| Abstract: |
Interest in the submerged lands of the Solent was first roused in the 1980s, with the discovery of flint tools and chunks of forest floor in the trawler nets of local fishermen. Intermittent diving searches led to the discovery of a submerged woodland plateau with trees embedded in a thick bed of peat. This drowned landscape was dated to the seventh millennium BC. In 1999 flint implements of the Mesolithic period were recovered from a lobster burrow that was still energetically defended by its occupant. Further investigation demonstrated that the lobster had burrowed into a secure archaeological horizon that was still eroding at the foot of an underwater cliff. With confirmation that this was a stratified assemblage, and the only one of its kind in the UK, the Hampshire and Wight Trust for Maritime Archaeology initiated a multidisciplinary project to evaluate the nature, vulnerability and rate of loss of this archaeological resource. The project design embraced underwater excavation, box sampling and the sawing of trees. The results were subject to archaeological, palaeoenvironmental, dendrochronological, and geomorphological analyses, and calibrated with a suite of radiocarbon dates. The initial locus of investigation was named Bouldnor Cliff II (BC-II). This was located at the foot of the submerged clay cliff. The seabed here was peat, overlying a clayey sand at a depth of 11m below OD. Dozens of fresh-looking flint flakes and worked flint pieces were scattered where the cliff was actively eroding. The parent deposit from which the lithics were recovered at BC-II represents a streamside environment that had once flourished close to a wetland or lake; the build-up of a freshwater sand bar had occurred between c 6060–5990 cal BC and 6030–5980 cal BC. This was a period of encroaching sea level that, by c 6000–5910 cal BC, had triggered the accrual of brackish water and salt marsh around the fringes of a basin. While the work on BC-II was proceeding, bathymetric surveys were conducted along Bouldnor Cliff. This revealed a kilometre-long peat terrace at 11–11.5m below OD protruding from the base of a 7m-high cliff. A second, smaller, submerged cliff was recorded at the exposed edge of the terrace. Bathymetric surveys were also conducted in the north-west Solent, where similar, but shallower shelves, of peat were traced between Hurst Spit and Pitts Deeps. Diving investigations identified several sites of interest, including Hawker’s Lake, where submerged trees had been growing in a landscape that was now only 2.5–3m below OD by Hurst Spit. Other areas of significance included submerged deposits off Tanners Hard, 6km to the east, where evidence of anthropogenic activity was found associated with two peat horizons at 4m and 6m below sea level. To the south, at –7m OD, Bouldnor Cliff-IV (BC-IV) was the source of several knapped flint flakes that had eroded from the basal deposit, while, 200m to the east at –11m OD, Bouldnor Cliff V (BC-V) was found to be rich in worked organic material. The discoveries at BC-V were particularly significant as they contained evidence of woodworking and small-scale industry. An archaeological horizon just below the seabed was covered with burnt flints, charcoal, wood chippings, trimmed pieces of wood, and lengths of prepared string. The identification of a tangentially split oak timber suggests the construction of a large structure or possibly a log boat using techniques that do not appear in the British archaeological record for another 2000 years. The site, which was eroding from the exposed edge of the woodland plateau, is 424m west of BC-II. Analysis of the sediment archive associated with the submerged landscape enabled a reconstruction of events leading to the formation of the Western Solent. The evidence shows that the site had been a lacustrine environment or wetland associated with a river plain. |
