TABULAR VIEW OF MINERAL STRATA. 131 gneiss, and mica-slate, 6 or 7 inches in diameter. That stones of the size of a man's head, previously rounded by attrition, should build themselves up in a perpendicular wall, and stand steadily thus, till fine particles of hydraulic cement, should have time to envelop and fix them in their upright posture, is an absurd and impossible supposition. It is therefore demonstrable that these puddingstone strata were formed in horizontal, or slightly inclined beds, and erected after their accretion. Such effects would be produced on the convulsive emergence of the pebbly banks out of the primeval ocean, either at the deluge, or some preceding catastrophe. There are mountains 10,000 feet high in the Alps, formed of firmly conglomerated pebbles. It will be proper to introduce here, a general view of the order in which the mineral strata were progressively built up during the antediluvian period under that ocean; "whose bed laid dry by the last great revolution, now forms all the countries at present inhabited.”* TABULAR VIEW OF MINERAL STRATA. The granites, porphyries, sienites, hornblende, and hypersthene rocks, with greenstones, and basalts, being unstratified erupted rocks, occur in many different and irregular positions among the successive strata. CLASS I. PRIMITIVE OR INFERIOR Rocks. Order I.-Gneiss. Concomitants. Hornblende rocks. Quartz rock. • Cuvier.-Ossemens Fossiles.-Discours Preliminaire, p. 135. Order IV.-Second Tertiary Limestone. Marls, sand. Order V.-Last fresh water deposit. Buhr stone. Marls, Limestones of In all these strata, there is usually a repetition of beds of similar composition; that is, of the siliceous, argillaceous, and calcareous, with a texture becoming progressively less compact and crystalline, as they ascend in the scale of superposition. Such repetitions have been called formation suites. Thus we may have 50 beds of coal, alternating with an equal number of sandstone and shale, and 50 beds of chalk alternating with as many of flint, constituting the coal and chalk formations. When viewed in this aspect, the almost infinite variety of the strata becomes systematised and simplified into a manageable compass. The preceding table has been compiled partly from M. Boue's table of rocks, and partly from that of Messrs. Conybeare and Phillips. The following is by the Rev. Dr. Buckland. GEOLOGICAL EQUIVALENTS. A COMPARATIVE TABLE OF THE ENGLISH AND CONTINENTAL Formations of England. FORMATIONS. Passing into fine greywacke- Slate of Llandrindod near Builth, containing trilobites. Formations of the Continent. Abundant on the Continent. Slate of Angers in France, containing trilobites. Conglomerate of Killarney and Conglomerate of Valorsine. St. David's. 2. Transition Limestone. 2. Transition limestone occurs Beds of limestone occurring sub- subordinately in greywacke. ordinately in the upper region 1 Thin beds of it at Coblentz on of the greywacke formation ; the Rhine. Dudley, Wenlock edge, Lud- In Bohemia, near Prague, Tarenlow, Longhope, Llandilo. taise in Savoy, Banks of Rhine In its upper members composed of loose beds of red sandstone, red marle and congloIn its lower regions passing insensibly into com merate. 1. Variety of greywacke of Werner. Seldom appearing on the continent, occurs at Huy on the Meuse below Namur, where it lies under the mountain limestone. pact greywacke; abundant The Valorsine puddingstone is 4. New red Conglomerate. and of Omalins D'Halloy. Banks of the Meuse from Namur to Liege; is of rare occurrence on the continent. 3. Independent coal formation of Namur, Saare Brooke, Saint 4. Old red sandstone of Werner ; Exeter encircling the base of Base of Thuringerwald.; Lugano, in Italy. |