Page 303 - Laboratory Manual in Physical Geology

ACTIVITY 10.1 Geologic Structures Inquiry

Name: ______________________________________ Course/Section: ______________________ Date: ____________

A. Recall the Law of Original Horizontality, which states that layers of sedimentary rock and lava tend to accumulate as relatively
horizontal layers. The layers may remain undisturbed or they may be deformed—have their original shape or form disturbed
in some way. Analayze each image below. Beneath each image answer these two questions:

■ Are the rocks deformed or not deformed? ■ If deformed, then describe how and why you think the rocks were deformed.

1. Grand Canyon, Arizona rock layers. 2. Cliff face about 400 m tall, south-central Alaska (USGS
photograph by N.J. Silberling).

3. Quartzite, Maria Mts, Riverside County, California (USGS 4. Sandstone on a steep wall about 100 m tall, Little
photograph by W.B. Hamilton). Colorado River Gorge, Navajo Nation, Arizona

B. REFLECT & DISCUSS Based on your analysis of deformed rocks above, classify rock deformation into two categories, and
note what images above would be in each category. Be prepared to explain your classification to other geologists.

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