Sub-project 1: Natural and Cultural Sciences Holocene

Regional geological overview

The sediments of the coastal Holocene reach a thickness of up to 25 m in the back tidal flats (STREIF, 1990) and are composed of lagoonal, brackish and marine sediments with intercalated peat layers. In the Jade Bay area, the natural eastern boundary of the East Frisian Peninsula, a thickness of up to 15 m is assumed for the tidal flat sediments of the bay mudflats, and up to 25 m for channel areas. Older sediments only rarely come to light. They remain hidden in the underlying Holocene body and identify the Upper Pleistocene.

At the beginning of the Holocene, the area around today's Jade Bay is initially characterised by forested geest. At this time, the post-glacial coastline still runs approx. 400 km further north (BEHRE, 2003, Fig. 15). The relative sea level rises rapidly at a rate of approx. 15 metres per millennium (BEHRE, 2003), the sea advances rapidly to the south and reaches today's island area, the catchment area of the Jade basin, approx. 8,000 years ago. At the end of this phase, a reduced rise in relative sea level is recorded for the East Frisian Peninsula from 6,500 years before present, which is characterised on the one hand by eustatic sea level rise and on the other by glacio-isostatic coastal subsidence (e.g. SHENNAN 1987, AUGATH 1993, KIDEN, DENYS & JOHNSTON, 2002, TÖPPE, 1994, VAN BALEN ET AL. 2005). With an average relative rise of 1 m per millennium (BUNGENSTOCK, 2006, 2009), depositional conditions were created that allowed fens the time to grow at the beginning of this development. This resulted in the formation of large areas of peatland, some of which have flooded and dried out several times over the course of time (FREUND & STREIF, 2000; STREIF 2004) and are subsequently indicators of a prograding or retrograding coast.