Southern Exposures

Southern Exposures

Searching for the Pliocene: Southern Exposures Robert E. Reynolds, editor California State University Desert Studies Center The 2012 Desert Research Symposium April 2012 Table of contents Searching for the Pliocene: Field trip guide to the southern exposures Field trip day 1 ���������������������������������������������������������������������������������������������������������������������������������������������� 5 Robert E. Reynolds, editor Field trip day 2 �������������������������������������������������������������������������������������������������������������������������������������������� 19 George T. Jefferson, David Lynch, L. K. Murray, and R. E. Reynolds Basin thickness variations at the junction of the Eastern California Shear Zone and the San Bernardino Mountains, California: how thick could the Pliocene section be? ��������������������������������������������������������������� 31 Victoria Langenheim, Tammy L. Surko, Phillip A. Armstrong, Jonathan C. Matti The morphology and anatomy of a Miocene long-runout landslide, Old Dad Mountain, California: implications for rock avalanche mechanics �������������������������������������������������������������������������������������������������� 38 Kim M. Bishop The discovery of the California Blue Mine ��������������������������������������������������������������������������������������������������� 44 Rick Kennedy Geomorphic evolution of the Morongo Valley, California ���������������������������������������������������������������������������� 45 Frank Jordan, Jr. New records of fish from northern exposures of the Imperial Formation of Riverside County, California �� 53 Mark A. Roeder Shell rubble beds of the mollusk Thylacodes (Gastropoda: Vermetidae) in the upper Miocene Imperial Formation near Whitewater, Riverside County, California, previously called the “worm tube bed�” ���������� 65 Patrick I. LaFollette The desert fan palm: a recent invader in the American Southwest ������������������������������������������������������������� 69 James W. Cornett San Andreas fault geomorphology and slip rate in the Indio Hills, Riverside County, California ���������������� 72 David K. Lynch The Pliocene fossil record of Anza-Borrego Desert State Park, western Salton Trough, California ������������� 77 G.T. Jefferson, L.K. Murray, and S.D. Keeley Earliest delivery of sediment from the Colorado River to the Salton Trough at 5�3 Ma: evidence from Split Mountain Gorge ����������������������������������������������������������������������������������������������������������� 88 Rebecca Dorsey Before the big chill—a quick look at global climate in the Pliocene, Earth’s last sustained warm period ��� 94 Richard (Tony) VanCuren Searching for a pupfish migration route—back to the Pliocene? ����������������������������������������������������������������� 99 Jeffrey Knott Thermal tolerances for the desert pupfish (Cyprinodon macularius): a case for rapid evolution ��������������� 101 Allan A. Schoenherr The dazed and confused identity of Agassiz’s land tortoise, Gopherus agassizii (Testudines, Testudinidae), the new desert tortoise, Gopherus morafkai, and consequences for conservation ������������������������������������ 103 R.W. Murphy, K.H. Berry, T. Edwards, A.E. Leviton, A. Lathrop, and J.D. Riedle 2 2012 desert symposium What do we know about the effects of climate change, especially global warming, on desert tortoises? ����������������������������������������������������������������������������������������������������������������������������������� 105 Jeff Lovich Desert reptiles and climage change: winners and losers in a warming world �������������������������������������������� 108 Cameron W. Barrows Age, stratigraphy, depositional environment and vertebrate ichnology of the Pliocene Copper Canyon Formation, Death Valley, California ���������������������������������������������������������������������������������� 114 Torrey Nyborg, Paul Buccheim, and Kevin E. Nick Review of proboscideans from the Middle Miocene Barstow Formation of California ������������������������������� 125 Don L. Lofgren, Abby Hess, Drew Silver, and Peter Liskanich A near-complete skull of Castor canadensis from the badlands of El Golfo de Santa Clara, Sonora, Mexico ������������������������������������������������������������������������������������������������������������������������������������������ 135 Carrie M. Howard and Christopher A. Shaw Ichnites in the Bouse Formation, Amboy, San Bernardino County, California ������������������������������������������� 136 Robert E. Reynolds Was it washed in? New evidence for the genesis of Pleistocene fossil vertebrate remains in the Mojave Desert of southern California ��������������������������������������������������������������������������������������������� 140 J. D. Stewart, Michael Williams, Marjorie Hakel, and Scott Musick Quaternary offset of the Cady fault, eastern California shear zone, southern California ������������������������� 144 K. M. Schmidt and V. E. Langenheim Reynoldsite, a new mineral from the Blue Bell claims, California and the Red Lead mine, Tasmania �������� 151 Anthony R. Kampf, Stuart J. Mills, Robert M. Housley, Ralph S. Bottrill, and Uwe Kolitsch Early Neogene cat tracks from California and Utah ����������������������������������������������������������������������������������� 153 Robert E. Reynolds and Andrew R. C. Milner Fumaroles exposed by the dropping Salton Sea level �������������������������������������������������������������������������������� 160 David K. Lynch, Kenneth W. Hudnut, and Paul M. Adams The Oro Copia Mine, Orocopia Mountains, Riverside County, California �������������������������������������������������� 169 Larry Vredenburgh Sites I would like to see: moonshine still sites in the California Desert ���������������������������������������������������� 172 Frederick W. Lange Abstracts of proceedings—The 2012 Desert Studies Symposium ������������������������������������������������������������� 178 Robert E. Reynolds, compiler Front cover: Willis Palms Back cover: Mission Creek fan Title page: Curtis Palms 2012 desert symposium 3 4 2012 desert symposium Searching for the Pliocene: field trip guide to the southern exposures Day 1 Robert E. Reynolds Redlands, California, [email protected] Introduction—Recognition that glacial cycles occu- Continue past the East Main Street exit. pied the last ~1 Ma of the Pliocene has led to a redefini- EXIT I-15 at Barstow Road. The Mojave River Valley tion of the beginning of the Pleistocene Epoch, changing Museum is two blocks north. the beginning of the Pleistocene from 1.8 Ma to 2.6 Ma. The Pliocene is now defined as between 5.3 and 2.6 0.0 (0.0) Stop at signal. Re-set odometer. TURN LEFT Ma (Finney, 2011). Even though shortened, the Plio- (south) onto Barstow Road (Highway 247). cene was eventful, and these events can be seen in the southern deserts. Global climatic events, such as gradual 3.5 (3.5) Reach the summit (entrance to a landfill) of cooling and drying and the start of polar ice caps, and the Lenwood Anticline on western Daggett Ridge and altered ocean currents from the closing of the Isthmus enter Stoddard Valley. Gravels exposed in the road cuts of Panama, are overprinted by regional events, such as are probably Pliocene in age. They underlie fine-grained the rise of the Transverse Ranges and the resulting rain deposits that farther to the northwest contain an early shadow that created the Mojave Desert climate. This Pleistocene ash bed (Cox et al, 2002). period saw the inception of the Eastern California Shear 4.5 (1.0) Cross the Lenwood Fault at the north base of Zone and development of strike-slip faults that cut across Daggett Ridge, a ridge developed by compression along a most of the Mojave Desert. Many of the Mojave Desert’s left bend in the Lenwood Fault. coarse gravel deposits have been assigned to the Pliocene. We will visit sediments that herald and record Pliocene 4.9 (0.4) Continue past a right turn (west) to Stoddard tectonism and pluvial events. Road Early on Day 1, we will visit the Old Woman Sandstone, 5.9 (1.0) Continue past a left turn leading to the Peach dated by fossil mammals to the late Pliocene. These rocks Spring Tuff (18.8 Ma; Miller et al, 2010) and the early provides early Pleistocene constraints on the rise of the Miocene Barstow Formation of Daggett Ridge. We will San Bernardino Mountains. Lucerne Valley also contains next encounter middle Miocene sediments at Pioneer- the Blackhawk landslide, perhaps triggered by the Helen- town. Proceed south on Highway 247. dale fault and/or glacial cycles. Stops on both days will 9.1 (3.2) Pass the Slash-X Café. feature outcrops where we can compare textures of land- slides, fanglomerates, and conglomerates. 10.1 (1.0) Continue past a left turn to Stoddard Wash and Meridian gates. Late on Day 1 we will visit faults that are responsible for the topography of the modern eastern San Bernardino 13.0 (2.9) View (2:00) of a ridge with granitic boulders that Mountains. The Miocene precursor of the San Andreas remain from exhumation of the pre-Miocene erosional fault system may have assisted in the opening of the Gulf surface (Oberlander, 1972). of California, allowing the incursion of the Miocene–Plio- cene marine Imperial Formation. 17.2 (4.2) Cross the summit of Barstow Road at Goat Mountain Pass (el. 4148’), the junction of Stoddard Ridge Convene at the Desert Studies Center in Zzyzx; proceed (Jurassic Sidewinder volcanics), and the West Ord Moun- north toward I-15. tains (Jurassic-Cretaceous

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