weathering, mass movement & fluvial processes

What does physical weathering involve

• A type of weathering

• Rock is broken down into smaller pieces

• This occurs due to change in temperature e.g freeze thaw

• This use when water from rainfall collects in a crack in a rock, freezes and expands, the ice thaws then melts and freezes again etc

What does chemical weathering involve

• A type of weathering

• rocks disintegrate and dissolve in slightly acidic rainwater

What does biological weathering involve

• A type of weathering

• rocks are broken apart by the roots of plants

What is soil creep and what does it involve

• A type of mass movement where:

• The influence of gravity causes weathered material to slowly move down and slope towards the river

What is slumping and what does it involve

• A type of mass movement where:

• The slope is eroded by the river, undercutting the slope causing large scale movement of material down the slope

What are landslides and mudflows and what do they involve

• a type of mass movement where:

• Rapid examples of mass movement, usually triggered by a natural hazard e.g earthquake

How does climate affect weathering and mass movement

• in hot, wet climates chemical and biological weathering are dominant due to lots of rain and plants (e..g rainforest)

How does weather affect weathering and mass movement

• heavy rainfall increases mass movement

How does slope affect weathering and mass movement

• any slope over 5 degrees experience mass movement, the steeper the gradient the more mass movement

How does geology affect weathering and mass movement

• different rocks have different levels of resistance to weathering

How does altitude affect weathering and mass movement

• at higher altitudes, freeze thaw weathering occurs more frequently

How does vegetation affect weathering and mass movement

• roots bind the soil together, which limits mass movement

• However, an abundance of vegetation incraeses the likelihood of biological weathering

What is most of a rivers energy used for and where is it most common

• to overcome friction

• Most common in the upper course of the river as its shallow and narrow with larger rocks

What is erosion

• A fluvial process that involves the wearing away and movement of a material

Name the 4 erosion processes

• hydraulic action

• Abrasion

• Attrition

• Solution/corrosion

spells haas, f1 team <3

What is hydraulic action

• type of erosion

• Where the forces of the water removes material from the banks and bed of the river

What is abrasion

• type of erosion

• Occurs when materials carried by the river scrape away at the banks and bed

What is attrition

• type of erosion

• Occurs when the material being carried by the river hits each other, as a result, the pieces become rounder and smoother

What is solution/corrosion

• type of erosion

• Occurs when some rocks are dissolved by the slightly acidic water

What are the two direction erosion can occur in and at what course in teh river is each most commonly found

• vertical and lateral erosion

• Vertical erosion is dominant in the upper course of rivers, it incraeses the depth of the river

• Lateral erosion is dominant in the middle and lower courses of rivers, increases the width of the river

What are the 4 processes of transportation and how do they work

• traction - occurs when larger rocks and material are rolled along the riverbed

• Saltation - when smaller material is lifted by the water and bounces along the riverbed Saltation bed

• Suspension - occurs when lighter material is carried within the river flow

• Solution - is when the materials are dissolved in the water

What is deposition

• when a river does not have enough energy to carry materials, it drops them

• The heaviest load of materials are deposited first (bed load) then the lighter materials further downstream

What are the three fluvial processes

• deposition

• Transportation

• Erosion

How does climate affect fluvial processes

• heavy rainfall and/or low temps lead to higher discharge - increasing erosion and transportation

• Vice versa

How does slope affect fluvial processes

• rivers on a steep slope will be fast flowing so increased erosion

• Gentle slopes will result in more deposition

How does geology affect fluvial processes

• softer, less resistant rocks erode more rapidly than harder ones

How does altitude affect fluvial processes

• melting snow and ice increase discharge and therefore is more erosion and transportation