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The Canadian Shield is a U-shaped subsection of the Laurentia craton signifying the area of greatest glacial impact (scraping down to bare rock) creating the thin soils. The age of the Canadian Shield is estimated to be 4.28 Ga. The Canadian Shield once had jagged peaks, higher than any of today's mountains, but millions of years of erosion ...
The Laurentide ice sheet (LIS) was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glaciation epochs, from 2.58 million years ago to the present.
The Canadian Shield, Precambrian shield, makes up the bedrock geology highlighted by rocks and lakes [2] and a boreal forest area. There are transitional areas between boreal and tundra flora. [ 3 ] The lower boundary of the Canadian Shield cuts across the province diagonally from the latitude 57 degrees in the northwest to 54 degrees in the ...
The Southern province is a narrow region from Sault Ste. Marie to Kirkland Lake, is made of rocks dating 1.8 to 2.4 billion years ago. [1] The Hudson Bay lowlands, located north of the Canadian Shield, are mainly made of sedimentary rocks from the Silurian Period, although some parts date from the Ordovician and Devonian periods. [1]
The Southern Province is a portion of Proterozoic rock that ranges in age from 2.5 billion to 600 million years old. It represents a subdivision of the much larger Canadian Shield and forms the bedrock of portions of Ontario, Canada and the U.S. states of Michigan and Minnesota.
The earliest part of the shield is metamorphosed Archean rocks, originally volcanic in origin. Numerous terranes were accreted onto this Archean core during the Proterozoic to form the Canadian Shield. [4] The southern Archean province is the Superior Craton, it is formed by the combination of a greenstone-granite and a gneiss terrane. [5]
The Churchill Craton is the northwest section of the Canadian Shield and stretches from southern Saskatchewan and Alberta to northern Nunavut. It has a very complex geological history punctuated by at least seven distinct regional tectono metamorphic intervals, including many discrete accretionary magmatic events.
The Acasta Gneiss in the Canadian Shield in the Northwest Territories, Canada is composed of the Archaean igneous and gneissic cores of ancient mountain chains that have been exposed in a glacial peneplain. Analyses of zircons from a felsic orthogneiss with presumed granitic protolith returned an age of 4.031 ±0.003 Ga. [1]