Periglacial landforms and landscape development in southern England

Abstract

The south-central and south-east England Geological Conservation Review region is unique in Britain in lying completely outside the margins of Quaternary ice sheets. In view of this, the area has been described as a ‘relict periglacial landscape’. This implies that the region has evolved its current form substantially under the influence of seasonal and/or perennial frost. In fact, modern research has demonstrated that permafrost, either continuous or discontinuous, likely existed across probably the whole of the region at different times during the Quaternary. This has important implications for ground permeability and the strength of sediments and soils and this has, without doubt, influenced landscape development. Whilst the whole region appears to have experienced cold environmental conditions, the landforms, structures and sediments of some sites are particularly associated with periglacial processes. Allington Quarry, Spot Lane Quarry, Oaken Wood, Chiddingly Wood (known locally as Chiddinglye Wood), High Rocks and Rusthall Common have exhibited typical cambering structures with open or closed gulls. The latter three sites also display a fine range of surface weathering features. Hubbard's Hill is characterised by solifluction and active-layer detachment slides and associated subsurface shear structures, whilst the sarsen trains at Fyfield Down and Valley of Stones are also attributed to solifluction processes. Birling Gap and Pegwell Bay exhibit spectacular sediment brecciation and involutions. Pegwell Bay is also known for its thick layer of periglacial loess, a sediment that is also a feature of North Cliff, Broadstairs. Unfortunately, the dating of these landscape features has, so far, proved possible only at Hubbard's Hill and Pegwell Bay. Nevertheless, the sites reviewed here provide exceptional, and in some cases internationally important, indications of landscape development in cold, often permafrost, environments which justifies their status as GCR sites.