"FAUNAL RELATIONSHIPS OF THE MEGANOS GROUP" 297 



into formations was constantly kept in mind. In the special case 

 in point the writer regards the unconformity north of Mount 

 Diablo as being such a one as would separate the Tejon group into 

 formations, while Dr. Clark would make two groups. Dr. Clark 

 admits that this unconformity was not stratigraphically recognized 

 in the fine Tejon-Eocene section only a few miles distant on the 

 south side of Mount Diablo. 



Detailed mapping has failed to show any marked difference in dip and 

 strike between the Meganos and the Tejon in this southern area, such as occurs 

 to the north of the mountain (Mount Diablo). At a few localities there is an 

 apparent difference in dip between the beds of the two horizons; this, however, 

 could not be verified with certainity, the division being recognized by a sharp 

 change in lithology, and by faunal evidence [p. 141]. 



The footnote on this same page is likewise significant: 



In the former paper ["Meganos Group, a Newly Recognized Division in 

 the Eocene of California," Bull. Geol. Soc. America, Vol. XXXIX (1918), 

 pp. 281-96] referred to above, the writer stated that in this section there is a 

 marked difference in strike between the Meganos beds and those of the Tejon, 

 and the difference was taken as one of the evidences of unconformity between 

 the beds of these two horizons. Later work, however, has shown that this 

 apparent difference in strike is, in part at least, the result of faulting. Also it 

 was stated that to the east of this area the Meganos disappeared due to this 

 unconformity. At that time the writer had not recognized that the so-called 

 Tejon beds to the east, as described by Dickerson, were in part Meganos. 



Concerning the presence of unconformities in other parts of 

 California, Clark refers to his studies made in the vicinity of 

 Coalinga and Simi Hills, Ventura County, as follows: 



The results of this work show conclusively that beds of both Meganos 

 and Tejon age are present in all of these areas, and that there is in each an 

 unconformity separating the strata of those two series.^ .... As seen 

 between .... Domengine Creek and Cantua Creek (Coalinga Quadrangle), 

 the upper beds of the Meganos consist of a white sandstone which was mapped 

 by Anderson and Pack as a part of the Tejon. The contact between the 

 Meganos and Tejon comes in between this sandstone and somewhat similar 

 sandstones of the Tejon. It is, as a rule, marked by a conglomerate and is 

 irregular at numerous localities. The sandstones below the contact, due to 

 the unconformity, thicken and thin very noticeably along the strike. Also, 

 at a number of localities the lower sandstones show a dip and strike appreciably 

 different from those of the Tejon beds above. While these differences amount 



' Evidently series is used loosely. 



