Sedimentation and erosion at the Weichselian ice-marginal zone near Golczewo, Northwestern Poland

Abstract

The Golczewo end moraine was formed during the general ice-sheet recession after the Pomerania Phase of the Late Weichselian glaciation and represents a short period of steady state conditions at the ice-sheet margin. The end moraine is a SW-NE oriented zone formed of several, isolated, 10–15 m high ramparts, separated by low areas (‘gates’). The end moraine zone is located along the axis of the elevated Jurassic bedrock that much influenced the subglacial hydrology. The Golczewo end moraine is formed of two types of subaerial fan. Its major, and morphologically exposed part (hills), is represented by short, glacial-terminal fans. These fans have been partly eroded, especially at tunnel valley mouths. The eroded zones (‘gates’) have been filled with fluvial deposits forming flat sandur fans that extend across the end moraine foreland (plain). These morphological units (ramparts, ‘gates’ and sandur fans) which together form the end moraine zone, were formed synchronously. The ramparts are distinctly elongate hills, commonly asymmetrical, with steep proximal slopes. They comprise a complex sedimentary sequence that suggest alternating phases of sediment gravity flows and fluvial sheet floods. Flow tills indicate the ice-contact conditions. The ‘gates’ between hills and sandur fans are flat to gently inclined. They were formed by braided rivers, with sheet floods dominating at the fan apexes at the ‘gates’ and channelised braided rivers in more distal parts.