Chapter 9; Rivers

Geography in Action

stages of a river

youthful, mature, old

source

the place where a river begins

course

the route a river takes to the sea

confluence

two rivers or streams join together

tributary

stream or river that flows into a larger river

mouth

river ends

drainage basin

land drained by a river

watershed

high ground, separates two draining basins

estuary

tidal part of river mouth

processes of river erosion

hydraulic action, abrasion, attrition, solution

hydraulic action

physical force

abrasion

wearing away

attrition

breaking up

solution

mixture formed when one substance dissolves another

processes of river transportation

rolling, bouncing, suspension, solution

rolling

traction

bouncing

saltation

suspension

rocks floating in water

causes of river depostition

reduction in river's speed, increase in load size, reduction in river's volume, gradient levels off

source's erosion

vertical erosion

what does vertical erosion create

v shaped valleys, interlocking spurs, waterfalls

v shaped valley

steep sided valley

formation of v shaped valleys

hydraulic action, mechanical weathering and mass movement creates a deep, narrow valley

examples of v shaped valleys

river liffey, lee, moy

interlocking spurs

areas of high ground on both sides of v shaped valley

interlocking spurs formation

river flows around rock it cannot erode, river erodes vertically, creates areas high ground

examples of interlocking spurs

upper course of river barrow, slaney

waterfall

vertical drop in the course of the river in its youthful stage

formation of a waterfall

water erodes soft rock, river flows over edge

overhang formation

water falls into plunge pool, water splashes and erodes back wall, overhang collapses, waterfall retreats

examples of waterfalls

torc waterfall kerry, ashleigh falls co mayo

deped

describe, example, process, explanation, diagram

meanders

curves in a river

formation of meanders

hydraulic action erodes bank, eroded material goes inside the bend

examples of meanders

middle courses of river shannon, moy

oxbow lake

horseshoe shape, meander cut off from the river

formation of oxbow lake

sediment cuts off loop

examples of oxbow lakes

middle courses of river liffey, moy

youthful stage

fast, vertical erosion

mature stage

greater volume, vertical and lateral erosion

old stage

slow, carries load

flood plains

wide, flat land either side of river

formation of flood plains

alluvium spreads out on both sides, alluvium builds up

bluff line

highest point reached by a river when in flood

alluvium

makes soil fertile, good for farming

examples of flood plains

lower courses of river moy, liffey

leeves

build up of alluvium

formation of leeves

flood causes build up on sides of the river

examples of leeves

lower course of river moy, liffey

deltas

area of land where mouth of river goes into sea

patterns of drainage

dentritic, trellis, radial, deranged