Geology of England and Wales,” &c. 225 
granted. But it may be asked, “how are we to account 
for such a surprising accumulation of vegetable matter ar- 
ranged in repeated strata (sometimes to the number of six- 
ty and even more in a single district) separated from each 
other by intervening deposites of clay and sand?” Let u 
hear these authors in re 
“ Now the partial filling up of lakes and estuaries offers 
us the only analogies in the actual order of thi with 
which we can compare the deposites of coal; for in such 
situations we often find a series of strata of peat, and some- 
times submerged wood, alternating with others of sand, 
clay, and gravel, and presenting therefore the model ofa coal 
field on a small scale, and in an immature state.” p. 346. 
r. Mac Culloch has instituted a series of experiments 
to ascertain the nature, and account for the formation of 
coal. The following are the general results to which they 
conducted him. : i" 
‘Examining therefore the alteration produced by water 
on common turf or submerged wood, we have all the evi- 
dence of demonstration, that its action is sufficient to con- 
vert them into substances capable of yielding bitumen on 
Lh otsho same action. havi ted through 
distillation. —T 
is there aught in this change so dissonant from other chem- 
jet under compression, it was fused into perfect coal; and 
he admits, that this might have been the process - 
which the beds of coal, found in the earth, have passed ; 
though of opinion, that the agency of water is all that 1s ne- 
cessary to account for the ¢ 
oal measures are remarkable for the great abund 
- Thee é 
ance of yegetable remains found in them; the animal rel- 
Vor. VII.—No. 2, 29 
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