Lab 8_TopoGeo

Lab 8_TopoGeo - Lab 8 Topography and Geology Lab...

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Lab 8: Topography and Geology Lab Introduction In previous labs, various methods were discussed in which relative ages of geologic units and other geologic events could be determined by relative age dating, usually based upon the relative positions of these units and features. Below is a model example of how rock units with different dips (angles to the horizontal result in different outcrop patterns of the rock units at the surface. Clay models of layered rock units with different dips showing different outcrop patterns on the surface. Horizontal bedding (front left) gives outcrop pattern parallel to the topographic contour lines. Vertical bedding (rear right) gives outcrop pattern with straight lines completely independent of the topographic contours. Dipping bedding (left side and right side) give outcrop patterns that are distorted versions of the topographic contours down-dip, with the distortion increasing with the dip. Geologic maps, as shown in the first figure in Lab 6, typically include topographic contours in addition to geologic information. Topographic profiles are constructed, as described in Lab 7, then the process is repeated using the geologic contacts. An attempt is then made to join the geologic contacts in the subsurface to map the subsurface geology in the most simple configuration possible, i.e. , if the surface outcrops can be satisfied with horizontal layers, then horizontal layers are drawn; if the surface geology can be satisfied by flat, but dipping bed, then flat, dipping beds are drawn. Folds, faults, and changes in thicknesses on beds are only introduced if they are absolutely required, and preferably if there is some surface evident of these features. Folds and faults commonly have some topographic expression. Planetary Images, Topography and Geology
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This note was uploaded on 01/01/2011 for the course GLG 190 taught by Professor C.v. during the Spring '09 term at Arizona.

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Lab 8_TopoGeo - Lab 8 Topography and Geology Lab...

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