A Walk Along a Geologic Timeline #2 - California
Posted by: 
Volcanoguy
N 40° 26.274 W 121° 32.010
10T E 624378 N 4477394
Rock display at Kohm Yah-mah-nee Visitor Center.
Waymark Code: WMJR74
Location: California, United States
Date Posted: 12/22/2013
Views: 2
One of four large volcanic boulders around the Kohm Yah-mah-nee Visitor Center near the south entrance to Lassen Volcanic National Park.
Text of display sign:
A Volcanic Center — and, You are Here!
This andesite boulder formed approximately 600,000 to 470,000 years ago — a remnant of a giant composite volcano in the southwest portion of the park. Andesite is a fine-grained rock that forms as lava flows from andesitic volcanoes.
You are standing near the center of what was once the most active volcano in this region — 11,000 foot (3353 m) Mount Tehama. Over time glaciers and hydrothermal activity eroded the volcano (also called Brokeoff Volcano) leaving a large caldera of hot springs surrounded by lava flows.
Type of Display: Geological
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