S64j Prof. Bischof on the Natural History of 



several formations in a perfectly horizontal position, whose 

 newest portion (jiingstes Glied) is much fissured, and under 

 which an impervious stratum lies, then the meteoric water will 

 penetrate the former fissured stratum, but be retained by the lat- 

 ter. As long as this horizontal position remains undisturbed, 

 no rising springs can be supposed to exist in the whole of this 

 district, and the inhabitants of such mountains could only sup- 

 ply their want of water by wells (Senkbrunnen). We will 

 now suppose, that at two points of this district, volcanic masses 

 are thrown up, and that, in consequence, a partial elevation of 

 the strata takes place, as is shewn in the diagram, fig. 1. In 

 this case, the hydrographic relations undergo considerable al- 

 terations. The consequence will be not only a movement of 

 the water on the impervious stratum, in the direction of its in- 

 clination, but meteoric water will also penetrate at A between 

 the older strata, where, during their undisturbed horizontal po- 

 sition, not a drop of water could penetrate, and this water will 

 continue to flow in the direction of the inclination of the ele- 

 vated strata.* At B, where these strata are also elevated, but 



Fij?. 1. 



to a lower level, springs will commence rising ; and as many of 

 such springs may be supposed to exist in a district, as there are 

 alternations of impervious and pervious strata in these moun- 

 tains. The most copious springs, however, will be found be- 

 tween the mass that has been broken through and the oldest 

 formation of the stratified mountain, because here, in consequence 

 of the contraction of the former mass during its cooling, a cleft 



* The same holds good with regard to the springs of fresh water. Thus 

 on the Schtc'dbisch Alp springs are always found there where cones of ba- 

 salt or basaltic tuffa have been elevated on the jura-formation. Plieninger 

 jn Poggendorflf 's Annal. t. xl. p. 493. 



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