68. Natural History of Volcanos and Earthquakes. 
_ valleys of elevation. 'The most remarkable of these, are those 
of Pyrmont, Meinberg, and Driburg, where the well-known 
chalybeate springs rise, accompanied by a considerable disen- 
gagement of carbonic acid gas. Pyrmont and Meinberg lie 
precisely at those places where the directions of the northeastern 
system of mountains and of that of the Rhine intersect. 
Here, therefore, we find also a considerable disengagement of 
carbonic acid gas; yet no volcanic masses which have broken 
through; but only the secondary strata of shell limestone, of 
keuper and variegated sandstone, raised up and fractured. ‘The 
mineral springs are of another kind, and the alkaline carbonates 
are wanting, while sulphates and metallic chlorides supply their 
place. We may easily explain this by the absence of rocks con- 
taining alkalies; for instance, basalt or any other volcanic rocks. 
The clefts produced by these fractures reach certainly to great 
depths ; carbonic acid gas may be evolved from them, but its 
elasticity seems to prevent the penetration of meteoric water. 
The mean temperature of the mineral springs there, exceeds, 
therefore, but little that of the place of their occurrence. This 
is especially the case with the mineral springs at Meinberg, 
whose considerable annual variations of temperature prove that 
they take their origin very near the surface. The considerable — 
elasticity with which the carbonic acid gas escapes, and which is 
greater than I have observed at any place where gas is evolved, 
prevents, no doubt, the deep penetration of meteoric water. More- 
over, we may remark, that the inclination of the strata, from the 
centre downwards in every direction, carries the meteoric water 
away from the seat of the evolution of the carbonic acid gas. 
Even supposing, then, that the water could penetrate to the depth 
of the channels of carbonic acid, it would not rise, owing to the 
Fig. 3 
absence of the pressure of a column of water. The section - 
the valley of elevation of Pyrmont, taken from Hoffmann’ 
work, Fig. 3, distinctly shows the inclination of the seen 
cd, ef, gh, ik, lm, from the centre downwards. 
