) STRATIGRAPHICAL GEOLOGY 



Coblentzian in three subdivisions 



c. Slates Avith Spirifer paradoxus and Phacops laciniatus. 

 b. Quartzites with Spirifer auriculatus. 

 a. Grey \vacke with Homalonotus ornatus, etc. 

 Hundruch Slates with Phacops Ferdinandi, Homalonotus planus, 



Dalmanites rhenanus, and Spirifer primcevus. 

 Taunus quartzite with Spirifer primcevus, Rcnsellceria crassicosta, 



and Homalonotus Rccmcri. 



Variegated sandstones and slates with arkose and conglomerate at 

 the base. 



In the Kellerwald district east of the Rhine and north of the 

 Lahn the Middle Devonian consists mainly of shales with occasional 

 bands of limestone, and this series has been subdivided by means of 

 the Goniatites into the following zones : 



p., .,- fZone of Mreneceras terebratum. 



in \ ,, Tornoceras circumflexiferum. 

 Eifelian-f " Agoniatites occnltus. 

 ( ,, Mimoceras gracile. 



The Harz Mountains also largely consist of Devonian rocks, but 

 these have been the subject of much controversy, and it is only 

 within the last fifteen years that the difficulties have been partially 

 explained. The mountains form a range to the south of Brunswick 

 between Gottingen and Halle, the central part or Brocken being a 

 mass of intrusive granite rising to a height of 3700 feet. The 

 Palaeozoic area has a length of about 56 miles and a maximum 

 breadth of 20, the western part being known as the Upper Harz 

 and the eastern as the Lower Harz. Eecent researches have shown 

 that the whole area is much more plicated and dislocated than had 

 been supposed, 14 and that the supposed mixture of Silurian and 

 Devonian faunas can to some extent be explained by these disloca- 

 tions, for there is really a basal mass of Silurian age (see p. 185). 

 The extent of this and the plane of division between it and the 

 Devonian rocks have not yet been determined. The facts are these 

 below the Coblentzian quartzites there is a great thickness of 

 slates and greywackes (the so-called Hercynian Series), and these 

 contain few fossils except plant remains ; but here and there are 

 patches of limestone, and some of these are Devonian and con- 

 sequently of Gedinnian age. Thus the limestones of Scheerentheg 

 and Klosterholz containing Spirifer hercynicus, Sp. Decheni, and 

 Rhynch. princeps and that of Herzgerode containing the peculiar 

 Gastropod Hercynella (allied to recent Siphonaria) are referable to 

 the Devonian. 



The Coblentzian is represented by a set of quartzites without 

 fossils which pass up into fossiliferous sandstones containing many 



