Chapter LVI. Geology

Shakespeare tells us that “there are sermons in stones.” No science, except possibly astronomy, appeals more to the imagination or carries one further away from our present workaday world than geology. While geology “claims as its peculiar territory the rocky framework of the globe,” its object is, says the Encyclopaedia Britannica (Vol. 11, p. 638) “to trace the structural progress of our planet from the earliest beginnings of its separate existence through its various stages of growth down to the present condition of things.” It goes back millions and hundreds of millions of years to the first beginnings of things and unravels complicated processes by which the earth and each of the continents on it has been built up.

“It follows, even into detail, the varied sculpture of mountain and valley, crag and ravine.” It shows “that the present races of plants and animals are the descendants of other and very different races which once peopled the earth. It teaches that there has been a progressive development of the inhabitants.” Dead and cold though the rocks seem, they are filled, to one who can read their secret, with the tragedy of past life. Parts of Florida are but the graves where millions of corals, now crushed into massive limestone, once lived and died; the coal of Pennsylvania tells of ferns and other terrestrial plants matted together into a bed whence they originally grew; “the snails and lizards which lived and died within a hollow tree, the insects which have been imprisoned within the exuding resin of old forests, the footprints of birds and quadrupeds, the trails of worms left upon former shores—these and innumerable other pieces of evidence” tell of the tragedies of former times and “enable the geologist to realize in some measure what the faunas and floras of successive periods have been.”

The foundation for the study of the whole subject in the Britannica is the article Geology (Vol. 11, p. 638), equivalent to 125 pages of this Guide. It is by the highest authority in the world, Sir Archibald Geikie, long director general of the Geological Survey of the United Kingdom, and director of the Museum of Practical Geology, London. It deals with the general principles and gives an outline of the subject matter of the science. In particular it treats of,

The historical development of geological science;

The cosmical aspects of geology;
Geognosy;
Dynamical Geology;
Geotectonic or Structural Geology;
Palaeontological Geology;
Stratigraphical Geology;
Physiographical Geology.

While the student will doubtless be interested equally in each of these departments, the general reader will be especially interested in the historical development which—it is worthy of note—is almost the only concise account of geological history hitherto published in English. Especially interesting is the question, fully discussed, of the age of the earth. Lord Kelvin (Vol. 11, p. 653) declared some few years ago that the time “was more than twenty and less than forty millions of years and probably much nearer twenty than forty.” But the trend of later investigations, and especially the study of radio-activity, has led to the belief that the period must have been much longer. Sir Archibald Geikie sums up the evidence as follows (Vol. 11, p. 653): “In the present state of science it is out of our power to state positively what must be the lowest limit of the age of the earth, but we cannot assume it to be less, and it may possibly have been much more than one hundred millions of years.”

The general reader will find of interest, too, the table (Vol. 11, p. 670) representing the geological record or order of succession of the formations of the earth’s crusts from the earliest Archean, through Cambrian, Silurian, Devonian and Carboniferous to the Post-glacial or Human of to-day. A separate article is to be found on each of these different formations, namely: Archean (Vol. 2, p. 360); Cambrian (Vol. 5, p. 86); Silurian (Vol. 25, p. 109); Devonian (Vol. 8, p. 124); Carboniferous (Vol. 5, p. 309); Permian (Vol. 21, p. 176); Triassic (Vol. 27, p. 258); Jurassic (Vol. 15, p. 567); Cretaceous (Vol. 7, p. 414); Eocene (Vol. 9, p. 661); Oligocene (Vol. 20, p. 81); Miocene (Vol. 18, p. 565); Pliocene (Vol. 21, p. 846); Pleistocene (Vol. 21, p. 835); Recent, Post-glacial or Human under article Quaternary (Vol. 22, p. 718).

Full local geological information is found in geographical articles. See, for instance, in the article United States, the section on Geology (Vol. 27, pp. 624–632), by Professors R. D. Salisbury and T. C. Chamberlin of the University of Chicago; the section Geology in the article England (Vol. 9, pp. 415–416), by H. R. Mill, editor of The International Geography; the section Geology in the article Africa (Vol. 1, pp. 323–325), by Walcot Gibson, author of Mineral Wealth of Africa, etc. These special treatments are accompanied by sketch maps. Similarly, the articles on each of the different states of the Union has a section giving information on the geology, the flora and fauna, the climate, and the geography of the state. And in such articles on geographic topics as Great Salt Lake, Niagara, by G. Karl Gilbert, and Grand Canyon, by R. S. Tarr, there is valuable geological information.

Other important articles which the reader should consult are Petrology (Vol. 21, p 323), equivalent to 40 pages of this Guide, largely illustrated, by Dr. J. S. Fleet, petrographer to the Geological Survey of Great Britain; Mineralogy (Vol. 18, p. 509), equivalent to 25 pages of this Guide, by L. J. Spencer, editor of the Mineralogical Magazine; Mineral Deposits (Vol. 18, p. 504), equivalent to 15 pages of this Guide, by James F. Kemp, professor of geology of Columbia University, and geologist to the United States and New York Geological Surveys; Crystallography (Vol. 7, p. 569), equivalent to 60 pages of this Guide, also by L. J. Spencer; Mining (Vol. 18, p. 528), equivalent to 40 pages of this Guide, by Henry Smith Munroe, professor of mining, Columbia University, New York; Palaeontology (Vol. 20, p. 579), profusely illustrated, equivalent to 35 pages of this Guide, by Prof. Henry Fairfield Osborn of Columbia University, and president of the American Museum of Natural History of New York; Palaeobotany (Vol. 20, p. 524), profusely illustrated, equivalent to 100 pages of this Guide, written by three of the leading geological writers of the day: Dr. D. H. Scott, president of the Linnean Society, author of Studies in Fossil Botany; A. E. Steward, professor of botany of the University of Cambridge; and Clement Reid, author of Fossil Flora of Tegelen.

Of more popular interest are the three articles, Earthquake, Seismometer and Volcano. The article Earthquake is in two parts. The first (Vol. 8, p. 817) is an historical account telling of the extent and damage done by many earthquakes, including the terrible San Francisco earthquake of April 18, 1906, and that of Calabria and Sicily, December 28, 1908, by F. W. Rudler, president of the Geologists’ Association; the other part (Vol. 8, p. 820), by Dr. J. Milne, late professor of geology in the Imperial University of Tokio, deals with the physical theory of earthquakes. The article Volcano (Vol. 28, p. 178), equivalent to 45 pages of this Guide, is by F. W. Rudler, and gives us the reasons for and the history of volcanic disturbances. It is of interest both to the scholar and to the casual reader. Thus we learn that “while Herculaneum was buried beneath a flood of mud swept down from Vesuvius” in 79 A.D., Pompeii “was overwhelmed in great measure by loose ashes, capable of removal with comparative ease.” Nearly everyone of middle age remembers the famous eruption of Krakatoa in 1883 and the famous sunsets of that year. Concerning this the Britannica article tells us (p. 180):

Enormous quantities of dust ejected from Krakatoa in 1883 were carried to prodigious distances, samples having been collected at more than a thousand miles from the volcano; whilst the very fine material in ultramicroscopic grains which remained suspended for months in the higher regions of the atmosphere seems to have enjoyed an almost world-wide distribution, and to have been responsible for the remarkable sunsets at that period.

The article Dust (Vol. 8, p. 713), by John Aitken, inventor of the machine for counting particles of dust, explains the mechanical causes of this suspension. Besides there is much concrete information about volcanoes in articles on volcanic regions: for instance, on volcanoes in the possessions of the United States, see articles Hawaii, Alaska, Philippines.

The student should read also the articles on the different minerals, many of them long and important and all by well-known authorities. Thus the article Diamond (Vol. 8, p. 158), illustrated, equivalent to 20 pages of this Guide, is by Henry Alexander Miers, editor of the Mineralogical Magazine. Besides dealing with the general character of this stone, the article pays particular attention to diamond mining in South Africa, the text being illustrated by plates showing the Kimberley and DeBeers workings. The article Gem (Vol. 11, p. 560), is equivalent to 25 pages of this Guide. The article Gem, Artificial (Vol. 11, p. 569) is by the well-known chemist and physicist, Sir William Crookes. It tells of the changes induced by radioactive emanations and of the artificial production of the diamond, ruby, sapphire, Oriental emerald, amethyst and topaz. The reader will be interested, too, in the article Lapidary and Gem Cutting (Vol. 16, p. 195), by Dr. George F. Kunz, gem expert for Messrs. Tiffany & Co., New York.

There are special biographical articles in the Britannica on all the well-known geologists, and in these articles special stress has been laid on the part played by the subject of the memoirs in promoting the science. This is well shown, for instance, in the articles Agassiz (Vol. 1, p. 367); Hutton (Vol. 14, p. 16) and Lyell (Vol. 17, p. 158).

Geology, by its study of earth deposits, age of rocks, etc., and by its estimate of the date of certain extinct animals like the mammoth and hairy elephant, or of the time when certain animals, e.g., the elephant and reindeer, were found in parts of the world where they no longer occur, is an important adjunct to the science of anthropology, especially in the question of the antiquity of man. On this see the section of antiquity of man in the article Anthropology (Vol. 2, p. 114), and, in general, the chapter in this Guide on Anthropology and Ethnology.

From one point of view geology is only a branch of geography and the student of geology should consult the elaborate article on Geography in the Britannica, especially all parts dealing with physical geography or physiography. For a clue to this part of the book see the chapter in this Guide on Geography.

The following is a list of the more important articles on Geology in the Encyclopaedia Britannica:

List of Articles in the Encyclopaedia Britannica of Special Interest to Students of Geology

Abich, O. W. H. von
Abraum salts
Acadian
Acmite, or Aegirite
Agalmatolite
Agate
Agglomerate
Agricola, Georg
Aikin, Arthur
Alabaster
Albertite
Albian
Albite
Alexandrite
Allophane
Allport, Samuel
Alluvium
Almandine
Alquifou
Alunite, or Alumstone
Amazon Stone, or Amazonite
Amber
Amblygonite
Amethyst
Amianthus
Amphibole
Amphibolite
Amygdaloid
Analcite
Anatase
Andalusite
Andesine
Andesite
Anglesite
Anhydrite
Ankerite
Annabergite
Anning, Mary
Anorthite
Ansted, David Thomas
Anthracite
Apatite
Aphanite
Aplite
Apophyllite
Aptian
Aquamarine
Aragonite
Archean System
Archiac, vicomte d’
Arenig Group
Argentite
Argyrodite
Asbestos
Assise
Asteria, or Star-stone
Atacamite
Atherstone, W. G.
Augite
Autunite
Aventurine, or Avanturine
Avonian
Axinite
Aymestry Limestone
Azurite, or Chessylite
Bagshot Beds
Baily, William Hellier
Bain, Andrew Geddes
Bajocian
Bakewell, Robert
Bala Series
Barrande, Joachim
Barrett, Lucas
Barrois, Charles
Barton Beds
Barytes
Barytocalcite
Basalt
Basin
Batholite
Bathonian Series
Bathvillite
Bauxite
Bed
Beecher, C. E.
Belt, Thomas
Bembridge Beds
Benett, Etheldred
Benitoite
Bernician Series
Beryl
Beryllonite
Beudant, François S.
Beyrich, H. E. von
Bigsby, J. J.
Binney, E. W.
Biotite
Bismuthite
Bitumen
Blanford, W. T.
Blende, or Sphalerite
Bloodstone
Boase, Henry Samuel
Bole
Bomb
Bone Bed
Bonney, Thomas George
Boracite
Born, I. von
Borolanite
Bort, or Boart
Bostonite
Boucher de Crévecoeur de Perthes, J.
Boué, Ami
Boulder
Boulder Clay
Bournonite
Bovey Beds
Bowerbank, J. S.
Bracklesham Beds
Bradford Clay
Brander, Gustavus
Breccia
Breislak, Scipione
Bristow, H. W.
Brocchi, G. B.
Brochant de Villiers, A. J. F. M.
Brochantite
Brodie, P. B.
Brogger, W. C.
Bromlite
Brongniart, Alexandre
Bronn, Heinrich Georg
Bronzite
Brookite
Brucite
Brückmann, Franz Ernst
Buch, Baron von
Buckland, William
Bunter
Bytownite
Cainozoic
Cairngorm
Calamine (Smithsonite)
Calcite
Callovian
Cambrian System
Cancrin, F. L. von
Caradoc Series
Carbonado
Carboniferous System
Carnelian
Cassiterite
Cat’s-eye
Cave
Celestine
Cerargyrite
Cerussite
Chabazite
Chalcedony
Chalk
Chalybite
Charnockite
Childrenite
Chlorite
Chromite
Chrysoberyl
Chrysocolla
Chrysolite
Chrysoprase
Cinnabar
Cinnamon Stone
Clarke, William B.
Clay
Clay-with-Flints
Clinoclastite
Clintonite
Close, Maxwell H.
Cobaltite
Colemanite
Columbite
Concretion
Conglomerate
Connellite
Conybeare, W. D.
Copalite, or Copaline
Cope, Edward D.
Copper-glance
Copper-pyrites, or Chalcopyrite
Coprolites
Corallian
Cornbrash
Corundum
Cotta, Bernard von
Covellite
Crater
Credner, C. F. H.
Cretaceous System
Crocidolite
Crocoite
Croll, James
Crosskey, Henry W.
Cryolite
Crystallite
Crystallography
Culm
Cumming, Joseph G.
Cuprite
Cyanite
Dacite
Dalradian
Dana, James D.
Danburite
Datolite
Daubeny, Charles G. B.
Daubree, G. A.
Davidson, Thomas
Dawson, Sir John W.
Dechen, E. H. K. von
De la Beche, Sir H. T.
Delesse, A. E. O. J.
Deluc, Jean Andre
Demantoid
Des Cloizeaux, Alfred
Descloizite
Deshayes, G. P.
Deslongchamps, J. A. E.
Desmarest, Nicolas
Desnoyers, J. P. F. S.
Desor, P. J. E.
Devonian System
Diabase
Diallage
Diamond
Diaspore
Dick, Robert
Diluvium
Diopside
Dioptase
Diorite
Dolerite
Dolomieu
Dolomite
Dopplerite
Drift
Dufrenoy, O. P. A. P.
Dumont, André Hubert
Dumortierite
Duncan, Peter Martin
Durocher, J. M. E.
Earth pillar
Earthquake
Eclogite
Egerton, Sir P. de M.
Ehrenberg, C. G.
Eichwald, K. E. von
Elaterite
Elie De Beaumont
Emerald
Emery
Emmons, Ebenezer
Enniskillen, 3rd earl of
Enstatite
Eocene
Epidiorite
Epidosite
Epidote
Erubescite
Erythrite
Escher von der Linth
Esker
Etheridge, Robert
Ettingshausen, Baron
Euclase
Fall-line
Farey, John
Faujas de Saint-Fond
Fault
Favre, Jean Alphonse
Felsite
Felspar
Fitton, William Henry
Flint
Fluor-spar
Flysch
Fold
Forbes, David
Forchhammer, J. G.
Foster, Sir C. le Neve
Fouque, F. A.
Fournet, J. J. B. X.
Fox, Robert Were
Franklinite
Freestone
Freieslebenite
Fulgurite
Fuller’s Earth
Fumarole
Gabbro
Galena
Garnet
Gaudry, Jean Albert
Gault
Geikie, Sir Archibald
Geikie, James
Geinitz, H. B.
Gem
Geology
Gesner, Abraham
Geyser
Giebel, C. G. A.
Gilbert, Grove K.
Gilsonite
Glacial Period
Glauconite
Gneiss
Godwin-Austen, R. A. C.
Goldfuss, G. A.
Goniometer
Göthite, or Goethite
Granite
Granulite
Graphite
Gravel, or Pebble Beds
Green, A. H.
Greenockite
Greenough, G. B.
Greensand
Greisen
Greywacke
Griffith, Sir Richard J.
Groth, P. H. von
Guettard, J. E.
Gumbel, K. W. von
Guyot, A. H.
Gypsum
Haast, Sir J. F. J. von
Haematite
Haidinger, W. K. von
Hall, James
Hall, Sir James
Halleflinta
Harkness, Robert
Harmotome
Hatchettite
Hauer, F. von
Haughton, Samuel
Hausmann, J. F. L.
Hayden, F. V.
Hebert, Edmond
Heddle, M. F.
Heer, Oswald
Heim, A. von St. Gallen
Helmersen, Gregor von
Hemimorphite
Henslow, John Stevens
Henwood, William Jory
Heulandite
Hicks, Henry
Hiddenite
Hitchcock, Edward
Hochstetter, F. C. von
Holocene
Hone
Hopkins, William
Hornblende
Horner, Leonard
Hornes, Moritz
Hornfels
Hulke, J. W.
Humite
Hunt, Robert
Hunt, T. Sterry
Hutton, James
Hyacinth
Hypersthene
Idrialin
Ijolite
Ilmenite
Iolite
Itacolumite
Jade
Jameson, Robert
Jargoon
Jarosite
Jasper
Jet
Joints
Jones, T. Rupert
Jukes, J. B.
Jurassic System
Kaolin
Karrer, Felix
Karsten, K. J. B.
Kayser, F. H. E.
Kenngott, G. A.
Keuper
Kidd, John
Kimeridgian
King, Clarence
Kirwan, Richard
Kjerulf, Theodor
Kobell, W. X. F. von
Koenig, K. D. E.
Koksharov, N. I. von
Koninck, L. G. de
Kunzite
Labradorite
Laccolite
Lacroix, A. F. A.
Lamprophyres
Lapilli
Lapis Lazuli
Lapparent, A. A. C. de
Lapworth, Charles
Lasaulx, A. C. P. F. von
Laterite
Laumont, F. P. N. G. de
Lava
Leadhillite
Le Conte, Joseph
Lehmann, J. G.
Lepidolite, or Lithia-Mica
Lesley, J. Peter
Leucite
Lévy, A. M.
Lewis, Henry Corvill
Lias
Lignite
Limburgite
Limestone
Limonite
Lindstróm, Gustaf
Liroconite
Lister, Martin
Llandeilo Group
Llandovery Group
Llwyd, Edward
Loess
Logan, Sir William E.
London Clay
Lonsdale, William
Lory, Charles
Ludlow Group
Lyell, Sir Charles
McCoy, Sir Frederick
Macculloch, John
Maclure, William
Magnesite
Magnetite
Malachite
Mallet, Robert
Manganite
Mantell, G. A.
Marble
Marcasite
Marcou, J. B.
Marl
Martin, William
Meek, F. B.
Meerschaum
Melaconite
Mesozoic
Metamorphism
Metasomatism
Meteorite
Meyer, C. E. H. von
Mica
Mica-schist
Microcline
Micropegmatite
Miller, Hugh
Miller, W. H.
Millerite
Millstone Grit
Mimetite
Mineral deposits
Mineralogy
Miocene System
Mispickel
Mocha Stone
Mofetta
Mohs, Friedrich
Mojsisovics von Mojsvar, J. A. G. E.
Moldavite
Molybdenite
Monazite
Monzonite
Moonstone
Morris, John
Münster, Georg, count zu
Murchison, Sir R. I.
Muschelkalk
Muscovite
Mylonite
Napoleonite
Natrolite
Naumann, G. A. C. F.
Neck
Neocomian
Nepheline
Nepheline-syenite
Nephelinites
Neumayr, Melchior
Newberry, J. S.
Niccolite
Nicholson, H. A.
Nicol, James
Nitre
Noeggerath, J. J.
Obsidian
Oldham, Thomas
Oligocene System
Oligoclase
Olivenite
Olivine
Omalius d’Halloy, J. d’
Onyx
Oolite
Opal
Oppel, C. A.
Orbigny, A. D. d’
Ordovician System
Orthoclase
Osborn, H. F.
Oxfordian
Ozokerite, or Ozocerite
Palaeozoic
Parisite
Parkinson, James
Peach, C. W.
Pegmatite
Pendleside Series
Pengelly, William
Peperino
Peridot
Peridotite
Perlite
Permian System
Perovskite
Petalite
Petrology
Pharmacosiderite
Phenacite
Phillips, John
Phillips, William
Phillipsite
Phlogopite
Phonolite
Phosgenite
Phosphates
Phosphorite
Phyllite
Picrite
Pictet, de la Rive, F. J.
Pitchblende, or Uraninite
Pitchstone
Plagioclase
Pleistocene System
Pliocene System
Plot, Robert
Plumbago
Pneumatolysis
Pollux, or Pollucite
Porphyry
Portlandian
Portlock, J. E.
Powell, J. W.
Pre-Cambrian
Prehnite
Prestwick, Sir Joseph
Prévost, Constant
Proustite
Psilomelane
Pumice
Purbeckian
Puy
Pyrargyrite
Pyrites
Pyrolusite
Pyromorphite
Pyrope
Pyrophyllite
Pyroxene
Pyroxenite
Pyrrhotite
Quartz
Quartzite
Quartz-porphyry
Quarternary
Quenstedt, F. A. von
Rammelsberg, K. F. A.
Ramsay, Sir Andrew C.
Rath, Gerhard von
Reading Beds
Realgar
Renard, A. F.
Renevier, Eugène
Retinite
Reusch, Hans Henrik
Reuss, A. E. von
Rhaetic
Rhodochrosite
Rhodonite
Rhyolite
Rock
Rock-crystal
Roemer, F. A.
Rogers, H. D.
Rome de l’Isle, J. B. L.
Roth, J. L. A.
Rubellite
Ruby
Russell, Israel Cook
Rutile
Rutley, Frank
Salt
Salter, John William
Sand
Sandberger, K. L. F. von
Sandstone
Sapphire
Sard
Sardonyx
Satin-spar
Savi, Paolo
Scapolite
Scheelite
Schists
Schlotheim, Baron von
Schorl
Scolecite
Scoria
Scrope, G. J. Poulett
Sedgwick, Adam
Seismometer
Selwyn, A. R. C.
Sénarmont, H. H. de
Serpentine
Sharpe, Daniel
Sill
Sillimanite
Silurian System
Sinter
Slate
Smaltite
Smith, William
Smithson, James
Smyth, Sir W. W.
Sodalite
Soffioni
Solfatara
Sorby, Henry C.
Speeton Beds
Sphene
Spherulites
Spinel
Spodumene
Spratt, Thomas A. B.
Stalactites
Stannite
Staurolite
Steno, Nicolaus
Stephanite
Stibnite
Stilbite
Stoliczka, Ferdinand
Stone
Stoppani, Antonio
Stratigraphy
Strickland, Hugh E.
Strontianite
Studer, Bernhard
Suess, Edward
Sunstone
Syenite
Sylvanite
Sylvite
Symonds, William S.
Szabó von Szentmiklos
Tachylytes
Talc
Tate, Ralph
Tchihatcheff, P. A. de
Tertiary
Tetradymite
Tetrahedrite
Theralite
Thorianite
Thorite
Tonalite
Topaz
Torbernite
Torell, Otto Martin
Torridonian
Tourmaline
Trachyte
Trass
Tremolite
Triassic System
Tridymite
Trimmer, Joshua
Tuff
Turquoise
Vanadinite
Variolite
Variscite
Veins
Verneuil, P. E. P. de
Vesuvianite
Vivianite
Vogt, Karl C.
Volcano
Waagen, W. H.
Wachsmuth, Charles
Wad
Walcott, Charles D.
Waltershausen
Wavellite
Wealden
Webster, Thomas
Wenlock Group
Werner, A. G.
Whiteaves, J. F.
Whitney, J. D.
Willemite
Witherite
Wolframite
Wollastonite
Wood, S. V.
Woodward, John
Woodward, Samuel
Woolwich-and-Reading Beds
Wright, Thomas
Wulfenite
Yoredale Series
Zoelites
Zincite
Zircon
Zirkel, Ferdinand
Zittel, Karl A. von
Zoisite