130 Reviews — The Jurassic Rocks of England. 



fifth volume, which completes the Memoir on the Jurassic Rocks of 

 England. The Survey, however, promise us a concluding volume, 

 relating to the Jurassic Rocks of Scotland and Ireland, after those of 

 Scotland have heen mapped in detail. 



As in the previous volumes, Mr. Woodward avails himself largely 

 of the published observations of other workers in the same field, and 

 he has also received considerable assistance at various times from 

 local geologists. All these are duly acknowledged. The fossils 

 collected during the progress of his work have been named by 

 Messrs. Sharman and Newton, whilst Mr. Teall has examined and 

 described microscopic sections of the rocks. 



The Upper Jurassic (Middle and Upper Oolites) in this country 

 is essentially a pelolithic deposit, which in the East Midlands is 

 scarcely relieved by any shelly limestones ; whilst in the West 

 Midland and Southern Counties two great calcareous deposits 

 (Corallian and Portlandian), each supported on an arenaceous base, 

 serve to relieve the monotony of these extensive clay formations. 



As regards the uppermost limits of the system, Mr. Woodward 

 observes that the general relationship between the Purbeck and 

 Wealden strata has led many geologists to group them together. 

 He also considers that the local evidence would not justify us in 

 parting them, and it is only on wider grounds that the division 

 between Jurassic and Cretaceous is taken between the two. Thus, 

 he says, " We may be content to allow the claims of general con- 

 venience and of palaaontological succession established in Europe to 

 rule the limits of our principal chronological systems." 



However, he goes on to say that as regards the several sub- 

 divisions the case is different; such formations must be based on 

 their stratigraphical features, and he justly insists on the importance 

 of maintaining the original divisions of our strata as taken from the 

 typical localities. The following general arrangement is adopted : — • 



m\ ( Upper Purbeck Beds \ 



^ Purbeckian < Middle Purbeck Beds J Spilsby Sandstone. 

 2 { Lower Purbeck Beds ) 



u P tl d' ( Upper Portland Beds. 

 K, r a u | Lower Portland Beds and Hartwell Clay. 

 •3 / Kimeridgian. Kimeridge Clay. 



I Coral Rag and Coralline \ 

 Corallian <. Oolite ' Upware Limestone and Ampthill Clay. 



( Calcareous Grit ) 



I Oxford Clay. 

 \ Kellaways Beds. 



Oxfordian 



Oxfordian. — The author recognizes three palaeontological horizons 

 in descending order, viz. : Ammonites cordatns, Am. ornatus (perhaps 

 a generalized term), and Am. Callovieusis. He gives a useful 

 summary, and many details are now for the first time published. 

 As a rule, Oxfordian beds, south of the Humber, do not afford many 

 prominent features, so that their lithology and palaeontology must 

 be worked out, for the most part, in brickyards, well-sections, and 





