118 Rev. J. Clifton Ward — Geology of the Lake District. 



within the last million of years sank deeply beneath the sea, and 

 was re-elevated without, apparently, any long periods of rest, and 

 therefore without having left upon it many well-marked lines of 

 marine action. Moreover, supposing Mr. Croll's theory to be the 

 right one as to the cause of the Glacial Period, and taking the 

 time indicated by that theory, this submergence and re-elevation 

 must have taken place in some 200,000 years. Now, from what we 

 know of such movements at the present day, the rate of two feet per 

 century would appear high, and this rate would allow of no halt. 

 There might be plenty of time for the District first to become 

 shrouded in confluent glacier-ice, and then to be depressed and re- 

 elevated under changing climatal conditions ; but I must acknowledge 

 that the submergence to such an amount is somewhat embarrassing. 



Post-Glacial Period. — According to Mr. Croll, about 13 feet may 

 have been removed from the general surface of the country since 

 the close of the Glacial Period (i.e. in 80,000 years). I doubt very 

 much whether, taken all round, more than six feet has been thus 

 removed in the same period over the area of the Late District 

 mountains, and this would be at the rate of one foot in every 13,000 

 years. The ice-action is yet so evident over large tracts, that I 

 question whether even this may not be too high an average. The 

 Skiddaw Slate mountains with their greater softness may, however, 

 more than make up for the unyielding nature of the hard ice- 

 smoothed volcanic rocks. 



General rate of subaerial denudation in the Lake District. — The 

 low rate of denudation just now assumed for the period since the 

 close of the Glacial may be partly put down as resulting from the 

 polished state of the country, but that the general rate over so small 

 a mountain district must have been low is, I think, very probable. 

 If an accurate model of the Lake District be examined, it will be 

 seen that more material has been removed in the formation of the 

 valleys than has been left to form the mountains. The mountain 

 district might, indeed, as well be described as a valley district, so 

 close to one another are the several valleys, and so narrow the 

 mountain ridges separating them. 



The question then arises, at what average rate has denudation 

 been carried on since Carboniferous times ? Is the amount of 

 denudation effected ridiculously small for the amount of time sup- 

 posed to have been spent iq^on it ? or the reverse ? 



At the close of the Carboniferous Period we must, I think, believe 

 the area under description to have been elevated as a more or less 

 lofty table-land, constituting the rough-hewn block out of which 

 such a valley-system as that we now see has been carved. The 

 height of that table-land we cannot indeed accurately estimate, but 

 it may well have been higher than the height of the highest 

 mountains as they now stand. This is not, however, a necessity, 

 for much denudation may have been effected, ere, in times long after 

 the close of the Carboniferous, the base of the country, so to speak, 

 had been raised to its highest level, or, in other words, ere the move- 

 ment of elevation had finally ceased. Still, I think we may assume, 



