TRANSPORTATION LANDFORMS Traction: rolling stones along the bed  V-shaped valley:  Saltation: particles bounce along bed in a leapfrog motion Water is mainly slow  o flowing as most of the  Suspension: silt and clay-sized are carried within the water flow rivers energy is used to Solution: minerals dissolve in the water  overcome the friction of the river bed & obstructions Load is mainly o large, angular and rough  Interlocking spurs: In the upper valley a river is in the mountains. Water takes the easiest path downhill so twists & turns around the high land (spurs) forming interlocking spurs.  Waterfalls: EROSION They occur because the river flows over hard rock o Attrition: large particles such as boulders collide and break into  which erodes slowly. smaller pieces (occurs at higher part of river) Beneath is softer rock which is eroded faster to form a o “step”. Hydraulic action: the sheer force of the river dislodges particles  The force of the water erodes the bottom of the waterfall to o from its banks and bed form a plunge pool. Abrasion: smaller particles rub against the river banks and bed like  The hard rock gets undercut as the soft rock erodes so that o sand-paper; occurs at low part of river (smaller particles) it eventually collapses.  Solution: acids in river dissolve rocks (occurs at any part of river) Rapids: They form also where the river passes over hard rock, but  either the band of rock is not very deep or there are a series of shallow rock bands. DEPOSITION Potholes: Can be found in the  When a river lacks the energy to carry its load; it begins with the  upper & middle valley where a heaviest particles; happens when there is less water or where the river flows over solid rock. current slows down. Meanders:  Large boulders are deposited at the top, and very small particles  Wide sweeping bends found o are deposited at the end, resulting in sorting. in the lower part of the river. BRADSHAW MODEL They are formed by a o combination of lateral erosion & deposition. Valley is narrow with o Ox-bow  a narrow, shallow river Form when the neck of the meander becomes very narrow. o channel During high flow or floods the river cuts through the neck & o Valleys have steep sides o straightens its course. Channel has a steep o Deposition occurs on the bank of the river o gradient The cut-off meander is an ox-bow lake. o
TRANSPORTATION  Traction: rolling stones along the bed  V-shaped valley: LANDFORMS  Saltation: particles bounce along bed in a leapfrog motion  Suspension: silt and clay-sized are carried within the water flow  Solution: minerals dissolve in the water EROSION  Attrition: large particles such as boulders collide and break into smaller pieces (occurs at higher part of river)  Hydraulic action: the sheer force of the river dislodges particles from its banks and bed  Abrasion: smaller particles rub against the river banks and bed like sand-paper; occurs at low part of river (smaller particles)  Solution: acids in river dissolve rocks (occurs at any part of river) DEPOSITION  When a river lacks the energy to carry its load; it begins with the heaviest particles; happens when there is less water or where the current slows down.  Large boulders are deposited at the top, and very small particles are deposited at the end, resulting in sorting. BRADSHAW MODEL o Valley is narrow with a narrow, shallow river channel o Valleys have steep sides o Channel has a steep gradient o Water is mainly slow flowing as most of the rivers energy is used to overcome the friction of the river bed & obstructions o Load is mainly large, angular and rough  Interlocking spurs: In the upper valley a river is in the mountains. Water takes the easiest path downhill so twists & turns around the high land (spurs) forming interlocking spurs.  Waterfalls: o They occur because the river flows over hard rock which erodes slowly. o Beneath is softer rock which is eroded faster to form a “step”. o The force of the water erodes the bottom of the waterfall to form a plunge pool. o The hard rock gets undercut as the soft rock erodes so that it eventually collapses.  Rapids: They form also where the river passes over hard rock, but either the band of rock is not very deep or there are a series of shallow rock bands.  Potholes: Can be found in the upper & middle valley where a river flows over solid rock.  Meanders: o Wide sweeping bends found in the lower part of the river. o They are formed by a combination of lateral erosion & deposition.  Ox-bow o Form when the neck of the meander becomes very narrow. o During high flow or floods the river cuts through the neck & straightens its course. o Deposition occurs on the bank of the river o The cut-off meander is an ox-bow lake.
Revision-Notes-v-April-2018.docx