THEORIES OP ROY, LYELL, AND OTHERS. 261 



lauds/ During the same year Mr. Sandford Fleming published a detailed 

 description and map of the Davenport ridge and teirace, which are portions 

 of the highest Iroquois shore-line near Toronto, referring- them to the 

 action of Lake Ontario when it stood "about 170 feet above its present 

 level." ^ The Geological Survey of Canada, in its valuable Report of Prog- 

 ress to 1863, described these "ancient beaches, terraces, and ridges" on 

 pages 910 to 915, but presented no theory of their origin. In 1877 Mr. 

 George J. Hinde, in a paper on the glacial and interglacial strata of Scar- 

 boro Heights and other localities near Toronto, accounted for the drift by 

 the agency of ice-sheets during two great epochs of glaciation, separated 

 by a long interglacial epoch which had a climate nearly like that of the 

 present time. The Laurentian lakes, at the close of the Glacial period, 

 according to this author, were much larger than now, as shown by the old 

 shore-lines; but he is not sure whether their barrier was the receding ice- 

 sheet or "accumulations of glacial debris which have since been removed."* 

 The southern high shore-lines of these lakes, in the United States, have 

 been regarded by Wliittlesey, Newberry, Claypole, and Gilbert, as of fresh- 

 water formation, the lakes having been held higher than now by the ice- 

 sheet during- its departure; and Spencer and Taylor are the only recent 

 writers who have examined this region and believe the beaches to be sea 

 shores.* 



None of these writers has studied the question, Wliere was the ice- 

 sheet latest a barrier across the St. Lawrence Valley? The du-ections of 

 glacial striae and transportation of drift answer that the ice-sheet in tliis 

 region during the closing stage of glaciation was thickest upon a belt 

 crossing the St. Lawrence nearly from east-southeast to west-northwest in 



' Canadian Journal, uew series, Vol. VI, pp. 221-229 and 497, 498. 



nbid., Vol. VI, pp. 247-253. 



^Canadian Journal, new series, Vol. XV, pp. 388-413. 



<C. Whittlesey, "On the fresh-water glacial drift of the Northwestern States," 1864, pp. 17-22, in 

 Smithsonian Contributions, Vol. XV. J. S. Newberry, in Report of the Geological Survey of Ohio, Vol. 

 II, 1874, pp. 50-65, with three maps. E. W. Claypole, "The lake age in Ohio," pp. 42, with four maps, 

 in Trans. Geol. Soc. Edinburgh, 1887. G. K. Gilbert and J. W. Spencer, papers before cited. 



Since this page was first written, Mr. F. B. Taylor has claimed a marine origin for some of the 

 ancient beaches about portions of these lakes, and for deltas in the Mohawk Valley ("The highest old 

 shore-line on Mackinac Island," Am. Jour. Sci. (3), Vol. XLIII, pp. 210-218, March, 1892; "The deltas 

 of the Mohawk," Am. Geologist, Vol. IX, pp. 344, 345, May, 1892 ; and later papers in the Am. Geologist, 

 Vols. XIII-XV, 1894-95). 



