WEAVER: INVERTEBRATE PALEONTOLOGY AND HISTORICAL GEOLOGY 727 



on the eastern border are relatively thin and, although slightl.y warped, possess 

 a low seaward dip. In places the thickness is much greater in the Gulf area, 

 where the sediments accumulated in part as delta deposits. On the Pacific Coast 

 thicknesses of as much as 30,000 feet are recorded of both coarse and fine-grained 

 sediments which were deposited in downwarped and faulted basins. Prior to 

 1850 the general character of the Tertiary in eastern North America was made 

 known through the investigations of T. A. Conrad and others connected with 

 newly organized state geological .surveys. Thick deposits of sandstone, con- 

 glomerate, and shale of fl^uviatile, lacustrine, and alluvial origin which range 

 in age from Paleocene to Pliocene are widely distributed throughout the west- 

 ern interior of the United States and Canada. In the Great Basin area there 

 are several thousand feet of igneous rocks, including tuff, ash, lavas, and intru- 

 sive dikes. There has been much uncertainty concerning the age of the conti- 

 nental deposits but an increasing knowledge of the evolutionary development of 

 the fossil vertebrates, together with evidence from fossil plants, is making pos- 

 sible an acceptable scheme of correlation. 



The investigations made by W. B. Clark on the marine stratigraphy and 

 paleontology of the Tertiax-y of Maryland and the contributions of E. W. Berry 

 on fossil plants, together with papers by G. D. Harris, W. P. Woodring, Julia 

 Gardner, C. W. Cooke, W. H. Dall, K. V. W. Palmer, and many others have 

 aided in establishing the stratigraphic relationships of the many differing de- 

 posits in the Atlantic and Gulf coastal plains. The importance of these forma- 

 tions in connection with the occurrence of oil and gas has led to the publication 

 of many stratigraphical and faunal papers by geologists on the staffs of the 

 oil companies. The value of foraminifera for determining the age of strata 

 otherwise deficient in diagnostic fossils has made possible a more refined classi- 

 fication of the Tertiary of this area and the correlation of strata which show 

 marked lithologic changes in relatively short distances. 



The Tertiary deposits in California, Oregon, Washington, and British Co- 

 lumbia were made known during the middle of the past century through the 

 investigations of the Transcontinental Eailway Surveys, the Wilkes Exploring 

 Expedition, and the Geological Survey of California. In California fossiliferous 

 rocks in the vicinity of Tejon Pass were pronounced of Eocene age and ulti- 

 mately became known as the Tejon formation. Farther north in the Coast 

 Ranges other fossiliferous strata thought to be of the same age were also re- 

 ferred to under that name. In 1896 investigations by T. W. Stanton, of the U. S. 

 Geological Survey, and J. C. Merriam, of the University of California, showed 

 that the Martinez beds in central California which at first had been considered 

 Upper Cretaceous should be regarded as Lower Eocene. From this time until 

 1917 the Eocene of California was classified as Martinez and Tejon. During 

 the early part of the present century the Eocene rocks and faunas were inves- 

 tigated by students and faculty of Stanford University and the University of 

 California and the scientific results were published in the Proceedings of the 

 California Academy of Sciences and the Bulletins of the Department of Geology 

 at the University of California. Many investigations were carried on by the 

 U. S. Geological Survey, with the pul^lication of geological maps and reports. 

 Studies made by E. E. Dickerson, B. L. Clark, Ralph Arnold, C. A. Waring, 

 A. C. Lawson, J. C. Branner, F. M. Anderson, M. A. Hanna, G. D. Hanna, R. 



