124 



THE LIAS AMMONITES. 



Section of the JJjjper Lias at BocMijf, Easington Heights, north of Whithy, 

 altitude 681 /ee^ above the level of the sea} 



Thick- 

 ness. 



Okganic Remains. 



ft. in. 



Sandstone beds with plant-seams 

 Inferior Oolite, the Dogger 



ZamiacetB. 



Triyonia costata and other Inferior-Oolite fossils. 



Alum-shale, Zone of Ilarpocei-as bifrons. 



3 Dark grey shale 



4 Hard ok Cement-stone Seam, nume- 

 rous calcareous nodules, exclusively 

 manufactured into Roman cement ... 



Nodules in these and succeeding beds, 

 highly ferruginous 



Lowest level worked for alum, 90 feet 

 from the surface 



10 



25 



150 



Harpuceras bifrons, Sarp. Lythense. 



Stephanoceras commune, Steph. fibulalum, Steph. 

 subarmatum, Lytoceras cornucopicB, Phyllu- 

 ceras heterophyU.um, Leda ovum, Trigonia lite- 

 rata, Gresslya donaciformis, Discina rejtexa. 



Belemnites subtenuis, Bel. vulgaris, 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 



Harpocerusserpentinum, Harpo. exaratum, Harpo. 



ovafum. 

 Lepidotus, Pachychormus, Ptycholepis, Lepto- 

 lepis, Gyrosteus mirabilis. 



Middle Lias. 

 Zone of Amaltheus 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, where 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 Stephanoceras commune, Steph. annulatum, Steph. crassum, Steph. 

 fihulatum, Steph. Holandrei. Fhylloceras heterophyllum, is tolerably abundant, but 



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

 -' " Geology of Rutland," ' Memoirs of the Geological Survey,' p. 79, 1875. 



