Rivers Flashcards
What is Hydraulic action?
The result of the sheer force of the water hitting the river bed and banks and wearing them away. This action is particularly important during high-velocity flows.
What is Abrasion?
This is caused by material carried in the river rubbing against the bed and banks of the channel,so wearing them away. overall, abrasion costs the most erosion.
What is Solution?
Because river water is slightly acidic, it can dissolve some rocks and minerals that come in contact with the river. Limestone and chalk are mostly affected.
What is Attrition?
Sediment particles carried in the river collide with each other causing the edges to be knocked off. the continued collision of particles in the river causes the to become rounder and smaller downstream.
What is Weathering?
The breakdown and decay of rock by natural processes
Describe the upper course of the river?
Near the source the channel is narrow, shallow and full of angular stones. So friction slows the river down
What are meanders?
Bends found in a rivers course. This results in lateral erosion by undercutting and a steeper bank is formed
Describe the middle of the river?
the rocks are softer and more permeable
the river channel is wider and deeper
The river also erodes sideways
Describe the lower part of the river?
mostly soft mudstone
channel is wide, deep and smooth