1823.] the principal Mountain Chains of Europe. 143 



interesting details are also given in Villefosse sur la richesse 

 rainerale (torn. ii. p. 432 6c seq.) and illustrated in the magni- 

 ficent atlas of that work by sections exhibiting the contortions 

 &c. of the beds, and the mode of working them, from PJ 25 

 to 27. 



Proceeding still further along the northern border of the same 

 transition chain, against which all these deposits of coal repose 

 we rind the more recent formations (probably of the tertiary 

 class) intruding upon it, and concealing the coal till we cross 

 the Rhine near Bonn. On the right bank of that river, these 

 again recede to the north, and in this direction we again find an 

 extensive coal field proceeding along the small river Ruhr a little 

 above its junction with the Rhine : on the south the beds of this 

 coal field describe the segment of a circle, cropping out against 

 alternations of limestone, shale, and what is called greywacke 

 (our old red sandstone probably), which separate them from the 

 regular transition slate : on the north they are bounded by the 

 overlying and more recent deposits. An account and plans of 

 this district may be found in Villefosse, torn. ii. p. 424 and 

 PI. 24. 



A little on the south of the same district of transition rocks 

 whose northern border we have been hitherto pursuino-, limited 

 coal fields occur in the country between the Moselle and Rhine; 

 first, between Sarrebruck and Sarre Louis on the river Sarre, 

 and, secondly, near Waldmohr on the banks of the Glane' 

 extending to its confluence with the Nahe : the beds of the for- 

 mer coal field are described as ranging south-west and north- 

 east, and dipping north-west ; they are covered with red sand- 

 stone, and also surrounded by the same formation on the points 

 to which they rise, appearing, therefore, to repose upon it ; but 

 these appearances are very vaguely described ; " sur ces ores 

 rouges semblent quelquefois s'appuyer les couches de houille ; " 

 they are probably deceptive. A careful examination of the 

 country between this coal field and the northern transition chain 

 is necessary to ascertain its true relations. Villefosse, torn. ii. 

 p. 447, and PI. 27, may be consulted on this district. 



Keferstein has given a brief but very clear description of this 

 porphyry and coal district, extending on the south of the slate 

 mountains between the Rhine and the Moselle by Zweybruck 

 and Sarrebruck (Teutschland, &c. p. 81, No. 1). 



He describes the coal measures, exhibiting the ordinary mem- 

 bers and characters of this formation as extending between Sar- 

 rebruck and Neukirch ; they contain some alternating beds of 

 carboniferous limestone. The stratification is extremely con- 

 torted and dislocated ; masses of unstratified trap rocks (com- 

 prising porphyry wacke, amygdaloid, greenstone, and basalt), are 

 interposed among the coal measures. Agates abound in the 

 amygdaloid. 



