Final Grades

Advanced Field Geology, Spring 1998

Ramon Arrowsmith, ASU Geology

Phil Pearthree, visiting lecturer

Heidi Stenner, Teaching Assistant

First class meeting is February 2 at 5 pm in PSF566.

In four weekend field excursions, students will gain field experience with a variety of environmental and applied mapping problems. Dr. Phil Pearthree, who studies geologic hazards and Quaternary geology for the Arizona Geological Survey, will help teach the course. Emphasis is on geological mapping and careful observation in the field. Field maps and notebooks will be turned in at the end of each field excursion. These will be graded and returned. A short writeup on the relevant analyses (landslide geometry, soil chronosequence, paleoflood calculations, and earthquake hazard) will be due within two weeks of the field trip. There will be one class meeting at the beginning of the semester, and then a several hour meeting before each trip to discuss logistics and the key elements of the mapping problem and follow-up analysis.

February 7-February 8 [Local or camping]

Investigation of an active landslide adjacent to Highway 17 in the area of Black Canyon City.

Evaluation of the geometry and activity of this landslide is an area of interest for both the Arizona Department of Transportation and the Arizona Geological Survey. Mapping will be done at two scales over the weekend: on large scale aerial photography and with the Geology Department total stations. The airphoto bases will be used to document the rocks, landforms, and other features in the area to establish the context for the development of the slide, and then the total stations will be used in turns to make a high resolution topographic and structure map of the landslide. Along with the topographic and structural mapping, the total stations will be used to measure the locations of monuments that we plan so establish on the slide to monitor future movement.

February 28-March 1 [Local]

Mapping of range-piedmont-river area near the Agua Fria River in northernmost Phoenix.

This project will provide students the opportunity to map Quaternary surfaces and deposits at the urban fringe of northern Phoenix. This area is the focus of current and planned mapping efforts by the ASU graduate students and geologists with the Arizona Geological Survey, so our work will complement and contribute to those projects. Airphoto (and possibly airborne imagery) bases will be used for mapping. We plan to have some soil pits excavated in advance of the field work and the mapping will be complemented by trench logging and soil description so that students can develop a soil chronosequence to help with the relative dating of the surfaces and materials in the mapping area.

March 7, 8

Fluvial landforms and paleoflood hydrology along the Agua Fria River above Lake Pleasant

Along the Agua Fria River at this site, an excellent fluvial terrace sequence and evidence for the high water levels in past floods are preserved. Mapping will include documentation of the distribution of the preserved fluvial landforms and consideration of the soil development and potential ages of the terrace deposits. Furthermore, we will document the high water marks in the channel, survey their locations and channel reach geometry (slope and cross-sections) using the Total Stations. These data will be used in application of simple channel hydraulics (Manning equation) to estimate the magnitude of the discharge in the past floods. Those results can be compared with existing gauge data and more sophisticated paleoflood calculations.

May 1 (afternoon), 2, 3 Late date to allow for warmer weather [Camping]

Active faults and lava flows near Wupatki (northeast side of San Francisco Peaks)

Typical evaluations of earthquake hazard are based upon establishing the geometry and activity of faults in an area. The geometry can be determined by mapping to establish potential rupture length and trace continuity (depth issues can be considered with seismicity, etc--not for this class). Activity of faults refers to the slip rate and if possible slip per event. Quaternary lava flows are cut by normal faults near Wupatki, so we will map (using airphoto and topographic bases) the traces of a couple of faults and consider their activity by looking at the relationships to the lava flows and the degradation of the fault scarps. This area is in a zone of heightened seismicity (including several M6+ events this century) and earthquake hazard analysis for the Flagstaff region is timely.

Survey data from Wupatki project