THE PLEISTOCENE OR GLACIAL PERIOD. 403 



depart notably from horizon tali ty. Those of different stages of the 

 lakes frequently depart unequally from a common plane. In general, 

 they rise to the north and northeast. 



XIII. The Champlain sub-stage. — The significant feature of this 

 stage is represented in Fig. 522, which represents an arm of the sea 

 extending up the St. Lawrence to Lake Ontario, filling the basin of 

 Lake Champlain, and probably connecting southward by a narrow 

 strait along the site of the Hudson valley with the ocean. 1 The sedi- 

 ments deposited in this arm of the sea contain shells and bones of marine 

 animals. The marine fossils are found at various places about Lake 

 Champlain at altitudes varying from 400 feet or less about the south 

 end of the lake, to 500 feet at the north end, and about 600 feet near 

 the east end of Lake Ontario. 2 



The most distinctive deposit made in this Champlain arm of the 

 sea is laminated clay, the material for which was partially supplied 

 by drainage from the ice to the north. While the " Champlain clays" 

 are the best-known phase of the deposits of this stage, sand and gravel 

 were deposited contemporaneously in appropriate situations. The 

 clays of the Hudson valley are extensively used for brick. Similar clays 

 occur in the Connecticut and some other New England valleys, and 

 in the valley west of the Palisade riclge. In all cases, the clays rise 

 notably to the northward and serve as a rough measure of the post- 

 glacial change of altitude of the land. 3 



At about the same time the sea stood higher than now relative to 

 the land on the coast of Maine, where marine shells, including species 

 of Mya, Astafte, Leda, and Yoldia, among many others, occur up to 

 elevations of 200 feet or more. 4 Marine fossils of post-glacial age occur 

 up to elevations of about 600 feet above James Bay, 5 and other marks 



1 Peet, Jour, of Geol., Vol. XII (1904), pp. 415-469, 617-661; Salisbury, Glacial 

 Geol. of N. J., pp. 196-200. 



2 Dawson, G. M. Am. Jour. Sci., 3d ser., Vol. VIII (1874), p. 143; Dawson, J. W 

 The Canadian Ice Age, p. 201, and Am Jour. Sci., Vol. CXXV, 1883. 



3 Other papers touching the Champlain are the following: Reis and Merrill, 10th .Ann 

 Rept. N. Y. State Geologist, 1890; Reis, Bull. N. Y. State Mus., Vol. Ill, 1895; Bald- 

 win, Ann. Geol., Vol. XIII, 1894; Davis. Proc. Bos. Soc. Nat. Hist,, Vol. XXV, 1891; 

 Upham, Bull. Geol. Soc. Am, Vol. Ill, 1891; Kellogg, Science, Vol. XIX, 1892; aDd 

 Woodworth, Bull. 84 N. Y. State Mus. 



4 Dana, Manual of Geology, 4th ed., p. 982; and Store, Jour, of Geol., Vol. I, 

 pp. 246-254. 



5 Bell. Am. Jour Sci , 4th ser., Vol. I, pp 219-228, 1896. 



