During the field seasons of 1931–1933, geologists from Northwestern University were engaged in a study of the pre-Cambrian formations of the Sawatch Range in central Colorado. The present paper is the result of more detailed study in the summer of 1933 of reverse faults along the western slope of the range.
Generous co-operation of the U. S. Geological Survey, both in the loan of field equipment and in valuable professional assistance, is gratefully acknowledged. Special thanks are due to C. H. Behre, Jr., B. S. Butler, and T. S. Lovering for field conferences and criticism. The use of unpublished maps and other data has been most helpful. Thanks also are given to the following graduate students of Northwestern University for field assistance : F. F. Barnes, R. S. Cannon, D. V. Harris, A. D. Hoagland, E. F. Osborn, and E. H. Rainwater.
As a description . . .