The Deglaciation History of the Lake Superior Region and its Climatic Implications

1974 ◽  
Vol 4 (3) ◽  
pp. 316-339 ◽  
Author(s):  
Matti Saarnisto
Keyword(s):  
Lake Superior ◽  
Cold Climate ◽  
Northern Ontario ◽  
The North ◽  
Lake Algonquin ◽  
Western Lake ◽  
History Of ◽  
Ice Retreat ◽  
Main Lake ◽  
High Level

A zone of synchronous end moraines has been recognized in the Lake Superior region across northern Ontario and Michigan. The moraines were formed between 11,000 and 10,100 y.a. as cold climate resulted in successive halts in the general ice retreat. The cold climate is also indicated by the presence of tundra near Lake Superior until about 10,000 y.a. This episode is here referred to as the Algonquin Stadial. It was preceded and followed by rapid deglaciation. The Algonquin Stadial is comparable in age with the Younger Dryas Stadial of Europe, and indicates a reversal in the continuous trend toward a warmer climate during Late-Wisconsin (an) time. The apparent conflict between the present result (based on geologic evidence) and earlier pollen stratigraphical studies with no reversal is discussed.Glacial Lake Duluth formed in the western Lake Superior basin before 11,000 BP, followed by a series of Post-Duluth lakes between approximately 11,000 and over 10,100 BP. The Main Lake Algonquin stage in the Huron and Michigan basins terminated approximately 11,000 BP. The subsequent high-level post-Main Algonquin lakes, which were contemporaneous with the Post-Duluth lakes, existed in the southeastern Lake Superior basin. When the ice margin was along the north shore 9500 BP Lake Minong occupied the whole Lake Superior basin. By 9000 BP the ice had retreated north of Lake Superior-Hudson Bay divide.

GLACIAL FEATURES OF THE NORTH-CENTRAL LAKE SUPERIOR REGION, ONTARIO

1967 ◽  
Vol 4 (3) ◽  
pp. 515-528 ◽  
Author(s):  
S. C. Zoltai
Keyword(s):  
Lake Superior ◽  
Field Work ◽  
Aerial Photographs ◽  
Northern Ontario ◽  
Radiocarbon Dates ◽  
North Central ◽  
The North ◽  
Glacier Ice ◽  
History Of ◽  
Differential Uplift

The surficial glacial features and glacial events of a 13 000 square mile area in northern Ontario are described, based on field work and study of aerial photographs. Ice-laid and glaciolacustrine materials suggest a complex history of stationary ice fronts and glacial lakes during deglaciation. Lakes in the Lake Nipigon and Lake Superior basins inundated large areas. Post-Minong lake stages in the Superior basin intruded far to the north, dammed by ice at the largest moraine, the Nakina. The northern part of this lake was later separated from the post-Minong lake by differential uplift and was named Lake Nakina. After the withdrawal of the ice, Glacial Lake Barlow–Ojibway occupied the northeastern part of the area, and much of it was later overridden by the last glacial readvance. Stratigraphic correlations with radiocarbon dates suggest that the Nakina moraine was built some 9 400 years ago, and that the last glacier ice disappeared before 6 390 years ago.

scholarly journals The Northern Limits of Glacial Lake Algonquin in Upper Michigan

1981 ◽  
Vol 15 (3) ◽  
pp. 291-310 ◽  
Author(s):  
Richard P. Futyma
Keyword(s):  
Late Pleistocene ◽  
Lake Superior ◽  
Radiocarbon Dates ◽  
Maximum Extent ◽  
Lake Algonquin ◽  
Proglacial Lakes ◽  
Western Lake ◽  
Main Lake ◽  
A Minor ◽  
Glacial Lake Algonquin

AbstractA number of ancient shorelines formed by late-Pleistocene proglacial lakes have been found in eastern upper Michigan. These shorelines delimit several water planes, the uppermost of which is correlated with the Main Lake Algonquin stage. This correlation is based on the continuity of the highest water plane with Main Algonquin shorelines in Wisconsin and Ontario, the strength of the shoreline features, its altitudinal relationship with lower water planes, and a reinterpretation of radiocarbon dates from the Sault Ste. Maria area. The isobases of this water plane have a bearing of S75°E. At the time of the maximum extent of Lake Algonquin, ca. 10,600 yr B.P., its northern, ice-limited border lay along the Munising moraine, the northernmost of the two main morainic systems of eastern upper Michigan. This interpretation lends support to the idea of a period of slow deglaciation from ca. 11,000 to 10,000 yr B.P. An ice lobe occupied the central Lake Superior basin until early Holocene time. Radiocarbon dates on wood found beneath till or outwash at several sites indicate a minor ice readvance from the central Lake Superior basin ca. 10,000 yr B.P. If true, this would have prevented the development of the post-Duluth series of glacial lakes in the western Lake Superior basin until ca. 9900 yr B.P., well after the end of the main Lake Algonquin stage.

Water in the Wilderness: The Group of Seven and the Coastal Identity of Lake Superior

2021 ◽  
pp. e20200049
Author(s):  
Isabelle Gapp
Keyword(s):  
Environmental History ◽  
Lake Superior ◽  
Indigenous Communities ◽  
Coastal Lake ◽  
Group Of Seven ◽  
North Shore ◽  
The North ◽  
The People ◽  
Coastal Landscapes ◽  
History Of

This paper challenges the wilderness ideology with which the Group of Seven’s coastal landscapes of the north shore of Lake Superior are often associated. Focusing my analysis around key works by Lawren Harris, A.Y. Jackson, J.E.H. MacDonald, and Franklin Carmichael, I offer an alternative perspective on commonly-adopted national and wilderness narratives, and instead consider these works in line with an emergent ecocritical consciousness. While a conversation about wilderness in relation to the Group of Seven often ignores the colonial history and Indigenous communities that previously inhabited coastal Lake Superior, this paper identifies these within a discussion of the environmental history of the region. That the environment of the north shore of Lake Superior was a primordial space waiting to be discovered and conquered only seeks to ratify the landscape as a colonial space. Instead, by engaging with the ecological complexities and environmental aesthetics of Lake Superior and its surrounding shoreline, I challenge this colonial and ideological construct of the wilderness, accounting for the prevailing fur trade, fishing, and lumber industries that dominated during the nineteenth and early twentieth centuries. A discussion of environmental history and landscape painting further allows for a consideration of both the exploitation and preservation of nature over the course of the twentieth century, and looks beyond the theosophical and mystical in relation to the Group’s Lake Superior works. As such, the timeliness of an ecocritical perspective on the Group of Seven’s landscapes represents an opportunity to consider how we might recontextualize these paintings in a time of unprecedented anthropogenic climate change, while recognizing the people and history to whom this land traditionally belongs.

Geochronology of the North American Midcontinent rift in western Lake Superior and implications for its geodynamic evolution

1997 ◽  
Vol 34 (4) ◽  
pp. 476-488 ◽  
Author(s):  
D. W. Davis ◽  
J. C. Green
Keyword(s):  
North American ◽  
Lake Superior ◽  
Flood Basalt ◽  
North American Plate ◽  
Rift System ◽  
Midcontinent Rift ◽  
Subsidence Rate ◽  
The North ◽  
Western Lake ◽  
Midcontinent Rift System

Volcanism in the Midcontinent rift system lasted between 1108 and 1086 Ma. Rates of flood-basalt eruption and subsidence in the western Lake Superior region appear to have been greatest at the beginning of recorded activity (estimated 5 km/Ma subsidence rate at 1108 Ma) and rapidly waned over a period of 1–3 Ma during a magnetically reversed period. The age of the paleomagnetic polarity reversal is now constrained to be between 1105 ± 2 and 1102 ± 2 Ma. A resurgence of intense volcanism began at 1100 ± 2 Ma in the North Shore Volcanic Group and lasted until 1097 ± 2 Ma. This group contains a ca. 7 Ma time gap between magnetically reversed and normal volcanic sequences. A similar disconformity appears to exist in the upper part of the Powder Mill Group. The average subsidence rate during this period was approximately 3.7 km/Ma. Latitude variations measured from paleomagnetism on dated sequences indicate that the North American plate was drifting at a minimum rate of 22 cm/year during the early history of the Midcontinent rift. An abrupt slowdown to approximately 8 cm/year occurred at ca. 1095 Ma. These data support a mantle-plume origin for Midcontinent rift volcanism, with the plume head attached to and drifting with the continental lithosphere. Resurgence of flood-basalt magmatism at 1100 Ma may have been caused by extension of the superheated lithosphere following continental collision within the Grenville Orogen to the east.

Deglaciation chronology and revegetation in northwestern Ontario

1985 ◽  
Vol 22 (6) ◽  
pp. 850-871 ◽  
Author(s):  
Svante Björck
Keyword(s):  
Black Spruce ◽  
Lake Superior ◽  
The South ◽  
Migration Routes ◽  
White Pine ◽  
Cool Period ◽  
Radiocarbon Dates ◽  
Northwestern Ontario ◽  
History Of ◽  
Ice Retreat

Along a 420 km transect in northwestern Ontario, Canada, sediments from four lakes were analyzed with respect to lithology, pollen, and macrofossils. Radiocarbon dates show that the region was deglaciated between ca. 11 500 and 8000 years BP, and periods of both rapid ice retreat and readvance influenced the history of Glacial Lake Agassiz. In the south the ice sheet was succeeded by a lengthy interval of park–tundra with stands of spruce, ash, and elm. The ash and elm seem to have disappeared during a suggested cool period (11 100–10 200 years BP). Farther north the park–tundra phase lasted not more than 50–100 years after ca. 10 200 years BP before boreal trees dominated. The climatic change around 10 200 years BP permitted the very rapid migration of spruce, larch, birch, and jack or red pine into northwestern Ontario from northern Minnesota. The migration routes for Pinus strobus (white pine), Alnus rugosa, and A. crispa were divided, however: one from the south (south of Lake Superior) and one from the east-southeast (north of Lake Superior). White pine reached its maximum distribution 6500–6000 years BP, when the limit was probably 150–200 km north of today's. The composition of the boreal forest during the altithermal was only slightly changed, but the influx of presumed prairie pollen reached a peak ca. 8000–7000 years BP. Since then Picea mariana (black spruce) gradually became the dominating tree species.

VIII.—The High-Level Plateau Gravels on the North Side of the Tamisian Area, and their Connexion with the Tertiary History of Central England

1904 ◽  
Vol 1 (10) ◽  
pp. 497-497 ◽  
Author(s):  
Alexander Irving
Keyword(s):  
Present Note ◽  
The North ◽  
North Side ◽  
History Of ◽  
High Level

The author refers to his work in former years among the High-level Plateau Gravels south of the Thames, chiefly in Berks and Surrey, the results of which were given in various papers from ten to twenty years ago.6 The present note may serve as a supplement to those papers, in which the conclusion was arrived at that the gravels in question were to be regarded as distinctly of riverine origin and, upon the whole, of Pliocene age.

Late-devensian and flandrian vegetational history of Bodmin Moor, Cornwall

1977 ◽  
Vol 276 (946) ◽  
pp. 251-320 ◽  
Keyword(s):  
Bronze Age ◽  
Cold Climate ◽  
Pollen Record ◽  
The North ◽  
Pollen Content ◽  
History Of ◽  
Pollen Taxon ◽  
Palynological Study ◽  
First Time ◽  
Palynological Records

A largely palynological study of new exposures of lake and mire sediments from Bodmin Moor, Cornwall, together with radiocarbon dating of the polliniferous deposits has allowed, for the first time in southwest England, description of dated local and regional pollen assemblage zones which can be correlated with the pollen zones of Godwin and the chronozones of West. Reconstruction of the vegetational history of the Late-Devensian, early and later Flandrian periods is attempted by using, wherever possible, values for the pollen content of sediments to illuminate real pollen taxon percentage fluctuations. Deposition of limnic sediments in the Late-Devensian started shortly before 13000 b.p. when the dominant vegetation, open grass heaths, snow-beds and flushes, reflects the cold climate. Soils at this time were subject to erosion by snow melt-water. Ensuing climatic amelioration permitted invasion by juniper scrub and about 12000 b.p. expansion of tree birches took pace. Climatic recession occurring under strongly oceanic conditions (marked by considerable amorphous solifluction of the upland soils and the development of grass/sedge mires) was initiated about 11000 b.p., but its duration here cannot be accurately estimated. Within this threefold pattern of Late-Devensian deposition 12 distinct pollen assemblages are described from four profiles. Pollen of Artemisia norvegica, Astragalus alpinus and Saxifraga stellaris is confined to the earlier and later colder periods. In the intervening warmer period, but not the colder periods, there is slight pollen and macroscopic fossil evidence of Betula nana. An unexplained unconformity exists at the base of the Flandrian deposits. Early Flandrian vegetation is characterized by the spread of tree birches and Salix in the valleys, with Empetrum and juniper on the hillsides. The two latter genera are replaced before 9000 b.p. by Corylus followed almost immediately by the spread of Quercus. Throughout the Flandrian Quercus , Betula and Corylus , although the dominant woodland genera, probably colonized only the more sheltered sites on the upland. Archaeological and palynological records have been correlated as far as possible, the only substantial pollen record of human activity being that of Plantago , which spread encouraged by Bronze Age pastoralism. There is also pollen evidence of scanty cereal cultivation. Areas on the Atlantic fringes of Europe show a marked similarity in their early Flandrian forest history, particularly with regard to the slight role played by Pirns in relation to Quercus compared with stations further east. This similarity must derive from the proximity of the tempering influences of the North Atlantic Drift.

Glacial history of Northeastern Ontario II. The Timiskaming–Algoma area

1968 ◽  
Vol 5 (1) ◽  
pp. 97-109 ◽  
Author(s):  
A. N. Boissonneau
Keyword(s):  
Lake Superior ◽  
Great Lakes Basin ◽  
Upper Peninsula ◽  
North Shore ◽  
The North ◽  
Sequence Of Events ◽  
Glacial Chronology ◽  
History Of ◽  
Surficial Deposits ◽  
Upper Peninsula Of Michigan

The surficial deposits, ice movements, and glacial lakes within an area of 34 500 square miles in northeastern Ontario are described. Some of the moraines of the study are tentatively correlated with moraines to the west in the upper peninsula of Michigan, in the Nipigon area, and along the north shore of Lake Superior. The glaciolacustrine deposits and sequence of events in the study area in relation to the glacial features and chronology of the southern Great Lakes basin provide a basis for a partial glacial chronology for the study area. A knowledge of the glacial features of this area further elucidates the integration of movements of two advancing ice lobes, which was observed in northwestern Quebec.

Proterozoic reactivation of the southern Superior Province and its role in the evolution of the Midcontinent rift

1997 ◽  
Vol 34 (4) ◽  
pp. 562-575 ◽  
Author(s):  
Matthew L. Manson ◽  
Henry C. Halls
Keyword(s):  
Lake Superior ◽  
Dyke Swarm ◽  
Superior Province ◽  
Midcontinent Rift ◽  
Potential Field Data ◽  
Major Activity ◽  
The North ◽  
Western Lake ◽  
Narrow Belt ◽  
Radiometric Data

Major reverse faults associated with the late compressional phase of the 1.1 Ga Midcontinent rift in the western Lake Superior region appear to cut across the rift at the eastern end of the lake and join with reverse faults on the eastern shoreline, defined on the basis of geological and potential field data. The continuation of the faults across eastern Lake Superior is inferred on evidence drawn from nearshore shipborne magnetic surveys together with new interpretations of published bathymetric and GLIMPCE aeromagnetic data. In the Archean Superior Province about 100 km east of Lake Superior, paleomagnetic and petrographic data from the 2.45 Ga Matachewan dyke swarm show that the Kapuskasing Zone, a narrow belt of uplifted crust, can be extended to within 50 km of the Lake Superior shoreline and has bounding reverse faults that are almost continuous with two faults of similar dip and sense of displacement that define the inversion of the Midcontinent rift in the central and western parts of the lake. Since the Kapuskasing Zone is dominantly a Paleoproterozoic (about 1.9 Ga) structure, the continuity suggests that the Lake Superior faults, whose last major activity was during the Grenville Orogen, may represent reactivation of much older faults that were part of an extended Kapuskasing structure. Within the Superior Province to the north and east of Lake Superior, published radiometric data on biotites suggest a series of alternating crustal blocks of varying tectonic stability, separated by northeast-trending faults. The Lake Superior segment of the Midcontinent rift developed within the most unstable block, bounded by the Gravel River fault to the northwest and the Ivanhoe Lake fault (the eastern margin of the Kapuskasing Zone) to the southeast.

THE CONTRIBUTION OF E. M. MELETINSKY TO THE CAUCASIAN EPOS STUDIES. ON THE 100TH ANNIVERSARY OF THE BIRTH OF THE SCHOLAR

2020 ◽  
Vol 3 (4) ◽  
pp. 76-89
Author(s):  
Zurab D. Dzhapua ◽  
Keyword(s):  
Early Stage ◽  
100Th Anniversary ◽  
North Caucasus ◽  
The North ◽  
The People ◽  
History Of ◽  
High Level ◽  
Very High ◽  
Cultural Hero

The article analyses the contribution of Meletinsky to Caucasian epic studies. The role of Caucasian epic traditions in the study of the problem of the origins and the early forms of the epos is considered. A significant number of the comparative-typological studies of Meletinsky are based on the materials of mythoepic cultures of Caucasus mountain people. The scholar singled out the Caucasian epics, along with some other traditions, as the special early stage in the history of the epic. Meletinsky was one of the pioneers in the fundamental studies of the Caucasian Nart epics. Based on the analysis of materials available to him at that time, Meletinsky comes to the fundamental conclusions on the genre nature, national versions, images, subjects and motifs of the Nart epic. The scholar considered Sataney and Sasrykua to be the earliest characters in the epic, whose images clearly reflected the features of a cultural hero, especially in the close Abkhaz and Adyg versions. Furthermore, according to Meletinsky, the Transcaucasian legends about the chained heroes – Abkhaz Abryskil, Armenian Mger and Georgian Amiran – represent a kind of interweaving of mythological epic and heroic tales, in which the motives of cultural exploits are largely supplanted by episodes of the heroic struggle with Giants. In the studies of Meletinsky, the epic traditions of the people of the North Caucasus and Transcaucasia are subjected to the deepest analysis at a very high level of comparative studies.

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