In The Primitive Mountains Open To Our Researches, Real Grottoes, Those Which Have Some Extent, Belong Only To Calcareous Formations, Such As The Carbonate Or Sulphate Of Lime.

The solubility of these substances appears to have favoured the action of the subterranean waters for ages.

The primitive limestone presents spacious caverns as well as transition limestone,* and that which is exclusively called secondary. (* In the primitive limestone are found the Kuetzel-loch, near Kaufungen in Silesia, and probably several caverns in the islands of the Archipelago. In the transition limestone we remark the caverns of Elbingerode, of Rubeland, and of Scharzfeld, in the Hartz; those of the Salzfluhe in the Grisons; and, according to Mr. Greenough, that of Torbay in Devonshire.) If these caverns be less frequent in the first, it is because this stone forms in general only layers subordinate to the mica-slate,* (* Sometimes to gneiss, as at the Simplon, between Dovredo and Crevola.) and not a particular system of mountains, into which the waters may filter, and circulate to great distances. The erosions occasioned by this element depend not only on its quantity, but also on the length of time during which it remains, the velocity it acquires by its fall, and the degree of solubility of the rock. I have observed in general, that the waters act more easily on the carbonates and the sulphates of lime of secondary mountains than on the transition limestones, which have a considerable mixture of silex and carbon. On examining the internal structure of the stalactites which line the walls of caverns, we find in them all the characters of a chemical precipitate.

Enter page number Go  Previous Next
Page 422 of 779
Words from 114517 to 114789 of 211363