of Edinburgh, Session 1870-71. 
475 
2. Scheme for the Conservation of Remarkable Boulders in 
Scotland, and for the indication of their Positions on 
Maps. By D. Milne Home, Esq. 
Among many geological questions which wait solution, there is 
probably none more interesting or perplexing than the agency by 
which Boulders or “blocs erratiques,” as the French term them, 
have come to their present sites. I allude, of course, not to blocks 
lying at the foot of some mountain crag from which they have 
fallen by the decay or .weathering of the overhanging rocks, but to 
blocks which have manifestly been transported great distances, 
after being detached from the rocks of which they originally 
formed part. 
That many of the large isolated blocks lying on our mountain 
sides and on our plains have come from a distance, and by some 
means of tremendous power, is obvious even to an unscientific 
observer ; and the perception of this truth by the popular mind has, 
in many cases, so invested these boulders with superstitious interest, 
that they have received names and given rise to legends, which 
impute the transport of them to supernatural agents. 
There are two circumstances which very plainly indicate that 
these stones are strangers. 
One is, that many of these blocks are on examination found to 
be different from any of the rocks prevailing in or near the dis- 
trict where they are situated. 
The other is, that some of these blocks, whilst excessively hard, 
— so hard that it is difficult to break off a portion with the hammer, 
are nevertheless round in form — a form evidently acquired by 
enormous friction — such friction as would result from being rolled 
a long way over a rough surface. 
The inference drawn from these two facts was confirmed when 
it was discovered, as in many cases it was, that rocks of the same 
nature as the block existed in a distant part of the country, and 
from which, therefore, it had probably come. 
These round shaped blocks were the first to attract popular 
attention. The name given to them in Scotland of boulders has 
no doubt been suggested by their shape. 
It is accordingly only the rounded boulders which possess the 
