2 - Hydrosphere Flashcards
1
Q
HYDROSPHERE: WHAT IS HYDRAULIC ACTION?
A
when the force of water compresses air andpressure on the bank causes material to be dislodged.
2
Q
HYDROSPHERE: WHAT IS ABRASION?
A
when the force of water throws the bedload against thebanks wearing them down.
3
Q
HYDROSPHERE: WHAT IS SOLUTION?
A
when soluble rocks react with acids or salts in the water.
4
Q
HYDROSPHERE: WHAT IS ATTRITION?
A
when rocks in suspension hit off each other erodingfurther.
5
Q
V-SHAPED VALLEY: SETTING
A
- V-shaped valleys form in the upper course of rivers where the land is often steep and rivers have high energy.
- This causes vertical erosion to dominate through hydraulic action and abrasion.
6
Q
V-SHAPED VALLEY: PROCESSES
A
- Hydraulic action deepens the bed and is when the force of water compresses air and pressure on the bank causes material to be dislodged.
- Abrasion is when the force of water throws the bedload against the banks wearing them down.
7
Q
V-SHAPED VALLEY: OVER TIME
A
- Weathering causes the rocks and soils to break down on the sides of the valley. This happens quicker in colder, wetter areas.
- The hillslopes become unstable causing a mass movement (landslide) and the material falls into the river channel.
- Here it is broken up by attrition and used as tool for further erosion.
- A narrow valley is left with the river filling the whole valley floor.
- The river continues to zig zag down its course through interlocking spurs.
8
Q
WATERFALL: SETTING
A
- Waterfalls form in the upper course of rivers where there is a band of hard rock overlaying soft rock.
- This causes differential erosion as the rocks are eroded at different rates through hydraulic action and abrasion.
9
Q
WATER FALL: PROCESSES
A
- Hydraulic action deepens the bed and is when the force of water compresses air and pressure on the bank causes material to be dislodged.
- Abrasion is when the force of water throws the bedload against the banks wearing them down.
10
Q
WATERFALL: OVER TIME
A
- Softer rock is eroded more easily creating an overhang of hard rock as it is undercut.
6. The hard rock becomes unsupported and collapses into the plunge pool due to gravity. - Here material is broken up by attrition and used as tools for further erosion.
- As this process repeats itself the waterfall retreats upstream creating a gorge.
11
Q
MEANDER: SETTING
A
- Meanders form in the middle to lower course of rivers where water twists and turns arounds obstructions such as large boulders.
- The river starts to become more sinuous (curvy) as riffles and pools lead to changes in speed, depth and direction of the river channel.
- Pools are areas of deeper water whereas riffles are shallower with greater turbulence where lateral erosion can occur through HA and A.
12
Q
MEANDER: PROCESSES
A
- Hydraulic action deepens the bed and is when the force of water compresses air and pressure on the bank causes material to be dislodged.
- Abrasion is when the force of water throws the bedload against the banks wearing them down.
13
Q
MEANDER: OVER TIME
A
- The river flows fastest on the outside bend increasing erosive power.
- The river flows slowest on the inside bend leading to deposition.
- Helicoidal flow moves materials across the river channel. This leads to the development of river cliffs on the outside bend and beaches on the inside.
- As erosion and deposition continue the meander will migrate downstream.
14
Q
OXBOW LAKE: FORMATION
A
- Over time, meanders become more pronounced.
- The neck of the meander will become narrower as it is eroded.
- During a time of high energy (for example a flood or during spring when snow is melting), the water may cut through the neck of the meander.
- Deposition on the river’s banks seals off the old meander, so water no longer flows around it. This is called an ox-bow lake.
- As it is no longer being supplied by water, it will dry up.
15
Q
DRAINAGE BASIN INPUTS
A
Precipitation is all forms of moisture that reach the earth’s surface and is the only input into a drainage basin.
