Volcanos and Earthquakes. S75 



already existed at the distance of but a few steps from the 

 spot.* 



Phenomena, perfectly resembling those which are observed 

 where volcanic masses have actually broken through, present 

 themselves very frequently. A cleavage, reaching to great 

 depths, may also be a consequence of a preceding elevation 

 and fracture of the component strata, without an actual break- 

 ing through having taken place. These phenomena are found 

 in formations of all ages. Thus Hoffmann-f- has pointed out, 

 in the north-west of Germany, some peculiar valleys which, 

 originally perfectly closed, are surrounded on all sides by a 

 precipitous escarpment, whose component strata incline from 

 the centre downwards in every direction. He has given to 

 these valleys the name of valleys of elevation. The most re- 

 markable of these, are those of Pyrmont, Member^, and Dri- 

 burg", where the well-known chalybeate springs rise, accompanied 

 by a considerable disengagement of carbonic acid gas. Ft/r- 

 mont and Meinberg lie precisely at those places where the di- 

 rections of the north-eastern 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 



* A joint-stock company is also at this moment employed in boring into 

 clay-slate rock at Tlud-Ehrenhreitstein, near CoUentz, in order to procure ther- 

 mal springs. Since this spot lies scarcely two German miles distant from 

 the well-known hot springs of the temperature of 75° to 131° F. at Ems, and 

 at a lower level, and since an acidulous spring already exists there, the 

 possibility of the success of this undertaking is as little to be despaired of, 

 as a favourable result can be promised. Leop. von Buch's remarks on this 

 subject in Noggeraths Ausflug nach Bohmen. Bonn. 1838, p. 5. The in- 

 stance of the salt work of Nauenhebn, near Friedberg, where a salt-spring of 

 100° F. with immense disengagement of carbolic acid gas was obtained by 

 boring, proves that success is more likely to attend by boring into second- 

 ary formations, where a more frequent alternation of various strata exists. 

 At Hofgeisinar, near Ckt^sd, a new thermal spring with copious disengage- 



lent of carbonic acid gas was also obtained by boring in May 1834. 

 t PoggendorJBf's Ann. t. xvii. p. 151. 



