Stratigraphy and palaeobotany of Middle Pleistocene interglacial deposits in the North Sea
This study presents a detailed palynological investigation of Middle Pleistocene interglacial sediments from the North Sea. A borehole and three vibrocores from the Inner Silver Pit area of the southern North Sea, and a borehole from the Devil's Hole area of the central North Sea, have been investigated. The palynological investigation has been supplemented by micropalaeontological and sedimentological analyses and also by seismic data. The sequence recovered in borehole 81/52A from the Inner Silver Pit presents a depositional record from the mid-Anglian to the Wolstonian glacial stage. Glacigenic sediments overlying Cretaceous Chalk correlate with the Lowestoft Till (Anglian). The depositional history of the interglacial cycle indicates that during the pre-temperate substage extensive erosional activity occurred in coastal areas causing a large proportion of reworked pollen and a very low amount of contemporaneous pollen to be deposited. The sequence preserves a good vegetational record of the early-temperate (HoII), late-temperate (HoIII) and post-temperate (HoIV) substages. The pollen assemblages representing HoIlI and HolV are very similar to the pollen assemblages of these substages from Marks Tey, Essex. The pollen assemblage representing HoII is different from Marks Tey in having a high proportion of Picea; as such it shows similarity with the pollen assemblages found at Nechells, Birmingham. The sequence of the sands and gravels can be correlated with the Wolstonian sands and gravels at Tottenhill in the Nar Valley, North Norfolk and with Saalian sediments in the Dutch sector of the North Sea. Three vibrocores, 53/00/962, /1103 and /1104, from the Inner Silver Pit area provide additional data and represent various parts of the Hoxnian interglacial stage. Pollen data from borehole 81/34 from the Devil's Hole area suggests that the sequence representing the Ling Bank Formation does not represent a single interglacial stage but rather two interglacial stages (separated by a cold stage) within the Cromerian Complex.