Rivers Flashcards
What are the four different types of weathering?
- freeze-thaw
- onion skin
- chemical
- biological.
Describe the following type of weathering
freeze thaw
Moisture gets into a crack or a line of weakness. When the temperature drops, the moisture freezes resulting in the moisture expanding. The expansion of the moisture damages the rock, therefor making the crack deeper. When the temperature starts to rise, the moisture melts into liquid again. This process repeats, eventually causing the rock to break.
Describe the following type of weathering
onion skin
This is a process that mostly happens in the desert. During the day, the desert is hot. This heat causes the rocks to expand. During the night, the temperature drops significantly. This causes the rocks to contract. This eventually causes the rocks layers to peel off like an onion.
Describe the following type of weathering
chemical weathering
Limestone is a type of rock that is soft (chalk is like limestone as it is a form of it). Acid rain falls on limestone. The limestone then reacts with the acids in the rain, giving the limestone a pitted appearance.
Describe the following type of weathering
biological weathering
Seeds lodge in the cracks in the rocks. When they start to grow, the roots work their way down cracks and lines of weakness. This can lead to the rock breaking. The other form of biological weathering is when an animal (like a fox or a badger) burrows into a crack in a rock, making it bigger and eventually causing the rock to break.
What is the difference between weathering and erosion?
Weathering is is the process of rocks breaking down while erosion is the land wearing away.
What are the three processes that all rivers will go through.
- Erosion - wearing away of land
- Transportation- carrying rocks/soil along the river
- Deposition - depositing rocks/soil onto the land
Describe the four stages of how rivers shape the land.
- The river errodes down through rocks being pushed and scraped along the river bed causing the river channel to deepen.
- Weathering attackes the banks causing the material to loosen.
- Loosend material collapses into the river channel due to gravity or get washed in by rainwater.
- The river carries the material away,. leaving a v-shaped valley.
Give the definition of
the source
the place where a river starts
Give the definition of
valley sides
the slopes at either side of a river
Give the definition of
spurs
ridges of land around which a river winds
Give the definition of
V-shaped valley
The shape of a valley in its upper course.
Give the definition of
the channel
The course of a river
Give the definition of
river banks
The sides of a river
Give the definition of
the river bed
The bottom of a river channel
Give the definition of
Load
Material that is carried or moved by the river.
Describe the four stages in the formation of a waterfall
- Waterfalls usually form in the upper stage of a river occurring where a band of hard rock lies on top of softer rock. Falling water and rock particles erode the soft rock, below the waterfall creating a plunge pool.
- The soft rock is undercuts by erosional processes such as hydraulic action and abrasion creating a plunge pool where water and debris swirl around eroding the rock through corrasion further deepening it and creating an overhang.
- The hard rock overhanging above the plunge pool collapses as it’s weight is no longer supported.
- Erosion continues and the waterfall retreats upstream leaving behind a gorge.
4 features of the inside bend of river bend
- Deposition
- Shallower water
- Slowest flow
- Slip-off slope formed
4 features of the outside of a river bend
- Erosion
- Deepest water
- Fastest flow
- River Cliff formed
Draw a labelled diagram to show freeze-thaw weathering
- Water seeps into cracks and fratures in the rock
- When water freezes it expands which forces the rock apart
- Repeated freezing and thawing eventually breaks the rock.
