River Processes Flashcards
(21 cards)
Types of river erosions
Abrasion, attrition, hydraulic action and solution.
Types of river transport
Suspension, saltation, solution and traction.
What are interlocking spurs?
Interlocking spurs are found in the upper course of the river. They are caused by erosion and since the river is not powerful enough to cut through the ‘spurs’ of land, so it has to flow around them. They are also found in V-shaped valleys.
Where do waterfalls frequency occur?
On horizontally bedded rocks.
Whether are waterfalls formed?
Where the river meets a band of softer, less resistant rock (like sandstone7 after flowing over a relatively hard resistance rock (like basalt).
What is a gorge?
A gorge is a narrow steep-sided valley that is usually found immediately downstream of a waterfall. It is formed by the gradual retreat of the waterfall over hundreds or even thousands of years.
Give an example of a gorge caused by a glacier.
Cheddar Gorge in Somerset.
What are meanders a result of?
Erosion and deposition.
First stage of an oxbow lake forming.
The neck of the meander is gradually eroded.
Second stage of oxbow lake.
Water now takes the shortest (steepest) route.
Third stage of oxbow lake.
Meander is cut off, forming an oxbow lake.
Define slip-off slope
This is formed on the side of the river with the greatest deposition (the inside of the meander). It is simply deposited material that forms a small beach like area and gently sloping bank.
Define river cliff
This happens on the side of the river channel with greatest erosion (the outside of the meander). It creates a steep sided bank which ported leads to undercutting the bank.
Define Thalweg
The thalweg is simply where the channel flow is the quickest.
Define Riffles
Deposition of s course material that create areas of shallow water.
Define pools
Areas of deeper water between riffles.
Define Pools and Riffles
Developed in section along river channel which create different gradient of channel.
What do course pebbles create.
Steeper gradient than eroded pools.
Define bankfull discharge
This is when the river channel is full and cannot hold any more water, if the river exceeds bankfull discharge then it floods.
Define Bluff line
The outer limits of the floodplain. The bluff line is found just before the gradient of the valleys sides starts to increase.
Define strand line
This is the line of material left behind after a river has flooded. The strand line is found on the outer limit of the flood so,where on the floodplain. A strand line normally consists of pieces of wood and litter.
