Extra information:

NB: Each depositional unit is, plainly, also associated with a surface (e.g. the "Wentlooge Surface" is the upper surface of the Wentlooge Formation). The area between the sea walls is known as the Oldbury surface*, the Rumney Surface being the area of continued Rumney Formation deposition seaward of the wall.

A: "Wentlooge Formation": Up to 15m of blue-green estuarine slty-sandy clays. Lower part has ice wedge (Info) traces, suggesting deposition started close to the end of the last glaciation. Upper part has peats with trees indicating a period when the sea was retreating in the Neolithic and Early Bronze Age*. Above this marine sediments then continue. This matches the picture at Calidicot Castle in the lower Troggy (See Note). The Wentlooge Surface is 1.2m below the Rumney surface*. Generally, there has been an increase in the deposition rate since this the erosion of the Wentlooge*.

B: "Rumney Formation": the Rumney surface is at 0.5m above mean spring tides high water*. In the Oldbury Surface area deposition was interupted by the medieval reclaimations so it is ~1m lower than the Rumney Surface*. Generally there seems to have been an advance in the sea in the 13th-14th C leading to the seawall being moved inland, and the loss of habours like Abergwaitha at Magor Pill*

A detailed description on the rise and fall of sea level in the area and its relationship to settlement can be found in Rippon*.