This memoir describes the district around the City of Cardiff and Barry situated beyond the southern margin of the South Wales Coalfield. The variable geology encompasses gently folded Silurian, Devonian and Carboniferous rocks, now largely seen in inliers exposed through an unconformable cover of late Triassic and Lower Jurassic strata. These younger rocks and the basal unconformity are spectacularly displayed in classic coastal sections between Barry and Penarth.
It presents a description of the geological history of the district, which can be traced back some 420 million years, through an examination of the stratigraphy, palaeontology and depositional environments of the various rock sequences. Much new information from several boreholes drilled during the resurvey is provided. The deposits of the last glaciation, well developed in the north of the district, are also described together with the clays and peats flanking the Severn estuary north of Penarth, the products of the subsequent rise in sea level.
Further chapters deal with the tectonic evolution and economic geology, including the water supply, of the district.