Western pa rt of the Palatinate . Q33 



it cannot be dissembled, that in certain localities there ap- 

 pears to be a great connexion between the porphyry and 

 trap. Small beds of argilolite have been cited at Schaum- 

 berg, (i. e, of the rock which, in some places, forms the 

 paste of the porphyry), as appearing to alternate with the 

 trap rocks.t I have moreover observed, in some trap rocks 

 in the environs of Mont Tonnerre, rocks of a reddish colour, 

 which might be oifered as indicating a passage into porphy- 

 ritic rocks ; lastly the copper ore that has been worked ia 

 this porphyry, may also be noticed as indicating another re- 

 semblance between this rock and the trap, in which copper 

 so frequently occurs, that its name has been given to it. 



But on the other hand it should be considered that the 

 porphyry and petrosilex have no where been observed in 

 beds in the coal measures, or trap rocks ; that they, on the 

 contrary, form entire mountains or considerable masses of 

 isolated rocks, and that it has been observed at Creutznach; 

 that, independently of the great height of the escarpments 

 which confine the valley, the porphyritic rock was, at the 

 bottom of this valley, more than 60 metres [about 197 feet] 

 thick, without the mixture of any other rock ; that the posir 

 tion of these porphyritic masses with regard to each other, 

 does not permit us to regard them as parts of thick 

 beds interstratified with the other rocks ; lastly, that in 

 every place where a distinct superposition can be ob- 

 served, the porphyry occurs beneath the red sandstone, the 

 coal measures, and even the trap ; and as it appears to me 

 that more weight should be given to facts than to vague or 

 probable inductions, I also consider that the porphyritic 

 rocks should be regarded as very probably anterior to the 

 coal measures and trap rocks, and consequently as constitut- 

 ing the most ancient of all the formations we are acquainted 

 with in the Palatinate. If this be admitted, it becomes also 

 probable that the diiferent porphyritic masses situated on 

 the E. of the trap band, belong to a single formation, on 

 which rests the whole coal basin of the Glane. 



The conclusions to which the preceding observations have 



+ Steinheimer, Geognostiche Studien, &c. p. 83. 



