﻿STROMBECK ON THE NEOCOMIAN OF BRUNSWICK. 



105 



On the Neocomian Formation of the neighbourhood of 

 Brunswick. By Von Strombeck. 



[Zeitschrift. d. geolog. Gesellscli. vol. i. pp. 462 et seq., and Leonhard und Bronn's 

 Jahrb. f. Min. 1850, p. 230.] 



This formation for the most part consists of a bluish grey and some- 

 times shaly clay (Hils-clay, of Roemer*), having a thickness of several 

 hundred feet. Towards the upper part, at some spots of limited ex- 

 tent, small crystals of gypsum are found, also beds of argillaceous iron- 

 stone nodules, spathic iron, and impure limestone. Organic remains 

 are rare. 



Not far from the base of the formation there is an horizon marked 

 by the presence of heterogeneous rocks, occurring in a great quantity 

 and of varying thickness, up to as much as forty feet. They are 

 not, however, constant on the strike, and in some districts they appear 

 to be entirely wanting. The clay, by admixture with lime, sometimes 

 becomes marl, and from this passes into very hard, bluish grey lime- 

 stone. At other places, in slightly coherent, yellowish grey, argilla- 

 ceous limestone, occur angular or rounded fragments of clay-iron- 

 stone. When the calcareous cement disappears, a bed of pea-ore 

 [Bohn-erz] is found, which bears somewhat of an oolitic appearance. 

 In all these heterogeneous rocks many species of organic remains 

 occur, some in a good state of preservation, others in fragments. At 

 some places the fossils are found imbedded in pure clay. These fos- 

 siliferous rocks near the base of the formation are equivalent to the 

 Hils-conglomerate of Roemer. 



This formation rests upon the Upper Jura (Coral-rag and Portland- 

 stone) ; and where these rocks are absent, as near the foot of the 

 Hartz, it lies upon the Lias with Belemnites and the Opalinus-clay. 

 Near the Hartz it is covered by the Lower Freestone [Quader], which 

 is found as far distant as the neighbourhood of Hornburg ; and, where 

 the <e Quader" does not exist, as near the Eime and the Asse, &c, it 

 underlies the Variegated Marl [Flammen-mergel] . 



Gault, such at least as it appears in England, France, and Savoy, 

 is here wanting. 



Roemer has paralleled this formation with the Neocomian of Switz- 

 erland and South of France, and with the Lower Greensand of Fitton ; 

 and that this opinion is well founded, is proved by the fauna. 



In the lower fossiliferous rocks the Radiata and Mollusca of most 

 frequent occurrence are, — Toxaster complanatus, Ag. (Spatangus re- 

 turns, Lam.), Pyrina pygcea, Desor (Nucleolites truncatulus, Rcem.), 

 Terebratula oblonga, Sow., T. multiformis, Rcem., T. biplicata, var., 

 sella, Sow., Ostrea macroptera, Sow., Exogyra spiralis, Goldf., E. si- 

 nuata, Sow. (E. Couloni, Defr., and E. aquila and falciformis, Goldf.), 

 Pecten crassitesta, Rcem., P. atavus, Rcem. (Janira atava, d'Orb.), 

 Myopsis (Panopcea) arcuata, Ag., Belemnites subquadratus, Rcem., 

 Ammonites bidichotomus, d'Orb., and Am. Astierianus, d'Orb. 



Palseontologically considered, the Hils-conglomerate of Brunswick 



* [See notice of the Hils-clay and -conglomerate, Proc. Geol. Soc. vol. iii. 

 p. 324.— Transl.J 



