CAMBRIAN GEOLOGY OF THE ROCKY MOUNTAINS 



By CHARLES E. RESSER, 



Associate Curator, Division of Stratic/raf^Iiic Palcoiitolo(jy, 



U. S. Ahitioiial Museum 



For a nuiiil)er of years I have l)eeii carrying- on field-work, l)oth in 

 the western United States and in Europe, under the direction of 

 Dr. Charles D. Walcott, to obtain data to be used in systematizing 

 the Cambrian System and more particularly to find a Middle Cam- 

 brian section comi)lete enough to serve as a standard of reference for 

 these strata in other parts of the world. Owing to the lamented death 

 of Dr. Walcott in February, 1927. it became necessary for me to 

 interru]:)t this program and visit a wider area this past summer than 

 would otherwise have been done. 



Dr. Walcott was occupied during the last few years of his life 

 in summarizing the knowledge gained in the extensive researches con- 

 ducted throughout his long and fruitful career, with the result that 

 at his death he left a large uncompleted manuscript presenting a com- 

 prehensive treatment of the stratigraphy in the Canadian Rocky 

 Mountains where he made many remarkable discoveries. As I was 

 detailed to edit and attempt to complete this manuscript, it became 

 necessary to reexamine certain Canadian sections for stratigraphic 

 details which were found lacking when Dr. Walcott assembled his 

 data and which he had hoped to seek in the field himself. 



Since the motor truck used in previous years had been sold as no 

 longer useful for strenuous field-work, a new one was purchased in 

 Washington, through the generous assistance of Mrs. C. D. Walcott, 

 and driven across the continent. Our party traveled by this means 

 from the time of leaving Washington until the outfit was stored at 

 Salt Lake City, a total of more than 6,000 miles, traversing a con- 

 siderable portion of the continent. It was a pleasure to find that 

 Dr. R. S. Bassler, curator of stratigraphic paleontology, U. S. Na- 

 tional Museum, was willing to accompany me, and so I have had the 

 benefit of his advice and experience in stratigraphic geology, thus 

 assuring more certain results in the field determinations. My son, 

 Harold Resser, served as camp assistant. 



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