Chapter X

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

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