age progression 

with depth. In support of the fluvial hypothesis, some of the 

alluvial and fine-grained deposits and the intertonguing of 

some of the upper beds with coarse local sand and gravel suggest “slack water” deposition during Mojave River floods. Soil 

development (JR04D-157, table 2 of Reheis and Redwine, in 

press) and surface characteristics of the overlying alluvial fan 

are similar to those of other inset strath terraces and suggest an 

age younger than the last highstand of Lake Manix, consistent 

with the 8-ka luminescence ages. If the deposits have a fluvial 

origin, then a life-like assemblage of mostly unabraded, wellpreserved ostracodes was fortuitously redeposited at this site.

Retrace route out of Afton Canyon.

30.3 As we rise out of the canyon incised into pre-Lake 

Manix gravels, the view upslope along the former L7 lake bottom emphasizes scarps interpreted by Meek (1990) as representing erosion-resistant alluvial gravels that encroached over 

lake deposits during climatic intervals characterized by no or 

small lakes. The scarps are not at constant elevation, making 

another suggested interpretation of the scarps as wave-cut 

features (Wells and Enzel, 1994) unlikely.

31.0 TURN LEFT on power line road.

31.3 Drive along an erosional scarp exposing green muds 

of L7.

32.0 Route AF 313 and a pink shack on left. Continue 

straight on the power line road. Do not take AF 2423. We 

are driving on the base of L7, as indicated by the tufa-coated 

cobbles.

32.4 Drop down into a large wash (east fork of Dunn Wash).

32.6 Under the power lines, at 11:00 are excellent exposures 

of L6 deposits overlying distal fan deposits, also exposed 

at Stop 3.

33.2 Complex intersection. Fixer-upper home on left. Take 

the middle road.

33.4 TURN LEFT toward the fixer-upper. Pass it and park in 

the open spot north of the railroad cut for STOP 3.

Stop 3

The railroad cut (site M05-54; 552284 E, 3878805 N, 

478 masl) exposes, from top to bottom, a thin fan gravel (F7) 

overlying ~4.5 m of well-sorted sands exhibiting long sweeping crossbeds indicating east-directed flow. The sands are 

quartz- and feldspar-rich and similar to modern Mojave River 

sand. Green muddy sand forms a few thin (centimeters) layers in the upper part of the exposure on the south side of the 

cut; although these muds contained no ostracodes, deposits in 

similar stratigraphic positions (for example, M05-20 and M05-

65 west of the north Afton beach ridge) contain Limnocythere 

ceriotuberosa (J. Bright, Northern Arizona University, written 

commun., 2006) typical of Lake Manix deposits. The basal 

sand contains carbonate-cemented layers and nodules that 

resemble root casts. The sand overlies poorly sorted, indurated, distal alluvial-fan deposits (F6), and represents a valleyaxis facies of L6, the first lake to occupy the Afton subbasin. 

In other locations to the south and west (fig. 5), this sand 

is thicker and contains thin interbeds of distal-fan deposits, 

lacking soils, suggesting brief fluctuations in lake level. To the 

southwest, along the Mojave River, this same sand directly and 

conformably overlies fluvial gravel and sand, with clasts of 

dominantly mafic volcanic rocks probably derived from older 

fan deposits upstream near Buwalda Ridge (fig. 3). In turn, 

these fluvial deposits overlie the “Mayhem terrane,” a zone 

20 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
of chaotically mixed and plastically deformed blocks of Lake 

Manix muds and sands mixed with locally derived playa muds 

(fig. 5). These were seen at Stop 3 on the Pre-Trip Day, and 

can be accessed with a 4WD vehicle along the Mojave Road 

(the river bed), or by hiking 1.5 km heading S25°W from the 

railroad cut.

Return past the fixer-upper.

33.6 Continue straight on the good road. Head uphill (northwest) toward the freeway.

33.7 Cross under the power line, continue straight.

34.0 Cross under a smaller power line, continue straight.

341 TURN RIGHT on a paved frontage road. Cross Dunn 

Wash and climb to the Afton exit beach ridge.

36.0 TURN LEFT across the freeway and cross the cattle 

guard ahead (DO NOT take freeway); turn left on the paved 

frontage road. The store at this intersection offers water and 

minimal food, as well as long stories about the desert experience!

36.3 We are crossing through F8 and L8 deposits.

36.8 Tufa-coated cobbles are nicely displayed at the base of 

L7 greenish mud on both sides of the roads in steep road cuts. 

Cross the east fork of Dunn Wash. Climb onto a surface underlain by complicated thin sequences of L8 gravels and younger 

fan deposits.

37.1 Road takes a right-angle turn to the north and turns to 

gravel.

37.4 TURN LEFT onto the pipeline road to park in an open 

area on the right.

Stop 4

Stop 4 is shown on inset figure 3B. See the detailed 

description and measured sections in Reheis and Redwine (in 

press; their figs. 2 and 4); the following is summarized from 

that report. GPS coordinates for site M05-19 are 551615 E, 

3880169 N and mark a long bulldozer cut; other sites on those 

figures lie to the north, up the west fork of Dunn Wash.

Lake Manix reached highstands at or just below 543 

masl at least three times during the late Pleistocene, as suggested by Meek (1990, 2000). Highstands at this altitude are 

marked by well-preserved constructional beach barriers and 

locally by well-defined wave-cut scarps. Most such barriers 

are flat-topped with sloping, gently rilled flanks; some are 

nearly unbreached and retain fine-grained sediments deposited 

in back-barrier or lagoonal settings on the landward side (for 

example, the Afton exit barrier). At the Dunn Wash sites, at 

least four lake fluctuations are recorded (fig. 4 of Reheis and 

Redwine, in press). Dunn Wash was an active drainage during 

these fluctuations, and therefore lacustrine and alluvial sediments are interbedded. These two depositional environments 

are very difficult to distinguish in places where alluvial gravel 

was only slightly reworked during a subsequent lake-level rise. 

The oldest lake unit (unit 1 in section M05-19, fig. 4 of 

Reheis and Redwine, in press; equivalent to L7) has basal 

lacustrine gravel with thick tufa coats on clasts, overlain by 

green mud, silt, and sand that coarsen and thin shoreward. The 

tufa-coated gravel persists to an altitude of at least 539 masl. 

This unit is overlain by alluvial gravel of unit 2 (F8) and a buried soil with a Btk horizon. The buried soil is overlain by three 

packages of beach gravel and sand (units 3, 4, and 5, all fluctuations within L8) that rise and thin shoreward, typically with 

tufa-coated clasts at the base of each package and separated 

by weak soils or alluvial units. Lake units 4 and 5 (L8a and 

L8b) can be traced to an altitude of about 543 masl. Anodonta

shells near the base of L7 at site M05-20 yielded a finite but 

minimum-limiting age of 49,800±2,000 14C yr B.P. (table 1 of 

Reheis and Redwine, in press). A single preliminary U-series 

age on the basal tufa is 71±25 ka (J. Paces, U.S. Geological 

Survey, written commun., 2007). Lake unit 3 is only locally 

preserved and may represent a minor fluctuation within L8a. 

Anodonta shells within unit 4 (L8a), below a weak buried soil, 

yielded ages of 34,680±260 and 31,900±200 14C yr B.P. (sites 

M05-19I and M05-21). At two other sites in this drainage 

(JR04-D-1, immediately below a 543-m beach crest, and M05-

28B), the uppermost unit 5 (L8b) contained Anodonta shells 

that yielded ages of 25,420±120 and 26,030±100 14C yr B.P. 

A similar stratigraphy with comparable ages is preserved in 

the North Afton beach ridge. A younger highstand (L8c) that 

reached minimum elevations of 534 masl on the north Afton 

beach ridge and 536 masl on the south Afton beach ridge 

(south of the river) has yielded ages ranging between 20.6 and 

21.8 14C ka on Anodonta shells. Deposits of L8c have not yet 

been identified in the upper Dunn Wash area.

Retrace the route to the I-15 freeway and drive south to 

Minneola Road and campsite.

Day 2: Manix Subbasin of Lake Manix 

and Tectonic Disruptions

We will start from Calico Early Man Site at 8:00 A.M. 

The drive this day is about 30 miles round trip. Please carpool 

as closely packed as possible from camp, and be aware that 

at least 20 miles of the driving today will be on gravel and 

sand of lightly graded roads. High-clearance vehicles are not 

required, but there are two crossings of washes with loose 

sand.

Day 2: Manix Subbasin of Lake Manix and Tectonic Disruptions 21
Follow the Day 1 road log to Harvard Road and EXIT. Set 

odometer to 0 at stop sign.

0.0 TURN RIGHT on Harvard Road (south). Notice the flatness of the Mojave River fluvial plain. In this area, the gradient eastward is approximately 2 m/km.

0.1 TURN LEFT on Yermo Road, old Highway 40, now the 

frontage road for I-15.

0.8 Road climbs over cemented gravels of Tertiary age.

3.2 TURN RIGHT at Alvord Mountain crossroad, and cross 

the railroad tracks. Bear left along the dirt road fronting the 

railroad on the south; ignore the three other roads.

4.3 L7 beds on the right are capped by reddish sand of L8.

4.6 Manix Wash, where strath terraces consist of gravel of the 

Alvord Mountains.

6.6 Park in the wide area on the right as we cross an obscure 

boundary between Lake Manix gravels and alluvial fan gravels 

sourced from the low hills to the northeast. Buwalda Ridge lies 

to the south, with eolian sand decorating its gullies.

Stop 1

Walk about 1 km to the west tip of Buwalda Ridge to 

view shoreline deposits that lie above the common 543-masl 

shoreline of L8, as well as exposures of Manix fault splays. 

During the walk, we will cross dissected beach ridges composed of arkosic beach gravel and sand of L8. Note that the 

beach ridges are underlain by F8 deposits bearing a pavement of varnished volcanic clasts derived from Buwalda 

Ridge. Arroyo cuts both west and east of the beach ridges 

expose green sorted sands and local muds equivalent to L7 

in the Afton subbasin and to “upper Member C” of Jefferson 

(2003). Our observations suggest that the broad divide north 

of Buwalda Ridge was probably submerged by shallow water 

at the highest levels of L7, but evidence for this is patchy and 

largely covered by younger fan and colluvial deposits shed 

from both sides of the divide.

At Stop 1, refer to the detailed description and measured 

section in Reheis and Redwine (in press; their figs. 2, 4, and 

5); the following is summarized from that report. Outcrops 

on the southwest flank of Buwalda Ridge, adjacent to the 

Manix fault, expose two lake units separated by fan deposits 

(sites M04-75 and M05-06). At both sites, the older unit bears 

a moderately developed soil that formed prior to burial by 

the younger unit (figs. 4–7, Reheis and Redwine, in press); 

a similar moderately developed soil crops out at the surface 

on the north side of a strand of the Manix fault at the soil-pit 

site M04-76 (542395 E, 3870999 N) at 546 masl. The top of 

the outcrop south of the fault strand at M04-75 lies at about 

542 masl (542443 E, 3870921 N). Anodonta shells from 

the younger of two units in this outcrop yielded an age of 

22,470±70 14C yr B.P.

On the west end of Buwalda Ridge, two nested beach 

ridges (figs. 5, 6A, and 6B of Reheis and Redwine, in press) 

lie north of the Manix fault. The upper, moderately dissected 

beach ridge (soil pit M04-76) lies a minimum of 2 m higher 

than 543 masl. This upper barrier extends as high as 550 masl 

and once formed a loop attached to the hill to the east, but has 

been eroded to form two separate arms. A low, more sharply 

defined scarp, trending perpendicular to the Manix fault 

strands, is incised into the upper beach ridge at 543 masl, and 

this scarp grades downslope into a gravel-covered platform at 

537 masl (soil-pit site M04-77; 543356 E, 3870981 N).

The upper beach ridge has a packed desert pavement 

and clasts mostly covered with desert varnish, in contrast to 

the lower beach platform. Soil pits excavated in both surfaces 

showed significant differences in soil profile development. 

At site M04-76 on the upper beach ridge, stratified gravel 

overlies well-bedded, coarse sand at a depth greater than 62 

cm, and the sand contains lacustrine ostracodes (L. ceriotuberosa) and fish bones (R. Forester, U.S. Geological Survey, 

oral commun., 2005). Our observations at several nearby sites 

both south of the fault and near Troy Lake, all with altitudes 

higher than 543 masl, indicate that these higher shorelines 

were deposited by higher lake levels, not by fault displacement. The surface soil at M04-76 has a normalized PDI value 

of 0.11, and at site M05-46, a value of 0.07. The buried soil at 

M05-06 (542705 E, 3871027 N, 543 masl), in a deposit on the 

south side of the Manix fault, has a PDI value of about 0.13. 

Adding this value to that of the surface soil at M04-75, which 

formed on the overlying younger beach gravel, yields a total 

normalized PDI value of 0.17 as an estimate of cumulative soil 

development since deposition of the older gravel; this value is 

higher than that of the unburied older gravel nearby, perhaps 

due to erosion of the surface soil.

Retrace route west along railroad.

7.1 BEAR LEFT at a gate and take the road west toward the 

power line; DO NOT take the right fork after passing through 

the gate.

7.5 Road drops into Manix Wash.

7.6 Gravel surface is probably an exhumed fan between two 

lake deposits.

7.7 BEAR LEFT.

7.8 Cross Manix Wash. Beware the loose sand; 4WD is 

sometimes needed (we will scout in advance).

8.0 Exposures here are mud and sand of L7 (“upper member 

C;” fig. 4) with tongues of gravel and tufa-coated pebbles near 

the base. L8 (“member D”) forms a reddish slope above the 

22 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
greenish muds; it is composed of Mojave River gravel and 

sand.

8.4 White sand beds are visible in the sandy greenish muds 

of L7 on the right.

9.0 Cross road. Continue straight.

9.7 TURN LEFT onto main graded road.

10.3 We are at the base of a former stream channel that forms 

an incised meander valley in the fluvial plain. The channel 

evidently marks the route of the ancestral Mojave River that 

started to downcut locally after most or all of Lake Manix 

had drained, indicating that the knickpoint had migrated from 

Afton Canyon to somewhere near here at this time. Alternatively, the river may have made a local incision soon after the 

lake level dropped as it adjusted to the steepening of gradient to the east, from the delta top to delta slope. The river 

later initiated a channel in its present position to the south of 

this location. Strath terraces are composed of Mojave River 

gravels (granitic grus, rounded reddish quartzite, and volcanic 

rocks) on the south side of this channel; a preliminary quartz 

OSL date on sand beds is 21.1±2.0 ka (S.A. Mahan, written commun., 2007). Cosmogenic dates on surface pebbles 

of the strath yielded Pleistocene ages from 70.4±5.8 ka to 

121.5±11.0 ka (L. Owen, Univ. Cincinnati, written commun., 

2007) that we interpret as inherited ages from previous depositional sites in the Mojave River system.

10.8 BEAR LEFT at Vortek station (big bowling pin). Eolian 

sand ramps visible on the crest of the hills to the south are 

part of the Soldier Mountain ramp system, mostly out of 

sight. Note the broad swath of sand far to the east. All sand 

is sourced from the Mojave River. On windy days, this entire 

sand pathway is active (and you don’t want to be in it).

11.1 BEAR LEFT along the fence line. Prominent shorelines 

are visible to the south.

12.1 Park at the abandoned trailer.

Stop 2

Manix reference section stratigraphy and core interpretations. We will hike a short distance on rough terrain to 

examine the exposed Lake Manix section along the Mojave 

River channel to the south. George Jefferson (2003, and 

papers cited therein) established a sequence of members in the 

Manix Formation and contributed greatly to our knowledge of 

the stratigraphy and paleontology of the formation. Figure 4

shows schematically the stratigraphy we studied in outcrop 

and compares it to the core stratigraphy (drilled 0.5 km to the 

north) and the reference section by Jefferson (2003). Prepare 

for a sometimes-strenuous short hike and bring water for two 

hours.

The following summary of our findings regarding the 

stratigraphy in this area is quoted directly from an abstract in 

press by Oviatt and others (in press): 

“We have found that, except for Member A of 

Jefferson, which consists of alluvial fan deposits, 

and Member D, which consists of fluvial-deltaic 

sands, most sediments in the Manix Formation were 

deposited in shallow lacustrine to mudflat environments punctuated by short episodes of deeper water. 

Although some units can be traced for kilometers 

and are relatively uniform in character, some units 

undergo facies changes over short distances. For 

example, unit Upper B of Jefferson is a sandy gravel 

unit along the Manix Wash bluffs, a mud unit in 

the core several hundred meters away, and a widespread sand bed for several km to the west of the 

core site. Tufa-coated gravel beds mark episodes of 

lake deepening or lake transgression, and are found 

capping both lacustrine and alluvial gravels. Buried 

soil profiles or soil horizons within the lacustrine 

section can be identified in the core and outcrops, 

and suggest multiple periods of non-deposition on 

the low-gradient floor of the Manix subbasin during 

the Pleistocene.

Recently obtained radiocarbon ages of Anodonta

shells in the uppermost stratigraphic unit range 

from 31.6 to 44.2 cal ka. The Manix tephra bed 

(approximately 185 ka) serves as a valuable marker 

in the lower part of unit Upper C (Jefferson, 2003) 

in the Manix subbasin. We have evidence for seven 

paleomagnetic excursions and estimate the bottom 

of the Manix core to be ~450 ka. Additional studies 

of geochronology, including amino acid racemization, OSL, and U-Th, are in progress. Our studies 

suggest some refinements to Jefferson’s interpretations, including shorter lake cycles and somewhat 

different timing for parts of the section. The data 

suggest that the sediment record is reflecting Mojave 

River discharge and proximity of the Mojave River 

deltaic system.” 

“Member D” of Jefferson (2003) ranges from 8.5 to 10 

m thick, and its surface is nearly planar at an altitude of 535 

m, about 8 m below the 543-m Lake Manix highstands. It 

crops out only in this immediate area, and is not known east 

of Buwalda Ridge. The unit (fig. 4) is composed of reddishbrown grus-derived sand and fine gravel, with less common 

mud beds and laminae; the clast composition is strikingly 

similar to that of modern and latest Pleistocene Mojave 

River deposits. Sedimentary facies and structures also mimic 

those of the Mojave River, including cross-bedded channelfill deposits, crevasse-splay deposits, marsh, and floodplain 

deposits. Foreset beds expected for a delta environment are 

largely absent. However, thin intervals of very well sorted silt 

Day 2: Manix Subbasin of Lake Manix and Tectonic Disruptions 23
or sand beds may represent brief lacustrine deposition, and a 

few micro-delta beds are present. 

Radiocarbon results range from 40.0±0.6 14C ka from a 

shell 0.5 m above the base to 26.3±0.2 14C ka 1.2 m from the 

top. This time period spans 2 or 3 highstand beach-forming 

events elsewhere in the basin. We interpret the lake stands as 

brief to account for the lack of lacustrine facies in “Member 

D,” which apparently represents an active Mojave River fluvial 

plain during marine oxygen isotope Stage 3.

Retrace the route west along the fence line.

13.1 CONTINUE STRAIGHT along the fence.

13.6 BEAR LEFT along the power line road.

13.9 BEAR RIGHT on a main road skirting Camp Ironwood, 

which lies on a broad abandoned terrace of the Mojave River.

14.0 BEAR RIGHT.

14.2 BEAR RIGHT. Don’t take the sharp right turn. Look 

over your shoulders to read the signs for eastbound traffic 

entering Camp Ironwood. Any guesses on what kind of camp 

this is?

15.3 We are along the edge of the same incised meandering 

channel that we crossed earlier.

16.2 This is an uplift bordering the apparent trace of the 

Manix fault. Several anomalous topographic features occur in 

an east-west zone in this part of the fluvial plain.

16.6 BEAR LEFT along the power line road.

17.2 BEAR LEFT.

17.3 TURN RIGHT past the barn.

17.6 TURN LEFT along the power line road.

17.8 Cross Harvard Road. Watch for high-speed traffic.

18.8 We are now driving on local fan deposits shed from the 

Harvard Hills, ahead and to the right. The Harvard Hills are 

composed of Miocene fine- to coarse-terrigenous deposits, 

partly of the Barstow Formation. 

19.6 Stop near the crossroads. We will need to simply park 

in the road and stop any local traffic because adjacent fans are 

very soft with eolian sand. DO NOT PULL OFF!

Stop 3

Uplifted and faulted nearshore deposits of Lake Manix. 

The outcrops between the crossroads and Harvard Hill are 

mostly well-sorted, thin-bedded sands of Mojave River 

composition. Interbedded muds contain lacustrine ostracodes. 

Exposures locally show well-sorted and well-bedded pebble to 

cobble gravels, suggesting they are beach gravels. We interpret the assemblage of deposits to be nearshore Lake Manix 

deposits. The complex geometries of several exposures are due 

to approximately east-striking near-vertical faults that disrupt 

the section. Near here, one of these faults cuts latest Pleistocene or early Holocene alluvial-fan deposits that postdate the 

Mojave River fluvial plain. We consider these faults to be part 

of the Manix fault zone. Lake Manix deposits can be traced as 

high as 593.1±0.2 masl here, requiring a minimum of 50 m of 

uplift, if they date to a time when the lake levels were a maximum of 543 masl. The nearest Lake Manix deposits, deposits 

similar to “Member D,” are exposed about 700 m to the south 

along the Mojave River cliffs; the top of that unit is at ~552 

masl and the base of the exposure is ~539 masl. If older lake 

deposits equivalent to these exposed deformed deposits underlie “Member D,” then the uplift here would have been greater 

than 54 m. The uplift is probably a consequence of up-to-thenorth displacement along the Manix fault and up-to-the-east 

displacement along the Dolores Lake fault, which lies a short 

distance west of this location as originally interpreted by 

Meek (1994). The geometry of the faults, location of uplift at 

Figure 8. Sketch of geology at intersection of the 

Dolores Lake and Manix faults near Harvard Hill (Day 2, 

Stop 3). Based on unpublished geologic mapping of D.M. 

Miller and D.J. Lidke (U.S. Geological Survey).

24 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
the intersection of the faults, and evidence that both faults are 

active support the model of Dokka and Travis (1990) for uplift 

in block corners undergoing contraction (fig. 8); although a 

complex stepover is a possible explanation as well.

Continue west on the power line road.

19.8 Veer right through the poles, heading due west.

21.6 Drive along the edge of a small housing development.

22.1 Turn right on Coyote Lake Road, cross railroad 

tracks.

22.2 TURN LEFT on Yermo Road. Note the pale-colored 

east-dipping sands of the freeway cut (north side of the 

freeway). These are uplifted Mojave River deposits, probably 

analogous to those we saw at Stop 3 but fluvial rather than 

lacustrine in origin.

25.5 TURN RIGHT on Minneola Road and return to camp. 

If time permits, stop and park along the right side of Yermo 

Road before turning on Minneola Road for optional Stop 4.

Optional Stop 4

Uplifted and faulted gravels and sands of the Mojave 

River. The roadcuts here expose south- and west-dipping strata 

of the Mojave River, identifiable by the granitic grus, volcanic 

rocks, and well-rounded reddish-quartzite-pebble assemblage. 

Faults disrupt the beds in several places in cuts along the 

east side of Minneola Road. The Calico fault borders the east 

side of this hill and is prominent to the southeast as a zone of 

splaying faults that generally step strata of the fluvial plain 

down to the east (fig. 2). Latest Pleistocene terrace deposits 

bordering the Mojave River appear to be offset tens of meters 

in a dextral sense. The Calico fault cuts early and middle 

Holocene deposits south of here (Phelps and others, in press; 

Oskin and others, 2007). The Calico fault is interpreted by 

most workers to bend to the west-northwest at the north edge 

of these hills, in an apparent restraining bend, to cause the 

uplift of the Calico Mountains that can be seen to the northwest. However, the faults bordering the Calico Mountains do 

not show evidence for Holocene slip, raising the possibility 

that slip is transferred to other fault systems north of here. 

Recent surficial geologic mapping in this area (Phelps and others, in press) indicates that east-striking faults parallel to the 

Manix fault exist on both sides of the Calico fault, and hence 

complex interactions are likely. In addition, the Tin Can Alley 

fault of Dudash (2006) strikes nearly southerly, and is last visible just a few kilometers north of this hill (Miller and others, 

2005). None of these faults are known to have Holocene activity. The fault configuration presents a major puzzle, to which 

answers are not completely known.

Day 3: Coyote Lake Subbasin of Lake 

Manix and Post-Lake Manix Lake and 

River History

We will start from Calico Early Man Site at about 8:30 

A.M. The drive this day is about 25 miles. Most of the driving 

today will be on lightly graded roads and across a playa; highclearance vehicles are not required.

Follow the Day 1 road log to Harvard Road and exit. Set 

odometer to 0 at stop sign.

TURN LEFT over the freeway on Harvard Road.

0.3 Pavement ends. Continue north. We are heading toward 

the Alvord Mountains, with dark granitoids and a white streak 

of marble straight ahead.

1.8 Bear right (continue on Harvard Road).

2.4 Turn right on the power line road.

3.2 TURN LEFT on the Fort Irwin haul road. Watch for 

tank convoys! This road traverses the broad divide between 

the Coyote Lake and Manix subbasins. Much or all of the 

divide is underlain at shallow depth by fine-grained Miocene strata (Meek, 1990, 1994). Playas have formed between 

the encroaching dunes on the west and the broad aggrading 

Alvord alluvial fan on the east.

5.9 Cross a big longitudinal dune.

7.7 Crest of a broad compound barrier beach at about 543 

masl. Our view is northwest to the Coyote Lake subbasin, 

whose floor is about 7 km wide and at 520 masl. This barrier 

was built from northeast to southwest, based on morphology 

and clast composition. Its elevation suggests that it probably 

has a history similar to that of the north Afton beach ridge and 

was built during several lake phases. The broad divide between 

Coyote Lake and the rest of the Lake Manix basin may have 

been only 1 to 2 m deep at highstands of Lake Manix, so the 

waves that built this beach were derived solely from wind 

energy generated in the Coyote Lake subbasin.

8.0 STOP along the road.

Stop 1

A regressive shoreline on the flank of the southeast Coyote Lake beach (fig. 9) at this location mantles lake deposits 

dated with Anodonta shells. At this elevation, about 530 masl, 

a thin gravel beach deposit overlies sand that has Anodonta at 

its base; the shell yielded an age of 15,590±40 14C yr B.P. We 

interpret the unconformably underlying ripple-laminated sand, 

Day 3: Coyote Lake Subbasin of Lake Manix and Post-Lake Manix Lake and River History 25
SE Coyote Lake beach

Figure 9. Map of the southeast Coyote Lake beach (Day 3, Stop 1), locations of sites referred to in 

text, and profile with sites and dated strata. Base map is USGS digital orthophotoquad.

26 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
sandy mud, and massive muddy sand to represent shallow lake 

deposits. Many of the beds fine upward, suggesting periodic 

lake deepening. Mud cracks occur at the top, beneath the 

unconformity. An age of 19,660±70 14C yr B.P. on Anodonta

in fine laminated sand near the base of the exposure suggests 

that the entire deposit postdates the draining of Lake Manix.

We explored lateral continuity of these deposits in a 

series of shallow pits along the wash extending upslope from 

this exposure. The gravel-over-rippled-sands stratigraphy 

extends east about 150 m as a thin gravel and sand cap on 

underlying fines (fig. 9). About 160 m to the east, rippled sand 

is absent, and the gravel cap overlies shelly sand on muddy 

sand. There, Anodonta yielded an age of 16,710±90 14C yr 

B.P. At about 210 m to the east, the gravel fingers out into a 

sand that has several shelly layers; Anodonta at 20-cm depth 

yielded an age of 14,880±80 14C yr B.P. This shelly sand unit 

continues east about 270 m (altitude about 537 masl). Farther 

east, most near-surface strata are gravel and coarse sand.

At 1.2 km south of this location and slightly higher, at an 

altitude of about 536 masl, we excavated a deep pit in similar 

lacustrine units (also dated in a range of 20–15 14C ka), below 

which lay a possible weak soil on sands bearing Anodonta that 

yielded an age of 22,490±170 14C yr B.P., evidently representing the last of Lake Manix deposition. Deposits in this pit contain lacustrine ostracodes, in many places reworked as shown 

by abrasion and infilling with mud. Some have secondary carbonate accumulation. Articulated valves suggest only modest 

reworking in some cases. L. ceriotuberosa and Limnocythere 

bradburyi are present in all strata. It is possible that the ~19.6 14C ka deposits represent a slow decline from Lake Manix 

highstand levels as Afton Canyon was cut, separating Coyote 

Lake from Lake Manix. Alternatively, the Mojave River may 

have fed Coyote Lake at 19.6 ka, causing a brief lake in the 

otherwise dry lake basin. Preliminary dating of ostracodes in 

the Soda Lake core of Lake Mojave suggests that the lake was 

large before 19.6 ka, which requires that Afton Canyon was 

partly cut before that time, and hence the latter interpretation 

for an ephemeral Coyote Lake at 19.6 ka is preferred.

We interpret the ~19.6-ka rippled sands and sandy muds 

as near-wave-base deposits of an ephemeral lake fed by the 

Mojave River. These beds are overlain by a package of shelly 

sand with one prominent beach gravel that dates from ~16.7 to 

~14.9 14C ka, suggesting a period of fluctuating lake levels in a 

second, longer-lived, ephemeral lake fed by the Mojave River. 

At this location, evidence for yet younger ephemeral lakes in 

this basin are not supported from our studies, but Meek (1994) 

provided evidence for younger lakes in the form of dates on 

Anodonta of 13.6 ka and 11.8 14C ka near here. Our overall 

interpretation of the deposits in this area is very similar to that 

of Meek (1990, 1994), except the timing differs. 

We will next travel across the playa to a location where 

lacustrine landforms permit lake levels to be assigned for 

dated lake sediments, and we will show that beaches were 

formed just 1 to 2 m below the Lake Manix highstand during 

the Coyote Lake ephemeral lake stands.

Continue north on the haul road.

8.5 TURN LEFT on a small track that leads toward the playa. 

We are driving on thin-bedded lacustrine sands of OIS 2 (L8) 

lakes.

10.4 Turn left from the ruts and head southwest across the 

playa. Watch for fissures, sinkholes, channels, and ridges. This 

is NOT a high-speed playa! You have been warned!

11.4 Near here, personnel from the U.S. Geological Survey 

and California State University Bakersfield obtained some 

exploratory short cores in the playa. Dates on Anodonta shells 

are 48 to 49 14C ka (probably minimum ages for the sediment) 

at a depth of ~5 m, which we interpret to indicate that these 

deposits significantly predate the OIS 2 Lake Manix. Evidently, several meters of deflation have occurred on this playa.

12.8 VEER LEFT at an obvious two-track and leave the 

playa, climbing the southern playa-margin scarp of late 

Pleistocene muds and sands. Faults exposed in places along 

the south edge of the playa suggest either slumping down to 

the north or faulting along a zone coincident with the south 

margin of the playa, or both. The fault probably is related in 

part to perched ground water south of the playa (Hagar, 1966), 

which may be dammed by the fault.

14.2 VEER RIGHT on a smaller road.

14.8 Park along and near the road.

Stop 2

We will take a two- to three-hour hike from here over 

easy terrain. Bring water and a snack. The tour will visit 

several landforms recently highlighted spectacularly in LiDAR 

flown by University of Texas at Austin. We will discuss the 

origin of fluvial channels, now inverted topographically, as 

well as lacustrine beaches and platforms and closed depressions. The deposits and landforms bear evidence for several 

brief lake cycles that postdate the demise of Lake Manix after 

Afton Canyon developed.

Walk west along the ridge crest (fig. 10), watching the 

north and south sides as topography changes westward. The 

ridge becomes better defined with increasing height above 

basins on both sides. We will examine the clast composition of 

gravel in the ridge; the “grussy” composition strongly supports an interpretation of a Mojave River source. At the west 

termination of the ridge, examine the topography: a bench 

exists in this area and extends northeast and southwest. To 

the southwest, the bench (at 541.6 masl) closes off a lagoonlike feature that flanked the ridge on which we walked. We 

interpret the ridge as an inverted fluvial channel of the Mojave 

River, and that the adjacent flats were composed of fines that 

Day 3: Coyote Lake Subbasin of Lake Manix and Post-Lake Manix Lake and River History 27
Figure 10. Map of hillshade derived from 1-m LiDAR, southwestern Coyote Lake basin, flown and processed by University 

of Texas Austin. Landforms and sites mentioned in the text are identified, along with altitudes of several features.

eroded after deposition and cessation of river activity. We 

interpret the bench, which closes off the deflated area, at the 

truncated front of the ridge as a lacustrine wave-formed beach. 

By this interpretation, fluvial channels formed, followed by 

rapid deflation, and then the lake rose to truncate the channel 

and build a small barrier. However, deflation may also have 

postdated the new barrier construction. A narrow barrier beach 

formed on this bench farther to the southwest and is notable 

for its clast content: abundant volcanic rocks derived from 

local fans of the Calico Mountains. This barrier beach lies at 

542.2 masl according to LiDAR data.

Above and south of the “volcanic” barrier beach lie three 

more barrier beach remnants, each with crest altitudes of 543.3 

masl, and each bearing volcanic clasts. We interpret these as 

earlier beaches that formed during highstands of Lake Manix, 

although we have no direct dates or other evidence for their 

timing. Each barrier must have been abandoned as more northerly barriers formed, providing relative ages for the beaches. 

At least one time, Coyote Wash cut through a barrier after it 

was formed and before the lake rose again. The southernmost 

barrier has a bench cut into it at 542.5 masl adjacent to the 

modern Coyote Wash channel. We interpret the bench as having been cut as the lake rose to highstand after abandoning the 

southernmost beach, and before the next beach to the north 

formed to close off the area from wave energy.

Stretching below the “volcanic” barrier at 542.2 masl is 

a broad sand and fine-gravel platform that we have excavated 

to examine stratigraphy and chronology. Anodonta shells 

recovered from four positions in the ~3 m of section range 

from 16.2 to 15.1 14C ka, and thus are similar in age to the 

28 Quaternary Stratigraphy, Drainage-Basin Development, and Geomorphology of Lake Manix Basin
upper sequence we examined at southeast Coyote Lake beach. 

The deposits contain the ostracodes L. ceriotuberosa and 

L. bradburyi, confirming a lacustrine origin for many beds. 

Preliminary quartz luminescence ages (S.A. Mahan, written 

commun., 2006) in this section are younger than the calibrated 

radiocarbon ages, similar to mismatched dates described for 

lacustrine deposits cross-dated by Owen and others (2007) at 

Silver Lake. Here, the deposits lie between 538 and 541 masl, 

and are associated with a barrier beach at 542.2 masl, providing direct evidence that the ~16–15 ka lake level was about 

542 masl at its highest. This lake level may indicate a threshold control for overflow from Coyote Lake, as suggested by 

Meek (1990).

Farther north down Coyote Wash, a prominent loopshaped barrier beach (fig. 10) is cut by Coyote Wash. The 

beach crest is at 541.4 masl. Prominent inverted channels 

leading to the beach lie on older, higher beaches, including 

beaches at the altitude of this 16–15 ka site (fig. 9). The 541-m 

beach is built across a 3-m-thick sequence of grus sand and 

muddy sand that contains Anodonta dated at 14,335±40 to 

13,810±35 14C yr B.P. About 300 m farther down the wash, 

we recovered Anodonta dated at 13,145±45 14C yr B.P. These 

dates, stratigraphy, and landforms indicate that Mojave River 

fed one or more ephemeral Coyote Lakes that created beaches 

at ~541 masl between about 13.8 to 13.1 ka. We have not 

found evidence for younger lakes.

Meek (1994) outlined stratigraphic evidence for Mojave 

River deltas farther east (east of the informally named Agate 

Hill) where spectacular exposures of deltaic foreset beds were 

created along the wall of a giant trench (now filled in). He 

obtained a date of 17,140±1,500 14C yr B.P. on Anodonta in 

sands below the delta unit. We speculate that this delta may 

coincide with our dated record of ~19.6 14C ka lake sediments 

(noting that many of our dated shells appear to yield ages older 

than those reported by Meek as collected at the same localities). West of Agate Hill, most Mojave River interaction with 

ephemeral lakes appears to be one of distinct fluvial channels 

forming and later being truncated along shore zones. We found 

no distinctive deltaic sediments in this area, although thin 

intervals of cross-bedded sands are present at low altitudes 

near the south margin of Coyote Lake.

The available data point to two or more ephemeral lakes 

occupying Coyote Lake after the demise of Lake Manix, the 

first being at about 19.6 ka (uncalibrated) and perhaps being 

quite brief. Another period of ephemeral lakes appears to be 

16.7 to 14.9 ka and perhaps as young as 14.4 ka. The stand 

that formed the loop barrier in lower Coyote Wash apparently occurred about 13.8 to 13.1 ka. These times permit a 

single protracted period of lake occupation with fluctuating 

levels (~16.7 to 13.1 ka) or may represent numerous shortlived lakes. Regardless of the number of lakes, the point made 

by Meek (1994), that downstream Lake Mojave must have 

experienced periods of low water flow due to diversion of the 

Mojave River to Coyote Lake basin during the latest Pleistocene, is critical for interpreting climate history from Lake 

Mojave.

Continue south on the road.

15.0 Cross the 543-masl highstand beach of Lake Manix, 

here marked by coarse pebbles of volcanic rock derived from 

the Calico Mountains piedmont to the west.

16.4 Veer south on the main graded road.

Major parting point. For those headed EAST AND NORTH to 

Las Vegas, turn left (east) along the power line road to Harvard 

Road.

18.1 Slight jog left on gravel road.

20.1 Jog south to big power lines.

20.3 Turn sharp left on the power line road.

21.5 Turn sharp right, which is southbound on Harvard Road.

23.7 Intersection with freeway I-15; cross overpass and enter 

I-15 northbound.

For those headed WEST AND SOUTH to Los Angeles, continue south.

17.4 Complex branching of roads; stay on the center of the 

three roads.

19.2 Cross the power line road.

20.3 End at the paved road. Turn right.

20.7 Turn right on Yermo Road.

24.0 Turn right on Minneola Road.

24.2 Turn left, entering freeway I-15 southbound.

Day 3: Coyote Lake Subbasin of Lake Manix and Post-Lake Manix Lake and River History 29
Glazner, A.F., Walker, J.D., Bartley, J.M., Fletcher, J.M., 

Martin, M.W., Schermer, E.R., Boettcher, S.S., Miller, 

J.S., Fillmore, R.P., and Linn, J.K., 1994, Reconstruction 

of the Mojave block, in McGill, S.F., and Ross, T.M., eds., 

Geological investigations of an active margin: Geological 

Society of America Cordilleran Section Guidebook, 27th 

Annual Meeting, Redlands, Calif., San Bernardino County 

Museum Association, p. 3–30.

Hagar, D.J., 1966, Geomorphology of Coyote Valley, San 

Bernardino County, California: Amherst, University of 

Massachusetts, Ph.D. dissertation, 210 p.

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

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Great Basin deserts: Boulder, Colo., Geological Society of 

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Lowenstein, T.K., Li, J., Brown, C., Roberts, S.M., Ku, T.-L., 

Luo, S., and Yang, W., 1999, 200 k.y. paleoclimate record 

from Death Valley salt core: Geology, v. 27, p. 3–6.

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Rowan, L.R., 1988, Quaternary history of the Manix fault, 

Lake Manix basin, Mojave Desert, California: San Bernardino County Museum Association Quarterly, v. 35, nos. 

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Meek, N., 1989, Geomorphic and hydrologic implications of 

the rapid incision of Afton Canyon, Mojave Desert, California: Geology, v. 17, p. 7–10.

Meek, N., 1990, Late Quaternary geochronology and geomorphology of the Manix basin, San Bernardino County, California: Los Angeles, University of California Los Angeles, 

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

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