Rhine, instead of flowing as it now does, almost due north to the lake of Constance, was at one time deflected to the east, in the direction of the lake of Wallenstadt, owing to the barrier that originally existed at the pass of St. Lucie, where the mountains present the appearance of having been riven asunder by some subsequent violence. For the evidence in support of this I must refer to M. Ebel's work*.

The other thermal springs in Switzerland appear under circumstances for the most part similar. Those at Weissenburg, in the canton of Berne, rise out of a gorge of the same kind as that of Pfeffers; those of Loueche appear at the foot of the mural precipice of the Gemmi, in the midst of indications of great confusion; whilst the springs of Baden, in the canton of Argovie, from which that of Schinznach is not far removed, lie near the point where, in consequence of the two mountains of Staffelegg and Lagern having been severed asunder by some great convulsion, the waters of the Rhine and of the other rivers which appear to have constituted a single lake, extending from Coire in the Grisons to this mountain ridge, including the lakes of Zurich and Wallenstadt, with the intermediate country, in one continuous sheet of water, flowed off by the channel now taken by one of the rivers, the Limmat, alone. Thus the Rhine may be supposed to owe its original direction to the event which produced one hot spring, and its present course to that which occasioned another.

The springs of Loueche or Leuk, in the Valais, are situated in a deep and precipitous valley very near the foot of the Gemmi. They rise from limestone, but not a very great distance from the vast granitic chain which extends by the upper parts of the valley of Lauterbrunner to the Jungfrau. The evidence of disruption on a great scale in the valley is almost as clear (Professor Forbes says) as such evidence can be. It is surrounded by mural precipices of singular boldnesst.

The situation of the thermal waters in the beautiful moun* Manuel du Voyageur en Suisse.

+ Forbes, Temperature and Geological Relations of certain Hot Springs, Phil. Trans. for 1836.

tain region of Virginia, west of the Blue Ridge, which I visited in 1838, strongly corroborates the views above enunciated.

Several of the most noted indeed of the mineral waters resorted to in this country for their reputed medicinal virtues, seem to be only slightly thermal, and to derive their efficacy chiefly from the sulphuretted hydrogen with which they are impregnated ; such are the White, the Red, the Blue, and the Salt Sulphur Springs.

The three former acquire their distinctive appellation from their colour, the difference in which is probably attributable to that of the confervæ that grow on them, and impart their respective hues to the water; the latter, designated as the Salt, owes its name to the presence in it of a larger proportion of common salt than in the rest *.

One, the Sweet Spring,” is strongly acidulous, and slightly thermal; but two, which appear to possess no remarkable mineral impregnation, are designated by the names of the Warm, and the Hot Spring, from the more or less considerable elevation of temperature which belongs to them.

The Warm Spring I found to possess a heat of 96° Fahr., and the Hot Spring one of 102°, whereas the mean of the climate seems to be only about 56°:7.

Now both these springs lie at a distance of about three miles one from the other, in a valley, the direction of which is nearly north and south; whilst it may be seen, by reference to the section which Prof. William Rogers has appended to his “Geological Report of the State of Virginia,' 1836 I, that they are situated exactly at the anticlinal axis of the chain.

And on examining the rocks on either side of these springs, wherever the nature of the country allowed of my exploring them, I found every reason to place reliance upon the correct

The situation of these and other therinal springs in the United States is expressed in the Map at the end of the volume.

+ See a Sketch of the Geology of North America by the author, published by the Ashmolean Society.

And to his Memoir “on the Connexion of Thermal Waters in Virginia with Anticlinal Axes and Faults.”

ness of his representations. To the west of the Hot Spring, the most southern of the two thermal waters referred to, the rocks become more and more inclined towards the west, as they approach nearer to it, until at length in its immediate vicinity they assume an almost vertical position.

Immediately surrounding the spring, which issues from the bottom of the valley, are vertical beds of a blue fossiliferous limestone, the lowest but one of the rocks incumbent on those of the Blue Ridge which are included in his series.

A very compact sandstone, used as a freestone, succeeds, then beds of clayslate again, and afterwards a highly ferruginous sandstone. Up to this point, the rocks are inclined at so high an angle, that they may be regarded as vertical, and in consequence of being so near the axis of the movement, they are often contorted and much disturbed.

Farther to the west, however, they are succeeded by strata of sandstone conglomerate, ironstone, and clayslate, dipping at a gradually decreasing angle of inclination, and this continues to be the case until they become nearly horizontal.

To the east of this spring, the density of the forests is such as rendered it impossible for me to obtain any knowledge of the mineral structure of the subjacent rocks; but this desideratum was supplied by following the road running to the east of the Warm Spring, which, as I have already stated, lies in the same valley.

Here, as we ascend the so-called Warm Spring Mountain, we observe the same rocks successively presented to us which we had seen to the west of the Hot Spring, and these -equally vertical in the immediate neighbourhood of the spring--dipping in the reverse direction, and at a high angle, farther to the west—and at length subsiding to a moderate inclination at a still greater distance from the axis of elevation. Professor Rogers supplies similar facts with respect to the other thermal waters of the district :-thus the Sweet Springs, he says, flow out from the nearly vertical, and inverted limestone near the centre of the valley ; the Red Springs and Snake Run Group from points nearer to the junction of this rock with Formation III. of the Little Mountain. The axis in which the White Sulphur Springs arise, and that of the

a

8

Thermal of Brown's Mountain, are nearly, though not exactly, in the same line.

In short, out of 56 springs more or less thermal, 46 are situated on, or adjacent to, anticlinal axes; 7 on or near lines of fault and inversion; and 3, the only group of this kind yet known in Virginia, close to the point of junction of the Appalachian with the Hypogene rocks.

CHAPTER XXXV.

THERMAL WATERS, THEIR GASEOUS IMPREGNATION, Etc.

Gases evolved from thermal waters.—Nitrogen-at Bath, its quantity

-Buxton, &c.—Cardiff –Clifton— Pyrenees--Alps-Ceylon — United States.-Sulphuretted hydrogen.-Carbonic acid.—Petrifying springs.Valleys of elevation emitting carbonic acid.-Permanency of physical and chemical properties belonging to thermal waters.—Conclusions de. duced from these premises as to the connexion between thermal waters and volcanos.—Tabular view of the properties and temperature of the best-known thermal waters.

In the last chapter I gave many examples of thermal waters which make their

appearance

where there is evidence of some convulsive force having been exerted on or near the spot from which they have burst forth, and in conformity to the established notions on the subject, regarded the force so manifested as a result of those processes in which volcanos, earthquakes, and other allied phænomena originate. Hence I concluded that thermal springs, even when at a distance from volcanos now in action, may be regarded as proceeding from causes of the same description.

And although it may be truly said, that springs of all temperatures are wont to appear where there are fissures or dislocations of the strata, yet those who have examined the spots alluded to in the foregoing chapter as giving birth to thermal waters will admit, that the chasms and disturbances of the strata which are found where they occur, are on a larger scale, and imply a more than ordinary exertion of eruptive force.

But inasmuch as it may be alleged, that a high temperature might be imparted to the water in these instances, owing simply to the depth from which it took its rise, just as has happened in the noted case of the Artesian well of Grenelle near Paris, I will next proceed to show, that natural thermal springs are in general accompanied by the same gases which volcanos commonly emit.

These may either rise in bubbles, owing to their escape