Rock CYCLE AND Glaciation

Learning goals - Understand the rock cycle - Understand glaciation

Definitions Look in the glossary for : - Weathering - Erosion - Deposition - Glaciation

Rock cycle The rock cycle is another landform process, similar to plate tectonics. The rock cycle is a cycle it does not have a beginning. This is because geologic time is long that there has been many cycles of rock formation and destruction. The rock cycle shows different rocks, how they form and what forms them. Each rock has its own method of forming. The rock cycle is very related and dependent on plate tectonics.

Types of Rocks There are 3 types of rocks. Each with its own way of forming. - Igneous rocks - Sedimentary rocks - Metamorphic rocks

Igneous rocks These rocks form when lava erupts and cools on the surface of the earth as magma. Igneous rocks have crystals in them and on their outside. There two types of igneous rocks: Intrusive and Extrusive. Intrusive igneous rocks form under the surface. These rocks take longer to form because they take longer to cool. The long period of time they take gives opportunity of forming larger pieces of crystals Extrusive igneous rocks form on top of the surface. These rocks form much quicker. They cool almost instantly. The fact that they form quickly doesn't give time for large crystals to form, only tiny ones. These crystals are so small they cannot be seen with a naked eye.

sedimentary rocks Sedimentary rocks are formed from sediments. Sediments are the tiny particles of rock. Different rocks have different types of sediments. Overtime sediments of different rocks form layers underground or at the bottom of bodies of water. These layers, over the years, combine together forming sedimentary. Different minerals also, help in acting as a glue to hold the sediments together in a process called cementation. In the case where sediments settle in the bottom of water bodies, they are carried by currents. Usually sedimentary form in the continental shelf, closer to the banks. Sometimes the sedimentary rocks are carried to the surface by the movement of the Earth's crust. Sedimentary rocks could also hold fossils.

Metamorphic rocks Metamorphic rocks are "changed" versions of igneous, sedimentary, and other metamorphic rocks. These rocks form underground with the use of extreme amounts of heat and pressure caused by the movement of the Earth's crust. Metamorphism means change form. Sedimentary rocks that change to metamorphic rocks become much harder. When metamorphism happens to igneous rocks, they might form mineral deposits. These deposits can sometimes be big enough to be worth mining. These deposits include gold, nickel, iron, etc.

Summary Rock Cycle (Pages 40-42) • Igneous rock is new rock, formed from the molten material that originates from inside Earth. • Sedimentary rock is made up of deposited material that has been eroded from other rock. Oil, natural gas, and coal are found in this rock type. • Metamorphic rock is rock changed by heat and pressure. This is where metallic minerals such as iron ore, gold, and nickel are found. • Rocks are constantly changed in the slowly-operating rock cycle.

glaciation Glaciation is another landform process, although it is not as strong as plate tectonics and the rock cycle. Glaciation is a much slower process and cannot invade and change as much. Glaciation is the process of ice advancing and covering large areas of land. Glaciation has effects all over Canada. It might not be obvious because it is complicated. Even the book doesn't explain it. The book says "You will have to take a physical geography course to learn about them (detailed effects of glaciation). " Therefore we will focus on glaciation forces and how they produced the landscapes we live in. There are 2 main types of glacial effects: Erosional and Depositional

Erosional effects 1. Glaciers (land glaciers) were giant earth-moving machines. These big chunks of ice and snow collapsed sometimes. This collapsation created a landslide effect which eroded the soil. This resulted in a country with a little to no good soil. This is because it erodes the top soil, which is the best soil for agriculture and farming. As you can see now and as we learned in a previous unit, 86% of Canada's land has no capability for agriculture (Class 7). 2. Glacial erosion completely changed drainage basins. Especially lakes and river made from loose earth material. As the land eroded the drainage basin made from weak and loose material such as soil was replaced with rock- based drainage basins as the glaciers melted.

Glacial deposition falls into 2 categories: Depositional effects Glacial deposition falls into 2 categories: Deposition by ice Deposition by meltwater When this happen materials are not sorted by size forming a mixture called glacial till. Effects: 3. They create small, featureless hills and valleys called till plains. Till plains are composed of sediments and rocks. 4. They create moraines. These are deposits of till that form on the edges of glaciers. This occurs when large amounts of ice melt and form water that scrapes rocks, sediments and soil. Effects : 5. Meltwater erodes just like floods but it can carry bigger objects like gravel and rock. While moving with the big flow the rocks drop first, then gravel, then the soil, then the sediments. This forms landform features that show sorting by size, unlike deposition by ice. 6. Sometimes meltwater can settle, with the objects it carries in lakes. Therefore making the lakes smaller.

Summary Glaciation (Pages 43-46) • Huge ice sheets (glaciers) covered most of Canada four different times in the past 2.5 million years, and as recently as 15 000 years ago. • Glaciers scraped away much of the soil from northern Canada, leaving a large area with little to no soil (erosional effects). • Glaciers deposited till plains and moraines in southern Canada (depositional effects). • Melting glaciers formed glacial lakes, some of which remain today. Others drained away and left behind flat areas with deep soil, ideal for farming.