Amongst these latter
may be mentioned memoirs by Prof. Phillips, and Messrs Salter,
Hicks, Belt, Plant, Homfray, Ash, Holl, &c.
CHAPTER IX.
THE LOWER SILURIAN PERIOD.
The great system of deposits to which Sir Roderick Murchison
applied the name of "Silurian Rocks" reposes directly upon the
highest Cambrian beds, apparently without any marked unconformity,
though with a considerable change in the nature of the fossils. The
name "Silurian" was originally proposed by the eminent geologist
just alluded to for a great series of strata lying below the Old
Red Sandstone, and occupying districts in Wales and its borders
which were at one time inhabited by the "Silures," a tribe of
ancient Britons. Deposits of a corresponding age are now known
to be largely developed in other parts of England, in Scotland,
and in Ireland, in North America, in Australia, in India, in
Bohemia, Saxony, Bavaria, Russia, Sweden and Norway, Spain, and
in various other regions of less note. In some regions, as in
the neighbourhood of St Petersburg, the Silurian strata are found
not only to have preserved their original horizontality, but
also to have retained almost unaltered their primitive soft and
incoherent nature. In other regions, as in Scandinavia and many
parts of North America, similar strata, now consolidated into
shales, sandstones, and limestones, may be found resting with
a very slight inclination on still older sediments.
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