An updated radiocarbon-based ice margin chronology for the last deglaciation of the North American Ice Sheet Complex

The North American Ice Sheet Complex (NAISC; consisting of the Laurentide, Cordilleran and Innuitian ice sheets) was the largest ice mass to repeatedly grow and decay in the Northern Hemisphere during the Quaternary. Understanding its pattern of retreat following the Last Glacial Maximum is critical for studying many facets of the Late Quaternary, including ice sheet behaviour, the evolution of Holocene landscapes, sea level, atmospheric circulation, and the peopling of the Americas. Currently, the most up-to-date and authoritative margin chronology for the entire ice sheet complex is featured in two publications (Geological Survey of Canada Open File 1574 [Dyke et al., 2003]; ‘Quaternary Glaciations – Extent and Chronology, Part II’ [Dyke, 2004]). These often-cited datasets track ice margin recession in 36 time slices spanning 18 ka to 1 ka (all ages in uncalibrated radiocarbon years) using a combination of geomorphology, stratigraphy and radiocarbon dating. However, by virtue of being over 15 years old, the ice margin chronology requires updating to reflect new work and important revisions. This paper updates the aforementioned 36 ice margin maps to reflect new data from regional studies. We also update the original radiocarbon dataset from the 2003/2004 papers with 1541 new ages to reflect work up to and including 2018. A major revision is made to the 18 ka ice margin, where Banks and Eglinton islands (once considered to be glacial refugia) are now shown to be fully glaciated. Our updated 18 ka ice sheet increased in areal extent from 17.81 to 18.37 million km2, which is an increase of 3.1% in spatial coverage of the NAISC at that time. Elsewhere, we also summarize, region-by-region, significant changes to the deglaciation sequence. This paper integrates new information provided by regional experts and radiocarbon data into the deglaciation sequence while maintaining consistency with the original ice margin positions of Dyke et al. (2003) and Dyke (2004) where new information is lacking; this is a pragmatic solution to satisfy the needs of a Quaternary research community that requires up-to-date knowledge of the pattern of ice margin recession of what was once the world’s largest ice mass. The 36 updated isochrones are available in PDF and shapefile format, together with a spreadsheet of the expanded radiocarbon dataset (n = 5195 ages) and estimates of uncertainty for each interval

Pleistocene Eider Duck (Somateria cf. mollissima) from Champlain Sea Deposits near Shawinigan, Québec

Most of a pelvic bone of a large eider duck (Somateria cf. mollissima) was collected in place in a unit of stratified clay and sandy silt near Shawinigan, Québec. The fossil is important because it is the first bird specimen from Champlain Sea deposits to be identified to the generic level. Evidently the duck died and was deposited near the northern shore of the Champlain Sea a few hundred years before the sea drained. A sample from a bed of large, marine mollusc shells (Mya arenaria) found in place just above the eider duck fossil yielded a radiocarbon date of 10 300 ± 100 years BP.L’os pelvique relativement complet d’un eider de grande taille (Somateria cf. mollissima) a été récolté en place, dans un dépôt de silt argileux et sableux stratifié, près de Shawinigan, Québec. Ce fossile est important car il représente le premier spécimen d’oiseau identifié, au niveau du genre, dans les dépôts de la mer de Champlain. Cet os a été enfoui près de la rive nord de la mer de Champlain. Son origine remonte à quelques centaines d’années avant la fin de la régression marine. Des coquilles de mollusques marins (Mya arenaria), prélevées à environ 50 cm au-dessus du fossile d’eider, ont donné un âge de 10 300 ± 100 BP, en années 14C de coquilles de mers froides

Recherches archéologiques dans les Monts de Blond (Haute-Vienne). Apports chronologiques-Notes préliminaires.

International audienc

Unité fluviatile à échardes volcaniques d’un interstade à Bétula/Pinus antérieur à 53ka (début du MIS3) et optimum glaciaire pendant le MIS4 au nord des Vosges Centrales

National audienceA continuous sedimentary sequence has been deposited for more than 53 ka in the Fave River Valley, laterally to the intra-Vosgian basin of St-Dié. The coarse material of the lower alluvial sheet of the sequence is the result of torrential flows from melting neves and ice masses accumulated during MIS 4 on the highlands at the South of the valley. The upper alluvial silty sheet records a slow deposition of fine sediments without interstratified torrential beds. There was no significant accumulation of neves or ice on the southern watershed of the Fave River during the LGM and Late Glacial. The upper sheet of the sequence contains a stratified and discontinuous peaty basal unit dated to more than 53 ka and containing volcanic glass shards and interstadial Betula/Pinus pollen followed by stadial cold steppic species. The local interstadial is correlated to the Goulotte episode of the pollen sequence of Grande Pile, at the beginning of MIS 3. The age is compatible with the St-Germain tephra. These data from the northern edge of the central Vosges Mountains provide further support for the glacial model established in southern Vosges, with early heavy snowfalls during the beginning of the Middle Würmian (MIS 4) and smaller extent of the glaciers with dryer and colder climatic conditions during late Würmian (MIS 2).Latérale au bassin intra-vosgien de Saint-Dié, la vallée de la Fave a enregistré une séquence sédimentaire continue depuis plus de 53 ka. Le matériel de la nappe grossière inférieure résulte d’apports torrentiels attribués à un épisode de fonte de névés et de masses de glace accumulés pendant le stade MIS 4 sur les reliefs au sud de la vallée. La nappe alluviale supérieure, à dominante silteuse, indique une sédimentation lente sans épisode torrentiel et l’absence d’accumulation significative de névés ou de glace sur le bassin versant pendant le Dernier Maximum Glaciaire et le Tardiglaciaire. Elle inclut une unité basale stratifiée et discontinue à échardes volcaniques, à matière organique datée à plus de 53 ka et de contenu pollinique à Betula/Pinus suivis d’espèces de steppe froide. L’Interstade local est dans la position palynostratigraphique de l’Interstade de Goulotte de la séquence de la Grande Pile, au début du MIS 3. Cet âge est compatible avec celui du tephra de Saint-Germain. Ces données sur la marge nord des Vosges centrales confirment le modèle d’histoire glaciaire mis en évidence dans les Vosges du sud, avec un maximum d’enneigement précoce au début du Würmien moyen (MIS 4) et une extension glaciaire plus restreinte sous climat froid et sec pendant le Würmien supérieur (MIS 2)

Quaternary geology and the environment

International audienc

1400 ans d'interactions homme-milieu : évolution des sols sur le Saint-Mont (Remiremont, Vosges)

International audienceThe SolHoM(a) project aims at determining the degree of landscape anthropisation in the Fossard massif (Remiremont, Vosges, France) by estimating the impact of past human occupations on current soils. Nowadays, a forest covers this relatively inhospitable mountain (hard climate, steep slopes, acid soils ...), but some remains suggest human presence for at least 1400 years.The Saint-Mont is a variscan orogenic granitic summit (height 672m) with valuable preserved archaeological relics, located south of the Fossard. At the top was founded the monasterium Habendum (from the 7th century to the French Revolution), which potentially comes after a late-antic castrum.Furthermore, monumental enclosure dry-stones walls, not yet clearly linked with the monastery, crosses the massif.Our methodology is first experienced on the Saint-Mont, well documented by recent archaeological research. It features:- sampling soil transects presenting a clear gradient from highly to poorly human impacted areas. According to those transects, soils are sampled and characterised (physico-chemistry, soil micromorphology, analysis of organic matter, dating); this should highlight traces of past human activity;- a development of algorithms to detect geometric structures in the raw LiDAR data provided by the PCR AGER(b) (Ch. Kraemer, dir). This research might help archaeologists to determine areas influenced or not by men.Once tested on the Saint-Mont, this approach will be applied to another archaeologically less investigated area of the Fossard.First field works highlight two soil sequences:- the first one, near a probable merovingian wall close to the monastery, reveals a very black 80cm deep unit,- the second one, far-off the monastery and beside the enclosure dry-stone wall, is less thick but have a thin black unit buried under 20 cm of pedogenised sediment.Physico-chemical and soil micromorphological analyses are in progress. The coming study of profiles/sequences more distant from archaeological sites will contribute to estimate the degree of soils anthropisation in the Saint-Mont.(a) Interactions Sol-Hommes-Milieux(b) ArchéoGEographie du premier Remiremont et de ses abord

1400 ans d'interactions homme-milieu : évolution des sols sur le Saint-Mont (Remiremont, Vosges)

International audienceThe SolHoM(a) project aims at determining the degree of landscape anthropisation in the Fossard massif (Remiremont, Vosges, France) by estimating the impact of past human occupations on current soils. Nowadays, a forest covers this relatively inhospitable mountain (hard climate, steep slopes, acid soils ...), but some remains suggest human presence for at least 1400 years.The Saint-Mont is a variscan orogenic granitic summit (height 672m) with valuable preserved archaeological relics, located south of the Fossard. At the top was founded the monasterium Habendum (from the 7th century to the French Revolution), which potentially comes after a late-antic castrum.Furthermore, monumental enclosure dry-stones walls, not yet clearly linked with the monastery, crosses the massif.Our methodology is first experienced on the Saint-Mont, well documented by recent archaeological research. It features:- sampling soil transects presenting a clear gradient from highly to poorly human impacted areas. According to those transects, soils are sampled and characterised (physico-chemistry, soil micromorphology, analysis of organic matter, dating); this should highlight traces of past human activity;- a development of algorithms to detect geometric structures in the raw LiDAR data provided by the PCR AGER(b) (Ch. Kraemer, dir). This research might help archaeologists to determine areas influenced or not by men.Once tested on the Saint-Mont, this approach will be applied to another archaeologically less investigated area of the Fossard.First field works highlight two soil sequences:- the first one, near a probable merovingian wall close to the monastery, reveals a very black 80cm deep unit,- the second one, far-off the monastery and beside the enclosure dry-stone wall, is less thick but have a thin black unit buried under 20 cm of pedogenised sediment.Physico-chemical and soil micromorphological analyses are in progress. The coming study of profiles/sequences more distant from archaeological sites will contribute to estimate the degree of soils anthropisation in the Saint-Mont.(a) Interactions Sol-Hommes-Milieux(b) ArchéoGEographie du premier Remiremont et de ses abord

Deglacial to Paraglacial History of the Lake Saint-Jean Lowlands: A Geomorphological Perspective

International audienceThe Lake Saint-Jean lowland is a particular area in eastern Canada as it constitutes an important Late Quaternary depocenter compared with other surrounding onshore regions. Here, the recent literature about the Late Quaternary history of the Lake Saint-Jean depocenter from the glaciated period to present-day is summarized; subsequently, we present some preserved landscape features that record such history