1888.] 
139 
[Upham. 
nal position. To such glacial thrust and uplifting I would attrib- 
ute likewise the tilted condition of the beds forming the base of 
Sankoty Head and the elevation of the included layers of shells. More 
than this, I believe that the same cause will account for the elevation 
and folding of the wonderful section of steeply inclined Miocene 
strata which underlie the terminal moraine in Gay Head. 1 It 
may well be true, therefore, so far as paleontologic evidence can 
inform us, that this part of our coast, extending south to the far- 
thest limit reached by the continental ice-sheet, held approximately 
the same relation to the sea level in preglacial and interglacial time 
as now. 2 During the final melting of the ice-sheet, however, the 
land was higher, or, as I would prefer to say, the sea was lower 
than now, as is shown by channels of drainage, which extend south- 
ward from the terminal moraines across the bordering plains of 
modified drift on Long Island, Martha’s Vineyard, Nantucket, and 
Cape Cod, continuing beneath our present sea level. 3 Nor have 
we any proof in marine beds overlying the glacial drift that the sea 
there has stood higher than now at any time since the glacial pe“ 
riod. 
Near Boston and northeast to Cape Ann the coast seems to 
have been submerged to a slight depth, probably not exceeding 
10 to 25 feet, when the ice-sheet retreated from this area. 4 In 
New Hampshire this submergence amounted to 75 feet or more, 
and the fossils in the marine beds overlying the glacial drift, being 
partly of arctic and partly of temperate range, show that the se- 
vere climate of the glacial period was gradually changed until the 
ocean became as warm as now before it sank to its present level. 5 
Hlitchcock’s Geology of Massachusetts, 1841; Lyell’s Travels in North America in 
1841-2, vol. i, pp. 203-6. 
2 The fossils in South Marshfield and Duxbury, Mass., which I once referred to the 
Pleistocene (Am. Naturalist, vol. xiii, p. 557), extend back to the Miocene in the South- 
ern States, and seem more probably to be of similar age with the beds of Gay Head 
(Hitchcock’s Geology of Mass., 1833, pp. 199-201; do., 1841, pp. 91, 427). 
3 Am. Journ. Sci., ill, vol. xiii, 1877, pp. 142-146, and 215; vol. xviii, pp. 89, and 198- 
205. Am. Naturalist, vol. xiii, 1879, p. 553. 
4 Evideuced by layers of shells of thecommon or long clam, mussel, oyster, and other 
species at Lechmere point in Cambridge (Outlines of the Mineralogy and Geology of 
Boston, before cited, p. 96), and by fossils discovered by Professor Shaler at Gloucester, 
Mass. (Proceedings of this Society, vol. xi, 1868, pp. 27-30). In the same notice with the 
former of these localities, the authors mention a stratum of clam shells, observed on the 
side of a hill in Cambridge at the distance of a half mile from the Charles river, which 
seems from its description to be probably an aboriginal kitchen-midden. 
6 Geology of New Hampshire, vol. iii, pp. 165-7. 
