44 LAl^D HAS BEEN EAISED, [Ch. V. 



CHAPTER V. 



ELEVATION OF STRATA ABOVE THE SEA HORIZONTAL AND INCLINED 



STRATIFICATION. 



"Why the position of marine strata, above the level of the sea, should be referred 

 to the rising up of the land, not to the going down of the sea — Upheaval of 

 extensive masses of horizontal strata — Inclined and vertical stratification — An- 

 ticlinal and synclinal lines — Bent strata in east of Scotland — Theory of folding 

 by lateral movement — Creeps — Dip and strike — Structure of the Jura — Vari- 

 ous forms of outcrop — Rocks broken by flexure — Inverted position of disturbed 

 strata — Unconformable stratification — Hutton and Play fair on the same — Frac- 

 tures of strata — Polished surfaces — Faults — Appearance of repeated alterna- 

 tions produced by them — Origin of great faults. 



Land has been raised^ not the sea loivered. — It lias been already stated 

 that the aqueous rocks containing marine fossils extend over wide conti- 

 nental tracts, and are seen in mountain chains rising to great heights 

 above the level of the sea (p. 4). Hence it follows, that what is now dry- 

 land was once under water. But if we admit this conclusion, we must 

 Imagine, either that there has been a general lowering of the waters of the 

 ocean, or that the solid rocks, once covered by water, have been raised 

 up bodily out of the sea, and have thus become dry land. The earher 

 geologists, finding themselves reduced to this alternative, embraced the 

 former opinion, assuming that the ocean was originally universal, and 

 had gradually sunk down to its actual level, so that the present islands 

 and continents were left dry. It seemed to them far easier to conceive 

 that the water had gone down, than that solid land had risen upwards 

 into its present position. It was, however, impossible to invent any sat- 

 isfactory hypothesis to explain the disappearance of so enormous a body 

 of water throughout the globe, it being necessary to infer that the ocean 

 had once stood at whatever heio;ht marine shells mio-ht be detected. It 

 moreover appeared clear, as the science of Geology advanced, that certain 

 spaces on the globe had been alternately sea, then land, then estuary, 

 then sea again, and, lastly, once more habitable land, having remained 

 in each of these states for considerable periods. In order to account for 

 such phenomena, without admitting any movement of the land itself, we 

 are required to imagine several retreats and returns of the ocean ; and 

 even then our theory applies merely to cases where the marine strata 

 composing the dry land are horizontal, leaving unexplained those more 

 common instances where strata are inclined, curved, or placed on their 

 edges, and evidently not in the position in which they were first 

 deposited. 



Geologists, therefore, were at last compelled to have recourse to the 

 other alternative, namely, the doctrine that the solid land has been re- 

 peatedly moved upwards or downwards, so as permanently to change ita 



