Geomorphology Field Research Project
GSC 323 - Applied Geomorphology
Cal Poly Pomona University
Professor Jeff Marshall
San Gabriel Mountains, with Claremont, Pomona, and Ontario in the foreground
Photo by D.M. Morton, U.S. Geological Survey
INTRODUCTION
The goal of our field project is to allow you to synthesize your classroom learning in geomorphology into a single, focused study of a set of local landforms. You will work in small groups to investigate the origin and significance of a series of flat-topped mesas and isolated hills that rise above the gently sloping surface of alluvial fans along the San Gabriel Mountain foothills. To complete this project, you will be expected to formulate a research plan, complete a background literature search, and conduct independent fieldwork outside of class time. You are encouraged to work in teams on this project and to divide up responsibilities as you see fit. However, each individual student will submit a final written report and take part in an oral presentation at the end of the quarter.
FIELD SITES
Rapid Quaternary uplift along the frontal faults of the San Gabriel Mountains (Sierra Madre-Cucamonga fault system) has led to the deep incision of canyons and the production of large volumes of sediment. This eroded rock debris is transported by streams across the mountain front and deposited within broad alluvial fans that extend outward into the adjacent lowland basin. Quaternary fan deposits consist primarily of interfingered lobes of coarse gravels laid down by episodic stream flooding and debris flows. These massive gravel fans coalesce into a regionally extensive bajada formed along the base of the mountains.
For the most part, this landscape consists of a broad, low relief and gently sloping surface that extends outward from the San Gabriel mountain front into the Pomona-Ontario basin. However, in several areas, remnant surfaces occur at higher elevations along the edges of the alluvial fans (e.g., mountain front at La Verne, Claremont, Upland). Also, in several locations, the alluvial fan surface is disrupted by small flat-topped hills such as Red Hill in Rancho Cucamonga, and Indian Hill in Claremont.
These hills have particular geomorphic and geologic characteristics that may shed light on their origin and significance. Your task as a geomorphologist is to study these anomalous landforms by making field observations, collecting data, generating maps and cross sections, and developing multiple working hypotheses about their origin. Be sure to consider all geomorphic processes operating in the landscape, and think about the significance of these landforms in both a local and regional context.
ASSIGNMENT
Due: 12/1 (last week of class)
1) Report: Each student will submit a research report with at least 5 pages of text, plus illustrations, and a reference list. This report should follow standard research report format (see lab guidelines handout).
2) Presentation: Each student will also give a class presentation on their results during the last week of class. This presentation should include some form of visual aids (overheads, Powerpoint, photos, poster, etc)
PROJECT DETAILS
The investigation:
Your investigation should begin by familiarizing yourself with the field sites on maps, in aerial photos, and in person.
You should work with your group to develop a research plan, to schedule fieldwork, and to divide up responsibilities accordingly.
Spend some time viewing your field sites on air photos under the stereoscope. Take careful notes and make trace maps if appropriate.
Make use of library resources to conduct a background literature search. Look for papers/reports on your specific field areas, as well as general studies of alluvial fans and related landforms. You should reference these sources of information in your final report. I will provide you with some initial reference material to get you started.
Plan to visit your field sites several times with the goal of carrying out specific tasks (e.g. recon mapping, measuring section & describing units, completing soil profiles, etc.). One particular challenge is that these sites are in suburban areas and exposure will be limited. You will have to work with scant field data and make inferences about what you can't see. In some cases, data from one site may have to be extrapolated to another site.
Be sure to develop "multiple working hypotheses" about your landform. Your goal will be to choose one favored hypothesis by process of elimination.
The report:
The final project report should be organized and formatted in a professional manner. All maps, illustrations, and plots should be neat, accurate, and drawn to scale.
The report should include the following sections: Introduction, Methods, Field Observations, Field Data & Results, Discussion, and Conclusions.
In addition to 5+ pages of text, your report should include:
- a geologic map, focusing on Quaternary deposits
- a stratigraphic column, with detailed lithologic descriptions
- two or more topographic profiles with cross sections of underlying units
(these should show landform from several different perspectives)
- a soil profile
- any other useful diagrams or photographs
- a reference list
SOME REFERENCE MATERIAL TO GET YOU STARTED:
Your text book:
Ritter, D.F., Kochel, R.C., and Miller, J.R., 2002, Process Geomorphology, Fourth Edition: New York, New York, McGraw-Hill Companies, Inc., 560 p.
Research papers & reports:
Eckis, Rollin, 1928, Alluvial fans of the Cucamonga District, southern California: Journal of Geology, v. 36, no. 3, p. 224-247.
Ritter, J.B., Miller, J.R., Enzel, Y. and Wells, S.G., 1995. Reconciling the roles of tectonism and climate in Quaternary alluvial fan evolution. Geology 23, 245-248.
Schumm, S.A., Baker, V.R., Bowker, M.F., Dixon, J.R., Dunne, T., Hamilton, D., Hjalmarson, H.W., and Merritts, D., 1996, Alluvial Fan Flooding: Washington, D.C., National Research Council, National Academy Press, 172 p.
Useful web sites:
http://www.nap.edu/books/0309055423/html/index.html
http://scamp.wr.usgs.gov/scamp/html/scg_ie_com.html#cucamonga
http://scamp.wr.usgs.gov/scamp/html/gm_sb_cuca.htm
http://geopubs.wr.usgs.gov/open-file/of01-311/
http://www.wild-environment.com/projects.htm
http://gmw.consrv.ca.gov/shmp/download/evalrpt/ont_eval.pdf