Rev. J. Clifton Ward — Geology of the Lake District. 117 



are each lowering their basins at rates intermediate between these 

 extremes. We might, I think, assume that the sea acting as a great 

 planing agent, aided by the atmospheric forces working on those 

 parts well above water, might denude at the rate of one foot in 750 

 years, the elevation along the main axis going on at about the same, 

 or but little more than the same rate. But even this comparatively 

 high rate of denudation would require 15 millions of years to do the 

 work which was effected. 



There can be no doubt that the Old Ked Period (i.e. all the time 

 between the close of the Upper Silurian and the commencement of 

 the Carboniferous, as shown by the deposition of the basement beds) 

 was one of great duration. Palasontological facts demand a great 

 length of time, and the facts of physical geology, not only in 

 England, but markedly in Scotland, demand the same. Still, it is 

 with some little compunction that one draws on Time's bank as 

 large a draft as 15 million years. 



Carboniferous Period. — A large proportion of the thickness of 

 Carboniferous rocks is undoubtedly deltaic in character. If we 

 allow the British Carboniferous to have a thickness of some 20,000 

 feet at the outside, then taking 12,000 feet as delta deposits, and 

 8000 feet as limestone and extra-deltaic, we arrive at the following 

 conclusion : — 



12,000 feet at rate of -ro of an inch per annum =1,440,000 years 

 8,000 feet „ -fr „ „ =4,800,000 „ 



100 feet of Coal „ r h> „ „ = 120,000 „ 



6,360,000 years, 

 or, in round numbers, we will say 6^ million years. If the whole 

 thickness be taken at the rate of - 5 -V of an inch per annum, the period 

 indicated is 12 million years. 



Post- Carboniferous Periods. — In England the various Post-Carbon- 

 iferous formations do not amount in total thickness to more than 

 20,000 feet; but when we consider the large development of some of 

 these formations abroad — example^ the Eocene and Miocene — it is 

 necessary in any calculations of total length of time to make a 

 greater estimate than 20,000 feet. Accordingly I will take 40,000 

 feet — almost certainly an over-estimate — of rock deposited at the 

 uniform rate of -gV of an inch per annum. This represents a period 

 of 24 million years. 



Glacial Period. — For this last episode of geological history it is 

 difficult to find data either of deposition or denudation to go upon. 

 According to Mr. Croll's theory, the epoch commenced some 250,000 

 years ago, and ended about 80,000 years back. I have already 

 stated that I believe there is evidence in the Lake District of a 

 submergence to the amount of 2,000 feet, and Professor Ramsay long 

 since stated that he believed there was like evidence in Wales. But 

 although I see no other way of accounting for the facts, yet do I 

 fully acknowledge the difficulty of the supposition. I am supposing 

 that the Lake District group of mountains, which for so many 

 geologic ages were being elaborated under subaerial agencies, now 



