Flint gravel deposits from our marine South Coast licences – Areas 372/1 (Nab Tower/East Isle of Wight) and Area 435 (Owers/off Littlehampton) – are consistent, dependable, coarse materials with a medium-coarse grained sand content. They reflect their high-energy river-deposited origins being originally derived from the Cretaceous chalk flints of the Weald of south east England and laid in deep river channels (over 15-20m thick in places) and associated floodplains from the original River Solent (now the Test and Itchen) and River Arun (Owers) from the last ice age.
Glacial-derived gravel deposits from our Humber licence, Area 106/400, are a highly consistent material. They reflect their depositional environment: being the coarsely-graded sediment deposited directly by glaciers. This material is mostly derived from subglacial erosion and entrainment by moving glaciers of sediments originally from Scotland and Northern England.
Areas 212, 240, 328, 361-242 and 401-2 are all sand and gravel-rich deposits typical of a large scale meandering braided river system. The system had a channel that consisted of a network of small passages separated by small and temporary islands. The high-quality gravel and medium-sized sand deposits now extracted were generated as a result of varying sediment supply, stream gradient, rapid and frequent variations in water discharge, erodible banks and a steep channel gradient; all of which occurred during the last Ice Age when much of the North Sea was exposed as a land bridge to Europe.
English Channel Region (ECR)
The ECR deposits, seen in the gravel deposits from Licences 473, 474 and 460, are materials typical of the extremely high energy and large-scale fluvial system in which they were generated. Offshore, the development of these complex systems resulted in channels up to depths of 50m below sea level and 3km wide. Multi-phase channelling and infilling is evident. The English Channel continental shelf has been periodically flooded by post-glacial sea-level rise during the Quaternary, leaving behind a complex sedimentary record that is an amalgamation of fluvial, coastal and marine deposits that has been substantially reworked to provide the quality material extracted today.
The high-grade, homogenous sand deposits of Licence Area’s 472 and 470 are extracted from large sandbanks within the Bristol Channel. This area is underlain by Jurassic base rock within which a submarine valley system was reported to have formed during the late Tertiary – early Quaternary, and the sand deposits were modified by glaciations and inter-glacials, during the late Quaternary. This submarine system sits on top of the basal deposits in the form of large scale sand-waves and lag deposits. The floor of the Bristol Channel is characterised by positive localised features of several types including tidal sand ridges (the most important being Culver Sand, known as Area 472).