The Glacial Theory. 



141 



cannot with precision be referred to determinate centres. Blocks are 

 seen extending from one mountain-chain to another, across consider- 

 able depressions of the surface ; the accumulations of blocks trans- 

 ported from one place to another are no longer arranged in linear 

 continuous series as in the valleys, where they form mounds or ram- 

 parts, which are moraines properly so called, but they are dispersed 

 irregularly over the surface ; the nature of the rocks mixed together 

 in these accumulations no longer indicates an origin so limited as that 

 of those moraines even which are at the mouths of the valleys. The 

 dispersion of these blocks in different countries has not hitherto been 

 described with sufficient care, and more particularly the erratic an- 

 gular blocks with a rough surface have not been sufficiently distin- 

 guished from those that are rounded, polished, and scratched. There 

 are, however, very important differences in this respect. In Swit- 

 zerland, for example, we nowhere meet with large blocks, whe- 

 ther angular or round, whose surface is rubbed, polished, and 

 scratched with rectilinear striae, at great distances from their origin. 

 Whatever may have been the cause of the transport of the erratic 

 blocks of the Alps and the Jura, it always happens that the great 

 mass of the large blocks have arrived there with rough surfaces and 

 well marked angles, and that the pebbles of smaller dimensions alone 

 are worn, rounded, polished, and scratched with rectilinear striae. 

 We may easily convince ourselves of this fact by walking along any 

 part of the Jura chain. Another peculiarity worthy of attention is, 

 that with us the large angular blocks generally repose on the more 

 or less considerable masses of rounded and polished pebbles, and that 

 these latter often pass into a fine sand or a clayey paste, which 

 covers directly the polished surfaces of the solid rocks wherever the 

 pluvial water, the melting snow, and the torrents resulting from it, 

 have not caused them to disappear. This arrangement is very well 

 seen in the environs of Neuchatel. 



The state of matters is by no means the same in Britain, and more 

 particularly in Scotland. There the erratic blocks of all dimensions 

 are, in certain circumstances, rounded, perfectly smooth and polished, 

 and even scratched with rectilinear striae, like the polished solid rocks 

 — a feature only observed in the smaller pebbles in Switzerland. It is 

 not to be understood that there are no large angular blocks in England 



