THE SURFACE OF THE GLOBE. 33 



which these layers themselves have undergone. There are indeed 

 considerable portions of these primitive layers exposed, although in 

 situations even lower than those of secondary layers ; if they had not 

 been exposed by subsequent convulsions, the latter would have con- 

 cealed them. Vast and various blocks of primitive substances are 

 found scattered, in particular countries, over the secondary layers, 

 separated by deep vallies; or even arms of the sea, from the- summits 

 or crests whence they must have come. They have been either 

 thrown there by eruption, or the depths which would have arrested 

 their progress did not exist at the period of their removal, or else the 

 fury of the waters which conveyed them there exceeded in violence 

 anything that we can imagine from our own experience * 



Here then is a combination of facts, a series of epochs anterior to 

 the present, the order of which ean be infallibly verified, although the 

 period of their intervals cannot be precisely defined. They are so 

 many points which serve as rules and directions in the ancient 

 chronology. 



Examination of the Causes which operate at present on the Surface 



of the Globe. 

 Let us now examine what is at present operating on the habitable 



* The voyages of Saussure and Deluc present us with a multitude of these facts ; 

 and these geologists have judged that they could only have heen effected by sur- 

 prising eruptions. M. M. de Buch and Escher have employed themselves on this 

 subject more recently. The memoir of the latter, inserted in ' La Nouvelle Alpina 

 de Stein-Muller,' vol.i, details the wbole in a remarkable manner, of which this is 

 the summary : — Those blocks which are scattered in the lowlands of Switzerland or 

 Lombardy came from the Alps, and have descended along the vallies. They are 

 in all parts and of all dimensions, even to fifty thousand cubic feet, in the great ex- 

 tent which separate the Alps from Mount Jura, and they are found on the declivities 

 of Jura which front the Alps to the height of four thousand feet above the level of 

 the sea ; they are on the surface or in the superficial layers of remains, but not in 

 those of freestone, or pudding stone, which occupy nearly the whole space in ques- 

 tion ; they are sometimes found perfectly isolated, sometimes in masses : the height 

 of their situation has no relation to the size, only that the smaller appear sometimes 

 a little worn, but the larger not all so. Those which form the bed of any river are 

 found, on examination, of the same kind as the mountains of the peaks or sides of 

 the high vallies, whence arise the sources of these rivers ; we observe them in the 

 vallies, and they are found accumulated especially in those places where they are nar- 

 rowest ; they have passed over defiles when they have not exceeded four thousand 

 feet ; and^then we see them on the other sides of the summits in the cantons between 

 the Alps and Jura, and on Jura itself ; it is opposite the openings of the vallies of 

 the Alps that they are seen of greatest size and in greatest numbers ; those in the 

 space between are carried less high ; in the chains of Jura, the most distant from 

 the Alps, they are only found in places exactly opposite to the openings of the nearest 

 chains. 



From these facts, the author draws this conclusion, that the conveyance of the 

 blocks took place subsequently to the deposites of freestone and pudding stone : that 

 it was probably effected at the last revolution of this globe. He compares their re- 

 moval to that which still occurs amongst the torrents ; but the objection of the vast- 

 ness of the blocks, and that of the depth of the intervening vallies, seem to us to 

 offer a powerful opposition to this part of his hypothesis. 



VOL. I. F 



