190 Proceedings of the Royal Society 
a. “ In the Pentlands there is a boulder of mica slate, weigh- 
ing 8 or 10 tons, on the east end of Hare Hill (see plan annexed, 
M. 1 ). It reposes on the surface of the west side of the glen leading 
north from Habbies How to Bavelaw, on a declivity about 80 feet 
above the bottom. The nearest spot from which this mass could be 
derived is the portion of the Grampians about Loch Yennacher or 
Loch Earn, 50 miles distant” (page 301). 
Further, this block tells us that the surface of the hills where it 
now rests must have been in a different condition when it was 
deposited. It lies on the side of a declivity, where a large stone, 
either hurried hither by a current, or dropped from an iceberg, 
would not stop, but roll down to the bottom of the valley. The 
reasonable inference is, that the valley between Hare Hill and 
North Black Hill was then filled with “ materials which have since 
been washed away ” (p. 302). 
b. Half a mile south from this, three greenstone boulders of 2 
or 3 tons weight each are lying on the edge of a precipice, about 
200 feet above South Burn. (See plan, M. 2.) 
These have certainly travelled some miles, and the bed of clay 
seen below them is no doubt a remnant of that which then filled 
up the ravine, and prevented them descending to the bottom. 
c. On the east end of West North Black Hill there is a sandstone 
boulder of 8 tons weight. (See plan, M3.) 
This block may not have travelled far. But it rests on a surface 
as steep as the roof of a house (inclined both above and below at 
45°), and about 400 feet above the bottom of the valley. 
It is impossible that it could be dropped here, or brought to the 
spot by a current, without descending to the bottom, unless sustained 
in its place by matter since removed. 
This single block informs us that the ravine about 100 yards wide 
at the surface of the marsh, which separates Black Hill from Beild 
Hill, must then have been filled up with alluvial matter to the height 
of 400 feet at least above its present bottom, which is probably 50 
feet above the true bottom in the rock (page 302). 
d. On the south declivity of Harbour Hill, about 300 feet above 
the level of the Compensation Pond, there is a very large boulder 
of greenstone weighing 12 or 14 tons. (See plan, M. 4.) 
The surface it rests on is not steep. But the boulder must have 
