Pollen and dinoflagellates from the Red Crag at Walton-on-the-Naze, Essex: evidence for a mild climatic phase during the early Late Pliocene of eastern England

Abstract

Spot sampling of the Red Crag Formation at Walton-on-the-Naze, Essex (= Walton Cray) has revealed a diverse record of dinoflagellates, pollen, and other palynomorphs. Pollen from a basal horizon is dominated by Pinus, but also contains high values of Sciadopitys and a small but diverse component of deciduous mesothermal trees. Taxodium is more common at 2 m above the base of the Red Crag and may represent a different part of a climate cycle. A mild- to warm-temperate climate is inferred for the Walton assemblages and a correlation with the Reuverian B pollen substage (Late Pliocene, 3.0 to >2.6 Ma) is demonstrated, thereby constraining the timing of an important marine transgression in eastern England.

Dinoflagellates from the basal horizon and from 2 m above the base of the Red Crag generally indicate a restricted marine environment, but outer neritic to oceanic dinoflagellates are occasionally present, and imply the penetration of more saline North Atlantic water masses into the southern North Sea basin. Mild- to warm-temperate conditions are indicated by the presence of several thermophilic species. The Walton assemblages have strong similarities with those of the mid-Pliocene Coralline Crag Formation of eastern England, but differ in the presence of Bitectatodinium tepikiense, which, along with an apparently reduced species richness, gives evidence of cooler conditions. A number of thermophilic species at Walton are not reported from younger Pliocene deposits in eastern England, perhaps reflecting a less equable climate after Northern Hemisphere cooling at 2.55 Ma.