continuous dikes of trap. But in
this northern region, where the trap-rocks are unknown, it must have
been filled up with the boulder-clay, or with some still more ancient
accumulation of debris. And when the land had risen, and the streams,
swollen into rivers, flowed along the hollows which they now occupy, the
loose rubbish would in the lapse of ages gradually wash downwards to the
sea, as the stones thrown from the fields above were washed downwards in
a later time; and thus the deep fissure would ultimately be cleared out.
The boulder-stones lie thickly in this neighborhood, and over the
eastern half of Ross-shire, and the Black Isle generally; though for
the last century they have been gradually disappearing from the more
cultivated tracts on which there were fences or farm-steadings to be
built, or where they obstructed the course of the plough. We found them
occurring in every conceivable situation,--high on hill-sides, where the
shepherd crouches beside them for shelter in a shower,--deep in the open
sea, where they entangle the nets of the fisherman,--on inland moors,
where in some remote age they were painfully rolled together, to form
the Druidical circle or Picts'-house,--or on the margin of the coast,
where they had been piled over one another at a later time, as
protecting bulwarks against the encroachments of the waves. They lie
strewed more sparingly over extended plains, or on exposed heights, than
in hollows sheltered from the west by high land, where the current, when
it dashed high on the hill-sides, must have been diverted from its
easterly course, and revolved in whirling eddies. On the top of the fine
bluff hill of Fyrish, which I so admired to-day, each time I caught a
glimpse of its purple front through the woods, and which shows how noble
a mountain the Old Red Sandstone may produce, the boulders lie but
sparsely. I especially marked, however, when last on its summit, a
ponderous traveller of a vividly green hornblende, resting on a bed of
pale yellow sandstone, fully a thousand feet over the present high-water
level. But towards the east, in what a seaman would term the _bight_ of
the hill, the boulders have accumulated in vast numbers. They lie so
closely piled along the course of the river Alness, about half a mile
above the village, that it is with difficulty the waters, when in flood,
can force their passage through. For here, apparently, when the tide
swept along the hill-side, many an ice