. Elements of geology : a text-book for colleges and for the general reader. Geology. 78 AQUEOUS AGENCIES. course of the streams which issue from them, are generally found ex- tensive deposits of this substance. Being found mostly in volcanic regions, these springs are commonly hot. Kinds of Materials,—The material thus deposited is usually called travertine, but is very diverse in appearance. If the deposit is quiet, the material is dense; if tumultuous, the material is spongy; if no iron is present, it is white like marble; but if iron be present, its oxida- tion colors it yellow, brown, or
. Elements of geology : a text-book for colleges and for the general reader. Geology. 78 AQUEOUS AGENCIES. course of the streams which issue from them, are generally found ex- tensive deposits of this substance. Being found mostly in volcanic regions, these springs are commonly hot. Kinds of Materials,—The material thus deposited is usually called travertine, but is very diverse in appearance. If the deposit is quiet, the material is dense; if tumultuous, the material is spongy; if no iron is present, it is white like marble; but if iron be present, its oxida- tion colors it yellow, brown, or reddish. If the amount of iron be vari- able, the stone is beautifully striped. If objects of any kind, branches, twigs, leaves, are immersed in such waters, they are speedily incrusted, often in the most beautiful manner. Examples of such deposits are found in all countries. At the baths of San Vignone, Italy, a carbonated spring issuing from the top of a hill has covered the hill with a stratum of white, compact travertine 250 feet thick. In the conduit-pipe which leads the water to the baths, the deposit accumulates six inches thick every year. A similar deposit of travertine occurs at the baths of San Filippo. At this latter place, beautiful facsimiles of medallions, coins, etc., are formed by placing these objects of art in the spray of an artificial cascade. In Virginia, around the " Old Sweet " and the " Red Sweet" Springs, and in the course of the stream which flows from them for several miles, a brownish-yellow deposit of traver- tine has accumu- lated to the depth of at least thirty feet. The spray of Beaver Dam Falls, about three miles below the springs, incrusts every object in its reach with this deposit. In California, all about the shores of Lake Mono, abundance of beautiful and strangely-branched coralline forms are found, which. Fig. 73.—Deposits from Carbonated Please note that these images are extracted from scanned page imag
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