Page 251 - Laboratory Manual in Physical Geology

ACTIVIT Y 8.5 Infer Geologic History from a New Mexico Outcrop

Name: ______________________________________ Course/Section: ______________________ Date: ___________

A. Refer to the image below, an outcrop in a surface mine (coal strip mine) in northern New Mexico. Note the sill, sedimentary

rocks, fault, places where a fossil leaf was found, and isotope data for zircon crystals in the sill.
1. What is the relative age of the sedimentary rocks in this rock exposure? Explain your reasoning.

2. What is the absolute age of the sill? Show how you calculated the answer.

3. Locate the fault. How much displacement has occurred along this fault? ______________ meters

Sill has zircon
crystals with
BASALT SILL 98.9% U-235 and
1.10% Pb-207
atoms.

BASALT SILL

CLAY SHALE

CLAY SHALE

SANDSTONE Fault 2 m

SANDSTONE 1

0

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