Annual Report on the Geological Survey of Pennsylvania, Volume 2

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Page 88 - Trap family, usually fissile. It is sonorous when struck with a hammer, whence its name. Coal Formation. — This term is generally understood to mean the same as the Coal Measures. There are, however,
Page 89 - FAULT, in the language of miners, is the sudden interruption of the continuity of strata in the same plane, accompanied by a crack or fissure varying in width from a mere line to several feet, which is generally filled with broken stone, clay, &c., and such a displacement that the separated portions of the once continuous strata occupy different levels.
Page 90 - QUA-QUA-VERSAL DIP. The dip of beds to all points of the compass around a centre, as in the case of beds of lava round the crater of a volcano. Etym., yuA-qud versum, on every side.
Page 89 - GNEISS. A stratified primary rock, composed of the same materials as granite, but having usually a larger proportion of mica, and a laminated texture. The word is a German miner's term.
Page 90 - OXIDE. The combination of a metal with oxygen; rust is oxide of iron. OXYGEN. One of the constituent parts of the air of the atmosphere ; that part which supports life. For a further explanation of the word, consult elementary works on chemistry.
Page 91 - Low hills which skirt or lie at the foot of the great chain of the Apennines in Italy. The term Subapennine is applied geologically to a series of strata of the Older Pliocene period. SYENITE. A kind of granite, so called because it was...
Page 88 - Conglomerate or Puddingstone. — Rounded water-worn fragments of rock or pebbles, cemented together by another mineral substance, which may be of a siliceous, calcareous, or argillaceous nature.
Page 88 - ... lines, and which is invariably alluvial, was first called, in the case of the Nile, a delta from its resemblance to the letter of the Greek alphabet which goes by that name A. Geologists apply the term to alluvial land formed by a river at its mouth, without reference to its precise shape. DENUDATION. The carrying away by the action of running water of a portion of the solid materials of the land, by which inferior rocks are laid bare. Etym., denudo, to lay bare.
Page 88 - 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 quick lime is obtained by driving off the carbonic acid by heat.
Page 87 - 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.

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