CHAPTER X. Becker. _bull. Geol. Soc., Am._, Vol. Xix, P. 113. 1908.

Becker. Bull. Geol. Soc., Am., Vol. XIX, p. 113. 1908. Boltwood. Am. Journ. Science, p. 260. 1905. —— Am. Journ. Science, Vol. XXIII, p. 77. 1907. Boltwood and Rutherford. Phil. Mag., Vol. XXII, p. 586. 1911. Dewar. Proc. Roy. Soc. A., Vol. LXXXI, p. 280. 1908. —— Proc. Roy. Soc. A., Vol. LXXXIII, p. 404, 1910. Holmes. Proc. Roy. Soc. A., Vol. LXXXV, p. 248, 1911. Joly. Radioactivity and Geology, p. 211. 1909. —— Phil. Mag. September, 1911. Kœnigsberger. Geol. Rundschau, Vol. I, p. 245. 1910. Rutherford. Radioactivity, p. 486. 1905. Strutt. The Accumulation of Helium. —— Proc. Roy. Soc. A., Vol. LXXXI, p. 272. 1908. —— —— Vol. LXXXII, p. 166. 1909. —— —— Vol. LXXXIII, p. 96. 1910. —— —— Vol. LXXXIII, p. 298. 1910. —— —— Vol. LXXXIV, p. 195. 1910. —— —— Vol. LXXXIV, p. 380. 1910.

URANIUM FAMILY

ACTINIUM FAMILY

THORIUM FAMILY]

INDEX

α-particles, deflection of, 94 — nature of, 95 — penetration of, 94, 107, 108 — heating effect of, 96, 97 — kinetic energy of, 177 — atoms of helium, 96 Actinium and uranium, 100 Adams, 25 Age of earth, 86, 89, 125, 157 — minerals, 154-64 — moon, 15, 27 — oceans, 68, 89 — sediments, 86, 89 — sun, 112, 113, 120 Arrhenius, energy of sun, 117 Atmosphere, origin of, 25, 30 — as thermal blanket, 36 Atomic theory, 40 Atoms in 1 cc. helium, 140 — in 1 gr. hydrogen, 179 — in 1 gr. radium, 179 — disintegration of, 98, 102 — constitution of, 102 Autunite, age of, 100, 153 — radium-ratio in, 100 — lead-ratio in, 153

β-particles, deflection of, 94 — nature of, 95 — from potassium, 103 Barus, diabase fusion point, 125, 126 Barnes and Rutherford, heat output of radium, 101 Basic rocks, radium in, 130 — distribution of, 128, 134 Becker, age of oceans, 62, 63, 70 — age of earth, 127 Becquerel, discovery of radioactivity, 92 Becquerel rays, 93 Biology and the earth’s age, 20, 21 Boltwood,constancy of radium-ratio, 99 — origin of actinium, 100 — test of lead-ratio, 158 Boltwood and Rutherford, production of helium, 139 Bragg, ionisation, 107 Bückner, radium in rocks, 130 Buffon, 23

Calcium carbonate, accumulation of, 88, 89 Catastrophism, 4, 8 Chaldean chronology, 2 Chamberlin, planetismal hypothesis, 28-30 — tidal theory, 27 — rate of denudation, 79, 80, 81 Challenger expedition, 85 Chlorine in rain, 66 — in rivers, 53, 70 — in sea, 53 — in rocks, 70 Chronology, Chaldean, 2 — Persian, 3 — Hebrew, 3 — Indian, 3 — Byzantine, 4 Clarke, sodium in rocks, 67, 70, 71 — chemical denudation, 51-3 — volume of oceans, 63 — age of oceans, 63, 66 Cosmical energy, 120 Croll, glacial theory, 35-9 — marine erosion, 58 — age of earth, 86 Crust of earth, thickness of, 128, 134 — evolution of, 30, 134 Crystallisation of rock magmas, 145-8 Curie, Mme., radioactivity of thorium, 92 — discovery of radium, 93 Curie and Laborde, heating effect of radium, 96, 101 Cuvier, 8 Cycles of denudation and deposition, 85, 174, 175 Cyclic sedimentation, 44 — circulation of salt, 66-70

Dana, volume of limestone, 88 Darwin, geological time, 11 Darwin, Sir G., moon’s history, 15, 19 — age of moon, 27 Decay, radioactive, 98 — physical independence of, 102 — possible variation with time, 168 Deep-sea deposits, 59 Deluge, 4, 8 Denudation, initiation of, 25, 31 Denudation, chemical, 50, 54 — mechanical, 54 — marine, 58, 66 — present rates of, 78, 80 Deposition, 47, 81-5 Dewar, production of helium, 140 Diabase, fusion point, 125, 126, 128 Dittmar, salinity of oceans, 64 Dole and Stabler, denudation of N. America, 50, 55 Duane, heating effect of radium, 101

Earth, origin of, 22 et seq. — early history of, 25, 29, 73 — heat of, 12-16, 30, 122 — interior of, 134 — distribution of radium, 131-5 Earthquakes, 134 Electroscope, 93, 104 Emanation of radium, 97, 104 End products, 100, 140 Energy, conservation of, 11, 111 Eve and McIntosh, radium in rocks, 130

Farr and Florance, radium in rocks, 130 Fletcher, radium in rocks, 130 Fossils, early ideas, 5

γ-rays, nature of, 94 Geer, De, glacial clays, 41-4 Geiger and Rutherford, counting of α-particles, 138 Geikie, age of earth, 86 — marine erosion, 58 — on geological time, 78 Glacial periods, 33 Glacial periods, chronology of, 36 et seq. Glacial clays in Sweden, 41 Glaciation, indications of, 33, 34 — cause of, 35 Gilbert, Cretaceous sediments of Colorado, 44

Haloes, pleochroic, 107-9 Halley, salinity of oceans, 61 Heat, emission of, by radium, 96, 97, 101 — — by uranium, 116, 131, 132 — — by thorium, 116, 132 — escaping from earth, 122-4, 132 — of the sun, 110 et seq. Helium, discovery of, 95, 96 — from radio-elements, 96 — rate of evolution of, 138 — leakage of, 149 — as end product, 149 — accumulation of, 154 — — in phosphates, 154 — — in iron ores, 155 — — in zircons, 156 — — in sphenes, 156 Helium-ratio, as age-index, 143 Helmholtz, 12, 112 Hutton, 7, 22 Huxley, reply to Kelvin, 14, 20

Igneous rocks, exposures of, 71, 72, 73 — sodium in, 67 — radium in, 131 — thorium in, 131 Ionisation, 93, 104 Ionium, 99 Iron meteorites, 134 Iron ores, helium in, 155

Joly, estimation of radium, 105 — — thorium, 107 — radium in rocks, 131 — thorium in rocks, 131 — age of the earth, 86 — age of the oceans, 17, 20, 62 — on radioactive decay, 168

Kant, 23, 26, 110 Kelvin, duration of earth’s heat, 12-17, 124, 125 — — sun’s heat, 12-14, 111 — tidal retardation, 13, 26, 27

Lamarck, 8 Land, area of, 52 — degradation of, 57 Laplace, 23, 28, 35 Laplacian hypothesis, 23-25 — difficulties of, 28 Lapparent, de, 86 Lead in igneous rocks, 147 — genetic connection with uranium, 100, 140, 141 — in uranium minerals, 158-164 — rate of production of, 142 Lead-ratio as age-index, 143 Lowell, Polar caps of Mars, 39 Lyell, Principles, 9

Mars, Polar caps of, 39 Mass of electron, 95 — of hydrogen atom, 179 Mayer, sun’s heat, 12, 111 Meteorites and sun’s heat, 111 — radium in, 134 Mica, pleochroic haloes in, 109 Minerals, radium-ratio in, 99, 100 — actinium-ratio in, 100 — lead-ratio in, 141, 143 — helium-ratio in, 143 — choice of, 153 Mississippi as denuding agent, 55 — bottom load of, 54 Moon, 15, 19, 20, 27, 28 Moses and geology, 3, 9 Moulton, 28 Murray, area of land, 52 — salinity of rivers, 50 — volume of ocean, 63

Nebulæ, Laplacian, 24, 28 — spiral, 28, 29 Nebular hypothesis, 23-25, 28 Nile, annual deposit of, 81 North America, denudation of, 50, 56

Oceans, origin of, 25, 50 — mass of, 53, 64 — volume of, 53, 63 — saline content of, 53 — age of, 68, 89 Origin of earth, 22, et seq.

Perry, 16 Phillips, 10 Phosphates, helium in, 154 Phosphorescence of uranium salts, 92 Pitchblende. See Uraninite Pleochroic haloes, 107-109, 170 Polonium, discovery of, 93 Poulton, biology and geological time, 21 Products, final radioactive, 100, 140

Radioactive disintegration, 98 — — physical independence of, 102 Radioactive layer, 133 Radiation from uranium, 92 Radium, discovery of, 93 — detection of, 93, 103-107 — emanation from, 98, 104 — helium from, 96, 138-140 — α-rays from, 96, 138 — half-life of, 98, 99, 179 — atomic weight of, 142 — genesis from uranium, 99 — heating effect of, 96, 101, 129, 131 — end products of, 100 — in earth’s crust, 103, 131 — in igneous rocks, 131 — in sediments, 131 — in sun, 117 Ramsay, helium in minerals, 96 Reade, chemical denudation, 50, 62 — age of earth, 86 — volume of limestone, 88 River water, volume of, 53 — sediment in, 56, 57 — salinity of, 53 Rocks, radium in, 130, 131 — thorium in, 131 — chlorine in, 70 — sodium in, 67 Röntgen rays, discovery of, 92 — nature of, 94 Runge and Precht, heat output of radium, 101 Rutherford, age of minerals, 154 — Becquerel rays, 93 Rutherford and Barnes, heat output of radium, 101 Rutherford and Geiger, counting of α-particles, 138 Rutherford and Soddy, disintegration hypothesis, 96, 98 — radium and sun’s heat, 116

Schwarz, 49 Schuchert, 78 Schweidler v. and Hess, heat output of radium, 101 Sederholm, annual deposits, 43 — thickness of sediments, 43, 85 Sediment carried by rivers, 57 Sediments, volume of, 65, 68, 88 — pore space of, 65 — thickness of, 43, 44, 76, 77 — rate of deposit of, 81, 84 — rate of accumulation of, 47 — radium in, 131 — thorium in, 131 — sodium in, 67 — on Continental shelf, 83 — oceanic, 59 — time represented by, 86 Sedimentation, cyclic, 41, 43, 44 Soddy, generation of helium, 96 — — radium, 99 Sodium in rivers, 53, 64 — in ocean, 53, 64 — in igneous rocks, 67, 71 — in sediments, 67 — age of ocean, 64 — wind-borne, 66 — in sewage, 66 Solar system, origin of, 23 et seq. Solar constant, 113 Sollas, thickness of sediments, 76 — age of earth, 86, 87 — age of oceans, 62, 63 — biology and time, 21 — glacial retreat, 43 Steno, 5, 6 St. Meyer and Hess, heat output of radium, 101 Strutt, determination of radium, 105 — radium in rocks, 129, 130 — rate of generation of helium, 139 — leakage of helium, 149 — accumulation of helium, 154-157 Sun, origin of, 25 — helium in, 95, 117 — radium in, 117 — temperature of, 119 — duration of heat of, 12, 14, 112, 114, 120 Suzuki, age of earth, 128

Temperature—gradient of earth’s crust, 122 — due to radium, 128, 132 Thermal conductivity of rocks, 123 Thomson. See Kelvin Thorianite, generation of helium by, 139 Thorium, discovery as a radio-element, 92 — family of elements, 100, 190 — end product of, 100 — heat output of, 131 — distribution of, in rocks, 131 Tidal retardation, 13, 26, 27 Transformation, radioactive, 97, 98 — end products of, 100

Unconformities, 160 Underground temperature, 12, 13, 122-8 Uniformitarianism, rise of, 7, 9 — criticised, 12, 78, 174 Uraninite, generation of helium by, 139 — lead-ratio of, 151, 158-62 Uranium, atomic weight of, 142 — discovery as a radio-element, 92 — phosphorescence of salts 91, 92 — range of α-rays from, 178 — family of, 100, 190 — end products of, 100, 140-142 — generation of radium from, 99 — — helium from, 142 — — lead from, 142 — heat output of, 116, 131 — half-life period of, 179 — time-average of, 143, 179-182 Uranium-bearing minerals— Llano Co., 151, 152 Connecticut, 158, 159, Carolina, 159, 160 S. Norway, 161, 162 Brevig, 163, 164 Mozambique, 153, 160 — alteration of, 150-153 Ussher, chronology of, 3, 10

Van Hise, 88 Velocity of α-particles, 177

Watts, marine erosion, 58 — cycle of deposition, 85 Weathering of rocks, 48, 49 — of minerals, 150 Wilson, W. E., sun’s heat, 116

Zircon, helium-ratio in, 156 — lead-ratio in, 160, 164 Zoroaster, chronology of, 3

WILLIAM BRENDON AND SON, LTD. PRINTERS, PLYMOUTH