. And my next object in to-day's journey, after exploring this
ravine of the boulder-clay, was to ascertain whether the beds did not
also occur in a ravine of the parish of Avoch, some eight or nine miles
away, which, when lying a-bed one night in Edinburgh, I remembered
having crossed when a boy, at a point which lies considerably out of the
ordinary route of the traveller. I had remarked on this occasion, as the
resuscitated recollection intimated, that the precipices of the Avoch
ravine bore, at the unfrequented point, the peculiar aspect which I
learned many years after to associate with the ichthyolitic member of
the system; and I was now quite as curious to test the truth of a sort
of vignette landscape, transferred to the mind at an immature period of
life, and preserved in it for full thirty years, as desirous to extend
my knowledge of the fossiliferous beds of a system to the elucidation of
which I had peculiarly devoted myself.

As the traveller reaches the flat moory uplands of the parish, where the
water stagnates amid heath and moss over a thin layer of peaty soil, he
finds the underlying boulder-clay, as shown in the chance sections,
spotted and streaked with patches of a grayish-white. There is the same
mixture of arenaceous and aluminous particles in the white as in the red
portions of the mass; for, as we see so frequently exemplified in the
spots and streaks of the Red Sandstone formations, whether Old or New,
the coloring matter has been discharged without any accompanying change
of composition in the substance which it pervaded;--evidence enough that
the red dye must be something distinct from the substance itself, just
as the dye of a handkerchief is a thing distinct from the silk or cotton
yarn of which the handkerchief has been woven. The stagnant water above,
acidulated by its various vegetable solutions, seems to have been in
some way connected with these appearances. In every case in which a
crack through the clay gives access to the oozing moisture, we see the
sides bleached, for several feet downwards, to nearly the color of
pipe-clay; we find the surface, too, when it has been divested of the
vegetable soil, presenting for yards together the appearance of sheets
of half-bleached linen: the red ground of the clay has been acted upon
by the percolating fluid, as the red ground of a Bandanna handkerchief
is acted upon through the openings in the perforated lead, by the
discharging chloride of li