302 TRANSPORTATION OF ALPINE ERRATICS, CHAP. xv. 



is quite irreconcilable with the supposition of tlie scattered 

 blocks having been dispersed by floating ice when Switzerland 

 was submerged. 



As ojiposed to the latter hypothesis, I may also state that 

 nowhere as yet have any marine shells or other fossils than 

 those of a terrestrial character, such as the bones of the 

 mammoth, and a few other mammalia, and some coniferous 

 wood, been detected in those drifts, though they are often 

 many hundreds of feet in thickness. 



A glance at M. Morlot's map, above alluded to,* will show 

 that the two largest areas, indicated by a single color, are 

 those over which the Rhone and the Ehine are supposed 

 to have spread out in ancient times their enormous moraines. 

 One of these only, that of the Ehone, has been exhibited 

 in our diagram, fig. 42, p. 299. The distinct character 

 of the drift in the two cases is such as it would be if 

 two colossal glaciers should now come down from the higher 

 Alps through the valleys traversed by those rivers, leaving 

 their moraines in the low countr3\ Tlie space occupied 

 by the glacial drift of the Ehine is equal in dimensions, 

 or rather exceeds, that of the Ehone, and its course is not 

 interfered with in the least degree by the Lake of Constance, 

 forty-five miles long, any more than is the dispersion of the 

 erratics of the Ehone, by the Lake of Geneva, about fifty 

 miles in length. The angular and other blocks have in both 

 instances travelled on precisely as if those lakes had no 

 existence, or as if, which was no doubt the case, they had been 

 filled with solid ice. 



During my last visit to Switzerland in 1857, I made excur- 

 sions, in company with several distinguished geologists, for 

 the sake of testing the relative merits of the two rival theo- 

 ries above referred to, and examined parts of the Jura above 



*• See map, Geological Quarterlj' Journal, vol. xviii. pi. 18, p. 185. 



