﻿484 S. V. Wood,jun. — American and British Surface- Geology. 



Mr. Geikie insists on the purely terrestrial origin of all this nn- 

 stratified Glacial clay, and urges his views in the " Great Ice Age " 

 with the amplitude for which a work specially devoted to the 

 Glacial formation affords scope. It is impossible to meet his various 

 contentions within the limits of a paper like this ; but to insist, as 

 he does, that rock -basins and great valleys of erosion have been 

 excavated by the tremendous agency which is exerted by the 

 combined vertical and horizontal foi'ce of glacier-ice thousands of 

 feet thick moving over its bed, and at the same time to contend that 

 this ice can have passed over finely-stratified sands, such as the 

 IMiddle Glacial, pushing at the same time under it a thick moraine 

 of clay brought from a distance, without disturbing the stratification 

 in the slightest, does appear to me a most striking inconsistency. 

 We are reminded by it of the steam-hammer which forges a 100-ton 

 gun and cracks a nut without crushing the kernel ; but glacier-ice 

 is not kept under the delicate control that a steam-hammer is. Not 

 onl}^ is the stratification undisturbed, but within very few feet of the 

 junction of this undisturbed stratified sand with the morainic clay 

 there occurs in several places, both in the East Suffolk cliff and in 

 sections inland, a band of molluscan remains, mostly fragmentary, 

 but containing intermixed with them an abundance of small papy- 

 raceous specimens of Anemia ephippium, and of the valves of Balanus, 

 sharp and unworn, both of which have evidently fallen from objects 

 floating in the sea. These small Anomice are so thin and tender that 

 in the fossil state in which we find them they exfoliate, and may be 

 blown into fragments by a strong breath ; and in their living state 

 they must have been very fragile. Are we to suppose that glacier- 

 ice hundreds, nay, according to the extreme glacialists, thousands ' 

 of feet thick passed over these sands, rolling its moraine as it pro- 

 gressed, without either distorting the stratification of such sands or 

 crushing the tender organisms within them which lie but very few 

 feet from the line of junction ? 



This inconsistency becomes to my mind enhanced by Mr. Geikie's 

 contention that the worn shells and shell fragments which occur in 

 some of the morainic clays, as, for instance, in the purple clay of 

 Holderness, the chalkless clay to the north of it, and in the Lanca- 

 shire clays, are due to the ploughing out of anterior (inter- Glacial) 

 sea-beds, and the intenningling of the ploughed-out shelly matter 

 with the land-derived moraine material ; for how, if such things 

 occurred, could the sea-bed formed of the Middle Glacial sands to 

 which I have referred have escaped destruction if the glacier 



^ In objecting in my paper, " On the Climate Controversy," in this Magazine 

 for September, 1876, to the extreme thickness assigned to the ice of Britain dm-ing 

 the Glacial period, I spoke of the existing Antarctic ice being at least 5000 feet 

 thick. In this I -^vas led a-way by the instances of bergs of tabular form having 

 been met •with in Southern seas -which rose more than 500 feet or 600 feet above 

 the sea, given by Dr. Croll in his work on " Climate and Time." From the descrip- 

 tion of the Southern bergs, however, given by the Challenger Expedition, I do not 

 see how the Antarctic ice can at its sea termination much exceed 2000 feet, even if it 

 reaches that. It seems probable, however, so far as Greenland and Spitzbergen 

 disclose the case, that land-ice is of less thickness at the glacier terminations than 

 where it lies in greater masses further inland. 



