Prelude
Many mountainsides, stream canyons, and road cuts contain exposures of rock units that tell a story of the geologic past. Even on the hand sample and microscopic level, rocks tell a story of their past. On the larger scale, these relations are typically represented on geologic maps and cross sections. Let's chat about some of the ways you can determine the geologic history of an area.
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Figure 3-1. Geologic history displayed in the Monument Creek area of Grand Canyon NP. The view from the Tonto Trail towards the Colorado River (left). Ford hikes along the Tonto Trail below the South Rim (right). Remember to click on the highlighted images to see larger versions. |
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What Will You Do Today?
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Review the basics about geologic time and dating methods to interpret geologic cross sections |
A. Telling Geologic Time - Review the basics of geologic time
B. Relative Geologic Dating Principles & Unconformities - Learn how to employ several important relative age dating principles to decipher unconformities and sequence diagrams
C. Isotopic Age Dating - Find out how specific "number ages" are determined for rocks
D. Geology of Loco Canyon - Interpret the geology displayed in a sequence diagram of "Loco Canyon"