1821.] Mr. Weaver on Floetz Formations. 349 



celebrated for the remains of extinct species of the bear, and other 

 quadrupeds, found in them. The Scharzfeld cavern extends 

 about 350 feet in length. 



The rauhkalk of the forest of Thuringia lies sometimes above 

 swinestone. According to M. Heim, it is found in two states ; 

 as a loose friable marly earth, employed in manuring sandy soil; 

 or as a grey compact rock, with intermingled calcareous spar, 

 distributed in every direction; and destitute of organic remains. 

 It is tough and firm, and generally porous, cellular, or cavernous, 

 containing cavities, from the size of the fist to that of the body 

 of a man, which are mostly filled with dusty marl. This is its 

 usual state. But by M. von Hoff, it is described rather as a 

 crystalline granular limestone, more or less porous and rifted, 

 and grey, of every shade, but particularly yellowish-grey; con- 

 taining frequently ochry spots and ferruginous particles, and 

 traversed by numerous veins of calcareous spar of variable thick- 

 ness, the lowest strata passing into swinestone. It sometimes 

 contains pectinites and beautiful corallites.* The rauhkalk of 

 the Forest frequently occurs in large shapeless masses, with- 

 out the smallest trace of a stratified structure ; and when distinct 

 strata do appear, they are often in great disorder from disrup- 

 tions and sinkings of the earth, produced by the enormous 

 fissures that are so characteristic of that rock. These fissures 

 are mostly vertical, and either empty, or partially filled with 

 stalactite or clay ; and being occasionally expanded in their 

 course, they form in some places extensive caverns, some of 

 which contain bones. It is stated by M. Heim, that this lime- 

 stone obtains in the forest of Thuringia a thickness of 70 to 120 

 fathoms, and if the subordinate beds of the formation be also 

 included, a thickness of 200 fathoms. 



The rauhkalk of Leitnitz, near Blankenburg, is traversed in 

 every direction by veins of lamellar heavy spar, from 2 to 16 

 inches thick, and by slight strings, of the same substance, which 

 ramify and disappear. It contains heavy spar also in the form 

 of beds and layers, as well as in scattered portions, both massive 

 and disseminated. 



Near Weyda, between Gera and Neustadt, the lowest beds of 

 llu' formation, which there repose immediately on greywacke 

 and greywacke slate, consist of a siliceous drusy limestone, 

 alternating with thin layers of sandy clay marl, and bearing nests 

 ;ni(l thin layers of copper ores, which form in the aggregate a 

 thickness of six, or eight, and sometimes even 30 inches. 



Ferriferous Limestone (Eisenkalk). — This is found more parti- 

 cularly at the southern, south-eastern, and eastern foot of the 



* I lanm von Schlotheini has observed in the cavernous limestone, near Gliicksbrunn 

 and LiebenBtein, keratophytes dubius, k. anccps, and escharitis retiformis ; also gry- 

 phitcs aculeatus, g. speluncarius, tellinites dubius, mytilites ceratophagus, m. striatus, 

 iircliratulitcs cristatus, t. pelargonatus, t. suftlatus, t. elongatus, trochilites helicinus, 

 ciicrinite* raniosus, and trilobites problematicus. (See Pctrcfactcnkundc.) 



