se of their very wide diffusion.

[16] _Principles of Geology_, 11th Ed., Vol. I., p. 258.

[17] On Limestone as an Index of Geological Time.

[18] In his _Preliminary Report on Oceanic Deposit_, Mr. Murray says:--"It
has been found that the deposits taking place near continents and islands
have received their chief characteristics from the presence of the _debris_
of adjacent lands. In some cases these deposits extend to a distance of
over 150 miles from the coast." (_Proceedings of the Royal Society_, Vol.
XXIV. p. 519.)

"The materials in suspension appear to be almost entirely deposited within
200 miles of the land." (_Proceedings of the Royal Society of Edinburgh_,
1876-77, p. 253.)

[19] _Geographical Evolution. (Proceedings of the Royal Geographical
Society._ 1879, p. 426.)

[20] Professor Dana was, I believe, the first to point out that the regions
which, after long undergoing subsidence and accumulating vast piles of
sedimentary deposit have been elevated into mountain ranges, thereby become
stiff and unyielding, and that the next depression and subsequent upheaval
will be situated on one or the other sides of it; and he has shown that, in
North America, this is the case with all the mountains of the successive
geological formations. Thus, depressions, and elevations of extreme
slowness but often of vast amount, have occurred successively in restricted
adjacent areas; and the effect has been to bring each portion in succession
beneath the ocean but always bordered on one or both sides by the remainder
of the continent, from the denudation of which the deposits are formed
which, on the subsequent upheaval, become mountain ranges. (_Manual of
Geology_, 2nd Ed., p. 751.)

[21] _Nature_, Vol. II., p. 297.

[22] Sir W. Thomson, _Voyage of Challenger_, Vol. II., p. 374.

[23] The following is the analysis of the chalk at Oahu:--

Carbonate of Lime 92.800 per cent.
Carbonate of Magnesia 2.385 ,,
Alumina 0.250 ,,
Oxide of Iron 0.543 ,,
Silica 0.750 ,,
Phosphoric Acid and Fluorine 2.113 ,,
Water and loss 1.148 ,,

This chalk consists simply of comminuted corals and shells of the reef. It
has been examined microscopically and found to be destitute of the minute
organisms abounding in the chalk of England. (_Geology of the United States
Exploring Expedition_, p. 150.) Mr. Gup