128 PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



lower group is Martinez, the Coalinga-Cantua area is the most important area 

 of Martinez in California. 



Mr. Lawson suggested that the organic shales referred to the Tejon by Mr. 

 Taff may possibly be of Lower Miocene age, and the conditions of sedimenta- 

 tion comparable to the alternating conditions of sandstone and organic shale 

 deposition in the Contra Costa Miocene. Since organic shale had not been 

 found elsewhere in the Tejon, he hesitated to accept the reference of the 

 organic shale portion of the Coalinga-Cantua section to the Eocene. 



Mr. Stalder made mention of an unconformity at the same horizon as the 

 one described by Mr. Taff but a few miles north of the limits of Mr. Taff's 

 area. The unconformity here was shown by borings and by considerable dis- 

 cordance in dips. 



SUGGESTED PALEONTOLOGIC CORRELATION BETWEEN CONTINENTAL MIO- 

 CENE DEPO'SITS OF THE MOHAVE REGION AND MARINE TERTIARY BEDS 

 OF SAN JOAQUIN VALLEY, CALIFORNIA 3 



BY JOHN C. MERRIAM AND ROBERT W. PACK 



(Abstract) 



In the formations of the Mohave region numerous mammalian remains have 

 recently been found. The fauna of the Mohave region is most nearly allied 

 with that of the Upper Miocene formation in the western border of the Great 

 Plains region. 



The continental deposits of the Mohave region extend to the foot of the 

 mountain range to the east of Tehachipi. The great marine and fresh-water 

 series of the San Joaquin Valley lies on the west flank of the range only a 

 short distance from the most westerly exposure of the Mohave beds. Recently 

 R. W. Pack has obtained from marine Tertiary beds in the Tejon Hills, on the 

 west flank of the range, a small collection of vertebrate remains. This collec- 

 tion includes the phalangeal elements of Merycodus, a small deerlike form, 

 similar to a species known in the Mohave beds, and teeth of a horse similar 

 to Merychippus calamarius of the Mohave region. Associated with these re- 

 mains are shark's teeth and a number of marine shells. The known inverte- 

 brate fauna of these beds has been presumed to indicate their Lower Miocene 

 age. The question arises as to whether the mammal-bearing beds of the 

 eastern border of the San Joaquin are of the same age as the presumed Lower 

 Miocene of the Kern region, or whether there is a discrepancy between the 

 age determinations based on the one hand on mammalian fossils judged by 

 comparison with the Great Plains faunas, and on the other hand on marine 

 forms compared with those of the Atlantic coast. 



3 Presented by permission of the Director of the U. S. Geological Survey. 



