On the Geological Arrangement of Ancient Strata. 3S1 



By a reference to the present condition of the ocean, too, sonae lighl^ 

 may be thrown on the mode of formation of the ancient strata. 



Thus, the upper portions of tte ocean are much agitated by cuirr^p,^, 

 and winds, while the lower portions remain comparatively calnj^ and ua- 

 disturbed. Gneiss, and the so-called primary schists, have evidently 

 l?een deposited at great depths where the water was still ; hence tbeir 

 iiegular lamination of structure, the minute and uniform comminution, 

 cjf their particles, and the still and placid manner i^ which these par^ 

 tides have been deposited. 



The transition series again marks a period of commotion and turbu- 

 lence, of rocks violently broken up into fragments, and of water-worn 

 pebbles, transported by currents, and accumulated in frequent layers of 

 varied conglomerates. The same observations will apply to the older 

 sandstones, while the calcareous mud of the lias points out the action of 

 currents, carrying the lighter detritus of rivers a considerable way intQ 

 the deeper sea. The oolites, again, are still more littoral ; and being 

 i^ormed nearer the genial surface of the water, afford a suitable bed for 

 those numerous species of melauise or infusory tribes, of which the 

 lipherical portions of this rock are, according to Ehi^enberg, supposed to 

 be chiefly composed, and which impart to it its peculiar character. 



The mountain limestone-beds were most probably reefs of corals 

 and encrinites rising nearly to the surface, but constituting a loca- 

 lity different in temperature and other respects, from the more 

 littoral oolite. Over these reefs, probably after they have suf- 

 fered depression, or some other change, the coal,-nieasures appear 

 IjQ have been deposited. These carboniferous beds, extending in 

 thickness from 2000 to 3000 feet, appear to be an exception to th^ 

 other marine strata in this respect, that there is a uniformity of fossils 

 throughout, the same organic remains appearing in the lower beds as in 

 the upper. This is to be accounted for from the circumstance that the 

 fossils are almost all vegetables which have grown on the earth's surface, 

 ^d muat^ have been successively transported into their position by flu- 

 yiatile currents from the land ; or, that part, if not the whole, may have 

 successively grown on the surface of the same locality on which they are 

 now found, and that this surface has repeatedly been submerged by the 

 gradual or periodical sinking of the strata below. A few fluviatile shells 

 and fishes are occasionally interspersed, as also, layers of marine lime- 

 stone, with fossils ; but the different spe<;ies dp not assume that succes- 

 sive position which the true marine-beds uniformly do, even in strq,ta of 

 the thickness of a few hundred fathoms. This exception of the coal 

 strata to the general law appears to afford an interesting test of the 

 mode of arrangement which is universally pi^ev^lent in all the other series. 

 The presence or absence of any one of the series of geological formations 

 may also be readily accounted for from the depth or shallowness of the 

 ancient ocean on aiiy giveji loc^ty. Thus, the prevalence of the oolitic 



