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THE POPULAR SCIENCE MONTHLY.
Typical Exposure of the Ricardo Pliocene near Ricardo. (Photographed by C. L. Baker.)
in the El Paso Range on the western border of the desert, hut no additional material representing this stage has as yet been found.
To the whole series of older or Tertiary sediments of the Mohave area, O. H. Hershey has given the name Rosamond series. Mr. Baker has shown that the series is divisible into a number of quite distinct divisions. Some of these may represent quite widely separated periods. Evidence which the writer obtains from a study of the faunas indicates that the deposits north of Barstow containing a Miocene fauna, may represent a formation quite distinct from that at Ricardo containing a Pliocene fauna. The term Barstow formation is used for the beds containing the Upper Miocene fauna. The lower portion
Exposures of Ricardo Pliocene, Showing Characteristic Bad-land Structure in Outcrops near Ricardo. (Photograph by C. L. Baker.)
