HR: 0800h
AN: U21B-0817    [Abstracts]
TI: A Geophysical Survey of the Quaternary Beatty Junction Paleolake Shoreline Deposit, Death Valley National Park, California
AU: * Craig, M
EM: mitchell.craig@csueastbay.edu
AF: California State University, East Bay, Dept. of Geological Sciences, 25800 Carlos Bee Blvd., Hayward, CA 94602 United States
AU: Warnke, D
EM: dietz.warnke@csueastbay.edu
AF: California State University, East Bay, Dept. of Geological Sciences, 25800 Carlos Bee Blvd., Hayward, CA 94602 United States
AU: Teitler, L
EM: lorateitler@yahoo.com
AF: California State University, East Bay, Dept. of Geological Sciences, 25800 Carlos Bee Blvd., Hayward, CA 94602 United States
AU: Narvaez, R
EM: orwaves@isp.com
AF: California State University, East Bay, Dept. of Geological Sciences, 25800 Carlos Bee Blvd., Hayward, CA 94602 United States
AB: We conducted a ground-penetrating radar (GPR) and seismic refraction survey of the Beatty Junction Shoreline Deposit in Death Valley National Park in March 2005. The deposit is a beach barrier bar approximately 500 m long, 50 m wide, and 5 m high, at an elevation of about 30 m above sea level and corresponds to a relict shoreline of the former Lake Manly (Orme and Orme, Phys. Geog., 12, pp. 334-346, 1980). The bar is oriented WSW-ENE, slopes to the east and is cut by the Beatty Junction Road. The longitudinal profile of the bar slopes to the east and is slightly concave upward. A total of 730 m of GPR data were recorded, including a longitudinal line 360 m in length, oriented along the crest of the bar, and four transverse lines, each approximately 100 m long. A hammer seismic refraction line was also recorded along the crest of the bar, and yielded a 3-layer model consisting of a surface layer about 1 m thick with a velocity of 200 m/s, a second layer 4-9 m thick with a velocity of 700 m/s, and a basal unit with a velocity of 1500 m/s. The uppermost layer apparently corresponds to an unconsolidated surface veneer of coarse gravel that has been winnowed to form desert pavement. The second layer is presumably sand and gravel that forms the main portion of the bar, and which thins in the longitudinal direction, from 9 m in the west to 4 m in the east. The third, basal layer represents older, more consolidated fan sediments. Shallow reflectors on the lakeward side of two of the transverse GPR lines have a distinct step-like appearance that may represent berms. All GPR lines show a thin surface layer, about 1 m thick, that unconformably covers all reflectors in the interior of the deposit, similar to the Hanaupah Shoreline Deposit at Tule Spring, described by Ibbeken and Warnke ( J. Paleolimnology, 23, pp. 439-447, 2002). The age of the deposit is given as 153 ± 12 Ka, late in Marine Isotope Stage 6 (Orme and Orme, 1991). Since this age range overlaps with that given by Machette et al. for the Tule Spring deposit ( GSA Abstracts with Programs, 34, pp. 257-258, 2003), we consider both deposits nearly time equivalent, deposited near or during Termination II.
DE: 0925 Magnetic and electrical methods (5109)
DE: 0935 Seismic methods (3025, 7294)
DE: 3344 Paleoclimatology (0473, 4900)
SC: Union [U]
MN: Fall Meeting 2005