Vol. 57.] OP TSE NORTH C0TTE8WOLDS. 147 



it would not have had its peculiar shape. These four circumstances 

 are : — 



(1) The position of the River Wiadrush ; 



(2) The outcrop-line of the Great O )lite in the disirict, which normally, and 



if unaffected by faults, should run about from Turkdean to Icomb ; 

 (8) The axis of the anticline of the Bajocian denudation; and 

 (4) Faults in the Stow district. 



Of these circumstances, (1) the Eiver Windrush would produce a 

 valley directed SDuth-eastward from Bourton, though it would not 

 account for the extension of the Yale in the ISlaughter district. 



But such an extension is partly accounted for by the outcrop-line 

 of the Great Oolite. Along the Fullers' Earth strike there would be a 

 tendency to lateral widening of a valley. That tendency, however, 

 would not be great it there were the normal mass of Inferior Oolite 

 to be encountered, from where the Great Oolite had been removed. 

 But then there was not. From where the Great Oolite had been 

 removed there remained as a protective stratum only a thin band of 

 Inferior Oolite, a few feet in thickness, dae to the Bajocian denu- 

 dation. That was easily broken through, and removed, when the 

 soft clays of the Lias, which were at once encountered, favoured 

 valley-formation. 



The Vale of Bourton is, therefore, due 



(i) To the normal cutting by the River Windrush; 

 (ii) To the removal of the Great Oolite by Tertiary denudation ; 

 (iii) To the removal by Jurassic denudation of the^ m lin mass of Inferior- 

 Oolite Limestone, which otherwise would have offered a thick protective 

 covering. 



Under such circumstances, then, the Vale of Bourton is quite 

 normal, except that it is blocked northward by the high ground of 

 Stow. Its western flank ought to exteiid in line with the eastern 

 flank of the Cotteswolds by Bourton-on-the-Hill, Longhorough, and 

 Slaughter. It does not do this, on account of the faults in the Stow 

 district. These faults let in the Great Oolite below the normal level, 

 and thereby provided a thicker protective covering for the strata of 

 the Stow district. 



Thus the shape of the Vale of Bourton is seen to be dependent on 

 the four circumstances mentioned, but especially on the Bajocian 

 denudation. For, had there been in this vale 200 feet of Inferior 

 Oolite to cut through, instead of only a few feet, then there would 

 not have been the lateral expansion of the Vale. It would have had 

 a character such as it possesses at Harford and Naunton — narrow 

 and steep-sided. 



{h) Penecontemporaneous Erosions and the Position 



of Coal. 

 There is something in this connection which may be considered, 

 A Jurassic anticlinal axis runs about in the line of the Vale of 

 Moreton. An anticlinal axis indicates a line of weakness. A line of 

 weakness, once formed, tends to produce subsequent lines of weak- 

 ness. Therefore the Jurassic line of weakness may indicate former 

 lines of weakness; hence former anticlines ; hence denudation. 



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