310 Dv Ch. Martins ofi the Marks of Glacial Action 



picked up by any observer. The action of the waves po- 

 lishes them, but never striates them. But, besides all this, 

 if, at the foot of the glacier of Grindelwald, you examine 

 the pebbles which form its terminal moraine, you will find 

 that they are all striated. These same pebbles, how- 

 ever, ere long, fall into the torrent which escapes from the 

 glacier, where, rolling one upon another, they speedily lose 

 all their striae. Hence it becomes impossible to find in the 

 torrent a single striated pebble at the distance of two hun- 

 dred fathoms from the glacier. My friend, Mons. Ed. 

 Colomb, has made observations precisely similar in the tor- 

 rent of the Thur, which runs through the ancient moraine 

 of Wesserling in the Vosges, which is very much composed 

 of striated pebbles. On one occasion he offered a reward to 

 any workman in the manufactory who would bring him a 

 striated pebble procured from the torrent at the distance of 

 two hundred fathoms from the moraine ; but the reward was 

 never challenged. Supposing, then, with Mr Miller, that 

 the streaked pebbles were marked by the passage of a floating 

 ice-block, these pebbles having been subsequently carried 

 away, and rolled by the current of no great depth, which 

 he invokes, and buffeted by the waves, all the striae would 

 speedily have been effaced, and the boulder-clay would not 

 have contained a single streaked pebble. 



As to the predominance of the longitudinal over the trans- 

 verse striae, it exists to a certain extent in the striated boul- 

 ders or pebbles of Scotland, as in those of the existing glaciers; 

 and it is the necessary consequence of this mode of formation. 

 In fact, all the pebbles which are placed between the glacier 

 and the overlying rock are by it drawn along in its insen- 

 sible progression. Compressed between the ice and the 

 rock, they are rudely fretted, worn, and striated ; whilst, at 

 the same time, it is plain that the pebbles will have a natural 

 tendency so to arrange themselves that their longitudinal 

 axis will be in the direction of the progression of the glacier. 

 Hence, then, the predominance of the longitudinal striae. 

 At the same time, I would remark that I do not attach any 

 considerable importance to what Mr Miller has said con- 

 cerning the direction of striae upon the pebbles. Even the 



