206 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [Jan. 25, 



the banks of the Torlin and Slaodridh Burns and their two main 

 tributaries ; and the best sections are within an easy distance of the 

 hotel. The Clenid Burn enters Torlin-water a little way above 

 Lag ; and on its eastern bank, about a quarter of a mile up, there is 

 a good development of these beds. The base of the section here, 

 over the sandstone rock, is an unstratified clay of a red or chocolate- 

 brown colour, often with a bluish tinge, full of boulders of all sizes, 

 both angular and rounded, usually striated and thrown together 

 pell-mell. The clay is excessively hard and tough, workable only 

 by the pickaxe. The stones are of all sizes, from small pebbles to 

 very large boulders, and confusedly mixed without reference to weight. 

 It is very striking to observe the striations upon the great majority 

 of the stones, the rounding off upon the edges and the high polish 

 acquired by all alike, of whatever size. The majority of the stones 

 are local ; but though sandstone is here the prevailing rock, and the 

 deposit rests on it, comparatively few of the boulders are sandstone ; 

 porphyry, syenite, and greenstone, which form the higher grounds 

 and hills northwards, abound ; but there are also granite of the 

 coarse-grained or Goat-fell variety, and slate, both from the nor- 

 thern mountains, between which and the present lodgment of the 

 blocks there are many high ridges and deep glens. 



The bed we have been describing is the true old Boulder-clay, or 

 lower Till, and that alone which ought to be designated by this 

 name. The mineral structure above assigned to it, its striated 

 stones, and unworkable nature are sufficient to distinguish it from 

 the other drifts. By the last character it is but too well known to 

 contractors and workmen ; it can neither be blasted nor digged into, 

 and is only effectually assailed by a heavy pickaxe, so that the process 

 of removing it in railway-cuttings and foundations is very tedious 

 and costly, more so than the same mass of solid trap or granite 

 would be *. 



In the Clenid Burn section this Boulder-clay is from 15 to 20 ft. 

 thick ; the upper surface declines southward, or down the burn, so 

 that the bed becomes thicker upwards. Over it and conforming to 

 its upper surface there is a bed of a fine dark clay, hard and com- 

 pact, with a good many small stones, not generally striated. This 

 bed is very different from that below, being much less compact 

 and more easily worked, and contrasting remarkably in the size 

 and markings of the stones. It is the repository of the shells, 

 and is 7 or 8 feet thick, in the upper part reddish and slightly 

 sandy, in the lower assimilating to the Boulder-clay below, thus 



* This character is familiar to Glasgow builders. The deposit swathes the sides 

 of all the hills and lesser slopes within the city, and the foundations of all the 

 higher streets are laid in it. Its rocky masses are most varied ; in fact, a nearly 

 complete collection of Scottish rocks may be made from its imbedded stones. 

 Such a collection was, in fact, exhibited in Glasgow at the last meeting of the 

 British Association there. From some of the sections of this deposit within 

 ■ the limits of the city we have obtained polished, grooved, and striated boulders, 

 "even more readily than in the termmal moraine of a Swiss glacier. The origin 

 'of many of these is to be sought only in the remote mountains of Dumbarton 

 and Argyle. 



