72 PROCEEDINGS OF THE COTTESWOLD CLUB 



Great Tew, and Dunstew to the Cherwell, defining its 

 watershed. All south of the divide as far as Woodstock 

 is on the Great Oolite, which is drained by the Darne 

 and the Glyme. The line of the southern Watershed of 

 the Deddington Basin and Stream marks the southern 

 termination of the extensive development of the Middle 

 and Lower Lias, occupied by the Deddington, Swere, and 

 Sor Brook Basins above Banbury, to the extent of 70 

 square miles. 



The Cherwell below North Aston occupies a narrow 

 valley cut out of and down to the Lower Lias, as far as 

 Northbrook Bridge. East of this the Lias entirely ceases 

 to appear, being overlaid by the Great Oolite. 



Basin of the Ray (Cherwell) 



The Rav enters or is confluent with the Cherwell 

 at Ishp, after draining about 114 square miles, and yields 

 a considerable but variable supply of water. The north- 

 ern part of the watershed of the Ray includes part of the 

 main watershed of the Thames Basin, and extends along 

 its northern boundary from Somerton on the west, to 

 Stoke Lyne, Sutton Audley, and Edgcot to Quainton to 

 the east ; the divide between the Ray and the Thame 

 rapidly turning south to Westcot and Weston Under- 

 wood, a little north of the Corallian and Neocomian 

 outliers of Brill and Woodbury Wells to Islip. The 

 western line or side of the Basin corresponds to the 

 eastern divide of the Cherwell up to Somerton again. 

 I give this area watered by the Ray and its tributaries as 

 being almost an exceptional geological district of consider- 

 able extent, and draining only three Jurassic groups of 

 rock : the Great OoHte 8 square miles, the Cornbrash 

 21^, and the Oxford Clay 75 ; the remaining strata being 

 fragmentary remains, composed of the Lower Calc. Grit, 

 Coral Rag, Kimmeridge Clay and Portland Beds ; with the 



