14 GEOLOGICAL MEMOIRS. 



remarks on the Lower Cretaceous beds near Brunswick ; his in- 

 tended memoir on this subject requiring more time for its completion. 



The whole of the Hils-conglomerate does not contain fossil Echi- 

 noderms. In the fullest development of the Conglomerate, where it 

 does not pass into one bed, the upper part contains no trace of Sea- 

 urchins, although it has many fossils common also to the lower por- 

 tion. The Echinoidea are confined to the older part. Here there 

 are in one and the same horizon two different /«cie5, passing however 

 one into the other ; the one is full of Spatangoidce ; the other in 

 its typical development exhibits only Cidaris remains. 



The Spatangoidce fades occurs in the Brunswick district, on both 

 sides the Asse (Berklingen, Gross-Vahlberg, Gevensleben, between 

 Denkte and Wittmar, &c.), — on the Oesel (particularly at the spot 

 called Busche), — on the Fallsteine (Achim and Wetzleben), — and be- 

 tween Goslar and Harzburg on the northern side of the Hartz. 



The Cidaris fades is seen on the southern brow of the Elms 

 (Rautenberg, near Schoppenstadt), — on the heights near Apelnstadt 

 and Salzdahlum, between Brunswick andWolfenbuttel, — on the Oesel 

 (Kissenbruch sand-pit), — and near Schandelah. 



When the Hils-conglomerate is not divisible into upper and lower, 

 it either contains no Echinites, — as at Bohnencamp near Querum, 

 not far from Brunswick (here the Neocomian sandstone of the Teuto- 

 burger Wald, described by F. Roemer, appears to belong), — or only 

 the Cidaris, as at Elligserbrink, not far from Delligsen in Hilse. 



With regard to its stratigraphical position, the Hils-conglomerate 

 in the Northern Hartz lies on the Jurassic strata (the lower, middle, 

 or upper, according to the several localities), and in the Hildesheim 

 district it rests on the Wealden. It is generally overlaid by a thick 

 mass of clay, which in its fullest development presents the following 

 members, from below upward : — 



1 . Clay with the fossils of the Speeton Clay, as cited by Phillips, 

 — but leaving out the Gault forms, &c. 



2. Clay with Belemnites semicanaliculatus, Blainv. (according to 

 D'Orbigny), and Ammonites Nisus, D' Orb. ;^ the Gargas-marl = 

 Aptian. 



3. Lower Gault Clay, poor in fossils ; locally replaced by a littoral 

 formation, the Subhercynian Lower Quader-sandstone. 



4. Upper Gault Clay with Ammonites auritus. Sow., Belemnites 

 minutus. Lister. (See Zeitschr. d. Deutsch. Geol. Gesellsch. vol. v. 

 p. 501.) 



Still higher are variegated marls [flammen-mergel], planer, and 

 lastly argillaceous and sandy marls (the latter with Bel. mucronatus) 

 of the age of the White Chalk. 



The clays nos. 1 to 4 were comprehended in the term '' Hilsthon," 

 given by A. Roemer before it was known that any of them possessed 

 a distinct and characteristic fauna, the publication of which M. von 

 Strombeck reserves to himself. The rich fossiliferous bed at Ellig- 

 serbrink, 4 to 12 feet in thickness, which Roemer likewise included 

 in it, is, as above mentioned, decidedly Hils-conglomerate. 



