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Canadian Landforms (page 22-29) BUILDING MOUNTAINS A geologic ______________________ has been going on for the past ________ billion years or so. Stresses and strains inside the Earth have been heaving up _____________________. Meanwhile, the forces of _______________ keep wearing them down. The Earth in Motion If you cut out the ______________________ on a world map, you’d be surprised at how well some of them fit together. Almost a century ago, German geographer ____________________________ noticed this pattern. Wegener believed that the continents had once been joined in one land mass that he called __________________, meaning “all lands.” He proposed the theory of ___________________________, which suggests that the continents gradually moved away from one another over time. The problem with Wegener’s _______________________________________ was that he could not explain how massive continents could _______________ across the face of the Earth. Most scientists __________________ continental drift theory. Years later, it turned out that Wegener was __________ – and it was a _______________________ who helped discover the reason why. Scientists rejected the theory of continental drift when it was first put forward because ______________ could not explain the driving force behind the movement of the continents. Plate Tectonics Think of the Earth as a round egg. __________________ sits on the thin, brittle outer shell, called the ____________________, or crust. Beneath the lithosphere is the _________________, a zone of molten magma where you’d find the egg white. At the center, the Earth’s ______________is like the yolk. It is the __________________ furnace that _____________ the rocks of the mantle above it. In the 1960s, Canadian ___________________________ got people interested in continental drift again. He recognized that __________________ could form deep in the mantle, and that __________________ could circulate above these hot spots, just as _________________water swirls in a heated pot on a stove. These ________________________________ might provide enough ________________ to push the crust apart, as Wegener suggested. Since then, _____________________ have confirmed that the ______________________ (Earth’s crust) has many _______________ called ______________. These plates are still moving. The field of ________________________________ investigates how moving plates can create _________________, build ________________________, and trigger _______________________. Volcanoes Canada has no active _____________________ today, but some along the Pacific Coast are classed as ____________________or sleeping volcanoes. This means they have been active in the recent past and could erupt again. These ________________Coast _________________________are part of the ______________________________________ a global system of ________________ volcanic mountains that circle the __________________ Ocean. What causes volcanoes? Scientists believe there are “_____________________” in the Earth’s _______________. Rising heat sets the molten material of the _________________ into huge ______________________ motions like warm air circulating in a room. As these _______________________________________ swirl, they drag the __________________ of the lithosphere (crust) with them. __________________open along the plate _____________, and _________________ forces its way through. Fold Mountains If you put a pile of binder paper between two textbooks and slowly push the two textbooks together, you will make a model of ___________ mountains. The textbooks are like thick __________ carrying ____________________, while the paper represents soft ______________________ rock layers on an ocean plate. Your arms are like ___________________currents __________________ the plates together to build _________________________. This is how most of __________________ mountain _________________ were formed. For example, the ___________________ Mountains were folded by the _____________________ of the Pacific and North American Plates. The diagram to the right, shows how Canada’s Rocky Mountains formed millions of years ago. The Rockies (located in Alberta) as well as the Coastal and Columbia Mountains (located in British Columbia) are still growing higher today as the North American plate and the Pacific plate collide. The Pacific Ring of Fire Study the map above. Follow the location of the Pacific ring of Fire. 1. Which parts of Canada (provinces and/or territories) does it pass through? 2. Compare the location of volcanoes in the Ring of Fire with plate boundaries. What pattern do you notice? What might explain this pattern? Canadian Landforms (page 22-29) BUILDING MOUNTAINS A geologic tug-of-war has been going on for the past four billion years or so. Stresses and strains inside the Earth have been heaving up mountains. Meanwhile, the forces of erosion keep wearing them down. The Earth in Motion If you cut out the continents on a world map, you’d be surprised at how well some of them fit together. Almost a century ago, German geographer Alfred Wegener noticed this pattern. Wegener believed that the continents had once been joined in one land mass that he called Pangaea, meaning “all lands.” He proposed the theory of continental drift, which suggests that the continents gradually moved away from one another over time. The problem with Wegener’s Continental Drift Theory was that he could not explain how massive continents could move across the face of the Earth. Most scientists rejected continental drift theory. Years later, it turned out that Wegener was right – and it was a Canadian who helped discover the reason why. Scientists rejected the theory of continental drift when it was first put forward because Wegener could not explain the driving force behind the movement of the continents. Plate Tectonics Think of the Earth as a round egg. Canada sits on the thin, brittle outer shell, called the lithosphere, or crust. Beneath the lithosphere is the mantle, a zone of molten magma where you’d find the egg white. At the center, the Earth’s core is like the yolk. It is the nuclear furnace that melts the rocks of the mantle above it. In the 1960s, Canadian J. Tuzo Wilson got people interested in continental drift again. He recognized that hot spots could form deep in the mantle, and that currents could circulate above these hot spots, just as boiling water swirls in a heated pot on a stove. These convection currents might provide enough force to push the crust apart, as Wegener suggested. Since then, geologists have confirmed that the lithosphere (Earth’s crust) has many pieces called plates. These plates are still moving. The field of plate tectonics investigates how moving plates can create volcanoes, build mountains, and trigger earthquakes. Volcanoes Canada has no active volcanoes today, but some along the Pacific Coast are classed as dormant or sleeping volcanoes. This means they have been active in the recent past and could erupt again. These West Coast volcanoes are part of the Pacific Ring of Fire, a global system of active volcanic mountains that circle the Pacific Ocean. What causes volcanoes? Scientists believe there are “hot spots” in the Earth’s core. Rising heat sets the molten material of the mantle into huge circular motions like warm air circulating in a room. As these convection currents swirl, they drag the plates of the lithosphere (crust) with them. Cracks open along the plate edges, and magma forces its way through. Fold Mountains If you put a pile of binder paper between two textbooks and slowly push the two textbooks together, you will make a model of fold mountains. The textbooks are like thick plates carrying continents, while the paper represents soft sedimentary rock layers on an ocean plate. Your arms are like convection currents dragging the plates together to build mountains. This is how most of Canada’s mountain ranges were formed. For example, the Rocky Mountains were folded by the collision of the Pacific and North American Plates. The diagram on the right shows how Canada’s Rocky Mountains formed millions of years ago. The Rockies (in Alberta) as well as the Coastal and Columbia Mountains (in British Columbia) are still growing higher today as the North American plate and the Pacific plate collide. The Pacific Ring of Fire Study the map above. Follow the location of the Pacific ring of Fire. 1. Which parts of Canada (provinces and/or territories) does it pass through? The Ring of Fire passes through Canada’s West/Pacific coast – British Columbia and Yukon. 2. Compare the location of volcanoes in the Ring of Fire with plate boundaries. What pattern do you notice? What might explain this pattern? You notice that the Ring of Fire is found along the Pacific Plate boundary or edges of the Pacific Plate. Volcanoes occur where: there are cracks in the Earth’s crust where tectonic plates subduct (one plate is drawn down beneath the crust) where tectonic plates are pulling away from each other