705 
of Edinburgh , Session 1871 - 72 . 
Boss and Cromarty stand next, then Perth , Argyll , Inverness , 
Kirkcudbright , and Forfar. 
2. In regard to s7ze, the largest boulder reported is one of granite, 
in the parish of Pitlochry, called “ Clach Mhor” (big stone), being 
about eight yards square, and estimated about 800 tons. 
There are two boulders between 500 and 600 tons weight, one in 
Ross, the other in The Lewis. 
There are three boulders between 200 and 500 tons, seven be¬ 
tween 100 and 200 tons, twenty between 50 and 100 tons. 
3. With regard to the nature of the rocks composing the boulders, 
the largest reported are of granite, though there is one known to 
the convener of the committee, still larger, of conglomerate, in 
Donne parish. The most numerous are composed of compact 
greenstone; but these are generally of small size. The next 
most numerous class are of grey granite. There are also many of 
gneiss, grey-wacke, and conglomerate. 
4. The boulders reported generally differ in regard to the nature of 
the rocks composing them, from that of the rocks of the district in 
which they 'are situated; and, in many of the reports, reference is 
made to the district from which the boulder is supposed to have come. 
Thus, in those parts of Perthshire, Forfarshire, and Kincardine¬ 
shire where the old red sandstone formation prevails, and over 
which multitudes of granite, gneiss, and conglomerate boulders are 
lying, most of the reporters have no hesitation in pointing out that 
the parent rock is in the Grampian range, lying to the north or 
west. So also in Wigtonshire, where the greywacke formation pre¬ 
vails, and on which many boulders of grey granite are lying, the 
general opinion is that they came from the granite hills of Kirk¬ 
cudbrightshire. 
But where a boulder happens to be of a species of rock the same 
as that of the rocks of the neighbourhood, it is more difficult to 
recognise it as a true erratic. Hence, in the Lewis, where there are 
huge single blocks of gneiss, which is also the prevailing rock of 
the country, the reporters say that they cannot tell whether these 
blocks are erratics or not. 
5. The boulders mentioned in the reports are of various shapes. 
Some approach a cube, well rounded of course on the corners and 
sides. That is the shape mostly possessed by granite boulders. 
