116 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 4, 



them the Cornbrash, continue unchanged in mineral character and 

 unchanged in their organic contents ; and others, as the Kim- 

 meridge Clay and Coralline Oolite, are supposed to disappear, while 

 either the "Wealden takes a great northern development, or the Lower 

 Greensand spreads out into an estuarine and fluviatile deposit. I 

 propose to present, on the present occasion, sections showing the base 

 and the top of the Great Oolite in the valley of the Cherwell. Here- 

 after I hope to offer similar data for the base of the cretaceous system, 

 at Culham, in the valley of the Thames. 



No. 1. Junction of Lias and Oolite, north of Oxford. 



ft. in. 



g. Oolite, compact, marly, or shelly * 



/. Oolite, of a rough shelly character 



e. Marly clay 



d. Brown ferruginous sands, and sandstone with calcareous 



and irony layers 13 



c. Upper Lias Clay, enclosing a band of ironstone-nodules 35 

 (Ammonites bifrons, A. heterophyllus, Belemnites api- 

 cicurvatus, &c.) 



b. Marlstone, solid, ferruginous 20 



a. Middle Lias Clay. 



This section is exemplified about Steeple Ashton, where, in 1805, 

 it was first sketched by "W. Smith*, who calls the beds by the title 

 of " Ovenstone," a term used in the valley of the Evenlode. 



At Worton, between Steeple Ashton and Banbury, the details of d 

 were thus recorded in 1855 : — 



No. 2. Small shells and sand, resting either on limited ft. in. 

 patches of calcareous flagstone (" plank") or on 



iron-ore 4 



Oolitic iron-ore in undulated and folded masses . . 6 



Stony bands, with plants 1 



Sands, with nodules of iron-ore and shells 5 6 



Calcareous band 2 



Water issuing from ferruginous clay (top of Lias). 

 In the country about Sandford the beds marked d become white 

 and yellow sand (16 or more feet thick) with irregular laminae of 

 calcareous sandstone, more or less blue in the centre, called " plank." 

 This is sometimes covered by 6 feet of clay. It is the equivalent of 

 the Stonesfield Slate, but contains only few of the fossils of this 

 latter locality. 



Ammonites heterophyllus is not known to me at any point further 

 to the south. 



The railway-cuttings and quarries near Stonesfield expose sections 

 much resembling that given by Dr. Fittonf, especially in the cir- 

 cumstance that layers of clay or marly bands alternate with the 

 white oolite. The top of the rock is uneven, worn, marked by 

 attached Ostrece, and much drilled by perforating shells. Above 



* Memoirs of W. Smith, p. 61. t Zool. Journal, 1827. 



