Geomorphology Flashcards
Agents of weathering
- Water
- Ice
- Acids
- Salts
- Plants
- Animals
- Changes in temperature
Types of physical weathering
- Temperature change
- Freeze thaw/ Frost Shattering
- Abrasion - Wind, Rain, Waves
Degree of chemical weathering depends on
- Type of rock
- Temperature
How acidic rain is made:
- Fossil fuels are burnt up, releasing oxides such as nitrogen, carbon and sulphur into the atmosphere
- These oxides combine with the moisture in the air, and form nitric acid, sulphuric acid, carbonic acid
Types of Biological weathering
- Trees and other plants
- Tiny organisms
- Burrowing animals
Difference between weathering, erosion, deposition
Weathering: occurs on the spot
Erosion: weathered rocks or minerals are transported away
Deposition: comes to rest
Transporting agents
- Gravity
- Water
- Wind
- Ice
River valley sections
- Upper Course (young)
- Middle Course (aged/mature)
- Lower Course (old)
Rivers goal
To erode all land to sea level
Agents of erosion
- Rivers
- Oceans
- Winds
- Glaciers
Meander is also called
River bend
Importance of rivers to man
- For our survival: water
- For food
- Irrigation, watering our crops
- Transportation
- Energy, hydro electric power
- Leisure
Characteristics of upper course
- Closer to the source
- Steep gradient
- Small river and flows quickly
Features in upper course
- V- shaped valleys
- Interlocking spurs
- Rapids
- Waterfalls
- Gorges and canyons
Types of erosion
- Hydraulic action
- Abrasion
- Attrition
- Solution
Types of transportation
- Traction
- Saltation
- Suspension
- Solution
V - shaped valleys
Deep valleys with steep sides
Interlocking spurs
- Erosion outside the banks and vertical erosion
- Results in ridges of high land (spurs) to project towards the river, decreasing in height towards the river
Waterfalls are commonly formed
When a river crosses a band of hard or resistant rock
White water shows
A lot of turbulence
What results in rapids
Friction that is caused
River’s velocity depends on
- Gradient
- Smoother the channel/path
- Volume
Rapids
Steep slope, with rough river bed (uneven due to alternating bands of soft and hard rock)
Characteristics of Middle Course
- Gradient not as steep as Upper Course
- Lateral erosion (erosion of the banks) more effective than vertical
- More wider, open appearance
- Some deposition takes place
- Meanders are common
Features in Middle Course
- Meanders: river cliffs and slip-off slopes
- Ox-bow lakes
Meanders with river cliffs and slip-off slopes
- Outside banks are undercut creating river cliffs
- Inside banks where water flows more slowly with deposition. Giving rise to gentler slopes/slip-off slopes