316 E. 8. COBBOLD ON THE EXPOSED STRATA OJF THE 



crossing of the railway by the cross road from Cowley to Garsington ; 

 and south-eastwards over a considerable portion of the sewage-farm. 

 A vertical section of the beds in the railway-cutting is given in 

 fig. 5. Here there are about 17 feet of alternate layers of marl 

 and clay, 37 in number and varying from 2 feet to 3 inches in thick- 

 ness. At the base the marl seems to graduate into limestone 1 foot 

 3 inches thick, which is succeeded by a bed of line sand 2 feet thick 

 with fragments of shells and spines. Below this is a very compact 

 and hard limestone very full of shells, also 2 feet 6 inches thick. It 

 was from this bed that most of the stone was quarried of which the 

 bridges on this part of the line were built. 



This is followed by the fine soft sand of the Calcareous Grit, which 

 contains very few fossils, and several layers of concretions of sandy 

 limestone. At 12 feet 9 inches below the top of this sand is a much 

 more continuous layer of similar stone, which has been found in 

 many places on the sewage-farm. 



In the longitudinal section of the railway- cutting (fig. 1) the 

 strata are seen to be inclined at a slight angle westwards ; but the 

 actual dip and strike have not been ascertained. At the Littlemore 

 Station, however, the inclination is reversed, and there seems to be 

 a slight anticlinal axis somewhere near the level crossing west of 

 the road ; but this may be apparent only, as the line of section neces- 

 sarily follows the curvature of the railway. 



From the west end of the cutting the section is prolonged to the 

 river Thames, passing through the site of the sewage-pumping sta- 

 tion, the foundations of which came in a deep irregular depression 

 in the surface of the Oxford Clay, suggestive of an old river-course, 

 but at a lower level than the existing one. 



The level of a spring on the side of the hill is also shown, as 

 giving a probable indication of the height to which the Oxford Clay 

 rises on this side of the valley. 



No strata corresponding to the Coralline Oolite of Headington are 

 to be seen in this cutting ; but apparently in the folds of the marls 

 on the west slope of the hill there are some pockets containing an- 

 gular fragments of limestone. Similar pieces may also be seen scat- 

 tered over the surface of the hill above the cutting ; so that possibly 

 it might be met with at a higher level. 



In laying the sewage-pumping main along the road up Sandford 

 Hill an interesting section was exposed, a sketch of which is given 

 in fig. 2. At the foot of the hill the shell-bed (here very full of 

 GervUUa) and its accompanying sand were found. These were suc- 

 ceeded by marls having a vertical height of about 15 feet, of a bluish 

 grey colour, unlike those in the railway- cutting and on the farm, 

 which are more or less white. As the road has been made in a 

 cutting in the side of the hill, the change of colour may be due to 

 the oxidizing effect of the weather not having yet penetrated so 

 deep. 



Above the marls was a thickness of about 12 feet 6 inches of very 

 hard fine-grained limestone in 3 or 4 layers with hardly any fossils, 

 evidently answering to the Coralline Oolite of Headington. Above 



