No. 5. — On the Occurrence of Fossils of the Cretaceous Age on the 

 Island of Martha's Vmci/ard, Mass. By N. S. Shaler. 



It has long been known that fossils apparently pf Tertiary age occur 

 in the peculiar rocks about Gay Head, on the western extremity of Mar- 

 tha's Vineyard. These strata of alternating clays, sands, and occasional 

 lignites occupy the western half of Martha's Vineyard, in which region 

 they rise above the sea level. They probably underlie the glacial de- 

 posits throughout much of the area of the island, and may have a yet 

 wider extension. Even where the Tertiary beds lie above the sea level, 

 they are generally covered by a thick coating of glacial debris. Where 

 this debris has the character of true shoved moraine, the accumulations 

 are often a hundred feet or more in depth. Where the detritus exists 

 in the form of a sheet, it is less continuous, but nevertheless covers the 

 greater part of the underlying rocks, which are only exhibited in a clear 

 manner along the gulf-like shores. 



In 1870, while engaged in some studies on the erosion of the coast 

 lines of this island, I found several fragments of a coarse sandstone at va- 

 rious points in the drift material, which contained extremely obscure mol- 

 luscan fossils. Among these were specimens of what appeared to me to 

 be Exogyra, a genus which, as is well known, does not extend to the Ter- 

 tiary period, and is practically limited to the lower portion of the Creta- 

 ceous. Although the evidence was extremely imperfect, it was enough 

 to warrant a careful search of the island, with the hope of finding in 

 place the beds whence the fragments were derived. I spent more than 

 a month in this systematic inquiry before attaining to any results what- 

 ever. At length I discovered two localities where these sandstone frag- 

 ments with imperfect molluscan remains were tolerably plenty. These 

 positions are indicated in the descriptive sketch, Plate T. One of them 

 lies on the western shore of what is called Lagoon Pond, immediately 

 west of Cottage City. At this point a skilled collector may in the 

 course of half a day discover half a dozen fragments scattered in the 

 drift, which are clearly referable to Cretaceous rocks. A second and 

 more important locality lies near the centre of the northern shore, at 

 the distance of about three fourths of a mile from the coast line on the 



VOL. XVI. — NO. 5. 



