﻿8. V. Wood, Jan. — American and British Surface-Geology. 483 



which there seems no evidence, the only fossil organisms which 

 occur in the deposits of the lake-basin being those of land or fresh- 

 water. So far as I can understand the case, however, there seems to 

 me no necessity to infer any depression until after the formation of 

 beds Nos. 1 and 2, as the phenomena indicated by these beds seem 

 explicable by returning warmth alone, and by the draining off of the 

 lake- waters after the deposit of No. 1; while the marine clays of the 

 Lower St. Lawrence, which, so far as I have been able to gather the 

 facts of American geology, alone afford evidence of any submergence 

 of the St. Lawrence basin, seem to me, as subsequently explained, to 

 belong to a later glaciation. 



Prof. Newberry contends that the lower and unstratified portion 

 of the Erie clay represents the material eroded by the glacier, which, 

 as the ice-sheet retreated northward, it thrust out and left behind ; 

 and which now forms a nearly continuous sheet of Boulder-clay over 

 the glaciated surface. He urges that this clay was not deposited 

 beneath the glacier-ice, because it covers the glaciated surface in a 

 sheet sometimes 100 feet thick, and that it must have accumulated 

 at the margin of the glacier as it receded. This, if we substitute the 

 sea in Britain for the lake in Ohio, is in chief measure, the mode of 

 origin for which I have for many years past been contending in the 

 case of the Glacial clay of England, as distinguished from Mr. James 

 Geikie's view of its origin beneath the ice itself. 



There is one feature, however, connected, according to my view, 

 with the origin of the unstratified Glacial clay of England to which 

 I find no parallel in Prof. Newberry's memoir, viz. the lifting of 

 portions of this extruded mass, and its distribution over the bottom, 

 partly from being dropped in small quantities, but principally in 

 sheets or masses. This seems to me to have been clearly the mode 

 of accumulation in the case of that part of the English clay which 

 overlies the Middle Glacial sands, as well as of some portion of that 

 part of the clay which has no Middle Glacial beneath it, but which, 

 as at Dimlington and Bridlington in Yorkshire, contains within 

 its mass beds of sand full of lamellibranchiate mollusca with 

 valves in some cases united. When, however, the vast area of the 

 American beds comes to be examined with the same minuteness as 

 has been the case with the comparatively small area of the British, 

 I do not doubt that pai'allel features will be found in them, unless 

 the water under which the moraine was extruded was too deep to 

 allow of this process.^ 



^ If, as some American geologists say, unstratified morainic clay has been found 

 overlying the forest surface in situ, then these would seem to me to be instances of 

 dropping from floating ice ; for if the ice passed over the forest, it must have destroyed 

 it. Some of our N orf oik geologists are now coming to the opinion that the long- 

 known Forest-bed of Cromer is not in situ, but transported; and if they are right, 

 the theories based upon the occurrence of peats and freshwater shells in the midst 

 of Glacial clay will require much reconsideration. This, however, does not apply 

 to the Pakefield and Kessingland root-indented bed, which is clearly in situ. If 

 it should turn out that the Cromer Forest and freshwater deposits associated with 

 it are not in situ, but stripped from some distant land-surface by ice, and transported, 

 analogy for such a thing may be found in some peaty masses which I have observed 

 imbedded in the midst of the marine-formed Contorted Drift in the Cromer cliff 

 itself. 



