A post-Lake Minong transgressive event on the north shore of Lake Superior, Ontario: possible evidence of Lake Agassiz inflow

1994 ◽  
Vol 31 (11) ◽  
pp. 1638-1641 ◽  
Author(s):  
Brian A. M. Phillips ◽  
Philip W. Fralick

Modification of an ice-contact delta built on the margin of Lake Minong (9500 BP) is ascribed to a transgressive event. Reworking of fluvial sediments by wave action and the infilling of the lower end of a distributary valley demonstrate a post-Minong transgression and reoccupation of the lower portion of the delta. Estimated to be in the order of 18 m, this water-level oscillation may represent evidence of one of several catastrophic discharges of Lake Agassiz into the Superior basin, proposed to have occurred between 9.5 and 8.0 ka BP.

1975 ◽  
Vol 12 (2) ◽  
pp. 300-319 ◽  
Author(s):  
Matti Saarnisto

Shoreline displacement in the Lake Superior basin was followed, independently of morphological data, by studying sediments of small lake basins at different elevations in the vicinity of Sault Ste. Marie, Wawa, and Marathon, Ontario. Emergence of small lakes, resulting from water level changes in the main basin, is documented in bottom sediments, and can be dated by radiocarbon and pollen analyses. The new stratigraphical findings were correlated with the earlier established morphological shorelines, and thus the Late Wisconsinan and Holocene history of lake levels was worked out.High post-Main Algonquin glacial lakes formed the highest shorelines along the east shore from Sault Ste. Marie up to Alona Bay between approximately 11 000 and over 10 100 B.P. Contemporaneously a series of Post-Duluth glacial lakes occupied the western Superior basin, subsequent to Glacial Lake Duluth. As the ice retreated to the north shore at 9500 B.P., Lake Minong came into existence. Its level was apparently controlled by a threshold higher than the present at Sault Ste. Marie. The water level of Lake Superior fell to the low water Houghton stage by 8000 B.P. The transgression which resulted in the Nipissing Great Lakes reached the Superior basin about 7000 B.P. and culminated 5500 B.P. Land uplift on the east shore of Lake Superior was very rapid immediately after the deglaciation, followed by decreasing rates up to the present, and there are all indications that the process has been continuous.


2021 ◽  
pp. e20200049
Author(s):  
Isabelle Gapp

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.


2020 ◽  
Vol 231 ◽  
pp. 105717
Author(s):  
Adam Hestetune ◽  
Paul M. Jakus ◽  
Christopher Monz ◽  
Jordan W. Smith

1982 ◽  
Vol 19 (9) ◽  
pp. 1796-1801 ◽  
Author(s):  
R. Garth Platt ◽  
Roger H. Mitchell

The Coldwell Complex of Northwestern Ontario is North America's largest structurally and petrologically complex alkaline intrusion. Situated on the north shore of Lake Superior, it consists of at least three intrusive centres and is cross-cut by a diverse suite of coeval–cogenetic dikes. The main intrusive rocks range from gabbros to ferroaugite syenites, nepheline syenites, and quartz syenites. The dikes are predominantly lamprophyric. A seventeen point whole rock Rb–Sr isochron (MSWD 2.22) gives an age of 1044.5 ± 6.2 Ma (2σ) and an initial ratio of 0.70354 ± 0.00016 (2σ). The age is late Neohelikian and is younger than the bulk of igneous activity (Keweenawan activity) prevalent in the Lake Superior Basin during the Neohelikian. The low initial ratio indicates an upper mantle origin for the parental magma of the complex.


1966 ◽  
Vol 3 (2) ◽  
pp. 203-210 ◽  
Author(s):  
Grant M. Young

Mapping in the McGregor Bay area of Ontario has shown the presence of a sequence of formations which closely resembles that of the original Huronian of the Bruce Mines–Blind River area. Iron-rich siltstones and argillites above the Lorrain formation are correlated with the lower part of the Animikie iron-formations of the Port Arthur region of Lake Superior and the north central United States. The oldest Proterozoic rocks of the region south of Lake Superior are considered to be correlatives of the Cobalt group of the north shore of Lake Huron.


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