arbonate of lime by the
percolating water, may possibly render its formation more abundant there,
than in more temperate climates. But the true theory of these
concretions, under any modification of temperature, is attended with
considerable difficulty: and it is certain that the process is far from
being confined to the warmer latitudes. Dr. Paris has given an account of
a modern formation of sandstone on the northern coast of Cornwall;**
where a large surface is covered with a calcareous sand, that becomes
agglutinated into a stone, which he considers as analogous to the rocks
of Guadaloupe; and of which the specimens that I have seen, resemble
those presented by Captain Beaufort to the Geological Society, from the
shore at Rhodes. Dr. Paris ascribes this concretion, not to the agency of
the sea, nor to an excess of carbonic acid, but to the solution of
carbonate of lime itself in water, and subsequent percolation through
calcareous sand; the great hardness of the stone arising from the very
sparing solubility of this carbonate, and the consequently very gradual
formation of the deposit--Dr. MacCulloch describes calcareous
concretions, found in banks of sand in Perthshire, which present a great
variety of stalactitic forms, generally more or less complicated, and
often exceedingly intricate and strange,*** and which appear to be
analogous to those of King George's Sound and Sweer's Island: And he
mentions, as not unfrequently occurring in sand, in different parts of
England (the sand above the fossil bones of Norfolk is given as an
example) long cylinders or tubes, composed of sand agglutinated by
carbonate of lime, or calcareous stalactites entangling sand, which, like
the concretions of Madeira, and those taken for corals at Bald-Head, have
been ranked improperly, with organic remains.

(*Footnote. Peron Voyage etc. 2 page 116.)

(**Footnote. Transactions of the Geological Society of Cornwall volume 1
page 1 etc.)

(***Footnote. On an arenaceo-calcareous substance, etc. Quarterly Journal
Royal Institution October 1823 volume 16 page 79 to 83.)

The stone which forms the fragments in the breccia of New Holland, is
very nearly the same with that of the cement by which they are united,
the difference consisting only in the greater proportion of sand which
the fragments contain: and it would seem, that after the consolidation of
the former, and while the deposition of similar calcareous matter was
still in progress,