[255] The pressures and densities here given are essentially the same as those previously worked out by others and already published. The temperatures are the results of recent preliminary computations made under the auspices of the Carnegie Institution, and are subject to change on further study. They are based on the assumption that the increase in density is due to compression. They are in general accord with the results previously reached by Dr. F. R. Moulton (see “A Group of Hypotheses Bearing on Climatic Changes,” by T. C. Chamberlin, Jour. of Geol., 1897, p. 674). The Rev. O. Fisher, in the Am. Jour. of Sci., 1901, p. 420, gives much higher results.
[256] Attention was called to this feature by Chamberlin in a paper before the Geol. Soc. of Am. at Rochester, December, 1901.
[257] These are reckoned by assuming that the temperature of no variation at 50 feet below the surface is 40° F.
[258] Am. Jour. of Sci., Vol. V, 1898, p. 161.
[259] Van Hise. Personal communication.
[260] Bull. 168 U. S. Geol. Surv., p. 14.
[261] Daniell’s Physics, p. 407.
[262] Heat. Tait, p. 225.
[263] All the feldspars are calculated as anorthite. Augite is used for hypersthene, ilmenite is included with magnetite, and all minerals are calculated as if of the isometric system.
[264] Physics of the Earth’s Crust, Chap. VIII.
[265] Penn Monthly, Philadelphia, May, 1876.
[266] The following conclusion by an eminent authority has come to our notice since this was written:

L’influence des marées océanienes sur la durée du jour est donc tout à fait minime et n’est nullement comparable à l’effet des marées dues à la viscosité et à l’elasticité de la partie solide du globe, effet sur lequel M. Darwin à insisté dans une series de Mémoires du plus haut intérêt. Par H. Poincaré, Bulletin Astronomique, tome XX (June, 1903), p. 223.

[267] On the Secular Changes in the Elements of the Orbit of a Satellite revolving about a Tidally-distorted Planet. Phil. Trans., Roy. Soc., Pt. II, 1880.
[268] Jour. Geol., Vol. VI, 1898, p. 65.
[269] Quar. Jour. Geol. Soc., Vol. 39, 1883, p. 140. Everett (Units and Physical Constants) gives 837 × 106 for steel, but as the modulus for granite seems low, we have taken the lower estimate for steel to avoid exaggerating the ratio between them.
[270] Nat. Phil. Thompson & Tait, Vol. II, p. 424, 1890.
[271] Computations made at the request of the authors. See also Fisher, Physics of the Earth’s Crust, p. 36.
[272] Of like import is the statement of Woodward—“If the crust of the earth were self-supporting, its crushing strength would have to be about thirty times that of the best cast steel, or five hundred to one thousand times that of granite.” Mathematical Theories of the Earth, Proc. Am. Assoc. for Adv. Sci., 1889, p. 49.
[273] It is assumed that the direction of the supporting thrust at the periphery of the dome is at every point parallel to the tangent to the domed surface. This is justified by symmetry in the case of a shell conforming to the sphericity of the earth, and in the other cases it would seem to be as favorable an assumption in the direction of high supporting capacity as can reasonably be made.
[274] Prepared at the authors’ request by W. H. Emmons.
[275] The terms are here used in their narrow technical sense. Extrusion is also used in a broad generic sense to indicate the whole process of outward movement.
[276] Gilbert. 14th Ann. Rept. U. S. Geol. Surv., Pt. I, p. 187.
[277] Gilbert, after a careful study of the moon’s topography, has suggested that the lunar pits may be indentations produced by infalling meteorites or planetoids, and has shown by experiment that pits of a similar type, with similar central cones, can be produced by impact. The Moon’s Face: A Study of the Origin of its Features. Presidential address, Phil. Soc. of Washington, 1892, Bull. Vol. XII, pp. 241–292.
[278] Structure and Distribution of Coral Islands.
[279] Corals and Coral Islands.
[280] Proc. Roy. Soc. Edin., Vol. X, pp. 505–18, and Vol. XVII, pp. 79–109; Nature, Vol. XXXII, p. 613; Narrative Chal. Exp., Vol. I, pp. 781–2.
[281] Bull. Mus. Comp. Zool., Vol. XVII, 1889.
[282] Ante, p. 22.
[283] Origin of Igneous Rocks. Phil. Soc. of Wash., Vol. XII, pp. 89–214.
[284] The Natural System of Volcanic Rocks. Cal. Acad. of Sci., 1868.
[285] Chemical News, April 9, 1897.
[286] Phil. Trans., 1873.
[287] Mechanics of Igneous Intrusion, Am. Jour. Sci., Apr., p. 269, and Aug., p. 107, 1903.
[288] Frank. Lehrbuch der Botanik, I, p. 576, 1892.
[289] Science, Vol. VI, p. 838, 1897. Zeitschrift für Anorganische Chemie, 1897.
[290] Reference works: Scott, Studies in Fossil Plants, 1900; Zeiller, Éléments de Paléobotanique, 1900; Potonié, Lehrbuch der Pflanzenpaleontologie, 1899; Seward, Fossil Plants, 1898; Solms-Laubach, Fossil Botany, 1887.
[291] Weed. Ninth Ann. Rept. U. S. Geol. Surv., 1887–88, pp. 613–76; also Bradley M. Davis. Science, Vol. VI, 1897, pp. 145–57.
[292] Cohn. Abhandl. Schles. Gesell. Naturwiss., Heft II, 1862.
[293] Deep Sea Deposits, p. 257.
[294] C. A. Davis. Jour. of Geol., Vol. IX, 1901, p. 491.
[295] Weed. Ninth Ann. Rept. U. S. Geol. Surv., 1887–8.
[296] Reference books: Zittel’s Text-book on Paleontology, translated and edited by Eastman; Williams’ Geological Biology; Nicholson’s Manual of Paleontology.
[297] After Zittel in the main.
[298] S. W. Johnson, How Crops Feed, p. 47.
[299] Reference works: Plant Relations, Coulter, 1900,—a convenient elementary work; Schimper, Pflanzengeographie, 1898; Warming, Lehrbuch der oekologischen Pflanzengeographie, 1896; Cowles, Botanical Gazette, Vol. XXVII, 1898.
[300] One of the earliest attempts to map these and develop their significance and value is found in Vol. II, Geol. of Wis., 1873–77, Native Vegetation, pp. 176–87.
[301] Chamberlin. A Systematic Source of Evolution of Provincial Faunas, Jour. of Geol., Vol. VI, 1898, pp. 597–609.
[302] Wallace. Island Life.
[303] For data, see Walther’s Einleitung in die Geologie, pp. 35–45.
Transcriber’s Notes: