224 Proceedings of the Royal Physical Society, 



greatly from those of the British Isles, 

 is, as its name implies, divisible into 

 groups. It is found all round the Harz. 



The German Trias 

 three well-marked 



(3.) Keuper, 



(2.) Muschelkalk, 



(1.) Bunter, 



Variegated clays and marls, with sandstone and gypsum. 



( Limestone, with Ammonites (Ceratites) nodosus. 

 Limestone beds and clays below oolitic lime- 

 stone, with Terehratula vulgaris, T. trigo- 

 nella, Lima striata. 



Dolomitic marls, with some gypsum ; no fossils. 



" Wellenkalk " and "Schaumkalk," with En- 

 crinus liliiformis, Turritella scalata, Turbo 

 gregarius, Trigonia Icevigaia, etc. 



Upper, 



Middle, 



Lower, 



Chiefly reddish or variegated sandstones, with beds of 

 roestone, gypsum, and rocksalt, almost unfossiliferous. 

 Posidonomya Germari. 



Large beds of rocksalt occur in the German as well as in 

 the English Trias. A thick bed occurs at Schonebeck between 

 the upper and middle divisions of the Bunter, as well as that 

 between the Zechstein and Lower Bunter, already alluded to. 



g. Jura. 



The Jurassic Eocks are developed in a narrow band along 

 the northern boundary of the Harz, and are divided into (1.) 

 Lias or Black Jura ; (2.) Dogger or Brown Jura ; and (3.) 

 Upper or White Jura. 



(1.) The Lias or lowest division is classified chiefly by its 

 Ammonites. 



Upper Lias, 



Middle Lias, 



!9. Clayey marls with Am. radians, striatus, Bel. tripartitus. 

 8. Bituminous marls : Am. serpentinus, communis, Posi- 

 donomya Bronni, Avicula substriata, etc. 

 (7. Dark plastic clays : Am. Amaltheus, spiriatus, Inocer- 

 I amus suhstriatus. 



6. Clay marls and grey oolitic limestones : Am. capricornus, 



{ A. curvicornus, fimhriatus, Belem. paxillosus, umhili- 



cdtus, clavatus, breviformis. 

 5. Oolitic limestones and red ironstones : Am. hrcvispina, 



Jamesoni, Terebratula numismalis, Spirifcr rostratus. 

 4. Grey and blue clays with ironstone and limestone 



geodes : A. planicostata, A. ziphus, obtusus. 

 3. Dark blue tough clays and red ironstone beds (worked 



at Harzburg) : Am. BucTclandi, GryphoBa arcvuita, 



Spirifer Walcotti {-'' arietes beds "). 

 2. Zone of Ammonites angulatus. 

 1. Yellowish clays with intercalations of sandy limestone : 



Am. Johnstoni [Sow.) = Spilonotus plicatus (Quenst.). 



(2.) Above the Lias comes the Dogger or Brown Jura, 



Lower Lias, 



