Loess of the Lizard Peninsula, Cornwall, SW Britain

The geology of the Lizard Peninsula, the UK’s most southerly projection into the English Channel, is dominated by serpentinised peridotites, gabbro and amphibolites of the Palaeozoic Lizard Complex. Its Cainozoic history dates to at least the Palaeogene, resulting in a relatively complete record of events, involving the deposition of the anomalous quartzose Crousa gravels, intense weathering, possible fault controlled uplift, development of the current drainage pattern, subsequent coastal modification by marine erosion prior to the deposition of presumed Mid to Late Pleistocene raised beaches, soliflucted diamicts, and Late Pleistocene loess. The Lizard Loess, a UK lithostratigraphic formation, is generally perceived as a thin deposit extensively developed inland and capping the thicker diamict/‘head’ sequences on the coast. This study indicates that these sequences (coastal ‘head’ units) are themselves loessic on the serpentinised peridotite and amphibolite coasts and gabbroic headlands. The location and distribution of loess on the peninsula have been influenced by its rock types and their local weathering/erosion regime. There appears to have an earlier phase of Late Pleistocene loess deposition, associated with dynamic periglacial processes, contemporaneous with other ‘head’ deposits both on the Lizard and elsewhere in south Cornwall. A later widely preserved phase with more quiescent conditions followed. The currently accepted (15.9 ka) age for the Lizard loess almost certainly belongs to this later phase.