Natural History of Voleanos and Earthquakes. ; 
¢ fs 
It is possible that the raising and fracture of the secondary 
strata in such valleys of elevation, was the consequence of the 
elevation of voleanic masses from beneath, which masses have 
not appeared at the surface. Supposing this to be the case, 
we can easily imagine that at such places, mineral springs may 
be produced which contain carbonates of alkalies, because the 
Meteoric water only can penetrate to these masses. But the 
low temperature of the acidulous springs in question, shows that 
meteoric water penetrates to very small depths only at these 
col 
es. 2 oe 
| Valleys of elevation of the kind described, seem to be of tole = 
| erably frequent occurrence; thermal springs and disengagements 
of carbonic acid gas are not, however, always met with, either 
for want of sufficient depth of the clefts, or for want of mate- 
rials which give rise to the disengagement of carbonic acid gas. La 
Instances of three of such valleys at the eastern end of the ba- 
sin of London, are given by Buckland.* See also his and Con- } 
ybeare’s+ description of the structure of the country at St. Vin- 4 
a cent’s rocks; and the example at Matlock long ago pointed out 
. by Whitehurst.{ Many other instances of this kind occur im 
Danbeny’s report. | Stifft$ also has long ago shown, that the 
Tocks in the neighborhood of the mineral springs of the Nassau 
territory manifest evident changes in the direction and inclination 
of their Strata, especially saddle-shaped elevations, often accom- 
Panied with fractures, 
_ Finally, dislocations or faults produced by elevations and 
intersecting stratified rocks, may direct the subterranean course 
of springs in a very different manner. Buckland has given 
Many instances of springs originating from causes of this kind. 
' We take a summary view of all that has been said on’ the 
Subject of thermal springs, we. shall find it impossible to avoid 
Feeognizing a relation between elevations of Plutonic masses, the 
Upraising of Neptunian formations, and thermal springs. Cause 
and effect have, however, been frequently confounded here. 
Thermal and mineral springs are seldom, perhaps never, the cause 
of those effects, Where, however, these effects are observed, 
® 
% Geological Transact. sec. ser. vol: ii, parti, p- 119. t Ibid, vol. i, 
t Theory of the Earth, 1786. || P. 66. 
: Rullmann Wiesbaden, &c. 1823, p. 103. 2 
Geology and Mineralogy, &c, London, 1836, Vol. ii, p. 106 and 110, 
