Theme 1 - Landform Process and Change Flashcards
fluvial?
referring to a river and it landforms
erosion?
the wearing away of the land
transportation?
movement of material by the flow of water
deposition?
dropping of the material carried by the river
bed load?
material carried by the river being bounced or rolled along its bed
meander?
a bend in the river formed by lateral erosion
why do river landforms change over time?
due to fluvial erosion, transportation and deposition
erosional processes of the river channel? 3
~abrasion
~hydraulic action
~solution
abrasion (river channel)?
stones and material carried by the river hitting the river bed and banks, wearing them away
hydraulic action?
the sheer force of water hitting the river bed and banks compressing air in gaps in the soil and rock which causes material to be washed away
solution?
slightly acidic river water dissolves chalk and limestone rocks which are made from calcium carbonate
erosional processes of the river bed load? 2
~attrition
~abrasion
attrition?
stones carried by the river collide together and are broken down becoming rounder and smaller
abrasion (bed load)?
stones and material carried by the river hitting the river bed and banks become eroded and turn smaller and rounder
when does deposition happen?
when the speed of flow is too slow for it to carry the load
where does deposition happen? 3
~where there is a lack of rainfall, so there is less water moving
~on the inside of a meander, as water here is moving slower
~at the mouth of the river, where the river water flows against the direction of the sea
river transportation? 4
~suspension
~traction
~saltation
~solution
suspension?
fine, light material is held up and carried within the rivers flow, this is called suspended load
traction?
large boulders and rocks are rolled along the river bed, load carried is called bedload
saltation?
small pebbles and stones are bounced along the river bed, this load is lifted then dropped alternatively
solution (transportation)?
minerals are dissolved in water, this s a chemical change affecting rocks such as chalk, load transported is called the solute load
examples of river landforms? 5
~meanders
~floodplains
~gorges
~waterfalls
~v - shaped valleys
where are v-shaped valleys found?
upper course of a river where the river is usually small and the land is steep
what creates the v-shape valley? 2 processes
~vertical erosion
~weathering
how is a v-shaped valley formed?
~water flows down a steep slope in a river
~flowing water carries sediment and starts to erode the sides of the valley
~over time the continuous erosion deepens and widens the valley creating a v shaped cross-section
processes used - hydraulic action, abrasion
waterfall?
water falling from a higher level to a lower level due to a change in rock structure or as a result of glacial erosion
gorge?
a steep sided narrow valley formed by a retreating waterfall
floodplain?
a flat piece of land on either side of a river forming the valley floor
vertical erosion?
erosion of the river channel that results n its deepening rather than widening
interlocking spurs?
hard resistant rocks that a river cannot easily erode and therefore the river goes around them
weathering processes that help develop a v shaped valley?
~freeze thaw
~biological weathering
what two ways can waterfalls be created?
~glacial erosion
~differential erosion
steps on how glacial erosion formed waterfalls?
~glaciers move slowly down slopes and valleys carrying rocks and sediments
~as the glaciers move it erodes the land beneath through plucking and abrasion
~eroded material is transported by glaciers
~when the glacier reaches a steep cliff or a change in slope, it starts to melt, and the water flows over the edge
~water flows in a waterfall creating a plunge pool
how are waterfalls formed by differential erosion?
~hard resistant rock is undercut by erosion of the soft rock
~the water falls over the hard rock lip and splashes against the soft rock on the back wall
~soft resistant rock is eroded on the wall causing it to move back
~a plunge pool is formed by the force of water and is deepened by abrasion
~the overhang collapses due to lack of support and the pull of gravity
~gradually the waterfall retreats upstream, leaving a steep sided gorge
when is a gorge formed?
when a waterfall collapses and retreats upstream
slip off slope?
a bank of gently sloping deposited material found on the inside bend of a meander
where are meanders usually found?
middle and lower course of a river valley
what are meanders caused by?
erosion on the outside of the bank and deposition on the inside of the bank