352 Mr. Weaver on Floetz Formations. [Nov. 



swinestone, rauhwacke, and zechstein, among which, however, 

 rauhkalk sometimes appears. When in contact with primary 

 rocks, the lowest bed is composed of the calcareous ironstone, 

 noticed above; accompanied with sparry iron ore, and heavy 

 spar, and sometimes also with ores of copper. On the other 

 hand, at the eastern and south-eastern foot of the forest, the 

 formation consists of the bituminous ferriferous limestone, with 

 beds of swinestone and bituminous marl shale. 



M. Freiesleben, in tracing the lower limestone formation, ex- 

 tends his views also into the south of Germany, Dalmatia, the 

 Pyrenees, &c; on which occasion he notices the opinion of Baron 

 A. von Humboldt, "that the zechstein of Thuringia is coeval with 

 the floetz limestone of the high Alps ; " and the representation 

 of Baron von Buch, " that the colossal calcareous chain which 

 forms the northern side of the Alps in Bavaria, Salzburg, Austria, 

 and Stiria, belongs to the same era, containing within that tract 

 the great deposit of gypsum and rocksalt."* 



The limestone formation of Upper Silesia, containing, near 

 Tarnowitz, galena, calamine, and ironstone, is also referred by 

 Baron von Buch to the same period ,f 



If we now turn to the English magnesian limestone formation 

 (which comprises also argillaceous and sandy limestone), as the 

 equivalent of the German, just described, we may find several 

 corresponding characters indicated in Mr. Winch's account of 

 Durham and Northumberland (Geol. Trans, vol. iv), and in Mr. 

 Farey's Description of Derbyshire (vol. i). For the general dis- 

 tribution of that formation (including the calcareous conglome- 

 rate), reference may be had to Mr. Greenough's Geological Map. 



3. Clay and Sandstone Formation of M. Freiesleben. 



Second Floetz Sandstoiie Formation of Werner. 



New Red Sandstone Formation. 



This passes by various gradations into the lower limestone 

 formation, and apparently also into the upper or shell limestone. 

 It is widely distributed, filling up those great basins or concavi- 

 ties that are enclosed by rocks of an earlier era, and appearing 

 always to increase in thickness in proportion to its distance 

 from the outcrop of the subjacent limestone formation. Its 

 strata are found very differently disposed, and generally uncon- 

 formable to the older formations; varying rapidly from the 

 horizontal to the vertical position ; also undulated and forming 

 troughs. In the forest of Thuringia, it acquires a thickness of 

 1200 to 1500 feet, but in those parts of Mansfeld which adjoin 



• But i* was reserved for Professor Buckland to establish this position in a clear 

 light, as well as to solve other doubtful points affecting the same regions, 

 t Von Buch. Geog. Beob. p. 104, and 108—113 of vol. i. 



