Re: Interested in U.S. physiographic regions + cross sections

From: Tom Cudzilo (tcudzilo_at_rcsis.com)
Date: 03/08/05 

Date: Mon, 7 Mar 2005 21:30:10 -0800

The "pimple" in the Great Valley Province north of
Sacramento is the Sutter Buttes. The buttes are volcanic
rocks of rhyolitic and andesitic composition that were
emplaced 1.3 to 1.8 million years ago. The volcanic rocks of
the buttes are unusual in the Great Valley. However, the
Lassen volcanic field is approximately 100 miles northeast,
in the Sierra Nevada Province last erupted in 1914. Until a
recent partial acquisition by the state, the Sutter Buttes
properties have been in private hands since the 19th
century.