46 report — 1865. 



whence icebergs, transporting blocks of stone, were floated southwards* from great 

 . Scottish glaciers which protruded into the sea. 



Corning hither in ignorance of what the several associations of local geologists 

 (which rival each other in their researches) have accomplished, I shall be happy to 

 learn that some of them have detected, in this portion of the kingdom, any of those 

 proofs of the existence of man at an early period, when large animals, now extinct, 

 prevailed in our islands, in ages so remote that, since then, the physical configura- 

 tion of the country has undergone considerable changes. This inference is, as I 

 have said, founded upon irrefragable evidence collected in different parts of Europe, 

 as well as in our own country. When, however, we come to consider the modus 

 operandi by which these great physical changes have been brought about, geologists 

 have different opinions. As one who holds to the beliefjthat in former periods the 

 crust of the earth was from time to time affected by an agency much more power- 

 ful than anything which has been experienced in the historic era, I do not believe 

 that the wear and tear clue to atmospheric subaerial erosive agency could, even 

 after operating for countless ages, have originated or even have deepened any of the 

 valleys and gorges which occur in countries as flat as the tract in which we are now 

 assembled. 



But whilst I adhere to my long-cherished opinion as to the great intensity of 

 power employed in the production of dislocations of the crust of the earth, and 

 though 1 cannot subscribe to the doctrine that the ordinary action of deep seas 

 remote from coasts can adequately explain the denudation of the old surface, even 

 by invoking any amount of time, I recognize with pleasure the ability displayed by 

 my able associates, Ramsay, Jukes, and Geikief, in sustaining views which are to 

 a great extent opposed to my own in this department of Theoretical Geology. 



Admiring the Huttonian theory, as derived from reasoning upon my native 

 mountainous country Scotland, and fully admitting that on adequate inclines ice and 

 w r ater must, during long periods, have produced great denudation of the rocks, I 

 maintain that such reasoning is quite inadequate to explain the manifest proofs 

 of convulsive agency which abound all over the crust of the earth, and even are to 

 be seen in many of the mines in the very tract in which we are assembled. Thus, 

 to brin" - such things to the mind's eye of persons who are acquainted with this 

 neighbourhood, I do not apprehend that those who have examined the tract of 

 Coalbrook Dale will contend that the deep gorge in which the Severn there flows 

 has been eaten out by the agency of that river, the more so when the deep fissure 

 is at once accounted for when we see the abrupt severance that has taken place 

 between the rocks which occupy its opposite sides. In that part of Shropshire, 

 the Severn has not worn away the rocks during the historic era, nor has it pro- 

 duced a deeper channel, whilst in its lower parts it has only deposited silt and mud, 

 and increased the extent of land on its banks. 



Then, if we turn to the district in which we were last assembled, the valley at 

 Bath is known to be the seat of one of those disturbances to which my eminent 

 friend Sir Charles Lyell candidly applied the term " convulsion "; the hot waters 

 of that city having ever since flowed out of a deep-seated fissure, clearly marked 

 by the strata on the one side of the valley having been upheaved to a height very 

 different from that which they once occupied *n connexion with those of the other 

 side. When, indeed, we look to the lazy-flowing, mud-collecting Avon, which 

 at Bath passes along that line of valley, how clearly do we see that it never 

 scooped out its channel ; still more, when we follow it to Bristol, and observe it 

 passing through the deep gorge of Mountain-limestone at Clifton, every one must 

 then be convinced that it never coidd have produced such an excavation. In fact, 

 we know that, from the earliest periods of history, it has only accumulated mud, 

 and has never worn away any portion of the hard rock. 



t See ' Silurian System,' p. 535. 



* The work of G-oikie, recently published, and entitled 'The Scenery of Scotland 

 viewed in connexion with its Physical Geology,' is an admirable illustration of that 

 author's descriptive powers. Though I am opposed to his view of the original formation 

 of valleys and deep depressions by rivers and the atmosphere, I quite agree with him as 

 to the great effect produced by glaciers when that moimtamous region was covered by snow 

 and ice. 



