PROCEEDINGS OF THE COTTESWOLD CLUB 9 1 



The exact proportion of the rainfall absorbed by the 

 different permeable strata, and which is given out again in 

 the form of springs, has yet to be determined, varying as 

 it does according to the lithological character of the water 

 bearing strata. 



In a district like that of Cricklade, Lechlade, Hampton, 

 etc., where the impermeable strata (Oxford Clay) pre- 

 dominates, the total deliveries will be large, following close 

 upon rainfall; whereas where the permeable strata predom- 

 inate as they do north of the strike of the Cornbrash, 

 over the Upper Cotteswolds, so will the rainfall be stored 

 in the jointed and broken nature of the Limestones, and its 

 delivery through springs due to the retentive Clavs of the 

 Lias and Fuller's Earth below will be spread over a 

 greater length of time. Hence the siinnner floio which, in 

 a dry season, consists almost entirely of the supplies from 

 deep-seated springs, such percolated waters being retained 

 and upheld by the two impervious Clays above mentioned. 



Doubtless the loss of water that takes place where the 

 streams run over the fractured and faulted Oolitic Lime- 

 stones, especially the Great Oolite, is for the time very 

 great, but there can be little doubt that a considerable por- 

 tion of what appears to be lost, enters the river at a lower 

 point by bottom and lateral springs. 



We know little or nothing of the nature of the deeply 

 seated water area occupied by the Lias below the Inferior 

 Oolite ; neither do we know anything of the extended 

 underground surface or strike of the Fuller's Earth which 

 upholds the thick and widely spread Limestones of the 

 Great Oolite and their large water supply, neither have we 

 any evidence of the dying out or thinning awav of the 

 Inferior and Great Oolites, or where they may come 

 together through the loss of the intermediate Fuller's 

 Earth; it may be between Burford and Witney, or deep 

 under the thick Oxford Clav towards Oxford. 



