s travelled in Tuscany, through
the region of extinct volcanos and its confines, or who has seen the map
constructed by Targioni (1827), to show the principal sites of mineral
springs, can doubt, for a moment, that if this territory was submerged
beneath the sea, it might supply materials for the most extensive coral
reefs. The importance of these springs is not to be estimated by the
magnitude of the rocks which they have thrown down on the slanting sides
of hills, although of these alone large cities might be built, nor by a
coating of travertin that covers the soil in some districts for miles in
length. The greater part of the calcareous matter passes down in a state
of solution to the sea, and in all countries the rivers which flow from
chalk and other marly and calcareous rocks carry down vast quantities of
lime into the ocean. Lime is also one of the component parts of augite
and other volcanic and hypogene minerals, and when these decompose is
set free, and may then find its way in a state of solution to the sea.

The lime, therefore, contained generally in sea water, and secreted so
plentifully by the testacea and corals of the Pacific, may have been
derived either from springs rising up in the bed of the ocean, or from
rivers fed by calcareous springs, or impregnated with lime derived from
disintegrated rocks, both volcanic and hypogene. If this be admitted,
the greater proportion of limestone in the more modern formations as
compared to the most ancient, will be explained, for springs in general
hold no argillaceous, and but a small quantity of siliceous matter in
solution, but they are continually subtracting calcareous matter from
the inferior rocks. The constant transfer, therefore, of carbonate of
lime from the lower or older portions of the earth's crust to the
surface, must cause at all periods and throughout an indefinite
succession of geological epochs, a preponderance of calcareous matter in
the newer as contrasted with the older formations.

THE END.

CONCLUDING REMARKS.

In the concluding chapters of the first book, I examined in detail a
great variety of arguments which have been adduced to prove the
distinctness of the state of the earth's crust at remote and recent
epochs. Among other supposed proofs of this distinctness, the dearth of
calcareous matter, in the ancient rocks above adverted to, might have
been considered. But it would have been endless to enumerate all the
objections urged