226 Proceedings of the Royal Physical Society. 



r2. Limestone, 1 to 2 ft., full of corals, especially Astrea 



Lower J helianthoides. 



Oxford group. ] 1. Marly limestones, with A. cordatus, A. biplex, Gryphcea 



I dilatata. 



h. Cretaceous. 



The Jurassic rocks around the Harz are covered conform- 

 ably by the basement beds of the Cretaceous system, which is 

 only found on the north side of the range. 



The Cretaceous system is divisible here, as elsewhere in 

 Germany, into 5 main groups : (1.) ISTeocomian (or Hils), and 

 (2.) Gault (Lower Chalk) ; (3.) Cenomanian ; (4) Turonian ; 

 and (5) Senonian (Upper Chalk). There is no representative 

 of the Wealden in the neighbourhood of the Harz. 



The Hils conglomerate and limestone form the base 

 of the system, and are covered by the Hils clay — a bed of 

 loose glauconitic sands with clays and marls. The conglome- 

 rate consists of little pebbles of limonite — the Bohnerz of the 

 Germans — which also occur in the Hils clay, and sometimes 

 form workable beds. The conglomerate at places fills worm 

 tubes which extend 1 or 2 inches downwards into the lime- 

 stone of the Kimmeridge group. The Hils limestone con- 

 tains among others the following fossils: — 



Toxaster 



Terehratula multiformis, ohlonga. 



Exogyra sinuata. 



Ostrea macroptera. 



Pecten crassitesta, etc. 



The Gault which overlies the Neocomian is well repre- 

 sented along the base of the Harz, especially near Langel- 

 sheim and Goslar, where it divides itself into the following 

 lithological groups : — 



(c.) "Flammenmergel," dark grey clay marls with white flame-shaped 



streaks. Numerous fossils : Avicula gryphceoides, Solarium ornatum, 



Ammonites inflatus, A. Mayoriaiius. 

 {I. ) Clays and Marls, variegated and glauconitic : Belem. Listeria Avicula 



gryphceoides, Pycnodus. 

 (a.) Gatiltsandstone (Lower Quader sandstone), a white or yellowish brown, 



very soft, finegrained, almost unfossiliferous rock. Quarried for 



sand to E. of Goslar. 



The Neocomian and Gault are classed as Lower Chalk 

 (Untere Kreide) and the Cenomanian, Turonian, and Senonian 

 as Upper Chalk (Obere Kreide). 



