MOUNTAINS OF JURA. 191 



Masses of conglomerate also occur upon the Jura 

 mountains, of the same varieties as those which occur in 

 fixed rocks at Valorsine, and other places in the vicinity 

 of Mont Blanc. Blocks of greywacke and of black 

 limestone are amongst the rolled blocks, and these also 

 can be traced as fixed rocks in the Vallais. 



Many phenomena of the same description are to be 

 observed in Scotland. It would be an interesting and 

 valuable addition to the geology of Great Britain, to 

 have a map constructed representing the distribution of 

 these blocks over the whole surface of the island. 



NOTE E. 9. p. 46. 



Salisbury Craigs. 



The front of Salisbury craigs, near Edinburgh, affords 

 a fine example of the natural chronometer, described in 

 the text. The acclivity is covered with loose masses 

 that have fallen from the hill itself; and the quantity of 

 debris is in proportion to the time which has elapsed since 

 the waters of the ocean formerly covered the neighbour- 

 ing country. If a vast period of time had elapsed since 

 the surface of the earth had assumed its present aspect, it 

 is evident, that long ere now the whole of this hill would 

 have been enveloped in its own debris. We have here, 

 then, a proof of the comparatively short period since the 

 waters left the surface of the globe, a period not ex- 

 ceeding a few thousand years. 



* 



NOTE F. 10. p. 46. 



On the diluvial Land of the Danish Islands in the Baltic, 

 and on the Coast of Sleswick. 



In this section, Cuvier gives a clear and distinct ac- 

 count of several kinds of alluvial formations. M. De 

 Luc, in the first volume of his Geological Travels, de- 



