older Deposits of the North of Germany and Belgium. 259 



The country around Siegen may be considered as one of the great domes of eleva- 

 tion of these provinces, the strata of which, after considerable undulations and 

 disturbances, plunge both to the N.N.W. and S.S.E. On the north side they are 

 covered by the upper bands of grauwacke, flagstone and impure limestone above 

 noticed ; and to the south they exhibit, as before explained, a similar ascending 

 order into the country east of Dillenburg, v^here the grauwacke flagstones are sur- 

 mounted by the black fossihferous slates of Wissenbach (PI. XXIIT. figs. 6 and 7), 

 followed by the Devonian groups. 



In a country so convulsed and so perforated by rocks of igneous origin, it would 

 be indeed unreasonable to expect a perfect symmetry in all the details of the sedi- 

 mentary deposits ; thus though several points of elevation may be observed upon 

 the Rhine, one for example near Unkel, another west of Coblentz, and a third near 

 Caub, between Coblentz and Bingen, none of these lines of disturbance can, we be- 

 lieve, be traced for any great distance into the country on either bank of the river. 

 In short, we think that many of these parallel lines of dislocation are of short 

 lateral extension, and have thus produced a number of undulations, and sometimes 

 of complete reversals. If the most patient investigation of the rocks on the deep 

 fissures of the Rhine fails to teach us more than this lesson, how hopeless must it 

 be to attempt to draw secure conclusions from any evidence to be collected in the 

 interior of this region, where the natural fissures are much less clear and per- 

 sistent ! 



These considerations lead us to say a few words upon some of the apparent ano- 

 malies of this country, and to endeavour to give some account of the position into 

 which the various rock-masses have been thrown. The section (PL XXIII. fig. 4) 

 exhibits the Silurian Rocks rising into mountain masses with a steady dip to the 

 N.N.W. , which carries them beneath the Devonian and carboniferous rocks ; and 

 this dip is persistent along the whole of the Westphalian frontier, as far as it is 

 flanked by the productive coal-field : but these transverse sections, if continued 

 further across the mountains towards the south, conduct us through certain 

 undulations to a great irregular central area, which forms a kind of mineral 

 axis to the whole region. From this wide area of elevation, which may be con- 

 sidered, in a general way, to range around the towns of Olpe, Drolshagen and 

 Siegen, the dip is reversed to the S.S.E. And if a section be extended from any 

 of the last-mentioned places to the Taunus (a distance of not less than sixty miles), 

 by Dillenburg, or Wetzlar, or Dietz, the geologist will find the great southerly dip 



1200 to 1900 feet, four only out of a list of eighty-three heights given exceeding 2000 feet ; the highest 

 mountain in the Westphalian country, the " Kahle-Astenberg," being 2536 feet above the sea-level; these 

 measurements are in Paris feet. The average heights of Nassau, Siegen, &c., are therefore very much 

 the same as those of the Silurian region. (See Mr. Murchison's ' Silurian System,' Map and Tables.) 



