CLIFFS OF PORT ROWAN 333 



mentation. The inclination of the beds toward the left is the result of a 

 land slip which has dropped a section of the cliffs 10 to 75 yards wide 

 and several hundred feet long into the waters of the lake. The bed 

 showing disturbed strata has a thickness of 10 or 12 feet. 



In seeking the cause of the highly inclined and disturbed condition of 

 the strata^ which at one point simulate the outline of a heart-shaped 

 figure, the history of these beds should be considered. They were laid 

 down when Lake Erie was held at a level more than 100 feet higher than 

 at present by the Lake Whittlesey ice-barrier. While the beds of this 

 section were being assorted and shifted into their present position by 

 Avave and current action, large icebergs and extensive fields of floating ice 

 were characteristic features of tlie surface of Lake Whittlesey, in which 

 these beds were laid clown. At this stage of its history Lake Erie must 

 have displayed in summer fields of fioe-ice and icebergs quite comparable 

 to those which today border the Greenland coasts in early summer. Any 

 one who has seen an Arctic ice-pack moving majestically and with im- 

 measurable force before the wind needs not to be told that an ice-pack 

 when it grounds before a gale is capable of plowing u]o and disturbing in 

 a very extensive fashion any unconsolidated beds on which it may l)e 

 driven by the wind. Various observers have testified to the efficiency of 

 grounded ice in disturbing bottom deposits on Arctic coasts. Quotations 

 in this connection from two of these will suffice. 



Lieut. Charles H. Stockton, of the United States Navy, thus describes 

 tlie action of this ice wheji it is driven ashore : 



"Sometimes a long line of heavy floe-ice from the pack grounds in the shal- 

 low water near the shore during northerly winds, pressed from behind by the 

 force and the weight of the entire northern pack. It is gradually forced up, 

 plowing its way through the bottom, at the same time rising gradually along 

 the ascent of the bottom toward the land." ^ 



Lieutenant Stockton made a hydrographic survey of the anchorage 

 near Point Barrow, in which he 



"demonstrated that the contour of the bottom is constantly changed by the 

 plowing and planing done by the heavy ice grounded and driven up by the 

 pressure of the mighty ice-pack, under the influence of northerly winds and 

 gales." ^ 



The Lake Whittlesey ice-])arrier which stretched along the Jiortli border 

 of the lake but a short distance north of the section under consideration 

 must have sent into the lake innumerable tongues of glacial ice, which 



■^Charles H. Stockton: Nat'l Geog. Mag., vol. ii, 1S91, pp. 182, 183. 

 8 Ibid., p. 182, 



