GLG410--Computers in Geology

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Simple analysis of topography (pencil and paper and spreadsheet)

The data below are taken from the topography at a site along the San Andreas Fault in California.

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Here is a picture:

Stream offsets at Wallace Creek, Carrizo Plain, California

View northeast across the San Andreas fault showing several offset stream channels. Main channel is offset about 130 m and was incised approximately 3,700 years ago. Channel farther to left on near side of fault has been displaced approximately 350 m, is beheaded, and was incised approximately 10,000 years ago. These offsets and ages provide a long term slip rate of approximately 35 mm/yr along the San Andreas fault here (Sieh and Jahns, 1984). Small gulches at right display about 5-9 m offset from the 1857 earthquake.


  1. Using the spreadsheet of the topography every 5 meters at Wallace Creek (WallaceCreek.xls), make two plots: The first is a contour plot, and the second is a 3D view (both are under Insert->Other Charts->Surface). Make sure that both plots are well labeled and that they have annotation (drawing and text that points out the San Andreas Fault). Make sure also that the view direction for the 3D view is useful and shows the features well. Turn this in as a separate spreadsheet from below. Hint: look at the Elliptic Parabaloid video on Lecture 3 to remind yourself about the surface plotting.
  2. Looking at the map I have provided (wc.gif or wc.pdf, please make two topographic profiles along the two red lines I have drawn ("Scarp profile" and "Wallace Creek profile") using a ruler and Excel. ( I did one in this figure to show you what it could look like: SampleProfile.jpg.) Steps to do this:

GLG410 Computers in Geology

Last modified: September 1, 2011