Distances are measured from N end of tunnel with NW face of shaft No.8 being at 6380 ft. from N end of tunnel. Carboniferous Limestone, Tournaisian
Locality details
Portway Tunnel, Avon Gorge, Bristol. Bristol Corporation Sewerage Scheme. Shaft No.8, 450 yds. SE (133o) of western end of Clifton Down Railway Tunnel and 50 yds. E of E bank of River Avon. Tunnel is on a bearing of 322o from shaft No.8