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Slide 2 Our Changing Earth Slide 3 Our earth is always changing. Some changes are S L O W FAST Slide 4 Scientists think that the surface of the earth has been slowly changing for millions of years. This is the called the theory of Slide 5 Continental Drift Slide 6 Slide 7 Some changes to the earth happen Rapidly! Slide 8 Landslides Slide 9 Mudslides Slide 10 Moving Water Slide 11 Forest Fires Slide 12 Earthquakes Slide 13 Slide 14 Volcanoes Some volcanoes change the earth quickly. Some volcanoes slowly build up the land over many, many years. Slide 15 Slide 16 Slide 17 Glaciers can also slowly change the surface of the earth. Slide 18 Review Continental drift is the theory of how continents move over Earths surface. Slide 19 Pangea was the Supercontinent on Earth millions of years ago before the continents drifted apart. Slide 20 Weathering is when rock is broken up into smaller pieces called soil, sand, or sediment. Erosion is when the sediment is moved from one place to another. Deposition is when the sediment is dropped in a new place. Slide 21 The surface of the earth can change slowly when... Lava comes out of a volcano and cools, building up into a mountain over time. Slide 22 The surface of the earth can change slowly when... Glaciers (thick sheets of ice that stay frozen all the time) slowly move, carving the land as they go. Slide 23 The surface of the earth can change slowly when... Water weathers rock as fast moving rivers carve deep canyons in the rock. Slide 24 The surface of the earth can change slowly when... Sediment is moved by water erosion and deposited in a new location. Deltas are made this way. Slide 25 The surface of the earth can change slowly when... water freezes in cracks of rocks. The freezing water expands, and the ice makes the cracks in the rocks bigger. Eventually the rocks break into small pieces. Slide 26 The surface of the earth can change slowly when... Wind carves away bits of rock like a sandblaster. Slide 27 The surface of the earth can change rapidly when... Volcanoes blast away the top or side of a mountain as it erupts. Slide 28 The surface of the earth can change rapidly when... two tectonic plates crash into or slide past each other. This causes an earthquake. Mountains and valleys can be made this way. Slide 29 The surface of the earth can change rapidly when... mass movement occurs. Landslides, mudslides, and sink holes all change the surface of the earth suddenly. Slide 30 Our earth is changing right now. Slide 31 Some of the graphics in this presentation may be copyrighted. This presentation is for educational use only.