52 



VERTICAL MOUNTAIN BEDS. 



the southern Pacific Ocean, are steepest on their western side. In 

 ranges of mountains that form the boundaries of lakes or of extensive 

 vales, through which large rivers flow, the mountains nearest to the 

 rivers h^ve the steepest declivities. The largest rivers have their ori- 

 gin from the sides of mountains which are most inclined to the hori- 

 zon, and most remote from the sea. 



The beds or strata of very lofty mountains are, generally, much 

 inclined, and are sometimes nearly vertical. Among these highly 

 inclined beds, we, not unfreqently, observe beds of limestone con- 

 taining marine shells, which must have been originally deposited at 

 the bottom of the ocean. In some instances we meet with vertical 

 strata containing rounded pebbles and water-worn fragments of other 

 rocks ; these must also have been originally deposited on a surface 

 nearly horizontal : we are therefore certain, that the present vertical 

 position of these strata is not their original one, and we hence also 

 learn, that all the strata associated with them in the same mountain, 

 and having the same inclination, were raised together. We have 

 further proof that, before the epoch when this great revolution was 

 effected, all these beds w^ere covered by the seas then existing, and 

 it was under the ocean that the change of position took place. 



No person who reflects on the appearances presented in a moun- 

 tainous district can believe that the broken and elevated beds, the 

 peaked summits, the impending cliffs, and the immense fragments of 

 rock scattered in the valleys and adjacent countries, were, originally, 

 created and placed as we now observe them. 



The traveller, who, in crossing an extended desert, should meet 

 with the remains of some unknown temple, could not for a moment 

 doubt that the broken and prostrate columns, the mutilated arches, 

 the scattered capitals and inscriptions, had been removed, by some 

 devastating cause, from their original position ; nor, is the proof less 

 certain, that the rocky pavement of our globe has been broken, and 

 its parts, which were once united, widely separated from each other. 

 Some of the phenomena, observed in mountains, were produced by 

 the disturbing force which first elevated them ; others were subse- 

 quently effected, either by vast inundations, or by torrents, that have 

 torn away considerable portions of the softer beds, or by the more 

 gradual decomposition and disintegration produced by atmospheric 

 influence ; by the latter cause, the lofty and exposed peaks and es- 

 carpments of rocks are, constantly, wearing down. 



During the two summers I passed in the Alps, I was much struck 

 with the circumstance that all the great openings or passages over 

 these mountains, called Cols, were made by excavations in beds of 

 soft slate; and the fact I think admits of an easy explanation, but I 

 do not know that it has been before remarked by geologists. 



If we suppose a portion of the Alps to be represented, Plate 11. 

 Fig. 2. the dotted lines above the present surface will mark the sup- 

 posed original prolongation of the different beds, at the period when 



