344 Mr. Weaver on Floetz Formations. [Nov. 



Organic Remains. — Of these, the zechstein is generally free, 

 containing them only in certain quarters. In Mansfeld, small 

 terebratulites and gryphites have been observed ; in the forest of 

 Thuringia, gryphites, but the principal depot of gryphites there 

 lies in the ferriferous limestone at the eastern foot of the forest. 

 In Sangerhausen and Bottendorf, small terebratulites. In Saal- 

 feld, ammonites ; and in Lower Saxony, the lower strata contain 

 entrochites in great number, and also serpulites and bivalves. 



Remark. — In those tracts occupied by the weissliegende, marl 

 shale, and zechstein, may be observed all those varieties of posi- 

 tion that are so common in coal fields ; inflections, troughs, and 

 saddles, with foldings of the strata, arising chiefly from the 

 inequalities of the fundamental rock, but seemingly also in part 

 from unequal pressure exerted in a lateral direction. To these 

 are to be added alternate depressions and elevations of the strata, 

 produced by slips or faults. The faults are true veins, usually 

 occupied by calcareous spar, heavy spar, and quartz, with mineral 

 pitch, and ores of copper, iron, cobalt, nickel, and galena ; some- 

 times also they are filled with a conglomerate, composed of frag- 

 ments of swinestone, zechstein, and shale. These veins penetrate 

 occasionally below the weissliegende ; very rarely, however, to 

 any great depth into the old red sandstone. 



Most of these beds acquire a greater thickness, in proportion 

 to their increased descent into the earth. 



Upper Portion. 



Rauhwacke. — When this appears, it reposes always on zech- 

 stein, varying from 21 inches to six, seven, and more fathoms in 

 thickness. It is a porous, siliceous, limestonfe, partly bituminous 

 and cavernous : the cavities in it sometimes occurring three or 

 four fathoms in breadth and height. Fetid, and of great variety 

 of aspect and structure. Grey and black, of various shades ; 

 compact, or foliated granular, with dull spots and streaks ; amyg- 

 daloidal, with round grains of white carbonate of lime ; vesicular 

 and scorious ; brecciated, with a sandy or compact base ; also 

 granular and oolitic. The foliated granular variety is sometimes 

 yellowish-white, and passes into sparry iron ore, or into ferrife- 

 rous limestone. 



Minerals occasionally intermixed : calcareous spar in grains, 

 or in single folia; earthy and slaty aphrite, in large nests, in 

 layers and strings, and disseminated ; quartz in round portions, 

 independent of the general diffusion of siliceous matter, and also 

 in crystals, in nests or layers of iron ochre and sparry iron ore ; 

 brown ironstone, in lenticular nests or nodules ; and, more 

 rarely, iron pyrites in filamentous veins, or disseminated. No 

 petrifactions have been observed in it. 



Rauhstein is chiefly distinguished from rauhwacke by its 

 greater simplicity of structure, and by containing only small 

 drusy pores. Fetid, and eflervesces violently with acids. Grey, 



