Ge121a: Advanced Field Geology:
Formation of inverted river deposits near Green River, Utah
Instructor: Michael Lamb
TA: Luca Malatesta
Goal: In this course we will map fluvial deposits from the Castlegate and Morrison Formations that have been inverted topographically. We will analyze the morphology of the inverted deposits (ridge relief, slope, shape and modern erosional processes) and reconstruct the characteristics of the rivers that formed the deposits by measuring sediment sizes, bed form types and sizes, channel scour surfaces and fill characteristics. This landscape is also an often-used analog for similar features on Mars.
Our measurements and mapping will focus on addressing the following research questions: 1) How and why do sandy channel bodies form? 2) What can sedimentary structures inform us about past hydraulic and environmental conditions? 3) What processes have caused the river deposits to be inverted topographically? 4) What information can we extract about the paleo rivers from the morphology of the modern day eroded ridges?
Post trip activities: We will meet once per week fall quarter to work through the analysis of data collected in the field. Tentative meeting time is Friday 3-5 pm, 267 Arms.
Deliverables: 1) Field notebooks. 2) Maps and strat sections. 3) Digitized data (Excel) from channel, bedform and sediment-size surveys. 4) Data analysis results (to be completed as a group after the trip).
DUE DECEMBER 6th
Driving Route Map
Google Earth File of some of the mapping areas from Williams et all (Please look at landscapes from above before the trip)
Required Readings (Please read before trip and bring your own copies on trip.):
Williams et al., field guide, 2011 and supplement.
Williams et al., 2009, Evaluation of paleohydrologic models for terrestrial inverted channels: Implications for application to martian sinuous ridges
Harris 1980, Exhumed Paleochannels in the Lower Cretaceous Cedar Mountain Formation near Green River, Utah*
Flood and Hampson, Blackhawk Formation channel bodies
Logistics: Camping will be wilderness with no running water or toilets. Expect highs in the 70s F and lows ~30 F and potentially below freezing at night. Bring warm clothes and warm sleeping bags. Please check the weather for Green River, UT.
The GPS Division will provide group camp gear (stoves, lanterns, tables, chairs, water jugs, ice chests, pots & pans, dishes). We also will bring measurement gear (hand levels, measuring tapes, pebble count tapes, stadia rods, shovel, field books, maps, gps, laptops, colored pencils). We will shop for food together. The Division will only partially cover your food costs ($10/day), so please bring cash to pool for excess food costs.
Students are responsible for their own field equipment. Please also bring your personal copies of the required readings. You may choose to bring your own laptop for calculations.
Caltech Policies. Please complete driver and field trip forms, and review alcohol policies and other Division policies.