Page:The American journal of science, series 3, volume 49.djvu/30

12 12 W. Upham — Champlain Subsidence and

the richly fossiliferous Leda clays, which last overlie the latest glacial drift in the St. Lawrence, Ottawa, and Cham plain valleys, may be referred to the closing stage or Champlain epoch of the Ice age ; and they both testify, like the partially forest-covered Malaspina ice-sheet in Alaska, of the close sequence of a warm climate, with luxuriant plant and animal life, during and immediately after the recession of the ice- sheet. The transition from the GTlacial to the Champlain climate seems readily explained by the epeirogenic depression which ended the Glacial period.*

The height of Lake Ontario is 247 feet ; and that of the old Iroquois outlet crossing the water-shed at Rome is 440 feet, above the sea level. Thence the Iroquois beach in its course northward adjacent to the eastern end of Lake Ontario has a gradual ascent of about five feet per mile along a distance of 55 miles to the latitude of Watertown, where the highest beach is 730 feet above the sea, showing that a differential up- lift of about 290 feet has taken place, in comparison with the Rome outlet. From Rome westward to Rochester, the beach has nearly the same height with the outlet ; but farther west- ward it descends to 385 feet above the sea at Lewiston and 363 feet at Hamilton, at the western end of Lake Ontario. Con- tinuing along the beach north of the lake, the same elevation as the Rome outlet is reached near Toronto, and thence east- northeastward an uplift is found, similar to that before described east of the lake, its amount near Trenton and Belle- ville above Rome being about 240 feet It is to be added that northward from Rome the Iroquois beach becomes divided into a series of distinct beaches, marking stages in the north- eastward rise of the land and having near Watertown a verti- cal range of 80 feet below the highest and oldest, which was before noted ; and that westward a similar series of strand lines also lies below the highest, likewise before noted, which there, however, contrary to the order northeastward, was the newest. The highest beach near Watertown was probably contemporaneous with the fossiliferous beds of Toronto ; some of the intermediate northeastern beaches corresponded to the delta deposits of Scarboro ; and the lowest northeastward lake level was continuous with the highest at Toronto, Hamilton^ Lewiston, and east to Rome.

Between Lakes Warren and Lundy the old water level near the west end of Lake Ontario fell 125 feet, minus some amount to be subtracted for the progressing northeastward elevation of the land. The two Lundy shores are 30 feet apart verti-

this Journal, III, vol. x, pp. 168-183, Sept., 1875. Warren Upham, G-lacialists' Magazine, vol. i, pp. 236-240, June, 1894.
 * J. D. Dana, Trans. Conn. Acad, of Arts and Sciences, vol. ii, 1870, p. 67;