GIS‐based multiproxy coastline reconstruction of the eastern Gulf of Riga, Baltic Sea, during the Stone Age

Abstract

We present early to mid-Holocene palaeocoastline reconstructions for the Tolkuse-Rannametsa area on the eastern coast of the Gulf of Riga. Radiocarbon-dated sediment stratigraphies and diatom analyses, supported by ground-penetrating radar data and GIS-based modelling, were used in the palaeogeographical reconstructions to strip back younger sediments and landforms from the LiDAR-derived digital elevation model. The reconstructions show an open coast environment during the Ancylus Lake stage and the formation of a peatland after the lake drainage at about 9000-8600 cal. a BP. The waters of the Litorina Sea flooded the study area between 8200 and 7700 cal. a BP, forming a 25-km-long and up to 5.5-m-deep lagoon with two connections to the sea. This brackish water lagoon existed in the area for about 4000 years and terminated around 3800-3500 cal. a BP as a result of isostatic uplift and growth of the barrier spit. The reconstructions illustrate the relationships between the lagoonal system and three Mesolithic and Neolithic settlement sites found in the study area. A comparative analysis which besides palaeogeographical and ecological data included a data set with more than 100 Stone Age sites from the eastern Baltic region, was used to propose the most suitable locations for coastal settlements in the Tolkuse-Rannametsa area. However, some of these areas are presently covered by a peat layer that is several metres thick, which may explain the relative scarcity of the archaeological finds on the shores of the palaeo-lagoon. The proposed multiproxy approach has the capability to delimit the areas that would have been favourable for prehistoric habitation, but might not be observable in the present-day topography. In return, this increases the likelihood of locating any well-preserved preserved settlement sites and artefacts that are buried under the protective sediment layer.Hando-Laur Habicht (hando-laur.habicht@ut.ee)and Raivo Aunap, studies and was incorporated into the current study for detailed palaeogeographical reconstruction of a palaeo-lagoon system in the coastal zone of the Gulf of Riga, the Baltic Sea.

A new early Holocene shoreline displacement record for Blekinge, southern Sweden, and implications for underwater archaeology

“…; Habicht et al . ). However, this approach is complicated by the deposition of sediments from the time of reconstruction to the present, which may lead to an underestimation of the inferred water depths.…”

“…Manipulation of the DEM data by shifting the position of the water level is an established method for visualization of past shorelines (e.g. De Smedt et al 2013;Sturt et al 2013;Habicht et al 2017). However, this approach is complicated by the deposition of sediments from the time of reconstruction to the present, which may lead to an underestimation of the inferredwater depths.…”

“…Sturt et al 2013;Harffet al 2017) and local (e.g. Habicht et al 2017;Muru et al 2017;Hansson et al 2018b) scales. Flemming (2017) lists a set of core variables needed for accurate landscape reconstructions, including bathymet-ric data, seabed sediment characteristics, sub-bottom acoustic data and palaeo-sea-level data.…”

Buried amber finds in the coastal deposits of Saaremaa Island, eastern Baltic Sea – their sedimentary environment and possible use by Bronze Age islanders

“…ATR-FT-IR spectra of amber finds from the Vintri BOM layer and comparison samples collected from the modern beach of Allirahu islet near Saaremaa (Fig. In Estonia other Bronze Age BOM layers are not known, but there are older BOM layers on Saaremaa Island (Saarse et al 2006(Saarse et al , 2009 and in SW Estonia (Veski et al 2005;Saarse et al 2006;Rosentau et al 2011;Habicht et al 2017) associated with early-to-mid Holocene coastal deposits. The grey box marks the range of the Baltic shoulder in the range of 1200-1250 cm À1 characteristic only of Baltic amber.…”

The Baltic Sea: geology and palaeoenvironmental evolution – introduction

“…Bendixen et al (2017) address this subject by reconstructing the depositional environment in the southern Kattegat from seismic and sediment core data. Another example comes from the eastern Gulf of Riga (Habicht et al 2017), where early to Mid-Holocene palaeocoastline reconstructions suggest lagoonal brackish-marine sedimentation after an open coastal environment during the Ancylus Lake stage that lasted until about 5500 ka and was terminated by the ongoing isostatic uplift and the barrier spit growth. One interesting example of the complex coastal processes that took place during the early Littorina Sea Stage in the southeastern Baltic Sea is presented by Sergeev et al (2017).…”