This guide describes Bristol, Bath and surrounding areas' local building stones in their geological context. It includes examples of buildings and structures where the stones have been used. The solid geology of the Bristol, Bath, North East Somerset and South Gloucestershire area is complex. The sequence is dominated by sedimentary rocks that range from Early Ordovician to Late Jurassic in age. A few minor volcanic rocks also occur, interbedded with Palaeozoic sediments in the Weston-super-Mare and Tortworth areas. In very general terms, the geology can be regarded as decreasing in age from west to east, but numerous unconformities and faults create a complicated outcrop pattern of inliers and outliers and a varied topography. The geological heritage of the area is very diverse: it includes a number of classic localities, such as the Avon Gorge, which have been highly instrumental in the development of British Lower Carboniferous stratigraphy, and the former Bristol and Somerset Coalfield, which played a key role in the economic and social development of the region