1900-1901. | A Geological Trip. 173 
of serpulites are found—z.e., the little calcareous cases of a 
small species of worm (Plate XVII. 1). You may examine this 
rock over wide areas and find nothing to speak of in the way 
of serpulites, but in some places it is crowded with them. 
This specimen, which I secured on the road between Aultna- 
eallagach and Inchnadamff, close to a small loch called Loch 
Awe, you see is crowded with the little fossils, and looks 
almost like a piece of ripe stilton cheese. I happened to come 
across a portion of this rock in a burn called Allt-an-Uamh, 
where it had been invaded by a dyke of basic igneous rock. 
Contact metamorphism had taken place, and the rit, 
which is here free from serpulites, was fused into a kind of 
bluish glass. Above the serpulite grits (fig. 2, C) come a 
series of limestones, probably laid in deep sea water, 200 to 
400 feet thick, Various fossils have been found in this 
series, but only at Durness. Formerly considered to be of 
Lower Silurian age, but now regarded as Cambrian, most of 
the beds are traversed by worm-casts in such a way that 
nearly every particle must have passed through the intestines 
of worms. It is seen in great thickness in the great limestone 
plateau at Inchnadamff. A few scattered cottages and the 
hotel comprise the little hamlet which is picturesquely 
situated at the southern extremity of Loch Assynt. The 
great thickness of the limestone here is due to the piling 
up of the strata due to overthrusts. Now referring to 
fig. 2 D again, we see that the land had been again tilted, 
and in such a way as to bring the Torridon sandstones 
back to their original level position, while all the overlying 
beds now dip away to the east at a low angle. That is 
roughly the position that they occupy now; but towards the 
east, as before mentioned, great dislocations, upheavals, and 
thrusts have taken place, and the broken-up mass has been 
pushed forward from east to west and piled up in lines, as I 
showed you before, marked by the outcrop of the three 
principal thrust planes—the Glencoul, the Ben More, and the 
Moine. The next diagram will make this clear (fig. 3). This 
diagram gives a section from Quinag east by Achumore, 
Glasven, Ben Uidhe, and head of Glen Beg, covering a distance 
of about seven miles. There are two of the great thrust planes 
shown here—that of Glencoul at the foot of Glasven, and of 
