1859.] WEIGHT IN1-ERI0B OOLITE. 5 



The dark-grey calcareo-argillaceous nodules rest on the clays of 

 the Upper Lias or true Alum-shale, containing Ammonites crassus, 

 Phil., A. communis, Sow., A. fibulatiis, Y. & B., Nucula ovum, Sow., 

 and Trigonia literata, Phil. 



Professor "Williamson * has truly observed, in reference to this 

 bed, " the top of this shale at Peak Hill appears to contain Am- 

 monites striatulus, Sow., enclosed in indurated masses ; and I am 

 not aware of its having been met with at any other locality. It 

 occurs so near the top [of the shale], that doubts are entertained 

 whether it belongs to the Alum-shale or to the overlying Inferior 

 Oolite." A careful examination of the lithological character of these 

 argillaceous nodules will enable a practised eye to distinguish their 

 matrix from that of the Alum-shale with which they have been con- 

 founded. 



A geologist who has studied and compared the Cephalopoda-bed 

 and Liassic Sandsf, as developed at Nailsworth, Haresfield, Frocester, 

 Cam-Long-Down, Uley Bury, and Wotton-under-Edge in Glouces- 

 tershire, cannot fail to observe the similarity of these deposits to 

 the yellow and grey sands and argillaceous nodular basement-bed, 

 which he between the Dogger and Alum-shale at Blue "Wick, and 

 of which they are the true equivalents %. 



§ III. Tlie Inferior Oolite of the South of England, and of York- 

 shire. 



1, The Zone of Ammonites Mukchisoile. 



Synonijms. — " Dogger" (part), Young and Bird, ' Geol. of the 

 York. Coast,' p. 120, 1822 ; John Phillips, ' Geol. of York.' p. 38, 

 I B29 ; " The Central and Lower Division of the Inferior Ooolite," 

 Mnrchison, < Geol. of Cheltenham,' p. 10, 1834 ; " Fimbria-stage of 

 the Lnferior Oolite," Lycett, ' Cotteswold Hills Handbook,' p. 34, 

 L857; " Zone of Ammonites Murchisonce," "Wright, ' Monogr. Ool. 

 Echinodcrmata,' 1856. 



Fori i : i, i Equivalents. — " Brauncr Jura /9," Qnenstedt, 'JHozgeb.' 

 p. ■'<■>. 1" I'.l ; •• Calcaire locdonien" (part), Marcou, 'Jura salinois,' 

 ]i. 70, L846; "Calcaire a entroqnes" (part), Cotteau, ' Bollet. Soc. 

 Geol. France,' p. 638, L861; "Brauner Beta," Qnenstedt, ' Der 



Jura,' p. '■>'.'<-. I-"> V : •• l)ii- Schichtcn defl Ammonites M archisonffi," 

 OppeLj • Die .lurafonnation,' p, 326, l v ~>i;. 



Description. — This gone attains a considerable development at the 

 western limits of the Northern Cotteswolds, where it consists of 

 thick-bedded oolitic limestones, resting "ii coarse calcareo-silioeona 

 ragstones containing a large pcr-ientage of the peroxide <>t' iron, 



* Trnns. Geol. Soc .«cr. 2. vol. v. p. 227. 



t See Quart Joarn. Q - roLxii.p.292 



| The reader mayooruolt with profit a paper by raj friend John Lyoett, Esq. 

 mi ih«- Bands intermediate to the Inferior Oofite and the [iasof the Ootteswolda, 

 oompared with a similar depoail <>n Iteooael of Yorkshire, in the Annals and 

 Mug. of Nat, Host for Sept IS '7 



