Morphology and origin of the palaeo cliff area in the Sambia Peninsula nearshore (SE Baltic Sea)

Abstract

The article scrutinizes stratigraphy, morphology, and origin of the terraced underwater slope of the Sambia Peninsula next to the Taran Cape, the SE Baltic Sea, using a combination of multi-beam and single-beam bathymetry, side-scan sonar survey, CHIRP, single-channel seismoacoustic data, and sediment grain-size results. The underwater slope and its minor landforms were formed by changes of a relative sea-level during the Late Pleistocene and Holocene. Landforms, such as terraces and palaeo cliffs, sinks, remnants, stacks, karst sinkholes, ravines, cuestas, and drowned valleys, are associated with positions of older shorelines, sea-level changes and outcropped Pre-Quaternary formations. Six main stages of the underwater slope development have been recognized. The most important topographic feature is a high palaeo cliff (10 m high) with its toe at a water depth of 26–34 m. The cliff was cut in Cretaceous deposits and has different age and origin in different locations. Its northern sector with a toe at a depth of 34–35 m is polygenetic, formed by tectonic faulting and subsequent abrasion at the Baltic Ice Lake stage. The southern sector, with a toe at a depth of 26–27 m, was cut by wave erosion at the Ancylus Lake stage. Terraces on the underwater slope at depths of 29 m, 34 m, 40 m, 43 m, 48 m and 52 m b.s.l. were formed probably by the Baltic Ice Lake and Yoldia Sea transgressions and survived owing to relatively rapid and short changes of the sea-level. At a depth of 0–26 m, at a sea-level slowstand, selective erosion formed a transgressive wave ravinement surface with karst and cuesta-like landforms on monoclinal Paleogene beds. The depths and the locations of described terraces and palaeo cliffs in the SE Baltic Sea allow us to rectify the relative sea-level curve for the Late Pleistocene-Holocene.