Structure, composition and significance of Medieval storm beach ridges at Caerlaverock, Dumfries and Galloway

A set of four gravel beach ridges at Caerlaverock on the north shore of the Solway Firth are shown to have formed in the twelfth and thirteenth centuries ad, the most recent such deposits on this coast. They were investigated by geomorphological mapping, altitudinal survey, sediment stratigraphic and clast lithological analyses to establish their internal structure and sediment sources. Gravel clasts were in part transported from rock outcrops on the west side of the Nith Estuary, and this observation implies that the current estuarine sediment fills of the inner firth were then far less extensive. The data suggest that the Medieval period was one of major coastal change. Fluctuations in sediment supply are demonstrated from the clast lithological analyses which may relate to shifts in the directions of storm tracks

Soft-part preservation in a bivalved arthropod from the Late Ordovician of Wales

A new component of the Early Palaeozoic arthropod fauna is described from a monospecific accumulate of carapaces in a Late Ordovician (Katian) hemipelagic mudstone from the Cardigan district of southwest Wales (UK). Its non-biomineralized carapace is preserved as a carbonaceous residue, as is more labile anatomy (soft-parts) including the inner lamella and sub-ovate structures near its antero-dorsal margin, which we interpret to be putative eyes. The depositional context and associated fauna indicate that the arthropods inhabited an area of deep water and high primary productivity above a pronounced submarine topography. The preserved density of carapaces suggests the arthropods may have congregated into shoals or been transported post-mortem into depressions which acted as detritus traps. The accumulate provides a rare example of soft-part preservation in hemipelagic mudstones and highlights the role of organic material as a locus for authigenic mineralization during metamorphism