Page:Walcott Cambrian Geology and Paleontology II.djvu/467



With the development of the mapping of the geological formations of the United States, it has increasingly become evident that the use of more than one term derived from the same geographic name is faulty in principle and confusing in usage. I have long been guilty of doing it in the use of Georgian for the Lower Cambrian series of formations, and I now find that the name I derived Saratogan from, for the Upper Cambrian series, was previously used for the Cretaceous Saratoga formation. (See page 306.) Much as we may regret the change to new terms, I think that in the long run of time it will facilitate the understanding of the nomenclature of the Cambrian system by the student.

Under the principle stated in the preceding paragraph, the term Georgian as used by me in 1891 is in bad form and should be replaced by a geographic name that has not been used for any geologic formation or group of formations. The history and use of the name Georgia is given in Bulletin 81, cited above, on pp. 98-113, 249-250, and 360.

Since the publication of Bulletin 81 in 1891, it has been found that the greatest development of the Lower Cambrian terrane is in Esmeralda County, Nevada, and the adjoining county of Inyo, California.

The Barrel Spring section of Nevada has several thousand feet of Lower Cambrian strata with a fine Lower Cambrian fauna. The Waucoba section, 30 miles to the southwest in California, is also finely exposed, and it has a well-marked Lower Cambrian fauna that extends through 4,000 feet of strata.