Fossils
In the sedimentary rocks one is apt to find remains of some of the animals and plants that lived at the time the rock was forming. While the soft parts of animals decompose rapidly, shells and bones are likely to be buried in the sediments, and if the conditions have been favorable, these remains may be preserved more or less perfectly. All through the millions of years that sedimentary rocks have been forming in the sea, in lakes, on river flood plains and in wind swept deserts, there was an abundance of life, as much as there is today; and our knowledge of that life is derived from these buried fossil remains, so that fossils have a great historic interest.
However as there have lived and died several times as many different kinds of animals as live today, the study of fossils becomes a separate subject, which cannot be treated in this book. Should any collector of rocks and minerals come upon fossils, he is opening a new field, and it will be necessary to turn to other sources for their identification. General books on this subject are scarce, but one or two are given in the literature list.
A List of the Elements, the Abbreviations Used for Them, and Their Atomic Weight, Which Is Approximately the Number of Times Heavier They Are Than Hydrogen.
| Name | Oxygen = 16 |
|---|---|
| Aluminium, Al | 27 |
| Antimony, Sb | 122 |
| Argon, Ar | 40 |
| Arsenic, As | 75 |
| Barium, Ba | 137 |
| Beryllium, Be | 9 |
| Bismuth, Bi | 209 |
| Boron, B | 11 |
| Bromine, Br | 80 |
| Cadmium, Cd | 112 |
| Cæsium, Cs | 132 |
| Calcium, Ca | 40 |
| Carbon, C | 12 |
| Cerium, Ce | 140 |
| Chlorine, Cl | 35 |
| Chromium, Cr | 52 |
| Cobalt, Co | 59 |
| Columbium, Cb | 93 |
| Copper, Cu | 64 |
| Dysprosium, Dy | 162 |
| Erbium, Er | 167 |
| Europium, Eu | 152 |
| Fluorine, F | 19 |
| Gadolinium, Gd | 157 |
| Gallium, Ga | 70 |
| Germanium, Ge | 63 |
| Glucinum, Gl | 9 |
| Gold, Au | 197 |
| Hafnium, Hf | 179 |
| Helium, He | 4 |
| Holmium, Ho | 165 |
| Hydrogen, H | 1 |
| Indium, In | 115 |
| Iodine, I | 127 |
| Iridium, Ir | 193 |
| Iron, Fe | 56 |
| Krypton, Kr | 84 |
| Lanthanum, La | 139 |
| Lead, Pb | 207 |
| Lithium, Li | 7 |
| Lutecium, Lu | 175 |
| Magnesium, Mg | 24 |
| Manganese, Mn | 55 |
| Mercury, Hg | 201 |
| Molybdenum, Mo | 96 |
| Neodymium, Nd | 144 |
| Neon, Ne | 20 |
| Nickel, Ni | 59 |
| Nitrogen, N | 14 |
| Osmium, Os | 190 |
| Oxygen, O | 16 |
| Palladium, Pd | 107 |
| Phosphorus, P | 31 |
| Platinum, Pt | 195 |
| Potassium, K | 39 |
| Præseodymium, Pr | 141 |
| Protoactinium, Pa | 231 |
| Radium, Ra | 226 |
| Radon, Rn | 222 |
| Rhenium, Re | 186 |
| Rhodium, Rh | 103 |
| Rubidium, Rb | 85 |
| Ruthenium, Ru | 102 |
| Samarium, Sm | 150 |
| Scandium, Sc | 45 |
| Selenium, Se | 79 |
| Silicon, Si | 28 |
| Silver, Ag | 108 |
| Sodium, Na | 23 |
| Strontium, Sr | 88 |
| Sulphur, S | 32 |
| Tantalum, Ta | 181 |
| Tellurium, Te | 128 |
| Terbium, Tb | 159 |
| Thallium, Tl | 204 |
| Thorium, Th | 232 |
| Thulium, Tu | 169 |
| Tin, Sn | 119 |
| Titanium, Ti | 48 |
| Tungsten, W | 184 |
| Uranium, U | 238 |
| Vanadium, V | 51 |
| Xenon, Xe | 131 |
| Ytterbium, Yt | 173 |
| Yttrium, Y | 89 |
| Zinc, Zn | 65 |
| Zirconium, Zr | 91 |
Table of Geologic Time
| Eras | |||||
|---|---|---|---|---|---|
| Periods and their Duration in Millions of Years | Important Physical Events | Important Organic Events | |||
| Cenozoic | |||||
| Quaternary | |||||
| Recent | Youthful land forms having high relief formed. | Dominance of man. | |||
| Pleistocene Epoch | 2 M.Y. | Period of glaciation; four great ice advances. | Heidelberg, Neanderthal, and Crô-Magnon man; extinction of large mammals. | ||
| Tertiary | |||||
| Pliocene Epoch | 10 M.Y. | Continuing world-wide land elevation. | Intermigration of North and South American mammals. Transformation of ape to man. | ||
| Miocene Epoch | 18 M.Y. | Cordilleras, Alps, Himalayas formed. Widespread vulcanism-basalt flows in northwestern United States. | Culmination of modern types of mammals. Apes appear in Old World. | ||
| Oligocene Epoch | 10 M.Y. | Land dominant; seas marginal. | Carnivores and ungulates develop into importance. | ||
| Eocene Epoch | 20 M.Y. | Extensive sedimentation; seas marginal. | Dawn of the dominance of mammals. Reptiles subordinate. | ||
| Cretaceous | 65 M.Y. | Widespread epicontinental seas. Laramide revolution at close of period—Rocky Mountains formed. | Climax and culmination of reptiles, especially dinosaurs; first flowering plants and grasses. | ||
| Mesozoic | |||||
| Jurassic | 38 M.Y. | Continent emergent; shallow seas on western North America. | Rise of birds and flying reptiles, first modern trees. | ||
| Triassic | 35 M.Y. | Continent emergent; seas marginal. | Rise of dinosaurs, cycads, and ammonites. | ||
| Paleozoic | |||||
| Permian | 35 M.Y. | World-wide continental uplift and mountain building. Widespread glaciation. | Extinction of most Paleozoic fauna and flora. First modern insects. | ||
| Pennsylvanian | 48 M.Y. | Continent alternately rising and sinking. | Great coal-forming forests, of ferns and seed-ferns. | ||
| Mississippian | 35 M.Y. | Low lands and widespread submergence. | Culmination of crinoids, numerous sharks. | ||
| Devonian | 40 M.Y. | Widespread submergence, local vulcanism. | First known land animals, first forests. | ||
| Silurian | 28 M.Y. | Widespread submergence, local deserts. | First lung fishes and scorpions, abundant corals. | ||
| Ordovician | 65 M.Y. | 60% of North America below sea. | Climax of invertebrate dominance, first vertebrate. | ||
| Cambrian | 105 M.Y. | Widespread submergence. | First abundant invertebrate fauna, trilobites dominant. | ||
| Proterozoic | 700 ± M.Y. | Long periods of granite intrusion, sedimentation, and mountain building. | Bacteria and seaweeds present. Most invertebrates probably present, but remains are lacking. | ||
| Archeozoic | 800 ± M.Y. | World-wide intrusive igneous activity; some sediments. | Blue-green algae present, primitive one-celled plants and animals probably present. | ||
BIBLIOGRAPHY
MINERALOGY
Getting Acquainted with Mineralogy. By G. L. English, 1936, McGraw-Hill Book Co. A beginning textbook of mineralogy.