published August 1, 1925, "First Edition 5000 copies" stated on title page; by Edwin T. Hodge, Professor of Economic Geology, University of Oregon; staple bound softcover; very good condition with unmarked pages; many b/w photos and illustrations; includes a "Topographic Map of The Three Sisters" mountains inside back envelope; covers have slight ageing and wear.
 
from Introduction -
"...Attracted by the beauty of the region, its glaciers and lava flows, the author selected it as the subject for actual field work during the Summer of 1924.  While engaged in this detailed study it was discovered: that the Three Sisters mountains rest upon the worn remnants of Oregon's greatest Pre-historic mountain, Mount Mulnomah; that this mountain once rose approximately a mile in height above the present snow-clad tops of the Three Sisters; that the top of this enormous mountain was lost by a gigantic explosion which left one of the largest calderas in the world; and that the Three Sisters and most of the adjacent peaks have acquired their present form as the result of later volcanic and glacial activity..."