26 SKETCH OF THE GEOLOGY OF DERBYSHIRE, 
stone system as individual things, we shall see that there is a break 
or unconformability between the two. The beds of the carbonife- 
rous system dip sometimes at a considerable angle, while those of 
the new red sandstone lie over them nearly or quite in an horizontal 
position ; and the new red sandstone does not lie only above the 
uppermost bed of the carboniferous system, but also on any of the 
lower ones that come within its range when the upper are absent.— 
This teaches us that between the formation of the two there was an 
interval, during which the beds of the carboniferous system were 
broken up, and some of them stripped off and washed away, and 
that, upon the irregular surface thus formed, the new red sandstone 
was afterwards deposited in a smooth and tranquil manner. If now 
for a moment we look from effects to their cause, and let the facts 
we have briefly examined speak for themselves, they tell us that, 
over all this district which is now the county of Derby (and did we 
extend our examination we should be obliged to extend our expres- 
sion to nearly the whole of England), at the remotest period to 
which we can trace its history, there existed a deep sea. In this sea 
abundance of animals lived, and moved, and had their being, peo- 
pling its tranquil depths with the happiness of existence, the old 
gradually dying, the young coming into life, life frequently cut 
short by accident or violence, everything, in short, proceeding as we 
know the business of existence now to proceed in similar situations. 
How long this state of things lasted we know not, but sufficiently 
long for beds of limestone many hundred feet thick to be deposited, 
and for generation after generation of these creatures to be born, to 
live their appointed time, and perish one after the other, each race 
leaving its relics entombed in the successive beds of rock that gradu- 
ally accumulated at the bottom of the sea. At what rate limestone 
is formed we cannot tell, but, even under the most favourable cir- 
cumstances, since we know it to be rather of the nature of a chemi- 
cal precipitate than a mechanical deposit, and as in far the greatest 
thickness of the mountain limestone there is no appearance of any- 
thing like mud or sand that could have been swept in rapidly from 
neighbouring lands, the period of time required for such an immense 
deposit must have been something enormous. At one, and in some 
parts two periods, we know, indeed, a sudden accession to have 
taken place by the outpouring on the bed of the sea of a considerable 
thickness of melted rock or lava, which, when cooled down and 
covered by other beds of limestone, became what is now called toad- 
stone. But even here we have proof of a lapse of time, because, 
