Post-glacial sedimentary evolution of a microtidal estuary, Dyfi Estuary, west Wales, U.K.

The,Dyfi Estuary is a microtidal estuary located on the shores of Cardigan Bay on the west coast of Wales. The inundation of the post-glacial sea-level rise has produced transgressive muddy or silly, late-glacial and post-glacial unconsolidated sediments in the pre-existing valley. These sediments are complicated by sea-level fluctuations and changes in tidal range. Modern facies-distribution patterns and sedimentary characteristics, extensive core data, and chronostratigraphic cross-sections provide a detailed history of the post-glacial sedimentary evolution of the Dyfi Estuary. The post-glacial estuarine evolution of the Dyfi Estuary has been subdivided into four phases. Phase 1: 15,000-10,000 yr BP, shallow-water, high-energy fluvially dominated facies. Phase 2: 10,000-6,000 yr BP, deep-water, low-energy, estuarine dominated facies. Phase 3: 6,000-3,500 yr BP, shallow-water, high-energy, tidally dominated facies. Phase 4: 3,500 yr BP-present, shallow-water, low-energy, estuarine salt-marshes dominated facies.