4. River Landforms Flashcards
What are Interlocking Spurs?
As the river cuts it’s deep V-shaped valley in its upper course, it follows the path of the easiest rock to erode. Thus it tends to wind it’s way along, leaving the more resistant areas of rock as interlocking spurs.
What are some features of the upper course of a river?
As the river moves through the upper course it cuts downwards. The gradient here is steep and the river channel is narrow. Vertical erosion in this highland part of the river helps to create steep-sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges.
What are Rapids in a river?
Rapids are a series of very short and fast falls. At the rapids, the river is shallow and flowing very quickly over rocks, boulders and stones sticking out above the water level.
When a river flows through an area of alternating bands of resistant and less resistant rocks, the less resistant rocks are eroded more quickly. Therefore, the less resistant rocks are at a lower level compared to the more resistant rocks. This results in the river falling in a series of steps along the bands of resistant rocks to form rapids.
What are waterfalls?
A cascade of water falling from a height, formed when a river or stream flows over a precipice or steep incline.
- The edge of a waterfall is called the overhang.
- ## The area where the water falls, is called the “plunge pool”.
What are some features of the middle course of a river?
In the middle course the river has more energy and a high volume of water. The gradient here is gentle and lateral erosion has widened the river channel. The river channel has also been deepened. A larger river channel means there is less friction, so the water flows faster.
What is a Meander?
A meander is a horseshoe-like loop in a river. It is formed due to both deposition and erosion.
The inner part of the river deposits material (deposition) due to a low current. This causes the outer bend with a fast current to slowly extend outwards in the opposite direction causing a bend in the river called a meander.
What is an Oxbow Lake?
An oxbow lake is a curved lake formed from a horseshoe bend in a river (meander) where the main stream has cut across the the narrow end and no longer flows around the loop of the bend.
What are some features of the lower course of a river?
In the lower course, the river has a high volume and a large discharge. The river channel is now deep and wide and the landscape around it is flat. However, as a river reaches the end of its journey, energy levels are low and deposition takes place.
What are Floodplains?
A floodplain is the area around a river that is covered in times of floods.
Floodplains are very fertile areas due to the rich alluvium (sediment deposited by rivers) deposited by floodwaters. This makes floodplains a good place for agriculture.
A build up of alluvium on the banks of a river can create levees, which raises the river bank.
What is a Delta?
As the sediment carried by the river approaches the mouth, the efficiency decreases, causing the sediment to be deposited. The deposition builds up at the mouth of the river and eventually forms small islands called deltas.
What is a Levee?
Levees are ridges or banks formed by deposits of alluvium (sediment deposited by rivers) left behind by the periodic flooding of rivers. Can also be artificially constructed banks or walls.
