Linlithgow, that I could give as of old an occasional hour to literature
and geology. The proof-sheets of my book began to drop in upon me,
demanding revision; and to a quarry in the neighbourhood of the town,
rich in the organisms of the Mountain Limestone, and overflown by a bed
of basalt so regularly columnar, that one of the legends of the district
attributed its formation to the "ancient Pechts," I was able to devote,
not without profit, the evenings of several Saturdays. I formed, at this
time, my first acquaintance with the Palaeozoic shells, as they occur in
the rock--an acquaintance which has since been extended in some measure
through the Silurian deposits, Upper and Lower; and these shells, though
marked, in the immensely extended ages of the division to which they
belong, by specific, and even generic variety, I have found exhibiting
throughout a unique family type or pattern, as entirely different from
the family type of the Secondary shells as both are different from the
family types of the Tertiary and the existing ones. Each of the three
great periods of creation had its own peculiar fashion; and after having
acquainted myself with the fashions of the second and third periods, I
was now peculiarly interested in the acquaintance which I was enabled to
commence with that of the first and earliest also. I found, too, in a
bed of trap beside the Edinburgh road, scarce half a mile to the east
of the town, numerous pieces of carbonized lignite, which still retained
the woody structure--probably the broken remains of some forest of the
Carboniferous period, enveloped in some ancient lava bed, that had
rolled over its shrubs and trees, annihilating all save the fragments of
charcoal, which, locked up in its viscid recesses, had resisted the
agency that dissipated the more exposed embers into gas. I had found, in
like manner, when residing at Conon-side and Inverness, fragments of
charcoal locked up in the glassy vesicular stone of the old vitrified
forts of Craig Phadrig and Knock Farril, and existing as the sole
representatives of the vast masses of fuel which must have been employed
in fusing the ponderous walls of these unique fortalices. And I was now
interested to find exactly the same phenomena among the _vitrified_
rocks of the Coal Measures. Brief as the days were, I had always a
twilight hour to myself in Linlithgow; and as the evenings were fine for
the season, the old Royal Park of the place, with its n