Preliminary notes on the revision of the geological map of eastern Colorado. 21 pages. W. C. Topelman. Digital PDF download. B-20D
Excerpted from the report introduction:
During the past year there has arisen a great need and demand for a revision of the present geologic map of Colorado. Because of this it has seemed advisable to place in bulletin form a brief synopsis of new information at hand, and to place before the interested public a preliminary map of the eastern part of the state where experience has shown considerable revision to be necessary.
The data upon which the present report and map are based have been derived from many sources. The major portion of the information has been derived from field work done under the supervision of the Colorado Geological Survey. Publications of the United States Geological Survey have been consulted freely and where the areal geology is known to be essentially correct, the results have been incorporated in the present work.