124 



THE LIAS AMMONITES. 



Section of the TJjJper Lias at Rocklijf, Easington Heights, north of Whitby, 

 attitude ^'^\ feet above the level of the sea} 



No. 



Petrology. 



Thick- 

 ness. 



Organic Remains. 



Sandstone beds with plant-seams 

 Inferior Oolite, the Dogger 



ft. in. 



Zamiacece. 



Trigonia costata and other Inferior-Oolite fossils. 



Alum-shale. Zone of Ilarpoceras bifrons. 



3 Dark grey shale 



4 { Hakd or Cement-stone Se.4M, nume- 



rous calcareous nodules, exclusively 

 manufactured into Roman cement ... 



Nodules in these and succeeding beds, 

 higlily ferruginous 



Lowest level worked for alum, 90 feet 

 from the surface 



Ilarpoceras bifrons. Harp. LytJiense. 



Stephanoceras commune, Stepfi. Jibulalum, Steph. 

 subarmatum, Lijtoceras cornucopia, F/ii/llo- 

 cerus Iieterophyllum, Leda ovum, Trigonia lite- 

 rata, GressJija donaciformis, Discina rejiexa. 



Belemnites subtenuis, Bel. vidyaris, Leda ovum. 



Jet-rock. Zone of Ilarpoceras serpentinum. 



Many pyritous nodules, very much 

 flattened 



Hard compact shale, very sandy, a few 

 small nodules mostly barren in fossils 



20 

 30 



Harpoceras serpentinum, Harpo. exaratum, Harpo. 



ovatum. 

 Lepidotus, PucJiychortnus, Ptycfiolepis, Lepto- 

 lepis, Gyrosteus mirabilis. 



Middle Lias. 

 Zone of Amaltlieus margaritatus. 



Professor Judd^ describes the Upper Lias of Rutland as occupying a large area in 

 Sheet 64 of the ' Geological Survey.' This division of the Lias is usually concealed by 

 Drift except on the steep slopes of the Oolitic escarpments, vi'here it attains a thickness of 

 about 200 feet, and consists almost entirely of clays, which Prof. Judd divides into the 

 following beds. The section is in a descending order. 



1. The Leda-ovum Beds form the highest beds of the Upper Lias, and consist of 



clays, with numerous layers of septaria, everywhere distinguished by the abundance of 



Leda ovum, Sow. The prevailing Ammonite is Harpoceras bifrons, which occurs in great 



numbers. Here are also Steph aiiocer as commune, Steph. annulatum, Steph. crassum, Steph. 



fbulatum, Steph. Holandrei. Phylloceras heterophyllum, is tolerably abundant, but 



^ Louis Hunton, ' Trans. Geol. Soc.,' vol. v, second series, p. 215, 1836. 

 - " Geoliigy of Rutland," 'Memoirs of the Geological Survey,' p. 79, 18/5. 



