120 



Lieut. Nelson on the Geology of the Bermudas. 



To the unequal distribution of that carbonate of lime in solution, which forms ordinary rock on 

 the upper parts of a section ; or druses and breccias, as it filters through the strata of red earth to 

 the lower beds or to the caverns where it crystallizes as stalagmite and stalactite, I attribute, 

 not only the caverns and sandflaws, but the pinnacled rocks almost equally common in the islands. 

 The most remarkable groups are at Tobacco Bay, St. George's Island (fig. IG), and at the North 

 rock. I cannot but consider these as merely blocks, sufficiently impregnated with the dissolved car- 

 bonate of lime to have resisted the attacks of the waters, with the same success as the 'Base rock.' 



Fig. 16. 



I apprehend that such caverns as those described in the preceding pages, are rarely found in 

 any but calcareous rocks. The Grotto of Antiparos ; the caves of Torquay, Chudleigh, Plymouth, 

 and Kirkby, as famous for their organic remains, as those of Gaylenreuth and others, in Ger- 

 many ; the various caverns in Derbyshire; Peter Frazer's Bear Den, near Picton, in Nova Scotia ; 

 the different subterraneous courses of certain rivers in England, &c. &'c. ; are all found in lime- 

 stones of various formations. It is almost trite to quote such instances to the general geologist ; 

 but I have thus reassembled them, to show how well the series is terminated by the corre- 

 sponding exam])les, which have supplied the materials of this section. 



Water. 



Fresh water may be had in nearly all parts of the islands, provided the 

 bottom of the well is not sunk under the level of low tide. Generally 

 speaking, it is deemed prudent to be contented with twelve or eighteen 

 inches of water, rather than incur the risk of rendering the well brackish ; 

 since, from the porous nature of the rock, the salt water always filtrates 

 through. 



At the naval wells below Mr. Langton's, where large quantities of water 

 are required for shipping, it is only taken between the half flood and half 

 ebb, to avoid the brackish quality of water drawn at improper seasons ; for 

 all the wells, on the sea coast, are affected by the tide ; and more or less so 

 those at a distance from it. 



