210 



DOLOMITTC CONGLOMERATE OP JiUrSTOL. 



the distance towards No. 3 shaft, forming nearly the bottom 

 of the tunnel for about that distance ; it then takes a quick 

 rise over the Carboniferous rocks to No. 3 shaft, where 

 it was found about twenty-six foot in thickness, afterwards 

 tliinning out to four feet at No. 4 shaft, on. the Monmouth- 

 shij-o shore of the Severn. This is very similar to Patch- 

 way Tunnel, although it was not found to disappear in so 

 short a distance, but shows the erratic manner in whicsh the 

 deposit was formed. It again appears above low-water mark 

 on the edge of the shoots, forming what is called the " ]jady 

 Bench." It would, be interesting to know to what extent it 

 is developed between that point and Almondsbury Eidge. 



South of Bristol, the Dolomitic Conglomerate is found 

 much more general than to the north, forming an almost 

 complete fringe to the Limestone rocks of the M.on.di]) 

 Hills. The road from Bristol to Congresbury, between 

 Flax-Bourton and the latter place, runs for the greater i)aT-l, 

 of its length through the Conglomerate, which fringes the 

 border of Backwell Hill and Wrington Warren. From near 

 Congresbury it takes an almost easterly direction, through 

 Wrington to Red Hill, whence it takes a nortli-oasterly 

 direction to Winford, where it ends, forming nearly a 

 complete circuit round the spur, the only exception being 

 between Winford and IJari'ow (xurnoy, whore the lower lias 

 clay runs directly upon the Mountain Ijimestone, forming a 

 kind of bay. 



The most extensive development of the (Jouglomorate in 

 the neighbourhood, of Bristol is, however, round the main 

 Limestone range of the Mendips, where, starting from East 

 Harptree to the north of the range, it is possible to follow, 

 almost without losing sight of it, in a north-westerly direc- 

 tion to Sandford near Banwell ; and afterwards in a south- 

 easterly direction from thence, via Axbridge and Cheddar, to 



