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Weathering and Erosion MOVING WATER • What do we call the movement of water? – Water Cycle (I hope you didn’t forget) • How do you think the water cycle causes weathering and erosion RUNOFF • Water moving from higher ground to lower ground because of the pull of gravity • What are some of the sources of runoff? – Rain – Snow melting Precipitation • As any form of precipitation hits the rocks/ground it causes weathering • Over time precipitation will wear the rock away until it becomes soil Precipitation • Some water seeps in to the ground • As the water trickles through the soil it eventually reaches solid rock • After the rock it reaches other water sources which then feed the roots • The water changes all surfaces it comes into contact with Physical and Chemical Weathering • Physical – Grinding off of small rock particles • Chemical – As water moves through rock it can combine with minerals in rock – This combination may cause changes in the original rock and any other rock the mineral water comes into contact with Shorelines • What do you think shorelines have to do with weathering? • As waves wash up on shore, the sand on the beach moves. • The shape of the shore changes along with the movement of the water Erosion • Water Erosion – Streams, rivers and rain erode the Earth’s surface over a long period of time. – Water erosion can cause new landforms. Erosion • Valleys – If water flows into a stream, over time that stream will become a river. – As river and streams flow over land, they cut into the land – Over time, these cuts create a valley – Sometimes the river dries up but the valley remains Erosion • Canyon – Deep narrow valleys with steep sides – Canyon usually have rivers or streams flowing through them – The Grand Canyon still has a small river flowing through it that has shrunk over time Canyons and Valleys Movement of Water • Fast moving water – Cut deeper into the land • Slow moving water – Shapes land at a much slower pace Meanders – Looping changes of direction in a river or stream – Water moves differently around a bend – The land near the outside edge or a meander erodes faster than land on the inside edge Tributary • A river or stream that does not reach the ocean • Tributaries join other rivers or streams Wind Erosion • Wind carries tiny particles • These tiny particles are then dropped in other areas changing the landscape Deposition • The process of adding sand, rock or soil to a new location • Fast Moving River – Rock is deposited near the mouth (where the river meets the ocean) of the river – A DELTA is a low, flat piece of land at or near the mouth of a river Delta • Formed by deposition • As a river flows it erodes small pieces of rock and soil • As the water moves the soil and rock continue to move • When the water meets the ocean it slows down causing the rocks and soil to settle at the bottom of the river • Deltas are very fertile – great for growing crops Floods • When snow melts and the water runs off into streams, rivers and tributaries • Floodplain is a flat land near a river form by deposition during floods – During a flood water flows over a rivers banks – When the water leaves the river it slows down – The rocks and soil are dropped becoming part of the flood plain Floodplain and Delta Found anywhere along rivers Continuously smoothing Found at the mouth of rivers