BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 VOL. 1, PP. 443-452, PL. 9 APRIL 21, 1890 



TERTIARY AND CRETACEOUS DEPOSITS OF EASTERN 



MASSACHUSETTS. 



BY N. S. SHALEE. 

 {Read before the. Society Deerhihn- 2<\, 1SKH.) 



CONTENTS. 



Page. 

 General Statement 443 



Age of the Martha's Vineyard Dislocations 445 



Glacial Origin of Bowlder Beds containing Fragments of Osseous Conglomerate. 449 

 Detailed Description of Sections 4-">0 



General Statement. 



In a memoir on the geology of Martha's Vineyard contained in the 7th 

 Annual Report of the Director of the U. S. Geological Survey, I gave a 

 preliminary account of the several deposits, mostly of doubtful age, exhib- 

 ited on the western part of that island. The conclusions there presented 

 were in the main those which had beeu derived from a study of the district 

 in the years between 1860 and 1872. Since this memoir went to press, I 

 have been able considerably to extend my studies in this field. A portion 

 of the results of this latter work are embodied in a recent paper entitled, 

 ''On the Occurrence of Fossils of Cretaceous Age on the Island of Martha's 

 Vineyard, Mass.'* In that paper I have endeavored to prove the existence 

 of middle or lower Cretaceous deposits in the central portion of that island. 

 About 15 species of fossils are there described as occurring in this deposit, 

 two of which, au Exogijra and a Camptonectes, appear to afford indubitable 

 evidence as to the Cretaceous age of the beds. 



In all my previous studies in this field it has been difficult to prepare well 

 determined sections of the principal outcrops for the reason that these occur 

 on the sea shore and had been extensively covered by rubbly material 

 which had gradually accumulated. In the autumn of 1888, a rain storm of 

 great violence, which led to the deposition of about five inches of water in 

 the course of two hours, scoured off these escarpments in such a manner as 



^Bulletin Mus. Comp. Zool., vol. XVI., No. 5, 1889. 

 LVtir— Bull. Gf.ol. Snc. Am., Vol. 1, 1889. (443) 



