346 Mr. Weaver on Floetz Formations. [Nov. 



inches in diameter, rilled with iron ochre, or iron-shot sand and 

 clay. It passes into rauhstein, rauhvvacke, and asche, and, 

 more rarely, into marl. Destitute of organic remains. 



In Mansfeld, the stratified swinestone is found interposed 

 between gypsum, or between asche and gypsum, and also alter- 

 nating with them in thin layers. In Stollberg, it lies between 

 rauhwacke and gypsum, and near Ihlefeld, above gypsum and 

 rauhwacke. In the west of the Harz, it lies above gypsum, 

 where it is partly oolitic, the oolitic swinestone forming, near 

 Herzberg, a bed several fathoms thick in the compact swine- 

 stone, the grains of the former attaining to the size of peas. 

 This oolitic structure appears also in the swinestone of other 

 quarters, e. g. near Gera, and near Tabartz in the forest of Thu- 

 ringia. The swinestone at ilmenau lies both above and below 

 gypsum, and it is found generally in the forest of Thuringia in 

 the lower portion of the limestone formation, which is the reverse 

 of the case in Mansfeld. 



The swinestone conglomerate usually forms a bed from one to 

 three, or even seven fathoms thick, occupying the place of asche 

 and swinestone, or lying between rauhwacke aud asche, or 

 between rauhwacke and swinestone. It consists of angular 

 pieces of swinestone, closely adherent to each other, or combined 

 by a base of porous rauhwacke, asche, black bituminous clay, 

 pure clay, or clay marl. The base sometimes contains nodules 

 of calcareous spar and aphrite, and also frequently copper 

 pyrites in small disseminated portions, or slightly investing the 

 pieces of swinestone. 



Clay. — In some districts, one or more beds of bluish or green- 

 ish clay occur, which are frequently of a marly nature, usually 

 containing thin layers or streaks of tender sandy rauhstein, or 

 nodular masses of rauhwacke. Toward the bottom, the clay or 

 marly clay is sometimes blackish and bituminous, particularly 

 when resting on swinestone, including also single crystals of 

 specular gypsum. In Mansfeld, it is most commonly found 

 covering swinestone, but it alternates also with swinestone and 

 gypsum ; or it lies between rauhwacke and rauhstein ; or 

 between rauhstein and the loose sand and conglomerate of the 

 new red sandstone formation, seeming to form in this quarter 

 the connecting link between that formation and the subjacent 

 limestone, and appearing in beds from one to ten fathoms in 

 thickness. In the Riegelsdorf districts, it occurs in slight beds 

 alternating with rauhwacke, or in beds from three to eight 

 fathoms thick, lying between rauhwacke and gypsum. 



Lower, or Cavernous Gypsum. — This is found in interrupted lying 

 masses, or in beds of greater or less extent, sometimes above, some- 

 times below swinestone, asche, and rauhstein, frequently also in 

 alternation with those rocks, but always above zechstein. When, 

 however, it acquires a great thickness, it sometimes displaces 

 one or more of those substances, as well as the rauhwacke, 



