Page:Narrative of a survey of the intertropical and western coasts of Australia, Volume 2.djvu/621

 596 APPENDIX. [Co where a' large surface is covered with a calcareous sand, that becomes agglutinated into a stone, which he con- siders as analogous to the rocks of Guadaloupe; and of which the. specimens that I have seen, resemble those pre* sented by Captain Beaufort to the Geological Society, from the shore at Rhode9.--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 deposlt.mDr. Mac Cullocli describe9 calcareous concretions, found in banks of sand in Perth9hlre, which "present a great variety of atalactitic forms, generally more or less complicated, and oken ex- ceedingly intricate and 8trangee, *' and which appear to be analogous to those of King George's Sound and Sweer*s Island :--And he mentions, a8 not unfrequently occurring in 8and, in diJerent parts of England, (the 8and above the fossile hones of Norfolk is given as an example,) long cylinders or tubes, composed of sand agglutinated by car- bonate of lime, or ' calcareous stalactites entangl!ng sand,* which, like the concretions of Madeira, and those taken for corals at Bald-Head, "have been ranked improperly, with organic remains." The stone which forms the fragments in the broccia of New Holland, is very nearly the same with that of the cement by which they are united ;the difl'erence consisting only in the greater proportion of sand which the fragments contain :--and it would 'seem, that after the consolidation of �"On an arenaceo-caicareous substance," &c.--Quartedy Jour- nal, (Royal !nstitutlon), Oct. 1823, vol. xvi. p. 79-83.

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