The Canadian Shield: The Laurentian Plateau

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The Canadian Shield also known as the Laurentian Plateau is a region of land within Canada that comprises two types of rocks: Igneous and Metamorphic (“Canadian Landforms: Rocks and Minerals” n,d). It is the exposed area of the Earth’s crust. It spans from Newfoundland and Labrador to Alberta with half of it concentrated in Ontario (Figure 1).
Figure 1: Physiographic Regions in Canada. The Canadian Shield colored in green shows how vast it is.
Geoscientist's use a combination of qualitative and quantitative properties to classify and categorize rocks and minerals. There are six qualitative properties that are used to identify rocks and minerals: Color, Lustre, Streak, Texture, Cleavage, and Hardness. A sample of rock that can be found in the …show more content…

Streak, cleavage, and hardness require additional tools and physical contact to determine. There are areas of the rock that contain flecks of black/grey. Additionally, the rock is shown to have a surface pattern of bands of grey colored lines.
Since the rocks are from the Earth’s crust, a natural deduction is that the rock sample shares a similar chemical composition. The Earth’s crust predominantly contains silicon and oxygen which bond together to form a group of minerals known as silicates (SiO4). A tetrahedral chemical structure indicates a crystal-like structure. Silicates often bond with other cations such as iron, magnesium, sodium, aluminum, potassium, and calcium which gives rise to new physical and structural properties (“Earth121: Minerals (Part One)” …show more content…

This particular sample of granite is phaneritic in texture as described by its visible crystals. The rate at which the rocks cool determines the size of the crystals, in this case, a steady cooling rate produces larger crystals (“Characteristics of Igneous Rocks” n.d). The rate at which rocks cool is also related to the temperature of cooling which determines a rocks mineral composition (“Characteristics of Igneous Rocks” n.d). A low cooling temperature yields rocks with higher amounts of potassium, aluminum, and silicon (“Characteristics of Igneous Rocks” n.d). This is evident by the abundance of potassium feldspar, which also makes granite a felsic

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