, all I can
say is that nature has laid a shameful trap to catch an unwary wretch. I
suppose that I have underrated the power of lakes in producing pebbles;
this, I think, ought to be well looked to. I was much struck in Wales
on carefully comparing the glacial scratches under a lake (formed by a
moraine and which must have existed since the Glacial epoch) and above
water, and I could perceive NO difference. I believe I saw many such
beds of good pebbles on level of lower shelf, which at the time I could
not believe could have been found on shores of lake. The land-straits
and little cliffs above them, to which I referred, were quite above the
highest shelf; they may be of much more ancient date than the shelves.
Some terrace-like fringes at head of the 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 yo