452 



PEOCEEDllirGS or THE GEOLOGICAL SOCIETY. 



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evidences of the mighty agent 

 which, ages since, caused the ele- 

 vation of the many thousands of 

 feet of stratified rocks which are 

 comprised in the Old Eed Sand- 

 stone, the Carboniferous Lime- 

 stone, and the Coal-measures of 

 the Mendips. This is visible in 

 a basaltic dyke of considerable 

 thickness emerging from beneath 

 the Old Red Sandstone at East 

 End near Stoke Lane, and also 

 under the Ridgeway, which forms 

 the most elevated part of this line 

 of hills. 



My attention was directed to 

 the spot by the report that some 

 peculiar minerals occurred there. 

 The dyke was not, however, visi- 

 ble at the surface, and I had to 

 remove the turf atdiiferent points, 

 immediately under which it ap- 

 peared in a deep-green-coloured 

 basalt, all the minutest cracks and 

 fissures of which were permeated 

 by manganese, giving its outer 

 surface a dark purple tinge. 

 Erom the general physical cha- 

 racter of the Mendips, it is not 

 improbable that the dyke is co- 

 extensive with the range. East 

 and west of a line of which Stoke 

 Lane forms nearly the centre, for 

 a distance of seven miles there is 

 an uninterrupted anticlinal. The 

 direction of the dyke from East 

 End towards Frome is evidently 

 south of Leigh-on-Mendip, and 

 between that village and Down- 

 head, and thence to Little Elm, 

 a distance of about four miles. 

 It then probably passes through, 

 and has modified, the Carbonife- 

 rous Limestone of the valleys 

 west of Erome, and has left its 

 last physical evidences at Oldford, 

 a mile north-east of that town, 

 where the Old Red Sandstone is 

 greatly contorted, and disappears 

 in that direction under the Ful- 

 ler's Earth. 



