26 



CAPE COD GEOLOGY 



The tooth of a mid-Tertiary rhinoceros and the rib of a walrus were col- 

 lected from the Miocene greensand bed at Gay Head by Mr. Daniel Vincent of 

 Chilmark, Mass. These and other vertebrate fossils from the greensand and from 

 the Aquinnah conglomerate (Hitchcock's osseous conglomerate) have been ex- 

 amined and described by Dr. G. M. Allen. 



The Aquinnah conglomerate and the greensand bed should be thoroughly 

 explored for other fossils, particularly the Aquinnah conglomerate, the only 

 known occurrence of which in place is in the face of Gay Head cliffs. 



A few fossils were found at Gay Head under circumstances that make it 

 doubtful whether they originally came from the horizon of the greensand beds. 

 Many fossils have been found in the Aquinnah conglomerate, which was once 

 referred to the Miocene, but which now seems to be made up of debris derived 

 from beds laid down at the beginning of the Pleistocene epoch, before the glaciers 

 covered this district. 



Edward Hitchcock * described and figured a tooth, which he referred to a 

 crocodile, found at Gay Head in the ' 'ferruginous sand," probably the oxidized 

 greensand. This tooth is described as silicified, a fact that led him to doubt its 

 geologic horizon. The specimen cannot now be found. 



Lyell 2 visited Gay Head in April, 1842, and collected some characteristic 

 fossils, in addition to which he found in the hands of a fisherman a part of the 

 skull of a walrus differing, as he thought, from the existing species (Trichecus 

 rosmarus Linn.) in having one more tooth on each side of the upper jaw. The 

 specimen is said to have been found in the osseous Aquinnah conglomerate. 



Lyell also collected from the osseous conglomerate several rolled cetacean 

 bones, one of which he illustrates under the generic name Hyperoodon and another 

 under Delphinus. Large numbers of these bones have been taken from the bed 

 or picked up on the slopes below it and along the adjacent beach, where they 

 become blackened on contact with sea water. Some of these have been described 

 and illustrated by Allen, 3 who refers certain vertebrae to the finback whale 



i Hitchcock, Edward, Report on the geology [etc.] of Massachusetts, p. 103, Amherst, 1833. Plates 

 illustrating the geology and scenery of Massachusetts, pi. xl, fig. 16, 1833. Catalogue of specimens, Ap- 

 pendix p. 655. Specimen No. 103. See also Hitchcock's Final report on the geology of Massachusetts, 

 pp. 330-341, pi. 19, fig- 13, 1841. Catalogue of State Collection, p. 803, specimen No. 103. Also in the 

 collection of rocks, minerals, and fossils in the State Cabinet of the Agricultural Museum at Amherst. 

 Catalogue of December 1, 1858, p. xvii. Section IV, Miocene Tertiary, specimen No. 48. Sixth annual 

 report of the secretary of the State Board of Agriculture for 1858. Appendix. 



2 Lyell, Charles, Travels in North America, 1, p. 258, pi. v. London, 1845. Also American ed., p. 204, 

 pi. v, New York, 1845. 



3 Allen, G. M., The whalebone whales of New England, Memoirs Boston Soc. Nat. Hist., 8, No. 2, 

 pp. 257, pis'., 1916. Description based on collections of the Museum of Comparative Zoology, Nos. 3742, 

 9742, 8743, 8744; and the Boston Society of Natural History, No. 9698. 



