Zusammenfassung der Ressource
Rivers Mind-Map
- Features
- Source = Beginning of a river
- Course of River = Route taken towards the sea
- Tributary = Smaller river/stream that joins a larger river
- Confluence = Where a tributary joins a river
- Mouth = Where a river enters the sea
- Estuary = Part of a river mouth that's tidal
- River Basin = Area of land drained by a river
- Watershed = High ground separating river basins
- Erosion (n) = Gradual wearing away of land
- 3 Stages of a River
- Upper/Youthful Stage
- Valley has narrow floor and steep sides
- Small amount of water but very fast
- Most energy used to erode
- Features: V-shaped valley, waterfalls, interlocking spurs, potholes
- V-Shaped
Valley
- Get name from shape
- Landscape eroded in shape of a V
- Vertical Erosion occurs. River cuts into river bed, making it deeper. Creates a narrow, deep valley
- Mechanical weathering & mass movement
- e.g. River Liffey
- Interlocking Spurs
- River meets areas of hard rock
- Cannot erode these so instead flows around them while eroding downstream
- Zigzag
course
- e.g. River Moy
- Waterfalls
- Rivers flow over areas of hard & soft rock
- River erodes the soft rock but can't erode the hard rock
- Falling water erodes deeper into the bed, creating a Plunge Pool
- e.g. Iquazu Falls
- One of the widest waterfalls in the world (1.5 miles across)
- On the border between Argentina & Brazil
- 13 million litres of water spill over per second
- Found towards the end of its river
- Middle/Mature Stage
- Valley has wider floor and sides are more gently sloping
- River starts slowing & deposits some materials
- Features: Wide river valley, meanders, flood plains
- Meanders
- Bends/curves along the river
- Formed by erosion and deposition
- Erosion occurs on one side while deposition occurs on the other
- e.g. River Shannon
- Lower/Old Stage
- Valley has flat floor and gentle sides
- Carrying lots of sand & silt
- Moving over flat land so moving slowly
- Lots of deposition
- Creates many features/landforms
- Features: Ox-bow lakes, levees, deltas
- Ox-Bow Lakes
- Horseshoe shaped lake found beside a river
- Formed when continued erosion and deposition create very pronounced meanders
- Eventually the river cuts through the neck of the meander
- Deposition then occurs which separates the ox-bow lake from the river
- Erosion Processes
- Hydraulic Action = Force of moving water wears away banks and bed of river
- Abrasion = Small stones carried by river wear away at banks and bed of river
- Attrition = Small stones wear down as they hit each other
- Solution = Rocks and soil are dissolved by acid in water
- Erosion Ability
- Speed of river (steeper = faster)
- Volume (more water = increased ability to carry material)
- Transporting Material
- All rivers carry material
- e.g. sand, stones
- River's Load = All material
- River Transportation = River moves its load
- Traction = Large stones rolled along river bed
- Saltation = Small stones bounced along river bed
- Suspension = Light material (sand, silt, etc.) is carried (floating) in river
- Solution = Dissolved materials are carried by river
- River Deposition
- Deposits materials when:
- River slows (flatter land)
- Volume decreases (e.g. drought)
- River reaches sea