THE DALES OF DERBYSHIRE. 63 
condition of affairs, the high grounds of England were 
covered with ice, and as this was gradually melted, glaciers 
flowed from the high ground, wearing out the strata beneath 
in the softest parts, and forming troughs or basins, and 
where the rocks were harder, flowing over it, and from these 
glaciers, icebergs became detached, which found their way 
into the surrounding shallow seas, and stranding here and 
there in the shallower waters, depositing the debris carried 
with them. Consequently, there is hardly a piece of high 
ground in Staffordshire where the limestone debris cannot 
be traced, and this limestone, owing to the similarity of the 
fossils, etc., occurring in it, can, without any difficulty, be 
traced to its-original home in Derbyshire. A good example 
of this kind occurred when the South Staffordshire Water- 
works’ Company were constructing their reservoir on the 
Outwoods, several roundish-glacier drifted boulders of lime- 
stone having been found. The glaciers wearing out the softer 
portions of the underlying rock and flowing over harder 
obstructions caused the limestone districts to be shut in by 
high barriers, through which the water pent up behind had 
to force its way. This water, acting partly mechanically 
by its falling force, and chiefly by the solvent action of the 
carbon dioxide in solution, left us the dales as we find 
them to-day, and this process is still being slowly continued. 
In order to emphasise the importance of this chemical 
action, I have estimated the amount of limestone carried by 
the Dove from the limestone districts of the Dove Valley 
in a year. We may take it roughly that the Dove 
discharges 250,000,000 gallons of water into the Trent in 
24 hours, and that each gallon of water contains Io grains 
of carbonate of lime. At this rate roughly 58,o00 tons 
of limestone are discharged annually, and this would require 
182 trains of 40 trucks each, each truck carrying 8 tons, 
to carry it. Or, to put it in another way, these 58,000 
would form a solid block of limestone 3 ft. high, 3 ft. wide, 
