332 LOWER OOLITIC ROCKS OF ENGLAND: 
to the base of the series, with the Inferior Oolite below them.* This 
riew, however, was opposed by Mr. Hudleston,f whose grouping coincides 
with that now adopted. 
The total thickness of the beds here assigned to the Great 
Oolite (Nos. 3 to 25), measures 74 feet. It is remarkable that 
this agrees within one foot with the measurement (73 feet) made 
by Mr. T. Beesley and Mr. E. B. Tawney,J because in one or 
two instances definite measurements were not to be made when I 
saw the sections. 
It will be noticed that there is a considerable proportion of marl 
in the Great Oolite, amounting indeed to about half of its mass. 
It should be mentioned that the thickness assigned by Mr. 
Hudleston, to the " Black Clay," and underlying marly clay is 
only 5 ft. 7 in. : Mr. Beesley notes this as 6 ft. 9 in., but it is 
mentioned that the thicknesses vary within short distances. I 
certainly saw a greater thickness on the east side of Langton Bridge, 
but have queried the amount as the beds may have been partially 
slipped. Referring to this " argillaceous series, " Mr. Hudleston 
remarks that; it seems " almost unconformable to the underlying 
beds." This indication of unconformity, which is afforded by the 
irregular character of the junction between the clay and under- 
lying limestone, may be compared with that seen in the section at 
the Cetiosaurus quarry at Chipping Norton. Mr. Hudleston 
adds that " It may be doubted whether this dividing Clay can 
be exactly referred either to the Upper Estuarine or to the 
Fuller's Earth." Considering that it is overlaid by beds of 
Stonesfield Slate character, as in the cuttings noted along the 
railway between Bourton-on-the- Water and Andoversford (see 
p. 293), we cannot but group the clay with the Fullonian. At 
no other locality to the east or north-east do we find any beds 
that we can definitely assign either to the Stonesfield Slate or 
Fuller's Earth if represented in point of time they are included 
in the Upper Estuarine Series. 
There can be no doubt that the beds grouped as Stonesfield 
Slate Series occupy the position of the beds at Stonesfield ; but 
it is noteworthy that we have current-bedded shelly oolites below 
the slaty beds instead of above them as in other localities near 
Burford and Notgrove. It is not unlikely therefore, as suggested 
by Mr. Walford, that the slaty beds here are developed at a 
somewhat higher horizon in the series than elsewhere ; but at all 
places the development of " slate " is uncertain and irregular. 
Lignite and obscure plant-remains occur in some of the beds*. A 
large Clypeus was noted by Mr. Hudleston, and Mr. Walford 
obtained from the higher beds a number of Polyzoa (Diastopora 
ventricosa) which were found around a piece of water-logged 
coniferous wood. Mr. G. R. Vine, who described the Polyzoa, 
counted from 20 to 30 layers of them, representing successive 
* Proc. Geol. Assoc., vol. T. p. 172. 
t Ibid., p. 388. 
j Ibid., p. 179. 
Ibid., pp. 381, 385. See also Beesley, Ibid., p. 172. 
