THE FOSSIL FISHES OF THE DIATOM BEDS OF 

 LOMPOC, CALIFORNIA 



In a previous paper (Fossil Fishes of Southern California: Leland 

 Stanford Junior University Publications, issued September 16, 1919) the 

 present writers have noted a number of new species of fishes, of Miocene 

 Age, from the deposits at Lompoc. 



Since that time, through the courtesy of Mr. Arthur H. Krieger, 

 director of the Celite Products Company, and his assistants, Messrs. Ed- 

 ward J. Porteous and Edward B. Starr, Dr. Gilbert and Dr. Jordan have 

 successively visited these deposits, making extensive collections. Still 

 later, Mr. Willard J. Classen, a student in Geology at Stanford University, 

 through the kindly interest of Mr. Timothy Hopkins, has spent some time 

 there securing fossil fishes for Stanford University. A large collection of 

 fish has been obtained, this forming the basis of the present paper. 



The Lompoc deposit itself is wholly unique. It lies in Santa Barbara 

 County, California, within an angle on the north side of the Sierra Santa 

 Ynez, a range composed mainly of Miocene sandstones and shales. This 

 angle or ancient bay covers about four square miles. In this space a 

 continuous and almost uniform mass of diatoms has been deposited, to 

 the maximum depth of 1,400 feet. 



The erosion of a stream on the west side has cut this deposit through 

 to its bottom of yellowish sandstone. Over most of this space, the diatom 

 deposits come to the surface, but in places the mass is overlaid by a 

 coarse, hard breccia or conglomerate, containing many bones of whales, 

 and occasionally teeth of sharks. On the extreme west, it is overlaid by 

 limestone in which a species of Pecten is very abundant. 



In places, there are thin layers of flinty rock, apparently of animal 

 origin, interstratified with diatoms. At one horizon, about six feet above 

 the Xyne layer noted below, there is a thin stratum of volcanic glass. 

 Scarcely anywhere in the whole mass does any sand or clay appear. This 

 shows that the deposit was made in quiet water undisturbed by fresh 

 water or rains. It may be noted that in deposits of the Monterey period 

 of the Miocene age, from Monterey to San Diego, diatoms abound, some- 

 times mixed or interstratified with sand or clay as about Los Angeles, 

 at other places forming immense deposits. It has been thought that 

 such deposits when buried under later rocks, as in Kern County and parts 

 of Santa Barbara, are the source of the oil found in these districts. When 

 the deposits are not covered, as at Lompoc, it is presumed that the oil 

 has all evaporated. 



