J. F. Campbell Collection > On the parallel roads of Lochaber

D. MILNE HOME ON THE PARALLEL ROADS OF LOCHABER. 643
X.W. across a deep valley. (" Proceedings of the Eoyal Society of Edinburgh"
for 1872-3, p. 162.)
At the east end of the Great Glen of Scotland, on the hills and elevated
plateaus west and south of Inverness, there are large Ijoulders of a coarse
granitic conglomerate, whose parent rocks are situated to the W.X.W. In the
district where Lochan Clachau is situated (al;)0Ut 8 miles S.W. of Inverness),
the striations on the rocks are due E. and W. On one of these rocks so
striated (at a height of 1259 feet above the sea) lies a large boulder, Avith its
sharj) point towards the west. Its broad end lies against a portion of the rock,
which has prevented its further progress eastward.
On the hiUs adjoining, there are numerous boulders, mostly on gravel drift.
One boulder, of large size, and visible at a great distance oft', is situated on the
ridge of the highest hill in the district, about 1100 feet above the sea. It is
called the "AVatch Stone." It is also a coarse granitic conglomerate. Its
position could not have been reached except by coming in a direction between
W.N.W. and W. by N. (See Appendix.)
A very difficult question, as it appears to me, remains to be solved, regarding
the agent which aff'ected the smoothing and striation of the rocks in Lochaber
and elsewhere iu Scotland. Those who have preceded me in this " Parallel
Eoads" inquiry have referred to it, and I cannot pass it unnoticed.
On one point most geologists are agreed, viz., that tlie detritus spread over
the countiy, and reaching to our highest hill ranges, is m vine.
Even Dr Macculloch, in whose day so little was known about these
matters, inferred from the facts which he saw, that " portions of the lines (or
roads) have been formed in a rounded and t /-a Ji.'^ported alluyium of pebbles, sand,
and gravel We suppose that a rounded alluvium had been hy precious causes
accumulated in the glens. If this took place from the action of former waters Jtoivinu
through the valleys {and to wliat other causes can tve assign it"), &c., p. 389.
Dakwin, who maintained the marine origin of the Parallel Roads, founded
his strongest argument on the undoubtedly marine character of the detritus,
on which these " Roads " had been impressed.
Professor NicoL, of Aberdeen, in his paper on the Parallel Roads, refers
particularly to tlie " detrital cover," in which he says "the lines are cut;"
and adds, "that it is a marine deposit, seems beyond doubt," p. 283.
Mr Ja:mieson describes the thick beds of stratified clay, sand, and gravel, in
various parts of Perthshire and Aljerdeenshire up to about 2000 feet above 2^ry^ ^«-<-^
the sea, as apparently marine ("Lond. Geol. Soc. Jour..'" vols. xvi. and xxi.). o/iUA.Ma^'U^
He considers that it was " during this submergence that the bi'ick clays 9uxUri,ixj
containing arctic shells were deposited, and that Ijoulders were drifted here
and there, by floating ice," p. 194, vol. xxi. In a previous paper (vol. xviii.
yi. 164), the same author was on this point still more explicit. "At the bottom
\(iL. xxvn. PAUT IV. s a