or liaised Beaches in Scotland, ^c. 287 



tween Dunkeld and Inveraray, I think it could not have 

 escaped me. One characteristic of the diluvium in the low 

 country is, that it contains far-travelled fragments of gneiss, 

 for instance, chlorite slate, and even granite, which, in con- 

 sequence of the long journey, are always much rounded; and 

 when portions of the diluvium are destroyed, these blocks are 

 found loose on the sea-shore, and in the channels of rivers. 

 In the long line from Taymouth to the Trossachs, I looked 

 carefully for blocks of granite, as the only ones to which a 

 distant origin could be safely assigned ; but among the my- 

 riads of fragments, large and small, in Glendochart, round the 

 head of Loch Earn, and along Lochs Lubnaig and Venachar 

 to the Trossachs, I did not discover a single piece even of one 

 foot diameter. I renewed my search at Inveraray with the 

 same want of success. Yet Inveraray is but fifteen miles from 

 the granites of Ben Cruachan, and Glendochart is about the 

 same distance from those of the Muir of Rannoch. We know 

 that masses of primary slate, from Perthshire or Argyle, have 

 crossed the Ochil or Campsie Hills, and reached the Lothians, 

 transported apparently by currents from the west. Are we to 

 conclude that similar currents could not convey blocks over a 

 much shorter distance — from the west side of the Grampians 

 to the east — through some of the openings in the chain \ Or, 

 shall we suppose that the Grampians, like the Alps, form a 

 " centre of dispersion'' — that, when they rose up by great suc- 

 cessive lifts, from the depths of the ocean, the water dislodged 

 by their upheaval rushed off in powerful currents to all points 

 of the compass, carrying fragments of their rocks with it, 

 mixing them with the pre-existing alluvium, which it tore up 

 and redeposited {remanioit^ as the French writers say), and 

 thus formed our rolled boulder clay % If this were admitted, 

 we might next suppose that the second alluvium, or clay with 

 angular boulders, was formed by the action of tides and cur- 

 rents afterwards, when the whole region was still under the 

 sea; and the upper alluvium of sand and fine gravel last. 

 But this is much too large a superstructure of theory to rest 

 on so scanty a basis of facts. 



A copy of the above article was sent to Mr Darwin, whose 

 speculations on the Parallel Roads of Glenroy (see Edin-- 



