rivers - river tees Flashcards
drainage basin
area that runs into river
v-shaped valley
valley - steep
river - narrow, shallow, turbulent
downstream
deeper and wider due to tributaries leading into it, less steap
less water incontact with bed and banks, velocity increases, large sediment load
valley - very wide and flat
upstream
narrow, shallow, turbulent - friction slows rate of flow
could encounter rapids (channel narrows, river deeper) which move faster
v-shaped valley - steep sided, v-shaped
vertical erosion
downwards
lateral erosion
across
deposition
when velocity of river decreases
no longer enough energy to transport sediment so is deposited
larger rocks upstream
finer sediment on river beds or banks further downstream
large amount at mouth when joins with tide along with very gentle gradient reducing river’s velocity
interlocking spurs
upstream, river not powerful enough to flow through so flow around
waterfalls
when river bed changes from harder rock to softer rock. soft rock eroded, harder isnt so drops and the hydraulic action creates plunge pool, undercut waterfall, hard rocks collapses and water fall retreats up stream
can also form when drop in sea level causes river to cut down into its bed creating a step (knick-point) in long profile of river
gorges
formed by waterfall retreating over many many years
at end of last glacial period huge quantities of water from melting glaciers poured off upland areas
some gorges form on limestone as a result of collapse of underground caverns
uk landscapes in general
wide variety of rock types responsible for creating our varying landscapes
more mountainous in north, south west, and wales, major rivers all around the country, coast around the whole island
hydraulic action
force of water hitting river bed and banks, most effective when water is moving fast and when there is lots of it
abrasion
when load carried by river repeatedly hits the bed or banks dislodging particles into flow of river
attrition
when stones carried by river knock against each other, gradually making stones smaller and more rounded
solution
when river flows over limestones or chalk, rock slowly dissolves because it is soluble in mildly acidic river water.