376 0. C. Marsh— Geology of Block Island, 



whales, sharks' teeth, petrified shells, and fossil wood, and agreed 

 that the cliffs were due to volcanic action, an opinion still 

 maintained by the existing Gay Head Indians. 



In 1824, John Finch, in discussing the " Tertiary Formations 

 in America" (this Journal, vol. vii, pp. 31-43, 1825), stated his 

 opinion that the Gay Head clays, as well as some on Long 

 Island, and at Amboy, New Jersey, and still others farther 

 south, were of the same age as the Alum Bay clays (Oligocene) 

 on the Isle of Wight. E. Hitchcock, in the same year, and in 

 the same volume of this Journal, pp. 240-248, regarded the 

 Martha's Vineyard clays as the equivalents of the Plastic clay 

 (Eocene) of Europe. Hitchcock, again in 1832, as state geolo- 

 gist, mapped and described this region as Tertiary, and in his 

 report published in 1833 gave figures and descriptions of Gay 

 Head fossils. The final report, 1841, contained a more com- 

 plete description, and the Eocene age of the clays of Martha's 

 Yineyard is still maintained. Lyell, in 1844 (Proc. Geol. Soc. 

 London, vol. iv, and this Journal, vol. xlvi, pp. 318-320), made 

 a study of Gay Head and other localities on the island, and 

 regarded the cliffs as of Miocene age. E. Desor and E. C. 

 CalDot, in 1849, announced that certain clays on Nantucket 

 were Miocene, and the equivalents of those on Gay Head (Quart. 

 Jour. Geol. Soc. London, vol. v, pp. 340-344). W. Stimpson, 

 in 1860, pronounced the strata at Gay Head, Cretaceous (this 

 Journal, vol. xxix, p. 145), but subsequently withdrew that 

 opinion in favor of their Tertiary age. 



In more recent times, also, this opinion still prevailed, and 

 even the later age of Post-pliocene or Quaternary was, in 1885, 

 assigned to the Gay Head clays by F. J. H. Merrill (Trans. N. Y. 

 Acad. Sci., vol. iv, p. 79). Shaler, whose valuable memoirs on 

 Martha's Yineyard and Nantucket (1888-'89) I quoted in my 

 previous article, still regarded the basal clays of both islands as 

 Tertiary or later. In another paper (Bull. Mus. Comp. ZooL, 

 vol. xvi, p. 89, 1889), he discussed the discovery of marine 

 Cretaceous fossils in the drift of Martha's Yineyard. In a still 

 later paper (Bull. Geol. Soc. America, vol. i, pp. 443-452, 1890), 

 he considered the lower portion of Gay Head, Cretaceous, and 

 the middle. Tertiary. He adds that A. F. Foerste observed, on 

 Block Island, beds probably of the same age as the Tertiary 

 at Gay Head. 



A study of the fossil plants of Gay Head, in 1890, by David 

 White, indicated that some of the clays of Martha's Yineyard 

 were Mesozoic, and they were pronounced by him Cretaceous, 

 and probably middle Cretaceous (this Journal, vol. xxxix, p. 99). 

 To this important paper, I am indebted for various references. 

 These researches were made under the direction of L. F. 

 Ward, whose comprehensive work on the Potomac formation 

 (U. S. Geol. Surv., 15th Ann. Kep., 1895) is invaluable to all 

 interested in that horizon. 



