The Foot-prints of the Creator : $b or, The Asterolepis of Stromness
John Stuart Mill · en
lately sent me by Mr. William Watt, from a quarry at Skaill, has much
the appearance of one of the smaller ferns, such as the moor-worts, sea
spleen-worts, or maiden-hairs. It exists as an impression in diluted
black, on a ground of dark gray, and has so little sharpness of outline,
that, like minute figures in oil-paintings, it seems more distinct when
viewed at arm’s length than when microscopically examined; but enough
remains to show that it must have been a terrestrial, not a marine
plant. The accompanying print (fig. 56) may be regarded as no unfaithful
representation of this unique fossil its state of imperfect keeping.
The vegetation of the Silurian system, from its upper beds down till
where we reach the zero of life, is, like that of the Old Red Sandstone,
almost exclusively fucoidal. In the older fossiliferous deposits of the
system in Sweden, Russia, the Lake Districts of England, Canada, and
the United States, fucoids occur, to the exclusion, so far as is yet
known, of every other vegetable form; and such is their abundance in some
localities, that they render the argillaceous rocks in which they lie
diffused, capable of being fired as an alum slate, and exist in others
as seams of a compact anthracite, occasionally used as fuel. They also
occur in those districts of Wales in which the place and sequence of the
various Silurian formations were first determined, though apparently
in a state of keeping from which little can be premised regarding
their original forms. Sir Roderick Murchison sums up his notice of the
vegetable remains of the system in the province whence it derives its
name, by stating that he had submitted his specimens to “Mr. Robert Brown
and Dr. Greville, and that neither of these eminent botanists were able
to say much more regarding them than that they were fucoid-like bodies.”
[Illustration: Fig. 54.
FUCOIDS OF THE LOWER OLD RED SANDSTONE.
a. _Smooth-stemmed species._
b. _Tubercled species._
(One sixth nat. size, linear.)]
[Illustration: Fig. 55.
a. _Smooth-stemmed species._
b. _Tubercled species._
(Natural size.)]