67 



times have been put upon it. Phillips and Conybeare state it 

 to be 600 feet, Buckland and Conybeare estimate it at from 

 1,500 to 2,100 feet, and in the "Memoirs of the Geological 

 Survey" its thickness on the Avon near Bristol has been 

 estimated at 2,340 feet ; but as far as I am able to judge, its 

 thickness on the Mendips opposite Mells and Vobster cannot 

 be far short of 3,600 feet. 



Briefly to recapitulate, we arrive at the following results : — 



ft. ft. 

 Depth from New Ked Sandstone to Great 



Vein of Upper Series under Clandown 1000 

 Thickness of Strata containing the Upper 



Series 250 



Depth from Bottom Vein of Upper Series 



to Red Shale Beds 250 



Total thickness of Upper Series ... 1500 



Thickness of Red Ground ... ... 150 



Depth from Red Ground to First Vein of 



Farringdon Series .... ... ... 240 



Thickness of Strata containing the Farring- 

 don Series ... 310 



Total thickness of Second Series ... 550 



Total thickness of Upper Division ... ... 2200 



Pennant Rock 3000 



Thickness of Strata containing Third Series ... 1600 



Thickness of Strata containing Fourth Series ... 1200 



Total of True Coal Measures 8000 



Add— Millstone Grit 500 



Mountain Limestone and Shales ... ... 3600 



Total Thickness of Carboniferous Strata of 



Somersetshire ... ... ... ... 12100 



