﻿488 8. V. Woodjjun. — American and Bntkh Surface- Geology. 



but in Holderness, where the chalky clay passes up into the purple, 

 and where, as explained in the sequel, the water was deeper, 

 though not deep enough to form bergs, the morainic chalky clay 

 does seem to pass up, throiagh an intermediate stage formed by 

 dropped sheets of morainic matter, into clay of the character which 

 Prof. Newberry describes the upper portion of the Erie clay to 

 be ; for though it is not usually laminated, it is full of lenticular 

 beds of sand, and to my eye presents the appearance of a clay 

 formed by marine deposit from the ground-up material of a glacier 

 carried away in suspension, and accompanied by copious droppings 

 of rock debris from floating ice (see the clays c and d, with lenti- 

 cular beds of sand and gravel, c' and d' therein, shown in the sheet 

 of sections accompanying the sequel of this paper). 



On the Canadian highlands, where the material acted on was 

 hai'der, and where free drainage, as he calls it, washed away the 

 finer portions, this clay. Prof. Newberry says, is largely replaced by 

 gravel-sands and boulders. As the gravel-sands of these highlands 

 could not, however, have been accumulated until the glacier-ice had 

 receded from thence so as to give place for their deposit, we seem 

 to have here a formation of Eskers and Kames, such as is discussed 

 further on. If the gravels of these Canadian highlands occupy, as I 

 imagine they do, elevations above the Erie clay, and also above that 

 to which the submergence imder which the Leda and Champlain 

 clays accumulated reached, it seems to me that they must be Eskers 

 or Kames formed by the melting of the glacier-ice when it ceased 

 to discharge its moraine beneath the Atlantic, and beneath the 

 lake waters, and had receded to these highlands. If, however, they 

 be not thus referable to Kame and Esker origin, or if they contain 

 marine organisms, they would, perhaps, answer to the Mountain 

 (Moel Tryfaen) and high-level (Macclesfield) sands of England 

 and Wales, which represent the latest portion of the Upper Glacial 

 formation when the ice-sheet had wasted back to the mountain 

 peaks, and North-west Britain had assumed the condition of an 

 archipelago. Assuming them, however, not to be of marine origin, 

 but Kames and Eskers (which, as presently explained, is the form 

 assumed by the moraine when the recession of the ice takes place 

 subaerially), it seems to me that they must be the product, and. 

 the latest product too, of the last glaciation to which the region 

 they occupy has been subjected ; for not only would the ice in its 

 subaerial recession leave such beds, but it must, it seems to me, 

 have ploughed out and destroyed the formations of any previous 

 glaciation wherever it encountered them in its advance, and there- 

 fore up to wherever such subsequent ice reached. 



Prof. Newberry observes that although the Erie clay occupies the 

 same relation to the glaciated rock- surface as do the " Leda," 

 " Champlain," and " Glacial " clays of the Atlantic coast, there is 

 not sufficient evidence to connect them as exactly synchronous ; 

 but he considers that these Atlantic coast clays were formed in a 

 similar way to that of the Erie clay ; that is to say, during a subsi- 

 dence of the Eastern coast of North America when the Atlantic 



