Reviews — The Jurassic Rocks of England. 131 



rail way -cuttings. It was a grand time for collectors when the 

 ornatus-clnys of Christian MaLford were cut through in making the 

 Great Western Railway. 



For many years subsequently little was added to our knowledge 

 of the Oxford Clay. But latterly the subject has again attracted 

 attention. The author and his colleagues, for instance, have carefully 

 investigated the strata at Kellaways itself. Moreover, the well- 

 sinking at Swindon added largely to our knowledge of Oxfordian 

 beds. This operation was watched and reported upon by the author 

 and Mr. E. T. Newton, with very complete results. To the cordatus- 

 zone was assigned 288 ft., to the ornatus-zone 220 ft., and to the 

 Calloviensis-zone (52 ft. The evidence agrees with that furnished in 

 other localities, that the Kellaways Rock is but an irregular and 

 sandy, impersistent bed towards the base of the Oxford Clay, locally 

 fossil iferous. The tendency to form great doggers on this horizon 

 in certain localities is well exhibited in a railway-cutting near 

 Cirencester. The total thickness assigned to the Oxfordian beds at 

 Swindon is 572 ft., being considerably in excess of Prof. Prestwich's 

 estimate of 300 ft. at Oxford. 



Passing on to the East Midlands, Mr. Woodward has had the 

 advantage of being able to consult Judd's " Geology of Rutland," as 

 well as the works of the late Thos. Roberts, who possessed a most 

 accurate and extensive knowledge of the fossils of the Upper 

 Jurassic clays. Several other members of the Survey have also 

 contributed of late years to our knowledge of Oxfordian beds in 

 Lincolnshire. 



Corullinn. — It is not a little singular that the term " Corallian," 

 which, strictly speaking, is of French origin, should in some quarters 

 be falling into disuse in that country, and that " Rauracien " and 

 " Sequanien " more or less occupy its place. However, in England 

 the term is exceedingly applicable for the variable series of strata 

 that occur between the Oxford and Kimeridge Clays. Messrs. 

 Blake and Hudleston supplemented the work of the older writers on 

 this formation, and Mr. Woodward has in many cases adopted their 

 local stratigraphical divisions. His general grouping is as follows : — 



TT ) Upper Calcareous Grit, Upper Coral I Zone of 



p PJ,. ] Rag and Ironstone, Coral Rag, and I Ammonites 

 uoraman j Coralline 0olite ( p Hcatilis. 



T \ i Zone of 



r, it ) Lower Calcareous Grit < Ammonites 



Corallian j [perarmatus. 



This arrangement differs from the original Survey mapping of the 

 strata from Dorsetshire to Berkshire, where a tripartite division was 

 maintained, the highest beds being called " Upper Calcareous Grit" 

 — a name borrowed from Yorkshire. Certainly, the highest 

 Corallian beds in Dorsetshire, and to a less extent in Wiltshire, 

 present marked peculiarities, such as extensive ferrugination, in 

 some cases amounting to an iron-ore. Moreover, the fauna is 

 peculiar, though this is to some extent due to physical differences. 

 Hence these beds are in a certain sense Kimeridgian, and it is just 



