Spey strike me as very suspicious. Mr. J. refers to absence of pebbles at
considerable heights: he must remember that every storm, every deer, every
hare which runs tends to roll pebbles down hill, and not one ever goes up
again. I may mention that I particularly alluded to this on S. Ventanao
(525/2. "Geolog. Obs. on South America," page 79. "On the flanks of the
mountains, at a height of 300 or 400 feet above the plain, there were a few
small patches of conglomerate and breccia, firmly cemented by ferruginous
matter to the abrupt and battered face of the quartz--traces being thus
exhibited of ancient sea-action.") in N. Patagonia, a great isolated rugged
quartz-mountain 3,000 feet high, and I could find not one pebble except on
one very small spot, where a ferruginous spring had firmly cemented a few
to the face of mountain. If the Lochaber lakes had been formed by an ice-
period posterior to the (marine?) sloping terraces in the Spean, would not
Mr. J. have noticed gigantic moraines across the valley opposite the
opening of Lake Treig? I go so far as not to like making the elevation of
the land in Wales and Scotland considerably different with respect to the
ice-period, and still more do I dislike it with respect to E. and W.
Scotland. But I may be prejudiced by having been so long accustomed to the
plains of Patagonia. But the equality of level (barring denudation) of
even the Secondary formations in Britain, after so many ups and downs,
always impresses my mind, that, except when the crust-cracks and mountains
are formed, movements of elevation and subsidence are generally very
equable.

But it is folly my scribbling thus. You have a grand problem, and heaven
help you and Mr. Jamieson through it. It is out of my line nowadays, and
above and beyond me.


LETTER 526. TO J.D. HOOKER.