October 28-30, 2005

Field Trip Coordinators:

Dave Miller, Chris Menges, Matt McMackin

Field Trip Leaders:

Dave Miller, Chris Menges

With contributions from:

Matt McMackin, Shannon Mahan, Jordon Bright, Richard Hereford, Kevin Schmidt, Jon Stock, Heather Lackey, Joanna Redwine, Roger Smith, and Jen Mendonca

Trip Summary:

We will present contributions from new regional to detailed surficial mapping, combined with geomorphologic, geochronologic, and tectonic studies, to a long-standing problem: the tectonic and geomorphic evolution of the intersection between three regional tectonic provinces, namely, the eastern California Shear Zone, Basin and Range, and the eastern Mojave Desert . This junction is centered southeastern Death Valley and northern Silurian Valleys and the bordering highlands to the southwest ( Avawatz Mountains ) and northeast (Sperry-Alexander Hills, Kingston Range and Shadow Mountains ). In addition we will present new observations on processes of piedmont and fan development, the role of depositional and eolian processes on soil hydrology, plants, and pedogenesis, the evolution of axial-valley drainage systems, and new chronologic data on local and regional surficial stratigraphy.

Trip Information and Logistics:

-- The trip will last 2.5 days, beginning officially on the morning of Friday, October 28, and ending at midday on Sunday, October 30, with a pre-trip campsite and meeting place set up for early arrivals on the Thursday evening, October 27.

-- The trip will be run from a single central group campsite on open public (BLM) land in Silurian Valley . Specifically, the campsite will be located on the southeastern margin of Silurian (dry) Lake . This can be accessed by turning east from California State Highway 127 about 25 feet north of milepost 19.0, proceed east 0.2 miles down a gently-sloping gravel berm to the lake, and then east about 1.2 miles across the lake bed. Camp is adjacent to the piedmont, which provides alternatives to the playa bed. The initial turn-off from CA 127 is located either: (a) from the south approximately 19 miles north of Baker CA (which is appropriate exit from Interstate 15), or (b) from the north approximately 36 miles south of Shoshone CA, (which can be accessed via several highways from Death Valley proper, from US Highway 95 via the Amargosa Valley turnoff, or Pahrump NV). Watch for the milepost markers.

-- We will be dry camping at this site for the entire trip (i.e., two official nights, Friday and Saturday). Pre-trip camping and orientation will also be available at the site on Thursday (October 27) (recommended). The nearest towns to this campsite are at Baker to the south and Shoshone to the north. Both of these towns have some motel accommodations, expensive gas, and limited convenience-store-style markets (including block ice and bottled water). More complete provisions are available at distances of 60 to 90 miles in Pahrump and Las Vegas to the northeast or Barstow to the southwest. We will not be formally entering any towns during the course of the trip (Friday through mid-day Saturday), so plan accordingly for sufficient food, water, ice, and gas during the course of the trip.

-- We may be restricted due to wildfire danger. If allowed, fires may only be built with firewood. No plywood or nails!

-- Plan for mid-fall weather in this low elevation (approx 200 to 600 m altitude) part of the Mojave Desert . Diurnal temperatures are somewhat unpredictable, but likely could vary from daytime maximums of 70 to 95 deg F and nighttime lows of 50 to 70 deg F. Expect lots of sun with the possibility of some wind and hopefully a very unlikely chance of showers.

-- Registration is open, but with a size restrictions of 250 persons, via either mail-in pre-registration form (downloadable from this website) or on-site, at a cost of $40.00 per person, which includes all group camping and guidebook costs. Field-trip tee shirts will be optionally available at additional cost as well.

Pre-registration is encouraged as soon as possible, preferably by October 19. Also we encourage sending as soon as possible an email of intent to attend the trip to cmmenges@usgs.gov , in order to ensure adequate campsite facilities and guidebooks. Please include the number in your party in the email.

Every attempt should be made to carpool to reduce vehicle caravan size. Also, some field trip sites are accessible only by high clearance vehicles, which may necessitate some car pooling by those attending in sedans or other low clearance vehicles.

-- Additional information is also available from Dave Miller ( dmiller@usgs.gov ) and Chris Menges ( cmmenges@usgs.gov ).

Click on the Registration Form below. All field trip participants should pre-register as soon as possible:

Field-Trip Registration Form (html version)
Or, click here to download the registration form as a MS Word document.

Summary -- 2005 Field Trip Itinerary

Friday, October 28

Present overview of the southern Death Valley and northern Silurian Valley area at the southern Salt Spring Hills and summarize major themes of field trip, including tectonic origin of main valley system. Examine fine-grained sediments on east side of hills and discuss evidence for lacustrine vs. ground-water origins for these deposits, as well as a pronounced marginal topographic bench. Examine anomalous late Quaternary axial valley incision into bedrock along this reach of Salt Creek.

Move to Valjean piedmont and look at: (a) evidence for historic climatic variations from local depositional patterns; (b) tectonic framework and depositional history of the large Kingston Wash tributary drainage, including evidence for a large Holocene debris/hypoconcentrated flow deposit; (c) summary of new geochronologic (luminescence) dates for surficial deposits in the area and relevance to nearby chronosequences in the area.

Saturday, October 29

Examine evidence for neotectonic contractional deformation along and adjacent to the northern and eastern range fronts of the Avawatz mountains that form the southern and western margin of the Death and Silurian valleys, respectively. Begin by traversing lower and medial piedmont below the eastern Avawatz Mountains front, looking at deposits, soils and evidence for warping and local fracturing of Pleistocene fans. Move to medial part of the southern Death Valley piedmont and discuss transportation mechanisms of alluvial fan deposits and their influence on deposit characteristics, intrafan incision, and soil development. Continue to the base of the adjacent northern Avawatz mountain front and look at exposures of late Quaternary contractional deformation, including thrust faults in bedrock and Quaternary alluvium, tilted Quaternary fan deposits interpreted as fault-propagation folds above buried thrusts, and concomitant uplift and incision of Pleistocene fan heads. Discuss implications of deformational features to Quaternary tectonic evolution of the range front.

Sunday, October 30

Examine evidence for neotectonic uplift origin for the bedrock highlands (“Tecopa hump”) on the northern margin of southern Death Valley and northern Silurian Valley , and implications for history of the Tecopa basin and Amargosa River drainage. Begin near the mouth of the Amargosa River Canyon on the southern flank of the highland and examine significance of fluvial terraces and river incision history for origin of the Tecopa hump from neotectonic uplift and warping. Also discuss studies of eolian landforms and processes at the nearby Dumont Dunes. Move northwestward and discuss nontectonic vs. tectonic origins for a sequence of inset strath (bedrock-floored) terraces and fans midway on the southern flank of the Tecopa Hump. Complete trip at overview of upper Amargosa Canyon and the northern flank of the Tecopa Hump near Tecopa with discussion of implications of active uplift for canyon formation and basin dissection. Final review of major themes presented during field trip before dispersing at mid day.