XXX PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



proceeded, is very approximately coincident with the directions of 

 the striae along the same line. A similar law holds with respect to 

 other blocks which can be traced to their respective original sites. 

 It may therefore be asserted as a law in this region, that the general 

 or mean directions of transport are approximately coincident with 

 the directions of the striae. 



If we refer to the analogous phsenomena of Scotland, we find the 

 general law which characterizes them is exactly that above enun- 

 ciated ; but when we examine the details of this latter case, it appears 

 that the general law is only approximately true, for the law of di- 

 vergency does not accurately hold with reference to one general 

 centre, but with reference to a number of particular centres. This I 

 have proved in the memoir on the granitic blocks of the South High- 

 lands of Scotland, inserted in the last Number of our Journal, with 

 respect to the granitic nucleus of Ben Cruachan, and that of the 

 group of mountains immediately on the west of the northern part of 

 Ben Lomond. To complete our knowledge of the Scandinavian striae, 

 it is necessary to ascertain whether such particular centres are found 

 also in the mountainous district of that region. This is one of the 

 points to which I would especially direct the attention of observers. 



So long as we restrict ourselves to the Highlands of Scotland, we 

 easily recognize the circumstances which have determined the parti- 

 cular directions which the blocks have taken. They have followed 

 the valleys which must have existed previously to their dispersion, 

 wherever those valleys were sufficiently defined to govern the opera- 

 tion of the transporting agents. And this would appear also to have 

 been the case in the more immediate vicinity of the Scandinavian 

 chain. "We may consider the striae, then, to represent the general 

 direction of transport, and we find them, as laid down on the map of 

 M. Sefstrom, exactly coinciding with the directions of the river- 

 valleys descending from the mountains. So perfect a coincidence 

 leaves little doubt of the influence of the pre-existing valleys in 

 the direction of transport. But as we recede from the mountain- 

 ous district, even in the limited space between the Highlands and 

 the eastern coast of Scotland, the configuration of the country no 

 longer presents, in many parts, those determinate features which 

 would necessarily give a definite direction to the masses transported 

 across it ; and how much more is this true with respect to the wide- 

 spread plains of northern Russia and of northern Germany ! And 

 yet, in all these cases, the directions of the striae obey with wonder- 

 ful regularity the same law of divergency as those nearer to the cen- 

 tral chain. We may easily understand how glaciers would descend 

 down the mountain-valleys, and, after reaching the level of the sea, 

 how the ice would float along the submarine continuations of the 

 same valleys, leaving striae along them, without the power of de- 

 viating from a fixed direction ; but after having escaped from the 

 valleys on the immediate flanks of the central mountains, what cause 

 can have operated to drive forward through the more open sea these 

 masses of ice, or the masses of other materials which may have been 

 the striating and grooving agents, in the same continuous direction. 



