Formation of Crater Lake  Crater Lake occupies a basin in Mount
Mazama, one of the volcanoes that make up the Cascades Mountain
Range along the west coast of the United States. The major
volcanoes of the Cascades include the following (listed from
south to north):    • California: Lassen Peak and Mount Shasta.
• Oregon: Mount Mazama, Three Sisters, Mount Jefferson, and
Mount Hood.   • Washington: Mount Saint Helens, Mount Adams,
Mount Rainier, Glacier Peak, and Mount Baker.  Animated image of
the formation of Crater Lake.  This generalized diagram of the
formation of Crater Lake is animated from the 1959 edition of
the 1:62,500 scale topographic map entitled "Crater Lake
National Park and Vicinity, Oreg."  Crater Lake is a beauty born
from violent eruptions of spitting fires and rocks. The phrase
"GREW, BLEW, FELL, and FILL" describes the process that created
Crater Lake. Mount Mazama grew, erupted, then collapsed to form
the caldera, and finally precipitation filled the caldera.
Although Crater Lake has be