354 



THEORY OF SIR JAMES HALL. 



valleys and cols in the softer beds and strata.* On the whole, the 

 theory of Sir Jannes Hall, affords perhaps the most satisfactory ex- 

 planatioi] of diluvian agency, that has yet been advanced. But 

 whatever difficulties may oppose the admission of this or any other 

 theory, the fact that the present continents have been subjected to 

 the action of a mighty rush of waters, seems confirmed by many 

 coincident phenomena. 



Granting the agency of a deluge, or a succession of deluges, there 

 are still phenomena left, that their action will not satisfactorily ex- 

 plain. In the midland counties of England, for instance, there are 

 beds of gravel, and fragments of rock, scattered over hills, that are 

 not only far distant from the rocks which have supplied the frag- 

 ments, but which are separated from them by deep valleys, over 

 which it is supposed that the fragments could not have been carried, 

 by any power of diluvian agency ; for in England, we have not the 

 glaciers to assist in their transportion. It has not been imagined, that 

 these fragments and beds of gravel, were deposited in their present 

 positions before the intervening valleys were scooped out. But any 

 subsequent deluge, sufficiently powerful to scoop out valleys must have 

 swept away the loose stones on the surface. The local elevation of 

 the surface would appear to offer a more satisfactory explanation. 

 The blocks of granite torn from Mont Blanc and the adjacent gran- 

 itic range, are scattered over the calcareous mountains, and in the 

 valleys of Savoy to the distance of 60 miles or more, from the pa- 

 rent rocks, and some of these blocks have traversed the Jura inta 

 France a distance of 100 miles. Two hypotheses have recently 

 been formed respecting them : the one, that these blocks of granite 

 were thrown from the mountains by an expulsive force at the period 

 of their elevation ; the other, that the calcareous mountains have 

 been subsequently raised with their load of granitic blocks upon 

 them. There are facts opposed to both of these theories, which ap- 

 pear to render them less satisfactory, than that of Sir James Hall 

 before stated. 



If any readers of this volume sliould visit Geneva, I would rec- 

 ommend them to devote a day to visiting the mountains called the 



* Those depressions in a range of mountains which offer the easiest aeeess ire 

 crossing from one valley to another, are in the Alps called Cols. I observed that 

 these cols were all in the softest beds ; and their formation admits of an easy ex- 

 planation by diluvial action. See Plate II. fig. 2. " A range of mountains, with 

 their beds highly elevated, is extended from a to dd. At cc the beds are of very, 

 soft slate or shale, which has been excavated so as to offer a passage over the 

 range, though the highest part is several thousand feet above the valley. Such i» 

 the Col de Balm above Chamouni. The beds probably extended, at the period of 

 their elevation, in the direction of the dotted lines. These cols could not be 

 formed by rivers, as very little water flows from them. The valley of Derwent, 

 (see Plate IV. fig. 1. between the hills 3 and 6,) was evidently formed by the ero- 

 sion of water, and not by the elevation of its sides ; as the beds oa each side are 

 the same. 



