. The elements of geology, for popular use : containing a description of the geological formations and mineral resources of the United States. Geology; Geology. CALCAREOUS SPRINGS. 179 At the hill of San Vignone, in Tuscany, a ther- mal spring issues from the summit of a rocky hill 100 feet high, composed of black slate and serpen- tine. Fig. B, Serpentine and Slate, a a, Limestone Deposite. A large mass of tufa, a a, or travertin in regular strata, descends on each side of the hill; one of the strata being compact, and about 15 feet thick, serves as an excellent building stone; while the
. The elements of geology, for popular use : containing a description of the geological formations and mineral resources of the United States. Geology; Geology. CALCAREOUS SPRINGS. 179 At the hill of San Vignone, in Tuscany, a ther- mal spring issues from the summit of a rocky hill 100 feet high, composed of black slate and serpen- tine. Fig. B, Serpentine and Slate, a a, Limestone Deposite. A large mass of tufa, a a, or travertin in regular strata, descends on each side of the hill; one of the strata being compact, and about 15 feet thick, serves as an excellent building stone; while the other, de- scending 250 feet in length, forms a mass about 200 feet deep. So rapid is the deposition of lime at these springs, that half a foot of solid limestone is deposited every year in a conduit pipe, inclined at an angle of 30 degrees. Where the water flows more slowly, the deposite is more compact, and rings when struck with a hammer; but where its current is swifter, it is cellular and porous, like the Paris buhr millstone; sometimes it assumes a mam- miliary form, and scales off in thin layers, like the coats of an onion. At the baths of San Filippo, among the Apen- nines, the water which supplies the baths falls into a pond, where it has been known to deposite a solid mass 30 feet thick in 20 years. A manufac- tory of medallions, in basso-relievo, is carried on at these baths. The water is conducted by canals. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lee, Charles A. (Charles Alfred), 1801-1872; Draper, Daniel, 1841-1931, donor. DSI. New-York : Harper & Brothers
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Keywords: ., bookcentury1800, bookpublishernewyorkharperb, booksubjectgeology
