274 
Proceedings of the Koyal Society of Edinburgh. [Sess. 
minerals insoluble in hydrochloric acid. It is clear that solution must have 
gone on to a considerable extent by the manner in which the glaciated 
limestone fragments have been cariously weathered after deposition as 
displayed on both their exposed and embedded sides. But the theory 
that the work has been done by current-action rather than by solution 
receives additional support from the fact that nearly all the flat stones, 
0 12 3 4 5 6 INCHES 
1 i i i J i l i I i I — i — I — i — 1 
pr-m-i | i | | | I ^ 
Q 40 80 120 J60 MM. 
Fig. 5. — Explanation as in text tig. 1. 
even when they have lain on their sides, have had parts of their under 
sides exposed. If the stones could be oriented, the direction of current 
would also be indicated (text fig. 6). 
The explanation above offered may also account for the curiously even 
and comparatively small size of the stones (on an average 3x2x2 inches), 
which seem to have been assorted according to their relative weight 
compared with their superficial area. It is only the flat and thin stones 
that reach a length of 4 inches or more. The larger stones with a greater 
