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Geomorphology Changing Landforms Chapter 2 Changing landforms What external forces alter the landscape? What internal forces change the landscape? Mt. Hood and Columbia Gorge: Erosion and Vulcanism Degradation (Wearing Down) Weathering-the process that breaks up rocks into smaller particles – Chemicals – Heat – Physical • Falling Rocks • Roots • Ice Water Water-water can move these smaller particles to different locations and create valleys and canyons Degradation (Wearing Down) Glaciers: Ice sheets and mountain glaciers – Scrape and push matter downhill slowly – They can move rocks bigger than houses – In mountains, they can form steep U-shaped valley Wind Wind-in deserts, on beaches and other places devoid of plants – Sand dunes – Loess Mountain Building Fault-block Develop where the earth’s crust breaks and land is pushed up by underground force Fault-block Folded Look like a huge corrugated roof Squeezing together of rocks into a series of rounded waves. Folded Dome mountains Molten rock pushes up the earth’s surface Softer stone is worn away Dome Mountains Volcanoes Formed from volcanic eruptions Heat from the earth’s core, travels slowly to the earth’s surface in the form of liquid rock (magma or lava) exiting out of volcanoes. Volcanoes Landforms: Hills Valleys Plains Plateaus, etc. Plate Tectonics The theory that the Earths’ surface consists of huge “plates” that float on the molten layer bumping into each other and causing all landforms. Plate Change Overtime, the plates drifted away from one another which leads to the current land setup of today. Plate Tectonicsshifting of the earth’s plates. Plate Movement 3 types of plate boundaries: – Plates pushing against each other • Trenches (Challenger Deep) • Volcanoes and other mountains (Cascades, Andes, Himalayas) – Plates moving away from each other. • Mid-oceanic ranges • Abyssal plains – Plates sliding past each other. • San Andreas Fault Plate Creations Trenches form when heavier plates collide with other plates heading downward, creating a deep abyss. These abysses are generally the deepest parts of the oceans’ floor. Other times, plates will collide and form mountains (such as the Andes of South America). Earthquakes When plates slide past each other, low mountains or faults may result (e.g. San Andreas fault).