8 On Drift. 



region. This is one of the points to which I would especially di- 

 rect the attention of observers. 



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

 we easily recognise the circumstances which have determined the 

 particular directions which the blocks have taken. They have fol- 

 lowed the valleys which must have existed previously to their dis- 

 persion, wherever those valleys were sufficiently defined to govern 

 the operation 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 repre- 

 sent the general direction of transport, and we find them, as laid 

 down on the map of M. Sefstrom, exactly coinciding with the di- 

 rections 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 mountainous 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 determin- 

 ate 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 wonderful regularity, the same law of diver- 

 gency as those nearer to the central chain. We may easily under- 

 stand how glaciers would descend down the mountain- valleys, and, 

 after reaching the level of the sea, how the ice would float along 

 the submarine continuation of the same valleys, leaving striae along 

 them, without the power of deviating 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 for- 

 ward through the more open sea these masses of ice, or the masses 

 of other materials which may have been the striating and groov- 

 ing agents, in the same continuous direction, and with such a force 

 and determination that they could not be turned aside by the nu- 

 merous projecting bosses of solid rock on which they have so ef- 

 fectively engraved the record of their transit % According to the 

 hypothesis which we shall probably all be ready to adopt, the more 

 elevated parts of the Scandinavian range must, at the period we 

 are referring to, have formed an island, round which ordinary 

 ocean-currents may possibly have passed in any direction ; but the 

 notion of such ordinary currents diverging in such various direc- 

 tions radiating from the central portion of this Scandinavian island, 

 can only be spoken of as an absurdity. And yet no other force 

 has ever been suggested, or is perhaps conceivable, except that of 

 currents, as efficient to drive large icebergs or a mass of looser 

 materials in a determinate direction, in defiance of numerous op- 

 posing obstacles. It appears to me, therefore, that we are driven 

 to the alternative either of rejecting all theory on the subject, or 



