<p> Isostatic rebound and climatic changes throughout the Holocene have resulted in several periods of lowered water-levels in the Great Lakes watershed. The Early Holocene lowstand phase corresponds with the Paleoindian period in the Great Lakes Region (11,000-9000 YBP), and subsequent water-level rise has inundated Paleoindian archaeological sites. This research sought to reconstruct the water-level history of Rice Lake (located north of Lake Ontario) in order to identify areas of high potential for submerged prehistoric sites. </p> <p> Over 750 line km of detailed geophysical data (single-beam bathymetry) and 16 sediment cores were collected over a 30 km2 area of Rice Lake. Sediment cores were visually logged and analyzed for particle size, microfossils and microdebitage. Water-level reconstructions accounting for sediment infill and isostatic rebound of the lake record a post Lake Iroquois (after 12 ka BP) Early Holocene lowstand (~10-12 m below present level (bpl)) (EH-1). At 10 ka BP, gradually rising water-levels and establishment of wetlands as indicated by thecamoebian assemblages coincide with a newly discovered Paleoindian occupation of the Mcintyre basin, where quartz microdebitage was found. Waterlevel continued to rise to almost 2 m bpi until 6.5 ka BP, when warmer and drier temperatures caused a sudden drop in water-levels as recorded by a pollen hiatus. After 4 ka BP, water-levels quickly recovered and stabilized as shown by rapid recovery of pre-hiatus thecamoebian biofacies and the establishment of wild rice stands. </p> <p> The small number of known, well-preserved Great Lakes Paleoindian sites has limited analysis of Early Holocene population densities, migration patterns, cultural diffusion, or the chronology of settlement. The method of modelling water-level fluctuations and associated archaeological potential developed in this thesis represents a substantial advance in our understanding of Early Holocene archaeology in the Great Lakes. These methods will have broader application to exploration of submerged terrestrial landscapes elsewhere in the Great Lakes and will allow for future regional synthesis of archaeological site distribution and characteristics. </p> / Thesis / Doctor of Philosophy (PhD)

I denna magisteruppsats kommer strategiska lägen och boplatsers relation till gravar att studeras. Arbetet riktas in på Arnäs och Själevad socken i Örnsköldsvik kommun som ligger in Västernorrlands län. Mer specifikt så är det järnåldersboplatser i Skommarskatan, Gene, Vågnäs and Sörvåge som inkluderas i uppsatsen. Terrängmodellerings kartor, viewsheds, landhöjnings kartor och historiska kartor, litteratur samt fältinventering används för att komma fram till vilket sätt boplatser blev strategiskt belagda och vilken rumslig relation det finns mellan boplatser och gravar. Det visar sig att gravar verkar vara anlagda nära boplatser, men resultatet tyder på att man inte nödvändigtvis ser gravarna från boplatserna på boplatslokalerna. Resultaten visar att viewsheds inte alltid stämmer med det man ser i fält.Resultatet antyder på att terräng, relation till vatten, närhet till färskvatten, kommunikation möjligheter, handelsmöjligheter, resurstillgångar, huskonstruktion och på vilket sätt människorna livnärde sig på har en inverkan på vilket sätt boplatser anlades. Tidigare så har mycket fokus varit lagt på hur RAÄ 22:1 i Gene var strategiskt lagd inom arkeologisk forskning, men i den här uppsatsen har fokus legat på andra typer av boplatser och andra delar av landskapet med hänsyn till fler lokaler. Denna studie har demonstrerat att tidigare studier av järnåldersboplatser i Arnäs och Själevad socken har varit begränsad i sin syn att belysas boplatsers relation till landskapet. Tidigare forskning var fokuset på en lokal och det har visat sig vara en brist när man jämför med landskaps studiemetoder använda i denna studie. Nu har agrara, jägare-samlare och säljägare boplatser studerats och vidgat perspektivet på boplatser strategiska lägen inom studieområdet.

Ten sediment cores (2.0-8.5 m long) from various locations in Lake of the Woods (LOTWs) and Shoal Lake (SL) were recovered in August 2006, using a Kullenberg piston corer. From the study of the macrofossils (primarily ostracodes and thecamoebians) and the sediments in six processed cores, variations in paleoconditions were observed both spatially and temporally, and the timing of these changes were identified in over 10,000 years of postglacial history. Ostracodes disappeared from the LOTWs record from about 9000 to 7600 calendar years before present (BP) (about 5800 in SL), after LOTWs became isolated from glacial Lake Agassiz. Thecamoebians appeared in many cores around 2000 calendar years BP, with the earliest appearance at 9200. Buried paleosols in three cores indicate portions of the lake dried on several occasions during the Hypsithermal, perhaps indicating the region’s future climate response. One core contained a pink clay bed indicative of the Marquette readvance about 11,300 years (BP), and the subsequent input of water from the Superior basin.

Ten sediment cores (2.0-8.5 m long) from various locations in Lake of the Woods (LOTWs) and Shoal Lake (SL) were recovered in August 2006, using a Kullenberg piston corer. From the study of the macrofossils (primarily ostracodes and thecamoebians) and the sediments in six processed cores, variations in paleoconditions were observed both spatially and temporally, and the timing of these changes were identified in over 10,000 years of postglacial history. Ostracodes disappeared from the LOTWs record from about 9000 to 7600 calendar years before present (BP) (about 5800 in SL), after LOTWs became isolated from glacial Lake Agassiz. Thecamoebians appeared in many cores around 2000 calendar years BP, with the earliest appearance at 9200. Buried paleosols in three cores indicate portions of the lake dried on several occasions during the Hypsithermal, perhaps indicating the region’s future climate response. One core contained a pink clay bed indicative of the Marquette readvance about 11,300 years (BP), and the subsequent input of water from the Superior basin.

La Côte Nord de l’Estuaire et du Golfe du St. Laurent (Québec, Canada) est caractérisée par une série de complexes deltaïques mis en place en contexte de chute de Niveau Marin Relatif (NMR) forcée par le rebond glacio-isostatique, lors du retrait des marges de l’Inlandsis Laurentidien. L’étude de trois complexes deltaïques montre qu’un motif d’évolution morphostratigraphique contrôlé par le retrait des marges glaciaires prévalait au premier ordre. Le premier stade de sédimentation se caractérise par la mise en place de cônes d’épandage juxtaglaciaires sous-aquatiques. Leur localisation au front de la marge glaciaire fait que la répartition spatiale des corps sédimentaires montre localement un empilement en rétrogradation. Dès l’émergence d’un front glaciaire continental, des deltas proglaciaires se développent en contexte de chute de NMR, formant des lobes dont l’altitude décroît vers le bassin. Ces derniers sont initialement associés à un système fluviatile en tresse alimenté en sédiments glaciogéniques par les marges glaciaires en retrait. Malgré des taux de chute de NMR de plusieurs cm/an, aucune incision fluviatile n’est observée à ce stade et la dynamique de transfert est prédominante du fait des forts taux d’apports sédimentaires. Plus tard, à la suite du retrait des marges glaciaires hors des bassins versants, le remaniement paraglaciaire se développe du fait de la réduction drastique des apports en eaux et sédiments. Le système fluviatile, devenu méandriforme, s’encaisse dans les anciens dépôts deltaïques maintenant inactifs et les bordures de deltas sont remaniées par les processus littoraux (plages soulevées, terrasses marines). Cette étude révèle que la majorité du volume de ces complexes deltaïques (10-20 km3) est mis en place en quelques milliers d’années seulement, immédiatement après la déglaciation ; le remaniement paraglaciaire n’ayant contribué à l’accrétion deltaïque que très marginalement. La modélisation numérique (Dionisos) valide les différents forçages identifiés par l’analyse morphosédimentaire. Une synthèse des complexes deltaïques à l’échelle de toute la Côte Nord du St. Laurent a permis de catégoriser 21 complexes deltaïques en 4 scénarios d’évolution morphosédimentaire, directement liés à la dynamique de retrait de la marge glaciaire. Leur décryptage offre une clef de lecture originale pour l’historique du retrait des marges glaciaires de l’Inlandsis Laurentidien sur la période 12-7.5 ka cal BP. / The North Shore of the St. Lawrence Estuary and Gulf is characterized by the presence of deltaic complexes that were emplaced under falling Relative Sea Level (RSL) forced by the glacio-isostatic rebound, immediately after the retreat of the Laurentide Ice Sheet (LIS) margin. The study of three deltaic complexes reveals that a common morphostratigraphic evolution forced by the retreat of the LIS prevailed for the edification of these structures, reflecting the retreat of the LIS margin. The emplacement of subaqueous outwash fans beyond the retreating or stillstanding glaciomarine margin constitutes the first stage of this evolution. As tied to the ice-margin position, these fans are characterized in places by a backstepping stacking pattern, in spite of the forced regressive setting. From the emergence of a continental ice front, the proglacial deltaic system develops and forms lobes staged accordingly to the RSL fall. These deltaic systems actively prograde at that time because they are fed in glaciogenics by the retreating LIS margin through braided meltwater streams. In spite of the RSL fall reaching several centimeters per years, no fluvial entrenchment occurs mainly owing to the significant amount of sediment supply. Later, when the LIS margin retreats from the drainage basins of feeding rivers, fluvial systems experience a drastic drop in sediment supply that forced the interruption of the deltaic progradation and the onset of paraglacial reworking. The paraglacial reworking consists in the entrenchment of a meandering fluvial system within former deltaic deposits and shows the prevalence of shallow-marine processes (waves, tides) at the delta rim (raised beaches, marine terraces). This study reveals that the bulk of the deltaic volume (c.a. 10-20 km3) for each complex was emplaced in only a few thousands of years following the LIS margin retreat when the latter was still located in the drainage basin. The paraglacial reworking had a minor influence on the deltaic accretion. A forward stratigraphic model (Dionisos) is used to validate the variety of forcing as understood from the sedimentary analysis. A synthesis including 21 deltaic complexes of the St. Lawrence North Shore allowed the establishment of a fourfold categorization. This scheme of deltaic evolution was used in order to refine the position of the LIS margin retreating upland for a period ranging from 12 to 7.5 ka cal BP.