466 J. W. SPENCER — PLEISTOCENE SUBMERGENCE. 



Although many have their own views upon this subject, few serious attempts 

 have heen made to solve the problem uncolored by theory. 



Evidence of recent regional Emergence. 



We must seek for the evidence of the recent regional submergence in the 

 remains of old shorelines, such as beaches, terraces and sea-cliffs, now ele- 

 vated and more or less disturbed and obliterated. Isolated remnants of 

 beaches are not accepted by all as proof of a recent elevation, although 

 found at high altitudes ; but the beaches often contain the direct proof of 

 their own elevation. 



No better example is found than the Iroquois beach of the Ontario 

 basin (shown in the map forming plate 19). This elevated shore-line is one 

 of the youngest and best preserved in the Great Lake region. It rests upon 

 the youngest till deposits. Since its formation it has been warped toward 

 the northeast, and thus at Fine, north of the Adirondack mountains, it has 

 been lifted over 600 feet above its own elevation at the head of Lake On- 

 tario.^ By another series of deformed shore-lines f it has been found that 

 the Iroquois beach, at the head of the lake, has been lifted its own height 

 above the sea. Hence, there is measured proof that the northern side of 

 the Adirondacks has been lately elevated 1,000 feet, or that it was recently 

 1,000 feet lower than now. The initial point of this movement w^as near the 

 head of Lake Michigan. Its maximum deformation occurs in the Adiron- 

 dacks, and amounts to six feet per mile. Whether this rise continues to the 

 Atlantic, or is transformed into a depression, or is faulted east of the moun- 

 tains, remains to be determined. Only fragments need be looked for east of 

 the region already explored, for the deserted shore has been traced into a 

 region of broken mountains and wilderness. 



Three hundred feet above the Iroquois plain, the Algonquin beach of the 

 Huron basin is located. J In, it there is a similar deformation to that re- 

 corded in the Iroquois shore, but the initial point of the warping is beyond 

 the head of Lake Michigan, With the deformation continuing toward the 

 northeast, it would appear that the Laurentian mountains, north of the 

 Great Lakes, were very much depressed during the Algonquin episode. The 

 evidence of the formation of the Algonquin beach at sea-level has already 

 been set forth. § 



While there is great deformation recorded in the higher beaches, the sur- 

 veys of these more broken geological records do not enable us to trace the 



*" The Deformation of Iroquois Beach and Birth of Lake Ontario," by J. W. Spencer: Am. Journ. 

 Sci., vol. XL, 1890, pp. 443-451. 



t Ibid., p. 447. 



t "Deformation of the Algonquin Beach and Birth of Lake Huron," by J. W. Spencer: Am. 

 Journ. Sci., vol. XLI, 1891. pp. 12-21. 



§Ibid., p. 21. 



