The Jaeren area, a border zone of the Norwegian channel ice stream

The coastal lowlands of Jaeren, southwestern Norway, have an extensive cover of Quaternary sediments. Lithological, biostratigraphical and geochronological investigations of a series of boreholes across Jaeren have allowed us to combine earlier and new information on these deposits into a temporal model of Quaternary sedimentation. The cores show evidence of at least four ice free episodes with marine deposition, during mainly arctic conditions. The oldest of these is considered to be ca. 200 ka old and the youngest one is the Sandnes interstadial which is ¹⁴C AMS dated to 32 ka BP. Interbedded between these units are 10-40 m thick units of till with components of marine material. These findings, together with a reevaluation of distinct morphological features on Jaeren, as well as earlier provenance studies, strongly suggest that Jaeren has been a boundary zone between an ice stream following the Norwegian Channel draining a substantial part of the southern region of the Fennoscandian ice sheet, and local ice from south-western Norway. Through multiple periods of glaciation starting ca. 1.1 myr (million years) ago, the Norwegian Channel ice stream has been the main conduit of erosion products from southern Scandinavia to the deep Norwegian Sea. Comparison with ice stream profiles from Antarctica suggests that the deposition of relatively young marine sediments as high as ca. 200 m a.s.1. on Jaeren is a result of glacial isostasy, rather than regional tectonic movements.