A facies analysis of the cambrian of wales
Abstract The Cambrian sediments of Wales are analysed with particular regard to lithology, directional and non-directional inorganic sedimentary structures and trace fossils. It is deduced that deposition occurred in a narrow, fault controlled, roughly northeast-southwest trending trough. The northwestern margin of the trough was variously situated on and to the northwest of Anglesey while the southeastern margin probably lay in the Welsh Borderlands or English Midlands. The axial terminations of the trough are unknown. Sediment transport within the trough appears to have been mainly by turbidity and other bottom currents, with the coarser sediment generally laterally derived from nearby fault uplifted landmasses and the finer sediment axially derived from a more distant southwesterly source. The biogenic and inorganic sedimentary structures are consistently in agreement in indicating that the sediments did not all accumulate in either shallow or deep water as has been previously claimed but in variable water depth at all localities. The depositional history of the area does not readily accord with the early stages of the generally accepted scheme of geosynclinal evolution and the Cambrian sequence should not therefore be considered as part of the so-called Welsh Lower Palaeozoic geosynclinal sediments as advocated by Jones (1938).