OOLITIC. 285 



ground is to a large extent moorland, while in the midland and 

 southern counties the Oolites form a rich tract of corn land and 

 pastures. 



In composition the Oolitic limestones contain, as a rule, from 90 to 95 per cent, 

 of carbonate of lime.^ In colour they are generally pale yellow or brown, when 

 seen in open quarries ; but when dug at great depths or otherwise obtained at 

 points where they have not been exposed to atmospheric influences, all the Oolitic 

 rocks exhibit an almost uniform deep-blue tint, which is apparently communicated 

 to them by a diffusion through their substance of small quantities of sulphide 

 of iron.^ 



LOWER OOLITIC. 



The subdivisions of the Lower Oolitic strata of England will 

 be best understood from the accompanying diagram (p. 286). 



Our knowledge of the strata, especially in the south-west of England, is largely 

 owing to the labours of William Smith, followed by Lonsdale (T.G.S. (2) iii. 241). 

 In the midland counties the classification is mainly due to the researches of Prof. 

 J. W. Judd (Geol. Rutland, etc.). Prof. J. Morris (G. Mag. 1869, p. 446), and 

 Mr. S. Sharp (Q.J. xxix. 285). In Yorkshire we owe our knowledge of the strata 

 chiefly to Prof. John Phillips (Geol. Yorkshire, Part i), Mr. W. H. Hudleston 

 (P. Geol. Assoc, iii. 283, iv. 353, v. 378), and Mr. C. Fox Strangways (Explan. 

 Sheets 93 N.E., 95 N.W., S.W., and S.E., 96 N.E. and S.E. Geol. Survey.) 



It will be most convenient to arrange the descriptions of the 

 rocks under three headings : — i. South-west of England, 2. Midland 

 Counties, and 3. Yorkshire. 



SOUTH-WEST OF ENGLAND. 



Inferior Oolite Series. 

 This Series is divided as follows : — 



ZONES. 



SAniinonites ( Cosmoceras) Parkinsoni. 

 ,, \Stcphanoceras) Hiimphi'iesianus. 



,, {llarpoctras) AIurchiso7ia [including sub-zone of 



A. {Harpoceras) Sower by i^. 

 Midford I ,, {Ilarpoceras) opalimis. 



Sands. ( ,, (Lytoceras) Jui-etisis. 



MIDFORD SANDS. 



The term Midford Sands was given in 1871 by Prof. Phillips to 

 the sands which occur between the Upper Lias Clay and the 

 Inferior Oolite.^ Midford is a little hamlet about three miles south 

 of Bath, and it was there that William Smith first studied the 

 Sands, and called them the ' Sand of the Inferior Oolite.' 



^ Prof. A. Voelcker. Q. J. xiv. 120. 



" Judd, Geology of Rutland, etc., p. 115 ; Phillips, Geol. Oxford, p. 396. 



=' Geol. Oxford, p. 118. 



