1846.] MURCHISON ON THE SCANDINAVIAN DRIFT. 371 



the traveller (after passing innumerable hillocks of rock whose 

 northern sides are rounded and worn) is suddenly immersed in a 

 chaos of angular blocks, some of them of a gigantic size. Through 

 these the road meanders amid the most profuse vegetation of aspen, 

 birch and fir trees that rise out from the crevices between the frag- 

 ments. Seeing no proof that these millions of angular blocks were 

 deposited on osar, like those before adverted to, and perceiving 

 that they were nearly all composed of similar granitic gneiss, we 

 began to think, particularly from the distinct linear arrangements 

 they afforded, that they must be simply fragments in situ, the sub- 

 jacent or parent rock being hidden by their great profusion in these 

 low eminences ; but we were once more thrown into doubt by per- 

 ceiving that as soon as we emerged from this forest near Hiirfsta, 

 true sandy osar, also trending from N.N.W. to S.S.E. and parallel 

 to the angular bloTik ridge, presented themselves, and were capped 

 by angular erratics. We further saw, that as the country opened, 

 the broader depressions and valleys were invariably exempt from 

 the large angular blocks, but that wherever an elevation occurred, 

 sometimes not exceeding fifteen or twenty feet above the lower levels, 

 it was covered with angular blocks of all sizes, accumulated in this 

 instance upon a substratum of clay. On entering Dalecarlia, how- 

 ever, we passed a true granitic plateau, which was covered in parts 

 with angular blocks, the mass of which, exactly like those above 

 alluded to, forcibly reminded us, by its superficial aspect, of the 

 broken volcanic "cherres" of Auvergne; and thus we had no doubt 

 that whilst the osar were capped with such materials which had been 

 transported from other localities, other linear ridges, particularly 

 those on which the whole surface is covered by rock, nearly all of 

 one kind, were indeed fragments in situ, the subjacent rock from 

 whence they had been broken off appearing here and there. This 

 view was completely confirmed when we passed over the low hills 

 to the south of Fahlun, where the angular blocks and the underlying 

 parent gneiss are clearly exposed. Without such an explanation, 

 the sea of wild and irregular fragments dotted over the plain im- 

 mediately south of the copper-mines of Fahlun would indeed seem 

 marvellous, since in that district the trees having been cut off or 

 withered by pestiferous sulphureous fumes, the tract might repre- 

 sent a return of chaos, or a period when life was extinguished upon 

 the surface of the globe. 



In Dalecarlia however, as in the central and southern regions, the 

 distinction between the erratic blocks and the water-worn osar are 

 strikingly displayed. This is well-seen in a long line of osar sepa- 

 rating the lakes between Jordbro and Hrusdeek on the river Dal 

 Elf, near the southern frontier of Dalecarlia, where transv(!rse or 

 east and west sections exhibit in one place finely laminated sands 

 covered with coarse worn boulders and gravel, and these again by 

 angular erratics, each from ten to twelve feet high. In this tract, as 

 represented in the accompanying diagram (fig. 15), the snuiU houses 

 of the Swedish peasants are seen built ui)on an os between lakes, 

 and the road is as it were half-buried under the great erratic l)locks. 



