412 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 4, 



ous wooded mass, the culminating points of which never exceed 3500 

 EngUsh feet above the sea, and whose main direction is from N.W. 

 to S.E. Its length from the environs of Eisenach on the N.W. to 

 those of Kronach on the S.E. is upwards of sixty miles, and swelling 

 in width from a narrow apex on the N.W. it attains a maximum 

 width of about twenty miles in its S.E. portion. 



The south-eastern half of this tract is essentially distinct from the 

 north-western ; the first or wide part being made up of very ancient 

 sedimentary strata, the second of crystalline rocks chiefly eruptive 

 and here and there of metamorphic character ; whilst the whole is 

 surrounded by a girdle of Permian rocks, followed by lower mesozoic 

 deposits which delineate the dominant direction of the mountains 

 which they subtend. 



Fig. 1 . — Diagram showing the General Succession of the Palaeozoic 

 Rocks in the ThUringerwald. Horizontal distance about 12 miles. 



N.W. S.E. 



1> t tx 



e, Permian (Rothe-todte-liegende, Zechstein, 



and Sandschiefer). 

 d. Lower Carboniferous. 



c. Upper Devonian. 



b. Lower Silurian {b*. Courses of limestone). 



a. Bottom rocks. 



Lower Grauwacke or Cambrian^ and Silurian. — The most ancient 

 rocks, as seen in the S. Thiiringerwald, consist of greenish talcose 

 schists, traversed by white quartz veins, and of ferruginous and 

 purple sandstone, the latter much resembling certain rocks of the 

 Longmynd in Shropshire. When examined in detail, these rocks 

 (marked a in the general diagram, fig. 1) exhibit towards the base 

 quartz rock and dark slaty schist, the latter containing aluminiferous 

 schist. These form the lowest courses, as seen in several undu- 

 lations ; the upper and chief part being the greenish slaty rocks above 

 mentioned, and in which whetstones occur. In these rocks ("griine 

 grauwacke" of Richter, or " Cambrian" of the British Geological Sur- 

 vey), which have all been affected by a slaty cleavage, no other organic 

 remains except Fucoids {Phycodes circinatus) have been found. 



These fundamental rocks («), exhibited in masses of great dimen- 

 sions, and attaining, in the Oberland of Meiningen, elevations of up- 

 wards of 3000 feet above the sea, are covered conformably by the 

 deposits which M. Richter termed grey grauwacke, an extensive and 

 diversified group (6) of slate and sandstone with some courses of alumi- 

 niferous schist {graue grauwacke, dach-schiefer, griff el-schiefer, &c.), 

 the whole of which is referable through its fossils to the Lower Silu- 

 rian rocks. The section, fig. 1, merely represents the general suc- 

 cession. But from the observations of M. Richter, we believe that 

 this fossiliferous Lower Silurian consists in its inferior portion of 

 roofing-slates and coarse grits (almost conglomerates), subordinate to 



