Thornback Rays stranding at Southend – March 26, 2009

The morning, stormy high tide at Chalkwell in Southend stranded a large ray on March 9, and the vertebra of this specimen, or more likely others, were found at Westcliff on March 11 and Southend on the 12th. The afternoon tide of March 16 stranded an undecayed specimen, curved and ventral-up on the high water mark at Thorpe Bay. It was a Thornback Ray Raja clavata lacking the yellow tag put on by Cefas for their Thames Ray Tagging and Survival 2007 - 08 study (‘’www.cefas.co.uk’’). After that the tides were generally at a lower level on the beach, but when the strandline of the afternoon tide of March 26 was studied at about the same height, the ray was found to have been converted into a curved skeleton which had moved 140 m to the east and over one groyne. It was ventral-up and showed the thin teeth of males in a head skeleton width of 125 mm, and a now partly preserved overall length of 0.5 m. Presumably it was eaten by gulls on the beach and then moved by the ides as they returned to the same elevation.

Hummocky Cross Stratification

Oct 7,2008

The photographs show a rectangular calcite cemented 0.15 m thick block of black laminated very fine grained sandstone interbanded with and cut by white bands and burrow fillings representing bioturbated clays deposited between offshore marine storms in the Eocene London Clay Formation. The block was dug up recently at a depth of 18 inches (c.0.5 m) in the front garden of Symonds Avenue in Eastwood, Essex, previously mapped by the British Geological Survey officer G.W. Green as basal Claygate Beds of Eocene age when it was a grassy field in 1972. More recently an excavation in the pavement there showed laminated orange sands and brown clays at the same depth and altitude (38 m above mean seal level). The occurrence of flint pebbles in the loose sands made it look like the local Quaternary Brickearth deposits showing similar banding elsewhere. Having a calcite cemented block of the sands, which include one 5 mm diameter quartz grain in the side, confirms the mapping of these sands as an uncontaminated Eocene storm deposit within the upper part of marine London Clay Formation. The way-up of the block was unrecorded and unclear, with fungal spores on the flatter side suggesting it was once on top in the soil and the cutting of the black sands by white clay-filled Eocene marine burrows (Chondrites and some larger ones) suggesting it is actually below. The other side of the block is absent and the adjacent part is fully bioturbated. It is probably the top of a rapidly deposited storm sand layer buried within offshore marine clays. The sandy sedimentary structures look like Hummocky Cross Stratification (HCS).