148 Rev. IV. D.Conybeare on a Geological Map of [Feb. 



trict is supposed to have a subterraneous connexion with that of 

 Petersbirge near the Hartz. 



(O.) Coal and Porphyry of Bohemia, and Bohemian Silesia. 



A zone of these formations crosses these countries from 

 south-west to north-east. It may be thus subdivided : 



1. The Pilsen Coal District. — A series of detached coal 

 basins reposing on transition slate, extending from Merklin, by 

 Pilsen and Radmtz, to Prague. Porphyry does not occur in 

 this tract. 



2. The Waldenburg District. — Extending from Landshut to 

 Waldenburg and Glatz between the Riesengebirge and Eulenge- 

 birge. It exhibits both porphyry and coal.* These formations 

 alternate ; a chain of them follows the slate mountains ; then 

 succeeds the red sandstone. The coal is very irregular in its strati- 

 fication ; the principal variety is slate coal, the ordinary coal 

 rocks occur : the beds are numerous. 



3. 'The Pilsen and Waldenburg Districts have evidently a sub- 

 terraneous communication beneath the intermediate plains in 

 which the coal formation often makes its appearance. No por- 

 phyry is seen at these points. 



4. At Freiheit Senile and Liebenau, the porphyry alone 

 appears. 



(P.) Moravian Coal District. 



Coal, unaccompanied by porphyry, occurs in the environs of 

 Brunn. 



(Q.) Upper Silesian Porphyry aiul Coal District . 



This is an extensive district including the following towns : 

 Pless, Freystadt, Tfoppau, Iagerndorf, Kosel. It lies partly in 

 Silesia, and partly in Poland : in the former, it exhibits coal 

 only ; in the latter, coal and porphyry. The coal formation 

 reposes immediately on the slate mountains of the Sudetenge- 

 birge. The strata are elevated in approaching that chain, but 

 more horizontal as they recede from it. The coal measures are 

 covered by the porphyry, which, in its turn, supports the Alpine 

 (magnesian) limestone. The coal measures pass by such a gra- 

 dual transition into the greywacke on which they repose, that, 

 according to Keferstein, it is difficult to ascertain the exact 

 demarcation between them. The usual rocks of the coal forma- 

 tion prevent grits of various textures ; millstone grit, shale, with 



* According to the map and sections of Von Raumer, the outcrop cf the principal 

 coal beds follows the border of the transition rocks ; but this writer mentions a conglo- 

 merate and a limestone among the upper beds of the transition series ; and as he (in 

 common with Bcudant, Humboldt, Daubuisson, &c.) always refers the old red sand- 

 stone and mountain limestone of English geologists to the transition class, he very pos- 

 sibly thus designates them here. The same map and sections show that a great part of 

 the porphyry and the red sandstone generally arc placed above the great coal formation. 

 But lie adduces instances of coal subordinate to the red sandstone, and inclines to consi- 

 der them as referable to one great formation. 





