Western part of the Palatinate. 225 



The line of separation formed by the course of the Nahe, 

 between the rocks of Hunsdruck and those of the Palatinate, 

 is prolonged in the same direction to the S.W. and then 

 nearly follows the basin of the Brems, which appears to 

 form the prolongation or pendant of the basin of the Nahe, 

 on the other side of the Schaumberg, which serves as the 

 point of division of the waters. But in that part of its 

 course where the Nahe turns out of its general direction 

 (between Kyrn and Creutznach) it no longer corresponds 

 with the limits of the two formations ; I have not any where 

 found, on the right bank , the schists and quartz rocks, ex- 

 cept at the spot where it joins the Rhine ; but, as I have 

 already noticed, the coal measures and even the red sand- 

 stones, in many points penetrate on the left bank, especially 

 on the north of Sobernheim, where traces of coal have been 

 observed on the slope of the mountains of the Uundsruck,* 

 and on the N.W. of Creutznach, where the red sandstone 

 forms the surface of the country for some extent. 



The course of a river between two formations of different 

 natures and epochs, is a fact frequently observed in geologi- 

 cal investigations, and which often appears to support the 

 idea of vallejs having been formed by running waters ; it 

 is then thought that the rocks, generally less compact in the 

 neighbourhood of the limits common to two rocks, may have 

 been more easily attacked and destroyed by the waters. 

 But it will be very difficult to draw the same conclusion from 

 the examination of the valley of the Nahe. In fact, between 

 the two formations of the Hunsdruck and the Palatinate, 

 there occurs a trap formation, composed of much harder 

 rocks than those of the two formations it separates ; and it 

 is in these trap rocks that the bed of the Nahe is hollowed 

 out for nearly its whole course, between two steep banks, 

 a circumstance the more remarkable, as the breadth of the 

 trap formation is often very inconsiderable, and that it is 



* Similar traces are known, in the same position, near the forges of 

 Abentheuer, on the VV. of Birkenfeld ; i. e. on the W. of the trap zone, 

 of which we shall presently speak; this is an exception to the general 

 disposition of that zone between the two formations of the Hunsdriick 

 and Palatinate. 



