UPPER LIAS. 275 



the Pecten-bed. Dr. H. C. Sorby has conckided that the Cleveland Ironstone 

 was at first a kind of oolitic limestone, interslratified with ordinary clays containing 

 a large amount of the oxides of iron mechanically derived, and also organic matter, 

 whicli, by their mutual re-action, gave rise to a solution of bi-carbonate of iron — 

 that this solution percolated through the limestone, and, removing a large part of 

 the carbonate of lime by solution, left in its place carbonate of iron.^ 



In Lincolnshire and Leicestershire, at Eastwell and Long Clawson, north of 

 Melton Mowbray, at Tilton, and Hohvell, near Market Harborough ; and in 

 Lincolnshire at Denton, Woolsthorpe, and Caythorpe near Grantham, the Middle 

 Lias Rock-bed is worked for iron-ore ; about 750,000 tons of ore being obtained 

 annually, which is sent to Stanton Bedale in Derbyshire to be smelted. Analysis 

 of the ore at Caythorpe showed calcic carbonate 62 per cent, and ferric oxide 25. 

 The stqne in many places contains much bluish or greenish matter, attributed 

 to phosphate, silicate, and sulphide of iron. The ironstone occurs in the upper 

 part of the Marlstone, and is 8 or 10 feet thick." (See also p. 273.) 



In many places the Rock-bed is quarried for rough building-purposes and for 

 road-metal. Near Banbury the Hornton Stone is of local repute ; near Ilniinster 

 the Moolham Stone has been quarried for building walls, and for road metal, 

 for which purposes the Marlstone is used in the neighbourhood of Yeovil. It is 

 sometimes burnt for lime. Marlstone from Bagpath, near Dursley, has been 

 polished. The lower beds are worked in places for brick-making, at Market 

 Harborough, at Gonerby north-west of Grantham, also near Ilminster and 

 Bridport. 



The Middle Lias furnishes a rich soil, particularly favourable in the south-west 

 of England to the growth of apple trees. The county of Rutland (red land) 

 probably acquired its name from the prevalent colour of the soil ; that on the 

 Middle Lias being highly productive. At Northampton the beds yield a copious 

 supply of vi'ater to the town. 



Tipper Lias. 



The Upper Lias consists of blue or grey shale and clay, with 

 nodules of blue limestone, and occasional beds of pale-grey earthy 

 limestone. It is characterized by the presence of Ammonites 

 SiTpentiiius, A. bifrons, A. annulaiiis, A. communis, A. Holandrei, A. 

 hi'ierophvllus, Nautilus intcrmedius, Belemnites Voltzii, B. vulgaris, 

 Euomphalus niinutus, Trochus duplicatus, Leda ovum, Nucula 

 . Hammcri, Discina 7-eflexa, etc. Among other fossils are Trigonia 

 literata (Yorkshire) ; the Corals Thccocyaihus and Trochocyathus ; 

 Fishes, Lepidotus, Pachycormus, Leptolepis, etc. ; and the Reptiles, 

 Ichthyosaurus and Plesiosaurus, including the huge P. Cramptom 

 from Whitby. 



The Midford sands (zone of Ammonites {Lytoccras) Jurensis) that 

 occur between the Inferior Oolite and Lias, were grouped with the 

 Upper Lias by Dr. Wright ; but these sands are more closely 

 related to the Inferior Oolite. 



The Upper Lias is sometimes termed the zone of Atnmonites 

 {Stephanoceras) communis ; while other zones, those of A. {Harpo- 

 ceras) bifrons and A. {Harpoceras) se7pentinus, are in places identified. 



^ Geol. and Polytech. Soc. W. Riding, iii. 460 ; Address to Geol. Soc. 1879 ; 

 see also J. Phillips, Q. J. xiv. 96 ; Tate and Blake, Yorkshire Lias, p. 165 ; G. 

 Barrow, Proc. Cleveland Inst. Engineers, 1880, p. 180 ; Explan. Sheet 96 N.E. 

 (Geol. Survey). 



* See E. Wilson, op. cit. p. 152. 



