Yosemite National Park Interactive Classroom

Yosemite in Depth: Geology

The key to unlocking the mysteries of how Yosemite Valley was formed is by studying and observing the landscape, as you are doing on your hike along the Mirror Lake trail. John Muir noted that "Patient observation and constant brooding above the rocks, lying upon them for years as the ice did, is the way to arrive at the truths..."

Geology
Habitat

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Overview Geologic Timeline Field Journal Activities Glossary Reference	.	Activity #1b: Know Your Rocks and Minerals How many different minerals do you see? Sometimes it is hard to distinguish one mineral from another. This rock has black, white, and grayish minerals. You might even be able to detect a slight pinkish tint. What kind of rock do you think this is?
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		Yosemite National Park Home Page http://www.nps.gov /archive/yose/education/depth/geology/activities/activity1b.htm Last modified Wednesday, 22-Dec-2004 10:14:43 Eastern Standard Time Yosemite National Park Web Manager

That is correct. This is a piece of granite, which is composed of quartz (which is white or grayish), biotite mica (which is black), hornblende (which is also black and elongated), and feldspar (which is pinkish).

Continue to the next page for activities about the park's Monster Rock!

Look at your field journal for suggestions. Do you need a hint? Try again.

That is incorrect. This is a piece of granite, which is composed of quartz (which is white or grayish), biotite mica (which is black), hornblende (which is also black and elongated), and feldspar (which is pinkish).

Continue to the next page for activities about the park's Monster Rock!