"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. Guppy also found chalk-like coral limestones containing 95 p.c. of carbonate of lime in the Solomon Islands.
The absence of Globigerinæ is a local phenomenon. They are quite absent in the Arafura Sea, and no Globigerina-ooze was found in any of the enclosed seas of the Pacific, but with these exceptions the Globigerinæ "are really found all over the bottom of the ocean." (Murray on Oceanic Deposits—Proceedings of Royal Society, Vol. XXIV., p. 523.)
The above analysis shows a far closer resemblance to chalk than that of the Globigerina-ooze of the Atlantic, four specimens of which given by Sir W. Thomson (Voyage of the Challenger Vol. II. Appendix, pp. 374-376, Nos. 9, 10, 11 and 12) from the mid-Atlantic, show the following proportions:—