LlASSlG AND OOLITIC ROCKS OF OXFORDSHIRE. 145 



Charlbury Eailway Station. The only evidence found was at Cal- 

 sham Bridge. On the right bank of the river, 40 yards below the 

 bridge, there crops out just above water-level a hard rock clearly 

 proved by mineral character and included fossils to be the marlstone 

 rock-bed ; above it lies vi situ a blue clay with Upper Lias fossils, 

 here 40 ft. thick and overlain by Inferior Oolite. This clay can be 

 traced down the valley to within ^ mile of Charlbury. 



From Calsham Bridge, where Upper Lias is at the surface, the 

 strata dip gently to the S.E. ; a fault N.W. of Charlbury brings up 

 the Marlstone, but does not interrupt the prevailing dip, which con- 

 tinues to a mile S.E. of Charlbury ; the rocks then rise again gently 

 till Pawler is reached ; here a sharp anticlinal has brought up the 

 lower clays <^, and broken the beds across, assisting the formation of 

 the coorabe : j mile S.E. of this anticlinal is a fault, where the 

 Liassic rocks disappear under the Oolites, and the main S.E. dip 

 continues in the direction of Oxford. 



Appendix (January 1886). — Since this paper was written, in 

 August 1885, little has been done at Pawler to elucidate the re- 

 lations of the bed <^, while the weather has rendered field-work 

 very difficult. I have, however, traversed the district between 

 Chadlington and Charlbury, seeking for evidence of the infra- 

 marlstone position of the clays there marked on the map as " (j^ f to 

 this end I have examined every ditch and stream. The rocks 

 between the lower clays and the Inferior Oolite would be at least 

 30 ft. thick here, probably 50 ft., and of these the Marlstone is very 

 characteristic and easily discerned. But clay has been traced from 

 below Inferior Oolite, right down to the river, without a fragment 

 of Marlstone appearing. The only Marlstone seen above Charlbury 

 has been at river-level, and the Lias clay was over it. 



Discussion. 



Prof. Prestwich remarked that the section described was an inter- 

 esting one. Its working had been abandoned for some years, but it 

 had been recently resumed, and extended considerably to the north. 

 It was within a mile or two of Stoneslield An interesting point 

 was the thinning-out of the Upper Lias and Oolites, pointed out by 

 Prof. Hull : but this new section showed that the Lower Lias does 

 not share in the thinning. Some fossils from the upper sandy beds 

 of the Lower-Lias clays would seem rather to show that they 

 belonged to the Marlstone. 



Mr. ToPLEY drew a sketch of the succession of tho beds in the 

 neighbourhood, showing that 50 feet represent all the Cotteswold 

 escarpment, and this thinning accounts for the greater part of the 

 dip of tho Inferior Oolite. 



Mr. Walford said that at Fawler the passage was gradual from 

 the Marlstone to the thin representative of the Cephalopoda-bed at 

 the base of the Upper Lias. Perhaps part of the Upper Lias was 

 removed bv denudation before the Inferior Oolite was deposited. At 



Q.J.G.S. No. 1G5. L 



