Western part of the Palatinate. 229 



ized formations of petrosilicious porphyry, and argillaceous 

 clay porphyry (argilophyre of M. Brongniart), have also 

 been observed in the Palatinate. The predominant rock 

 of this class has a whitish, greyish, or roseate paste, and con- 

 tains crystals of felspar, quartz, mica, and sometimes horn- 

 blende. 



These porphyries occur on both sides of the trap zone : 

 on the western side I have observed them, proceeding from 

 S. to N. 1st, at Dippenweiler (3 leagues on the N. of Sarre- 

 Louis) where they contain copper, which has given rise to 

 considerable works ; 2dly, near Selbach, Gumbsweiier, Eck- 

 elhausen, and Ellweiler ; 3dly, at Herrstein. These di£Fer- 

 ent positions are perhaps the traces of a porphyritic zone, 

 which would be situated between the schistose rocks of the 

 Hunsdriiek and the trap of the Nahe : at Harrstein the por- 

 phyry is even inclosed between the schist beds ; but its 

 paste is here greenish, it contains crystals of hornblende, 

 and perhaps belongs to a different formation. Porphyry 

 constitutes much more extensive masses on the E. of the trap 

 formation, which occur in the midst or on the edges of the 

 coal basin of the Glane. The principal of these masses are, 

 1st, the Donnersberg or Mont Tonnerre ; 2dly, the Konigs- 

 berg, near Wolfstein, and 3dly, the group on the S. of 

 Creutsnach. 1st, The porphyritic formation constitutes the 

 whole nucleus and a great part of the sides of the Mont 

 Tonnerre, the mass of which is at least 8 or 10 leagues in 

 circumference. This mountain is the most elevated point of 

 the Palatinate : its height is about 600 metres [1968 feet] 

 above the level of the Rhine at Mayence ; it is as if isolated 

 in the midst of a country of low hills, above which it rises 

 more than 400 metres [1312 feet]. These hills are, 

 on the N. and W. of Mont Tonnerre, formed of the coal 

 measures ; and to the E. and S. by micaceous red and slaty 

 sandstone. Two leagues to the S. of Mont 'J'onnerre, a red 

 sandstone of a different nature is found, mixed with quart- 

 zose conglomerate, which constitutes the last mountains of 

 the Vosges. On the ]V, W. and S.W. branches of the trap 

 formation ^re seen, which appear to rest agaiust the foot of 



