94 PROCEEDINGS OF THE SAINT LOUIS MEETING 



MEGANOS GROUP, A NEWLT RECOGNIZED DIVISION IN THE EOCENE OF 



CALIFORNIA 



BY BRUCE L. CLARK ^ 



{Abstract) 



An unconformity believed to be of more than local importance is recognized 

 in the Eocene deposits of Mount Diablo, California, in a section heretofore 

 recognized as representing the Tejon group of the Upper Eocene. This uncon- 

 formity is indicated by difference in strike and dip, together with other evi- 

 dences of erosion. The beds above the contact contain a typical Tejon fauna, 

 while those immediately below contain a faunal representation differing con- 

 siderably from that of the typical Tejon, and also differing from the typical 

 Martinez fauna of the Lower Eocene. Strata representing the Martinez are 

 found in this section unconformably below the newly recognized Stewartsville 

 group. 



The name Meganos is given to the new group situated between typical 

 Martinez and typical Tejon. It is believed that deposits of the Meganos group 

 have a wide distribution throughout the coast ranges of California. In certain 

 localities they have been referred to the Martinez group and at other places 

 to the Tejon. 



Presented in full extemporaneously. 

 Eemarks were made by Dr. Eliot Blackwelder. 



AGE OF THE MARTIN8BURG SHALE AS INTERPRETED FROM ITS STRUCTURAL 

 AND STRATIGRAPHICAL RELATIONS IN EASTERN PENNSYLVANIA 



BY F. F. HIINTZE 



(Ahstract) 



Isolated masses of Martinsburg shale occur several miles to the east of the 

 main body of shale and slate rock, lying unconformably on older rocks, from 

 the Hardyston (Lower Cambrian) to the Trenton. The Martinsburg has been 

 correlated with the "Hudson River" shale, and its age variously determined 

 to be Trenton or Utica on the basis of graptolite i-emains found at localities 

 in Pennsylvania, New Jersey, and New York. The decided unconformity of 

 the Martinsbui-g on the older Cambrian and Ordovician beds shows a period 

 of folding and considerable erosion prior to the end of Martinsburg time, 

 before the beds of which the isolated masses or remnants were deposited. 

 Fossils have not been found in these detached areas of Martinsburg shale, the 

 identification of the material as Martinsburg being based on lithologic charac- 

 ters which bear a very striking resemblance to those of the main body of the 

 shale. 



In New Jersey the Martinsburg has been described as following the Jack- 

 sonburg limestone (Lowville, Black River, and Trenton) in normal conform- 

 able sequence, and on the basis of graptolites found the lower part of the 

 Martinsburg is here correlated with the middle part of the typical Trenton of 



Introduced by John C. Merriam. 



