Geology of Carmarthenshire
The bedrock geology of Carmarthenshire in west Wales consists largely of Palaeozoic age sedimentary rocks. Unconsolidated (or 'superficial') deposits of Quaternary age in Carmarthenshire include a dissected cover of glacial till, valley floor alluvium and some scattered peat deposits in both upland and lowland settings.
Source: Wikipedia — Geology of Carmarthenshire (CC BY-SA 4.0)