1917] Nomland: The Etchegoin Pliocene of Middle California 197 



Thus no break has been found comparable to that assumed by 

 Arnold and Anderson between the Etchegoin and the Jacalitos in the 

 Coalinga region. On the contrary, the increase in the number of 

 species and closer study of the fauna of the Jacalitos have shown a 

 very decided similarity between the two, and that both are very 

 different from the Santa Margarita-San Pablo. The term Jacalitos 

 as a formational name must therefore be abandoned and, because of 

 its close relationship to the Etchegoin, it becomes necessary to include 

 the Jacalitos with that formation. In this paper the term lower 

 Etchegoin will be used when referring specifically to beds equivalent 

 to the Jacalitos, while upper Etchegoin will be used in reference t® 

 the Etchegoin as defined by Arnold and Anderson. The upper and 

 lower Etchegoin when considered together will be called the Etchegoin 

 group. 



Summary of List op "Jacalitos" oe Lower Etchegoin Species 



Total number of determinable species from the "Jacalitos" 93 



Number of Recent species in the "Jacalitos" 37 



Percentage of Recent species 40 



Number of species common to the "Jacalitos" and the San Pablo-Santa 



Margarita 31 



Number of species found in the Etchegoin (of Arnold and Anderson) or in 



later deposits 68 



Number of species known only from the "Jacalitos" 19 



Number of species found in the San Pablo, Santa Margarita, and "Jacalitos" 



but not known in the Etchegoin or later formations 2 



Number of species found in the "Jacalitos," Etchegoin and later formations 



but not known in the Santa Margarita-San Pablo 37 



THE ETCHEGOIN GROUP OF MIDDLE CALIFORNIA 

 Areal Distribution 



Flanking the eastern foothills of the Diablo and Temblor ranges 

 is a belt of slightly consolidated deposits which usually dip at low 

 angles under the alluvium of the San Joaquin Valley. In the Coalinga 

 district and some distance to the north these beds have been mapped 

 as the Tulare, Etchegoin, and Jacalitos formations. All these now 

 appear to be probably of Pliocene age. 



In the Eastside field, comprising the northern part of the Coalinga 

 district, the Etchegoin and the overlying Tulare as mapped by Arnold 

 and Anderson are present. The lower, or "Jacalitos," member is 

 without invertebrate fossils and the correlation with the type section 

 is more difficult. South of Coalinga, in the Jacalitos Hills and in the 



