316 DE. A. M. DAVIE8 AND ME. J. PEINGLE ON [June 1913*. 



on the microscopic structure and included organic remains of the 

 Calvert rock confirm its correlation with the Bicester bed. The 

 upper surface of the limestone is irregular and piped, and the over- 

 lying clays extending downwards into the pipes present an uneven 

 junction. Similar irregularities of surface of the ' Cream-Cheese * 

 top were noticed in the Bicester cuttings, and they are doubtless 

 the results of contemporaneous weathering. The sudden passage 

 upwards of a fairly pure limestone into clays with lignite denotes a 

 considerable change of level in the area of deposition ; and the fact 

 that at Calvert root-like processes were seen to extend down from 

 the overlying Forest-Marble clays into the infilled hollows of the 

 limestone, suggests that for some time the ' Cream-Cheese ' top was- 

 a land-surface. 1 There is at Calvert, therefore, as well as in the 

 Bicester cuttings, a non-sequence between the two groups. 



Underlying the highest member of the Great Oolite is a yellow- 

 ish marly limestone, 2 feet thick. It is the only bed that 

 possesses the characteristic colour of the Great Oolite limestones 

 exposed in the railway-cuttings between Bucknell and Ardley 

 "Wood. Unfortunately, the cores of the sandy shales were not 

 preserved at the boring, and so no comparison is possible ; it is 

 probable, however, that they represent the Stonesfield Slate. The 

 remainder of the section consists of grey marly clays and limestones, 

 which agree closely in character with the lower beds of the Great 

 Oolite exposed in the long railway-cutting between Ardley "Wood 

 and Fritwell Tunnel, the details of which are not yet published. 



The limestones and clays of the Great Oolite at Calvert are,, 

 generally, fossiliferous ; but the fossils, like those of the Forest 

 Marble, are badly preserved, the majority of them occurring in the 

 form of casts. The most abundant forms are Ehynclionella and 

 Ostrea; a horizon between the depths of 188 feet 3 inches and 

 193 feet 9 inches yielded hundreds of specimens. This band is- 

 clearly comparable with the marls overlying the Neceran Beds in 

 Sharp's-Hill Quarry. 2 In the present state of knowledge no attempt 

 has been made to give a definite name to the species to which the 

 Wiynclionellce belong, but the type with which the forms appear 

 most closely allied is named in the appended list. Begarding the 

 other fossils which were collected little need be said, since most of 

 them are characteristic of the Great Oolite. The Ostrea which is- 

 recorded in the list as Ostrea sp. nov.(?) is apparently an undescribed 

 form, and still remains to be identified. Many specimens of 

 Pholadomya cf. deltoidea (J. Sow.) were obtained at the depth of 

 156 feet, and they are similar to the Ph. deltoidea collected by 

 Mr. J. Bhodes and Mr. H. B. Woodward from the Puller's-Earth 



1 [On clearing the surface of the Great Oolite, after the removal of the core- 

 to the Aylesbury Museum, I found that the surface was very irregular, the 

 dark patches in the limestone having weathered out into rounded prominences, 

 almost certainly the result of subaerial weathering. — A. M. -D.] 



2 L. Kiehardson, ' The Inferior Oolite & Contiguous Deposits of the 

 Chipping-Norton District' Proc. Cotteswold Nat. F. 0. vol. svii, pt. 2 (191 1> 

 p. 207 ; also E. A. Walford, ' On some New Oolitic Strata in North Oxfordshire- ' 

 Buckingham, 1906, p. 8. 



