- Welcome to Mt. Shasta, the second highest volcano in the United States and a major peak of the Cascade range, a volcanic region which extends from British Columbia to northern California's Mt. Lassen. This magnificent mountain rises 14, 162 feet, and its base is more than 17 miles in diameter. Eight superb glaciers, California's largest, adorn its flanks. All of this is complimented by splendid ...shastaguides.com