Physical Geography - Earth's Structure & Processes PDF

Physical geography: The part of geography that deals with the natural environment -​ In physical geography, we examine the structure of the world around us and the process that leads to the creation of the natural world. 3 main layers in the Earth 1.​ The Crust (thin, brittle and made o...

Physical geography: The part of geography that deals with the natural environment -​ In physical geography, we examine the structure of the world around us and the process that leads to the creation of the natural world. 3 main layers in the Earth 1.​ The Crust (thin, brittle and made of rock) ​ Where we live ​ The Earth’s crust is made of continental crust (thicker) and oceanic crust (thinner) ​ The continental crust forms the land we see today, it is less dense making it more buoyant than an oceanic crust which sinks under the continental crust 2.​ The Mantle (thick layer of molten lava, in the middle) 3.​ The Core (dense and metallic) 2 layers of core, inner and outer -​ Each layer has a unique composition that affects the Earth’s surface Continental drift -​ In 1912, Alfred Wegner proposed all the continents were all once together. He called it Pangea (entire earth) -​ Continental drift is the movement of the Earth’s continents relative to each other by appearing to drift across the ocean -​ He couldn’t tell us why the plates would move -​ Jigsaw (every continent fits like a jigsaw puzzle) -​ Glacial Deposits (different rocks left behind from glaciers) -​ Fossils (animals traveling to a different continent they weren’t native in) -​ Mountain ranges (split and moved to different areas) Canadian John Tuzo-Wilson made 2 important observations -​ The plates move over hotspots in the mantle, which explains the formation of volcanic island chains (ex: Hawaii) -​ Discovered the third type of plate boundaries → Transform faults A new more complete theory was created, that of plate tectonics Plate tectonics: A theory that Earth’s outer shell is made up of individual plates that move, this explains why we have earthquakes, volcanoes, mountains and the formation of a new crust Harry Hess -​ Came up with a theory on how continents actually drift -​ Theory is: ‘sea floor spreading’ -​ The mid atlantic ridge proves this theory Canada’s west coast is located on a plate boundary (North American and Juan De Fuca plates), which is a location where two plates meet. When plates collide and move into each other it can cause earthquakes, tsunamis and volcanic eruptions. Tharp-Heezen Map -​ Illustration using sonar and the water depth -​ Revealed underwater mountains When two oceanic plates diverge (tear) from each other, it fills with magma and hardens when exposed to cold sea water. This has built underwater volcanoes like the mid ocean ridge, the largest underground mountain range. ​ It is almost completely underwater ​ It was discovered in the 1950s, and led to the discovery of the theory ‘seafloor spreading’ ​ Seafloor spreading is the addition of new crust on the ocean floor through volcanic activity (Magma rises from the mantle through currents, it cools when it reaches the oceanic crust) -​ Iceland was once a section of the underwater ocean ridge, over years it was pushed upwards. Convergent plate boundaries is when two plates collide creating mountain ranges Transform is when plates rub against each other Convection currents -​ Explains how the plates move -​ Describes the rising, spread, sinking of gas, liquid, or molten material when heat is applied -​ Convection currents go through a cycle, as it gets closer to the crust it gets colder but as it floats back down it gets warmer -​ This process creates waves within the mantle A fault line is where plates meet, Canada is located on a fault line Natural Disasters  -​ Events that occur in the world that often result in changes to the landscape, destruction and often death -​ As the name includes the word “natural” - these disasters occur naturally, but may be made worse by human activity -​ Potential natural disasters are: Avalanches, tornados, floods, landslides, severe storms Fukushima -​ Happened in 2011 -​ Massive earthquakes that hit Japan, 4th most powerful earthquake recorded since the 1900s -​ Caused a massive tsunami, which originated from the earthquakes -​ The tsunami damaged the Fukushima Daiichi nuclear plant, causing one of the most devastating disasters in recent history with over 20,00 deaths Why are glaciers important? -​ Glaciers contain 2% of all of Earth’s water -​ Considered the “world's air conditions” - their white surface reflects sun rays which moderate temperatures -​ Meltwater from glaciers help water crops -​ Glaciers help to generate hydroelectric power -​ About 70% of all freshwater on Earth is trapped in glaciers -​ This plays a significant role in the development of life on Earth -​ Water from glaciers flows into rivers all around the world Rock Cycles and Landforms -​ A landform is a natural feature on the earth’s surface 1.​ Mountains 2.​ Hills 3.​ Plateaus 4.​ Plains -​ Landforms affect where people live -​ Their development is connected to the rock cycle and glaciation -​ Landforms are formed through tectonic plates Canada’s landform regions -​ Divided into different regions (an area with certain characteristics that set it apart), since landscape is diverse across the country -​ A landform region is a geographic location with distinct characteristics -​ Impacts on where someone decides to live is climate, vegetation and soil The Landform regions fall into 3 categories Highlands (Mountains, high elevations) A)​ Appalachian Mountains B)​ Innuitian Mountains C)​ Western Cordillera Lowlands (Low lying regions, lower elevations) A)​ Great lakes - St Lawrence Lowlands -​ Most people live in this region due to climate, vegetation and soil B)​ Interior Plains C)​ Arctic and Hudson Bay Lowlands Shield (Oldest, largest region in Canada) A)​ Canadian Shield -​ Formed 3 billion years ago -​ Created through plate tectonics and erosion -​ It is mainly rock, that was once a mountain range millions of years ago -​ Glaciation has left the area with little soil → Not a good region for farming -​ One of the richest mining areas → Deposits of gold, silver, nickel Climate regions in Canada -​ Has a wide variety of climates -​ Northern areas within Canada have different climates than the Southern areas -​ There are 6 main factors that determine the climate (acronym to remember: LOWERN) 1.​ Latitude 2.​ Ocean Currents 3.​ Winds, Air masses 4.​ Elevation 5.​ Relief 6.​ Near Water The rock cycle is a cycle, there is no beginning or end. -​ There are 3 main types of rocks 1.​ Igneous: forms when magma or lava cools, most cooling happens either at the bottom of the ocean or inside earth’s crust ​ Igneous rocks that cool below Earth’s surface are intrusive rocks ​ Igneous rock formed from lava that cools on the surface are extrusive rocks 2.​ Sedimentary: created through compaction and cementation of loose sediments (fossils, little pieces of rock) other rocks broken down by weathering and erosion ​ Example: limestone, concrete (lime, sand, crushed stone and gravel) 3.​ Metamorphic: changed versions of igneous, sedimentary and other metamorphic rocks. Changes occur when the rocks are exposed to heat and pressure ​ Example: A metamorphic version of limestone is marble  Glaciation (the process of ice advancing and covering large areas of lands) -​ A glacier is a large section of ice and snow that moves across the lands, shaping and changing it -​ Glaciers do not melt completely in the warmer months, but they shrink/grow due to the temperature changes -​ Glaciation is not as powerful as plate tectonics, but still contributes to the creation of landforms -​ Glaciers changing is partially nature through temperature, but it has become less natural due to human intervention (greenhouse gases, climate change) How is a glacier made? -​ Two conditions are needed 1.​ Prolonged Cold (cold for a long period of time) 2.​ Accumulation of Snow (collection of snow) -​ Glaciers form when more snow and ice accumulate than the amount that melts Main types of glaciers are… -​ Alpine glaciers (high elevation, mountain areas) -​ Continental glaciers (old, thick mass, covering larger areas) The Effects of Glaciation ​ Across Canada, you are able to see the effects of glaciation even if it is not immediately obvious ​ There are two main effects of glaciation:  1.​ Erionsal (scraping) -​ As glaciers grow and move, erosion can take place -​ When they move, they scrape away soil and rocks that exist in those areas -​ In Canada, there are areas that don’t have soil because of this -​ Glaciers changed where rivers, streams and lakes drain → Lakes that existed in areas were destroyed and new ones were formed 2.​ Depositional (dropping off) -​ The process in which glaciers add sand, minerals, other materials to them, and they are dropping them off in a new area (changes landscape) -​ Till (mixture of loose sediments and rocks) is the material glaciers are scraping and moving -​ Common features created are: ​ Till Plains (flat land) ​ Moraine (glacial debris that has been pushed or formed at the edges of a glacier, on an angle) Deposition by Water -​ When water melts from a glacier, it’s called meltwater -​ Meltwater moves the debris below a glacier, and as the water slows down these particles are left behind -​ Meltwater flows into meltwater lakes, this is common in Canada Erratics are large (or can be small) rocks that are dropped in places that seem odd It matters if we don’t have glaciers in the future because we need freshwater, can affect the Earth’s ocean levels and are natural air conditioners Increased greenhouse gases and fossil fuels = glaciers melting -​ Significantly reducing emissions in the coming decades, more than third of the world’s glaciers will be gone by the year 2100 -​ If GHG aren’t reduced, the Arctic could be ice free in summer 2040 Rising sea levels ​ Melting glaciers is the main cause of sea levels rising ​ If all glaciers on Earth were to melt, sea levels would rise 70 metres flooding every coastal city on the planet → About 30% of the US population lives on a coast (100 million people) ​ Increasing chance of natural disasters A big issue is Algae -​ When glaciers melt and get warmer, it changes the temperature, when the temperature increases algae begins to grow -​ If glaciers are covered in algae, they won’t be able to reflect sunlight and melt faster -​ Causing less freshwater and extinction of species Soil regions -​ Each layer of soil has different characteristics and are split into different layers -​ Good quality soil = decent food -​ Lower quality soil in the Canadian Shield because of glaciation and in the north, it’s too cold as the soil will be frozen -​ If you have an area with higher quality soil, more people will settle there -​ Rich soil exists in areas where there is an effective combination of geology, climate and vegetation Types of soil: 1.​ Wet-climate soils (not great) -​ Too much precipitation (rain and snow) causes all nutrients to be washed away -​ Soil is less fertile 2.​ Dry-climate soils: -​ Not enough precipitation (soil is too dry) and soil will not be fertile 3.​ Tundra soil -​ Frozen soil and then when it unfreezes it makes too much water -​ Turns into wet-climate soil Vegetation -​ The plant life in a specific region -​ Canada has 3 types of vegetation 1.​ Tundra ​ Not a lot of plant growth ​ Only small trees grow 2.​ Forest 3.​ Grassland -​ There is a transition zone between each region where vegetation gradually changes Within Canada, there are 2 types of trees -​ Coniferous (evergreen) ​ Can survive in poor-quality soils ​ Waxy needles, think bark ​ Preserves moisture in dry conditions ​ Produce seeds in cones ​ Thin -​ Deciduous (broadleaf) ​ Not leaves in the winter ​ Don’t do anything in the winter ​ Wide