Earth, origin of, 46 

 outer shell of, 40 

 passage of, from molten into rigid 



state, 36 



place of, in universe, 4 

 positive areas in surface of, 50 

 primordial molten state of, 26, 33 

 readjustments in, 70, 71 

 shrinkage of, 48, 70, 71, 80, 109 

 sub-crustal shell of, 40 

 tidal strains in, 30 

 warping of, 70, 109 

 Echinoderms, 114 

 Eels, 90 



Efficiency, effect of climate on, 156 

 Eggs, 126 



Egypt, 90, 97, 179, 181, 182 

 Elephants, see Proboscidea 

 Energy, as factor in human progress, 



147, 155, 173, 174, 192 

 distribution of, on basis of climate, 



173 



electric, of chemical elements, 105 

 heat, 105 

 to what due, 156 

 "Energy traffic," 85, 102 

 England, iron in, 155 

 Englishmen, 148 

 Environment, changes in, 73 



fitness of, 88 



Enzyme theory, of Troland, 103 

 Enzymes, autocatalytic, 103 

 catalytic power of, 104 

 evolution of, 106 

 Eocene time, 46, 111, 137, 138, 145, 146 



time, climate of, 55 

 Eopaleozoic time, 79 

 Epi-Proterozoic interval, 119 

 Eras, duration of, 67, 68 

 Erosion, 32, 40, 54, 56, 57, 58, 60, 70, 



76, 78, 110 

 Erpetoichthys, 122 

 Eskimos, 151 

 Europeans, modern, 154 



INDEX 



Evolution, 73, 98 

 crises of, 112 

 cycles of, 80, 81 

 organic, 101 



I 99 



Fats, 84 



Finland, optimum temperature in, as 



shown by death-rate, 167, 169 

 Finns, 169, 171 

 Fire, discovery of use of, 174, 175 



life derived from, 99 

 Fish forms, 116 

 Fishes, 81, 89, 119, 123 



Age of, 46 



origin of, 65 



Flight, true, evolution of, 128 

 Floras, origin of, 65 

 Flying dragons, 73 



Food, dependence of, on climate, 154, 

 155 



effect of, on energy, 156 



use of fire in cooking, 175 

 Foot, reptilian, 124 



terrestrial, evolution of, 123 



terrestrial, origin of, 111 

 Footprint, earliest known, 123, 124, 



144 

 Footprints, Connecticut valley, 130 



Upper Triassic, 129 

 Formative era, 46, 47, 49, 50 



era, earth-growth in, 47 



era, volcanism in, 48 

 Fossils, 59 



living, 81 

 France, deaths in, 160, 164, 165 



Gabbro, 39 

 Gadow, H., 131 

 Galaxy, see Milky Way 

 Gale, H. S., 185 

 Galton, F., 147 

 Ganoids, 122 

 Geikie, A., 76 



