188 
Proceedings of the Royal Society 
Striated Rock Surfaces . — Only two localities were observed. Dr 
Croll, in a paper on “ The Boulder Clay of Caithness,” first made 
known that he had discovered a striated rock on the top of Aller- 
muir Hill, at a height of 1647 feet above the sea. I visited 
Allermuir Hill some time after this discovery, and was fortunate 
enough to find a portion of the striated surface. The rock of the 
summit of the hill is felstone, very much weathered and broken up, 
and it is only in the little hollows, which are covered with a blackish 
earth, that indications of rubbed or scratched surfaces are found. 
The portion I discovered, although it was only a few inches square, 
was finely striated, and I had no difficulty in making out the direc- 
tion of the striae, and the direction from which the striating agent 
had come, which was about W.S.W. (See Plan, H. 1.) The other 
locality I discovered during a very dry summer, when the water in 
Bonally Pond was very low. The striae occur here on a reddish 
sandstone, which crops out along the south-east side of the pond, 
at an elevation of about 1100 feet above the sea (H. 2). There is 
here a much larger surface of striated rock than on Allermuir 
Hill, but it is mostly always covered by the water of the pond. I 
had an opportunity, however, of seeing a portion of it again last 
summer. I then took the direction of the striations, and found 
them, as on Allermuir Hill, W.S.W. I may remark that this agrees 
with the direction of the stria3 on the rocks of at least twenty 
localities that I have examined in the neighbourhood of Edinburgh, 
and in no instance in this neighbourhood have I observed the rocks 
striated in a direction H.W. and S.E. 
Boulders occur at all heights up to 1400 feet, and all sizes up to 
10 or 12 tons. Several very large ones lie on the north side of 
Capelaw Hill, at about 1200 feet above the sea (H. 3). They are of 
a dark crystalline greenstone, unlike any of the igneous rocks in this 
district. Further west, on the west side of Harbour Hill, there is a 
great number of smaller blocks of the same greenstone (H. 4). They 
appear to me to lie on about a uniform level along the hill side, at 
about 900 or 1000 feet above the sea. The prevailing boulders in 
the northern portion of the hills are of greenstone, while those further 
to the S.W. are mostly sandstone. 
Boulder Clays . — I have observed two localities where these occur 
in considerable quantities, one at the north-west corner of Glencorse 
