I i GEOLOGY 



/ 



LETTER XXVII. 



July, IS20. 

 Mr Dear Sir, 



The gradual changes which are constantly car- 

 rying on in this globe by the agency of fire, wa- 

 ter, frost, and caloric, must in course of time de- 

 range its central gravity, and produce an over- 

 whelming revolution. The formation of stalac- 

 tites and stalagmites, by the gradual accretion of 

 calcerous matter, from water, filtrating through 

 the more porous lime-stone, is well understood — 

 and this accretion arises unquestionably from the 

 passage of the water when saturated with lime 

 from a heated to a cool atmosphere. The depo- 

 sition of calcareous substances in the fissures i 

 rocks from the water in which it was suspended, 

 constitutes alabaster. And whenever water, im- 

 pregnated with lime, comes in contact with cooler 

 er water, it will deposit its calcareous matter, which 

 will in course of time harden into stone. All the 

 streams and rivers of the west, are filled with car- 

 bonate of lime, sulphate of lime, argillaceous 

 schistus, and silicious stone, in a state o^ solution, 

 but principally with the first, and when they enter 

 into the lakes, rocks are gradually formed. The 



