Principles of Geology Part 95

ACROGENS. One of five cla.s.ses into which all plants may be divided; it includes such flowerless ones as grow from the top only, and whose stems consequently do not increase materially in bulk, as Mosses, Ferns, Lycopodiums, Equisetums, &c. The trunk of a tree fern is a good example. They are also called Acrobrya. _Etym._, a????, _acron_, the top, and ?e?es??, _genesis_, increase.

ADIPOCIRE. A substance apparently intermediate between fat and wax, into which dead animal matter is converted when buried in the earth, and in a certain stage of decomposition. _Etym._, _adeps_, fat, and _cera_, wax.

ALBITE. See "Felspar."

ALEMBIO. An apparatus for distilling.

ALGae. An order or division of the cryptogamic cla.s.s of plants. The whole of the sea-weeds are comprehended under this division, and the application of the term in this work is to marine plants. _Etym._, _alga_, sea-weed.

ALLUVIAL. The adjective of alluvium, which see.

ALLUVION. Synonymous with alluvium, which see.

ALLUVIUM. Earth, sand, gravel, stones, and other transported matter which has been washed away and thrown down by rivers, floods, or other causes upon land not _permanently_ submerged beneath the waters of lakes or seas. _Etym._, _alluo_, to wash upon, or _alluvio_, an inundation.

ALUM-STONE, ALUMEN, ALUMINOUS. Alum is the base of pure clay, and strata of clay are often met with containing much iron pyrites. When the latter substance decomposes, sulphuric acid is produced, which unites with the aluminous earth of the clay to form sulphate of alumine, or common alum. Where manufactories are established for obtaining the alum, the indurated beds of clay employed are called Alum-stone.

AMMONITE. An extinct and very numerous genus of the order of molluscous animals called Cephalopoda, allied to the modern genus Nautilus, which inhabited a chambered sh.e.l.l, curved like a coiled snake. Species of it are found in all geological periods of the secondary strata; but they have not been seen in the tertiary beds.

They are named from their resemblance to the horns on the statues of Jupiter Ammon.

AMORPHOUS. Bodies devoid of regular form. _Etym._, a, _a_, without, and ??f?, _morphe_, form.

AMYGDALOID. One of the forms of the Trap-rocks, in which agates and simple minerals appear to be scattered like almonds in a cake.

_Etym._, a??da?a, _amygdala_, an almond.

a.n.a.lCIME. A simple mineral of the Zeolite family, also called Cubizite, of frequent occurrence in the Trap-rocks.

a.n.a.lOGUE. A body that resembles or corresponds with another body. A recent sh.e.l.l of the same species as a fossil sh.e.l.l is the a.n.a.logue of the latter.

ANGOIOSPERMS. A term applied to all flowering plants in which the ovules are inclosed in an ovary, and the seeds in a pericarp or covering, as in all flowering plants except those mentioned under gymnosperms and gymnogens, which see. _Etym._, a????, _angos_, a vessel, and pe?a, a seed.

ANOPLOTHERIUM. A fossil extinct quadruped belonging to the order Pachydermata, resembling a pig. It has received its name because the animal must have been singularly wanting in means of defence, from the form of its teeth and the absence of claws, hoofs, and horns.

_Etym._, a??p???, _anoplos_, unarmed, and ??????, _therion_, a wild beast.

ANTAGONIST POWER. Two powers in nature, the action of the one counteracting that of the other, by which a kind of equilibrium or balance is maintained, and the destructive effect prevented that would be produced by one operating without a check.

ANTENNae. The articulated horns with which the heads of insects are invariably furnished.

ANTHRACITE. A s.h.i.+ning substance like black-lead; a species of mineral charcoal. _Etym._, a???a?, _anthrax_, coal.

ANTHRACOTHERIUM. A name given to an extinct quadruped, supposed to belong to the Pachydermata, the bones of which were first found in lignite and coal of the tertiary strata. _Etym._, a???a?, _anthrax_, coal, and ??????, _therion_, wild beast.

ANTHROPOMORPHOUS. Having a form resembling the human. _Etym._, a????p??, _anthropos_, a man, and ??f?, _morphe_, form.

ANTISEPTIC. Substances which prevent corruption in animal and vegetable matter, as common salt does, are said to be antiseptic.

_Etym._, a?t?, _anti_, against, and s?p?, _sepo_, to putrefy.

ARENACEOUS. Sandy. _Etym._, _arena_, sand.

ARGILLACEOUS. Clayey, composed of clay. _Etym._, _argilla_, clay.

ARRAGONITE. A simple mineral, a variety of carbonate of lime, so called from having been first found in Aragon in Spain.

ATOLLS. Coral islands of an annular form, or consisting of a circular strip or ring of coral surrounding a central lagoon.

AUGITE. A simple mineral of a dark green, or black color, which forms a const.i.tuent part of many varieties of volcanic rocks. Name applied by Pliny to a particular mineral, from the Greek a???, _auge_, l.u.s.tre.

AVALANCHES. Ma.s.ses of snow which, being detached from great heights in the Alps, acquire enormous bulk by fresh acc.u.mulations as they descend; and when they fall into the valleys below often cause great destruction. They are also called _lavanges_ and _lavanches_ in the dialects of Switzerland.

BASALT. One of the most common varieties of the Trap-rocks. It is a dark green or black stone, composed of augite and felspar, very compact in texture, and of considerable hardness, often found in regular pillars of three or more sides called basaltic columns.

Remarkable examples of this kind are seen at the Giant's Causeway, in Ireland, and at Fingal's Cave, in Staffa, one of the Hebrides.

The term is used by Pliny, and is said to come from _basal_, an aethiopian word signifying iron. The rock often contains much iron.

"BASIN" of Paris, "BASIN" of London. Deposits lying in a hollow or trough, formed of older rocks; sometimes used in geology almost synonymously with "formations," to express the deposits lying in a certain cavity or depression in older rocks.

BELEMNITE. An extinct genus of the order of molluscous animals called Cephalopoda, having a long, straight, and chambered conical sh.e.l.l. _Etym._, e?e???, _belemnon_, a dart.

BITUMEN. Mineral pitch, of which the tar-like substance which is often seen to ooze out of the Newcastle coal when on the fire, and which makes it cake, is a good example. _Etym._, _bitumen_, pitch.

BITUMINOUS SHALE. An argillaceous shale, much impregnated with bitumen, which is very common in the Coal Measures.

BLENDE. A metallic ore, a compound of the metal zinc with sulphur.

It is often found in brown s.h.i.+ning crystals; hence its name among the German miners, from the word _blenden_, to dazzle.

BLUFFS. High banks presenting a precipitous front to the sea or a river. A term used in the United States of North America.

BOTRYOIDAL. Resembling a bunch of Grapes. _Etym._, ?t???, _botrys_, a bunch of grapes, and e?d??, _eidos_, form.

BOULDERS. A provincial term for large rounded blocks of stone lying on the surface of the ground, or sometimes imbedded in loose soil, different in composition from the rocks in their vicinity, and which have been therefore transported from a distance.

BRECCIA. A rock composed of angular fragments connected together by lime or other mineral substance. An Italian term.

CALC SINTER. A German name for the deposits from springs holding carbonate of lime in solution--petrifying springs. _Etym._, _kalk_, lime, and _sintern_, to drop.

CALCAIRE GROSSIER. An extensive stratum, or rather series of strata, found in the Paris Basin, belonging to the Eocene tertiary period.

_Etym._, _calcaire_, limestone, and _grossier_, coa.r.s.e.

CALCAREOUS ROCK. Limestone. _Etym._, _calx_, lime.

CALCAREOUS SPAR. Crystallized carbonate of lime.

CARBON. An undecomposed inflammable substance, one of the simple elementary bodies. Charcoal is almost entirely composed of it.

_Etym._, _carbo_, coal.

CARBONATE OF LIME. Lime combines with great avidity with carbonic acid, a gaseous acid only obtained fluid when united with water,--and all combinations of it with other substances are called _Carbonates_. All limestones are carbonates of lime, and quicklime is obtained by driving off the carbonic acid by heat.

CARBONATED SPRINGS. Springs of water, containing carbonic acid gas.