0. C. Marsh — Geology of Block Island. 877 



Block Island, owing probably to its diminutive size and 

 isolated position, has attracted but little attention from geolo- 

 gists, altbongli situated as it is between Long Island and 

 Martha's Yineyard, it is an intermediate station of considerable 

 importance. The first notice of its geological features is 

 apparently that of C. T. Jackson, in ISttO, in his report as 

 state geologist of Ehode Island, pp. 111-120. He carefully 

 described the Block Island clays, and considered them of Ter- 

 tiary age, although he was unable to find in them any remains 

 of marine shells. 



The next notice of importance is by W. Upham, in 1879, 

 who regarded nearly all the Block Island clays as of glacial 

 origin. Some of them appeared to be older, but he makes 

 no statement as to their age. After discussing Long Island, 

 he sums up the effects of glacial action, as follows : — 



" Excepting the pre-glacial deposits which have been mentioned, 

 and a small area of gueiss and hornblende schist at Long Island 

 City and Astoria, the whole of Long Island, Block Island, 

 Martha's Yineyard, Nantucket, the EHzabeth Islands, and the 

 peninsula of Cape Cod, consist of drift deposits which owe their 

 accumulation, as has been here shown, to the action of the ice- 

 sheet and its rivers in amassing them at its termination" (this 

 Journal, vol. xviii, pp. 91, 92, and 207). 



This general opinion has widely prevailed, and I referred to 

 it in my previous article. Another paper on Block Island, 

 which I have not seen, is by Merrill, 1895 (Trans. N. Y. Acad. 

 Sci., vol. XV, pp. 16-19). 



The literature relating to the geology of Long Island is quite 

 extensive, but cannot be cited here. The basal clays of this 

 island have been variously regarded as Glacial, Tertiary, and 

 Cretaceous, but not older. The most important of the early 

 descriptions is by Mather, in his Report on the Geology of the 

 Lirst District of New York, 1843. One of the later papers of 

 special interest is by Merrill, On the Geology of Long Island, 

 1885 (Ann. N. Y. Acad. Sci., vol. iii, pp. 31:1-364). 



Newberry, in 1874, pronounced the plants from Lloyd's 

 Neck similar to those from the lower Cretaceous of the West 

 (Proc. N. Y. Lyceum Nat. Hist., voL ii, p. 127). This refer- 

 ence of the fossil plants of Long Island to the Cretaceous has 

 since been followed by many authorities. 



One of the latest writers on this subject is A. Hollick, who 

 has kindly sent me, at my request, a number of his papers 

 which I had not before seen. 



The mutual relations of all the series of strata here con- 

 sidered, which I regard as Jurassic, I hope to discuss in the 

 next number of this Journal. 



Yale University, New Haven, Conn., October 21, 1896. 



