Holocene relative shore-level changes and geoarchaeology of the prehistoric sites in western Estonia

In this thesis, past sea-level changes and palaeolandscapes were reconstructed for Pärnu, Hiiumaa and Saaremaa, using sedimentological and archaeological proxies and GIS-based landscape modelling. Three new relative shore-level (RSL) curves were constructed based on critically reviewed geological and archaeological sea-level indicators from the study areas providing new information about Holocene RSL trends and new perspective for future studies of Mesolithic submerged landscapes. The RSL curves complemented our previous knowledge about Early- to Mid-Holocene shore-level lowstand phases, and Late Holocene regression period, which led to improved interpretations about prehistoric coastal habitation patterns in western Estonia. Palaeogeographical reconstructions show that the oldest Stone Age settlement sites at the lower reaches of the River Pärnu were probably established further from the concurrent coastlines than previously proposed. Thus, the general Mesolithic context might justify the assumption of year-round habitation, with temporary fishers’ camps at the coastline, possibly even in the bottom of the present-day Pärnu Bay. In Hiiumaa the prehistoric hunter-gatherers mostly preferred the shores of the SE exposed Kõpu palaeobay, but the surroundings of the Kõivasoo palaeolake and its outflow were also utilized. The Mesolithic and early Neolithic campsites on the shores of the Kõpu palaeobay were located successively at lower elevations following the Litorina Sea shoreline retreat, while younger sites were established away from the shores, as the coastal zone had lost its centrality for the inhabitants’ nutrition due to the spread of farming. In Bronze and Viking Ages the sea had gained an importance for trade and communication and the Baltic Sea, together with nearby rivers, lakes and straits (including a former strait in Salme village), formed a prehistoric transportation network. Our data support the conclusion from other slowly uplifting areas in western BSB about the deceleration in the isostatic rebound. The relative sea-level trend has been a bit slower compared to the present-day absolute land uplift rate, indicating also a slow eustatic sea-level rise during the Late Holocene. As a result, in the Pärnu area, where the glacial rebound is the slowest in Estonia, the relative mean sea level shows already signs of rising.