NEW YORK, DECEMBER 1. 1893. 



REVIEW OP THE BIRTH OF THE GREAT- LAKES 

 AND THEIR DESERTED SHORES.' 



Page after page in the history of our Great Lakes has 

 been deciphered by the researches of Dr. J. W. Silencer. 

 This study has involved many of the most important ques- 

 tions in dynamical geology. First there was the long 

 continued high continental elevation, during which the 

 Laurentian valley was excavated by the erosion of the 

 great river, its tributaries and the multitudinous branches. 

 Afterwards, the old topography became disfigured, the 

 hills were swept off and the valleys filled up, and all the 

 other changes of the ice age followed, with the drowning 

 of the lower lands by the encroachments of the sea upon 

 the sinking continent. The lands had given place to the 

 sea; now the sea receded from rising lands. In the olden 

 days, the mountains had been worn down to mere trunks, 



salt or fresh is not yet known. Its shores upon both sides 

 of the Superior Ijasin, about Lake Michigan and Lake 

 Huron, on both sides of Erie, in Ontario and New York, 

 are now more or less known, but not the northeastern limits. 

 This is an enormous area for only three or four workers 

 to cover: nearly the whole region by the author under re- 

 view; New York and Ohio by Mr. G. K. Gilbert; north of 

 Lake Superior by Dr. A. G. Lawson ; about Lake Michi- 

 gan, south of Superior and northeast of Lake Huron by 

 Mr. F. B. Taylor, — this makes our list of workers. 



From one strand to another, lower, lower, lower sank 

 the Warren waters, and slowly rose the deserted shores of 

 the great inland sea or lake. But this subsidence of the 

 waters was caused by the rise of the land; not an 

 equal uj)lift of the continent, but a greater eleva- 

 tion towards the north and east than towards the 

 south and west. The lands about the shrinking lakes 

 were gradually expanding, so as to eventually dismember 

 the Warren water, when it was contracted within the sep- 



MAP SHOWING THE EASTERN PAKT OF ALGONQUIN LAKE. 



but with the pleistocene re-elevation which lifted the 

 later shore-lines the old water-levels were deformed and 

 broken. In our issue of June 3rd, 1892, we described the 

 manner in which the lake basins had been formed — just 

 ancient valleys closed by drift and by the warping of the 

 earth's crust in proximity to some of their outlets. Then 

 the history of these fresh-water lakes began. Fragments 

 of their story have now been discovered, and their well 

 preserved but deserted beaches mark the shrinkage of the 

 waters. 



About the close of the ice age, one great sheet of water 

 covered most of the Great Lake region, occupying 200 000 

 square miles or more. This was Warren water, whether 



'"Deformation of the Iroquois Beach and Birth of Lake Ontario." Am. 

 Jour. Sc., Vol. XL., 1890. 



"Deformation of the Algonquin Beach and Birth of Lake Huron." 

 "High-Level Shores in the Region of the Great Lakes and their Defor- 

 mation." Am. Jour. So., Vol. XLI., 1891. 



arate basins. At first there were two of these. The 

 greater was Algonquin Lake, covering most of the Su- 

 perior basin, reaching to near the southern end of the 

 Michigan, to near the southern end of the Huron, and ex- 

 panding far beyond the eastern margin of Georgian Bay, 

 and extending by a strait northeastward toward the On- 

 tario basin by way of the Nipissiug and Ottawa valleys. 



The other branch of the dismembered Warren water 

 was an unnamed union, embracing the waters in the On- 

 tario basin and in the Erie basin, to the extent perhaijs of 

 a hundred miles from the Niagara River. 



The waters at the level of the Algonquin and the lost 

 2)re-Erie beach tarried for a long period; but from these 

 levels they gradually sunk, leaving fainter beaches and 

 terraces until a level 300 feet below was reached — the 

 Iroquois beach 



Then Niagara River had its birth. At this level, the 



