rivers

• abrasion is the scraping and scaring of the the river banks
• attrition is when rocks bang together becoming rounfd and smooth
• hydraulic action is when water force cracks and breaks the river banks
• the upper course is fast, narrow, steep, erosion and transprtation
• the middle course uses erosion, transportation and deposition
• lower course is fastest, flat, wide, transportation and deposition
• to describe a river - course, valley, direction, width, landforms
• waterfall- water flows over a band of hard rock and soft rock, erodes the soft rock faster creating an overhang of hard rock. river erodes soft rock below waterfall creating a plunge pool. water swirls round and undercuts hard rock. erosion due to hydraulic action and abrasion. hard rock collapses and with retreat forming a gorge
• a levee is a natural embankment in the lower course. built up due to flooding. when flood, river leaves its channel and loses energy due to friction meaning it cant transport heavy materials. load deposited near the sides. every flood builds up the levee
• a v shaped valley forms due to vertical erosion through abrasion and hydraulic action. the river cuts down and the sides are exposed and attacked by physical weathering- freeze thaw. this breaks and loosens rocks. loose rocks roll down the slope helping with abrasion meaning the channel becomes deeper and wider.