8o PROCEEDINGS OF THE COTTESWOLD CLUB 



cease to appear ; the picturesque basin of Coin St 

 Aldwyn and Hatherop to the Quenington Fault being the 

 receptacle for the very large volume of water brought down 

 to Fairford, and thence flowing into the Thames at the 

 Round House, opposite Inglesham, and finally passing 

 over St John's Weir at Lechlade. 



The importance of the Fuller's Earth upon the water 

 system over the north-western Cotteswolds is scarcely 

 appreciated. Its first appearance is on the western side of 

 the basin of the Windrush, and first seen surrounding the 

 isolated and rectangularly faulted area east of the Upper 

 Lias Valley of Guiting Power, and north of the Vale of 

 Naunton, composed of the Great Oolite and Stones- 

 field slate. This highly faulted district is undoubtedly an 

 important feeder to the Windrush, and empties its 

 gathered waters on to the surface of the Lower Lias at 

 Upper Slaughter and Bourton-on-the- Water. The exten- 

 sive fault from Stow Gate close to the watershed, to 

 Harford Bridge, separates the Rowell, Guiting Power 

 and Naunton rocks from the highly faulted region of 

 Hawling and Aylworth Downs. The waters of the 

 Salperton and Notgrove Great Oolite plateau are entirely 

 released by the Fuller's Earth, the Inferior Oolite being 

 drained at Hasleton and Turkdean by a small Upper Lias 

 stream. 



The drainage area of nearly 90 square miles occupied by 

 the Churn, Coin, and Windrush is thus governed by 

 the Fuller's Earth ; upon the underground south-eastern 

 dip-slope of which, all water not thrown out by springs 

 or faults, north of the line I have indicated on the three 

 rivers, (or between the Fuller's Earth, north of Naunton 

 and the Bibury fault and spring to Burford) is lost to 

 the supply of the Thames. The waters received by the 

 overlying pervious Great Oolite, Forest Marble and 

 Cornbrash pass down through the fissured and jointed rocks 

 until probably arrested by the lower-lying clays of the 

 Lias. 



