140 COLE I ORIGIN AND FORMATION OF WOLD DALES. 
Table B. 
L. Cubic in. per acre per aim. ) 
See Table A. 
L. 1728 
L. 640 square acres 
L. 420 square miles 
Also — 
L. Grains per acre. 
See Table A. 
L. 640 square acres 
L. 420 square miles 
L. 70000 
L. 6-2565 
4-8450980 
•7971636 
Hence- 
(«) 
(h) 
5779 
8*2367831 
3-2375437 
4-9992394 cubic feet per acre. 
2-8061800 
2-6232493 
10*4285887 ann. rainfall in cubic ft. (a) 
6-8795275 
2-8061800 
2-6232493 
12-3089568 total grains per annum. 
5-6422616 
6*6666952 cubic ft. chemically removed 
by above per annum, (b) 
10-4285887 
6-6666952 
3-7618935 
i.e., fraction of foot by which chalk area is annually lowered 
or 1 feot in 5779 years. 
From these it appears that the amount of solid chalk annually 
removed in chemical solution, or in the process of turning soft water 
into hard, amounts to no less than 97,425 tons ; whilst, at the same 
rate, the general surface of the same area is lowered one foot in 5,779 
years. Mechanical action has not been taken into account, as being 
comparatively trifling. 
