on American Geology, 99 



conceive that the views which he is here urging are of the 

 highest importance to a correct understanding of the theory of 

 mountains. In the Canadian Naturalist for Dec. 1859, p. 425, 

 and in the Am. Jour. Sci. (2) xxx, 13*7 will be found an allusion 

 to the rival theories of upheaval and accumulation as ap- 

 plied to volcanic mountains, the discussion between which 

 we conceive to be settled in favour of the latter theory by 

 the reasonings and observations of Constant-Prevost, Scrope and 

 Lyell, A similar view applied to mountain chains like those of 

 the Alps, Pyrennees and AUeghanies, which are made up of 

 aqueous sediments, has been imposed upon the world by the autho- 

 rity of Humboldt, Von Buch and Elie de Beaumont, with scarcely 

 a protest. Buffon, it is true, when he explained the formation of 

 continents by the slow accumulation of detritus beneath the ocean, 

 conceived that the irregular action of the water would give rise to 

 great banks or ridges of sediments, which when raised above the 

 waves must assume the form of mountains; later, in 1832, we 

 find De Montlosier protesting against the elevation hypothesis 

 of Von Buch, and maintaining that the great mountain chains of 

 Europe are but the remnants of continental elevations which 

 have been cut away by denudation, and that the foldings and inver- 

 sions to be met v^rith in the structure of mountains are to be looked 

 upon only as local and accidental. 



In 1856 Mr. J. P. Lesley published a little volume entitled Coal 

 and its Topography^ (12 mo. pp. 224,) in the second part of which 

 he has, in a few brilliant and profound chapters, discussed the prin- 

 ciples of topographical science with the pen of a master. Here 

 he tells us that the mountain lies at the base of all topographical 

 geology. Continents are but congeries of mountains, or rather 

 the latter are but fragments of continents, separated by valleys 

 which represent the absence or removal of mountain land [p. 126] ; 

 and again "mountains terminate where the rocks thin out." 

 (p. 144.) 



The arrangement of the sedimentary strata of which mountains 

 are composed may be either horizontal, synclinal, anticlinal or 

 vertical, but from the greater action of diluvial forces upon anti- 

 ciinals in disturbed strata it results that great mountain chains are 

 generally synclinal in their structure, being in fact but fragments of 

 the upper portion of the earth's crust, lying in synclinals, and thus 

 preserved from the destruction and translation which have exposed 

 the lower strata in the anticlinal valleys, leaving the intermediate 



