S96 Messrs. Buckland's and Conybeare's Observations on the 



We have already described in the 2d chapter the elliptical valley which 

 extends from Roborough to Loxton. The conglomerate is here worked, both 

 at Roborough and Shipham, for calamine, which is found crystallized, com- 

 pact, and pseudomorphic. Some galena is also raised. These mines, though 

 on a small scale, are the principal ones now worked in Mendips. 



On the northern side of the Mendip chain, we find the conglomerate near 

 Mells, at the eastern extremity of the southern coal-tract, concealing the 

 junction of the coal-measures and the mountain limestone. It forms one of 

 the most striking features in the scenery of Mells park, and abutting- against 

 the truncated edges and sloping planes of strata of mountain limestone, flanks 

 the gorge of the Nettlebridge river from Mells house to a little below the 

 village of Mells, with steep banks and mural precipices more than 50 feet 

 high. The fragments which it here contains are enormous. At the western 

 extremity of the southern coal-tract, it crowns with mural precipices the abrupt 

 sides of the valley from Nettlebridge to Emborrow, resting in vast horizontal 

 masses on the coal-measures, which are only laid bare in the bottom of the vale. 

 A projecting precipice of conglomerate, called the Bulwarks, has been forti- 

 fied on its northern side, which alone was accessible. At Chewton Mendip, 

 and at East and West Harptree, the conglomerate lies in banks of enormous 

 thickness, and at the two latter villages has formerly been exceedingly pro- 

 ductive of calamine. From West Harptree it continues to maintain a con- 

 siderable thickness along the whole northern base of the Mendip chain, by 

 Burringdon and Banwell to Uphill on the Bristol Channel. We have already 

 noticed the occurrence of the conglomerate at the eastern base of the hills of 

 Worlebury and Woodspring, and at Redhill on the southern flank of Broad- 

 field down. It is particularly well displayed near Butcombe at the bottom of 

 the deep valleys which there cut through hills of lias : these valleys also 

 exhibit striking sections of the superior horizontal strata. It skirts the valley 

 of Nailsea along the north-western base Broadfield down, and occurs less 

 abundantly along the opposite slope of Leigh down. Towards the western 

 extremity of the latter, and on its south-eastern slope, immediately above the 

 village of Clevedon, we find insulated masses of a buff and red dolomite, 

 resting on the limestone. Similar masses occur further eastwards. The 

 conglomerate has previously been mentioned as lining the coast from Clevedon 

 to Portishead point ; it is also found at Portishead and Portbury, and, in the 

 interval between these villages and the Avon, it partially conceals the sub- 

 jacent old red sandstone. It crosses the Avon to the west of Cook's Folly, 

 and constitutes the upfilling of the vale of Westbury, between the opposite 

 ridges of Durdham and King's- Weston downs. We have before described it 



