During the last 10–15 years a number of excavations have significantly increased our knowledge about the Middle Mesolithic (c. 8300–5600 cal. BC) in Southeast Norway. Recent research has e.g. disclosed prominent and abrupt changes in settlement patterns and lithic technology at the transition from the Early Mesolithic, as well as great variability in Middle Mesolithic settlement sites regarding both types and sizes. Still, there has been a shortage of solid documentation from the very beginning of this development, especially C14-dated sites, and the changes in settlement systems and landscape exploitation in Middle Mesolithic are poorly understood.

This paper will present results from recent excavations conducted within the InterCity project in Vestfold. Having excavated five Middle Mesolithic sites, the investigation sheds new light on the settlement in the northwestern parts of the Oslo fjord area. By means of radiocarbon dates and a new shoreline displacement curve, the sites are dated to the period c. 8200–6600 cal. BC. The sites are situated close to the ancient shore in a rich marine environment with an abundance of small islands, inlets, sounds and sheltered bays. The sites vary from 55 to 13,000 square metres in size, and have yielded between c. 100 and 16,000 lithic artefacts. Some sites include rare finds such as charcoal-filled structures, culture layers including hazelnut shells, fragments of burnt bone, and lumps of birch bark pitch. Demonstrating great variability in size and character, the sites are interpreted as representing a diversity in activities and landscape use.