Weathering, Soil Erosion & Mass Wasting: Surface Processes Flashcards
When rocks are breaking into smaller pieces whether physically or chemically
Weathering
happens when rocks break up into tiny pieces without a change in their composition
Physical/Mechanical Weathering
Causes: frost wedging, water action, thermal stress, salt crystal growth, pressure release, gravity, exfoliation, plants and animals
Weathering
Examples of Physical Weathering
Frost weathering
Pressure-release
Abrasion
Organic Activity
Thermal expansion and contraction
process in which water freezes in a crack and then the expansion edges the rock apart
Frost weathering
process wherein tectonic forces lift deeply buried rocks close to the surface and then erosion removes the overlying rock, removing the pressure and causing the rock to expand and fracture
Pressure-release
process of grinding and rounding rock surfaces by friction and impact caused by waves and glaciers
Abrasion
process in which a rock is expanded by plant roots or broken by animal and human activities
Organic activity
occurs when temperature changes rapidly, causing the surface of the rock to heat or cool
Thermal expansion and contraction
happens when rocks break down into tiny pieces and change the rock’s composition or internal structure of minerals
Chemical weathering
some of its causes are oxidation, leaching, hydration, and carbonation
Chemical weathering
Types of chemical weathering
Dissolution
Hydrolysis
Oxidation
process in which a mineral or rock dissolves in water forming a solution like halite dissolved water
Dissolution
process in which mineral reacts with water to forma new mineral that has water as part of its crystal structure like feldspar to clay
Hydrolysis
process in which a mineral decomposes when it reacts with oxygen like rusting of iron
Oxidation
surface process characterized by the removal of rock particles from where they were formed
Soil Erosion
due to some agents such as water, wind, waves, rain, and ice
Soil erosion
major and universal agent of soil erosion
Running water
Causes: gravity, human activities (mining, logging, kaingin, burning grassland, infrastructure, and animals)
Soil Erosion
why does soil erosion reduce soil fertility?
because the topsoil which is rich in nutrients has been removed
bad effects of soil erosion
landslides, water shortages, deterioration of forests
Human activities that causes soil erosion
Kaingin farming or Burn method
Logging
Infrastructure projects
Mining
Overgrazing
farmers that don’t own lands for farming cut down trees and burn an area for planting their crops
Kaingin
after year of planting, the soil loses its fertility and farmers move on to other areas to have another __ without replanting the area
Kaingin
cutting down of trees for industrial purposes, some do not follow government regulations and some practice illegal logging, destroying forest covers
Logging
construction of roads, bridges, dams, etc., may cause soil erosion because of poor planning, inadequate provisions for drainage
Infrastructure Projects
digs and loosen rocks in the mountains and expose large areas to weathering and erosion
Mining
occurs in areas where there are farms for livestock where plants are consumed and eventually disappear, losing soil cover that may protect the area from landslides and flooding
Overgrazing
Methods to reduce effects of soil erosion
Rehabilitative method
Vegetative method
Mechanical method
Preventive Method
used in badly eroded areas
involves the use of vegetation and engineering structure
Rehabilitative method
Vegetative Methods
Cove cropping
Strip cropping
Contour tillage
Terracing
bare lands are planted with crops/crop rotation
Cover cropping
cultivated and uncultivated areas are plated alternately in rows
Strip cropping
soil is tilled across and not along the slopes
Contour tillage
slows down the flow of water; it prevents the formation of gullies, retains run-off water and protects human settler
Terracing
Advantages of cover cropping
Building soil health
Nutrient retention
Erosion control
Weed reduction
Mechanical methods
Riprapping
Farm ponds
usually done on a slope, covered with rocks fitted and cemented together
Riprapping
constructed on land depressions or holes to collect water and store it during the rainy season
Farm ponds
used in slightly eroded areas
involves forest fire prevention, proper land use, forest management, proper road construction and education of the people
Preventive Method
considered as the most important agents of erosion
transports, deposits weathered materials and brought by floods
Streams
prolonged rainfalls over several days, when intense rain falls over a short period of time, or when an ice or debris jam causes a river or stream to overflow onto the surrounding area
flood
Flood controls
dredging
dikes and levees
sandbagging during floods
loss of lives and properties
damage to infrastructure
loss of crops
communication and transportation cutoffs
Damaging effects of flood
appears to be more continuous and predictable process that causes damage to some areas
Shoreline erosion
Ways to lessen the effects of shoreline erosion
Building structures
Beach nourishment
Abandonment and relocation
short walls built at a right angle to the shore to trap moving sand
Groins
structures built parallel to the shoreline to protect it from the force of large breaking waves
Breakwater
barriers constructed to prevent waves from reaching the area behind the wall
Seawalls
involves the addition of sand to replenish eroding beaches
Beach Nourishment
in the PH, mangroves are planted along coastal areas to protect shorelines
Beach nourishment
removing storm-damaged structures along the shorelines and reclaiming the beach or relocating the people and structures along the shorelines to safer or elevated areas
Abandonment and Relocation
thick ice mass that forms over hundreds or thousands of years
move very slowly and is a dynamic erosional agent that accumulate, transport and deposit sediments
Glaciers
Types of glaciers
Valley or Alpine glaciers
Ice sheets
Ice caps
Piedemont glaciers
Mountain glaciers
Cirque glaciers
Hanging glaciers
Tidewater glaciers
glaciers that are found in lofty mountains that usually follow valleys originally occupied by streams
Valley or Alpine glaciers
mass of glacial ice of mroe than 50,000 km2
Ice sheets
contain about 99% of Earth’s fresh water
Ice sheets
aka Continental glaciers
Ice sheets
extend to the coast and over the ocean, they become ice shelves
Ice sheets
resemble ice sheets but are much smaller and occur in many places like Iceland and several islands in the Arctic Ocean
Ice caps
occupy broad lowlands at the base of steep mountains and form when one or move valley glaciers emerge from the confining walls of mountains
Piedmont glaciers
built by repeated snowfalls that accumulate year after year without completely melting
Mountain glaciers
to have mountain glaciers’ buildup of snow, which eventually becomes glacial ice, two ingredients are required
cold summers
heavy winter snow
named for the bowl-like hollows they occupy
Cirque glaciers
found on mountainsides and tend to be wide rather than long
Cirque glaciers
aka ice aprons, these glaciers cling to steep mountainsides
Hanging glaciers
wider than they are long; these glaciers are common in the Alps (where they often cause avalanches due to the steep inclines they occupy)
Hanging glaciers
these glaciers flow far enough to reach out into sea; they are responsible for calving numerous small icebergs
Tidewater glaciers
Two ways glaciers erode lands
Plucking
Abrasion
as glacier flows over a fractured bedrock and incorporates them into the ice
Plucking
function like sandpaper to polish and smoothen the surface below. It is simply the grinding and scraping of rock surface
Abrasion
the sediment deposited by a glacier
Glacial till
material left behind by a glacier by a moving glacier. This material is usually soil and rock
Moraine
movement of rock, soil, and regolith downward due to the action of gravity
Mass wasting
occurs on both terrestrial and submarine slopes
does not require a transporting medium like erosion
slope movement
Triggers
Water
Super steel slopes
Earthquakes
when pores in sediments become filled with __, the cohesion among particles is destroyed, allowing them to slide past one another with ease
Water
adds considerable weight to a mass of __ and the added weight in itself may be enough to cause the material to slide or move downslope
Water
trigger movements of unconsolidated granular materials
Super steep slopes
produces unstable slopes and mass movements in cohesive soils, regolith and bedrock
Super steep slopes
can dislodge enormous volumes of rocks and unconsolidated materials
Earthquakes (and its aftershocks)
Factors in mass wasting or slope movements
Type of material
Type of motion
Rate of movement
Type of material (factor of mass wasting)
A. Debris and mud
B. Rock
if soil and regolith dominate
type of material ( factor of mass wasting)
Debris and mud
when a mass of bedrock break, loose, and move downslope
Type of material (factor of mass wasting)
Rock
Type of motion (factor of mass wasting)
Fall
Slide
Flow
when movement involves the free-fall of detached individual pieces of any size
common from movement on very steep slopes
Type of motion (factor of mass wasting)
Fall
occur when material remains fairly coherent and moves along a well-defined surface
Type of motion (factor of mass wasting)
Slide
occurs when a material moves downslope as a viscous fluid and most are saturated with water and typically move as lobes or tongues
Type of motion (factor of mass wasting)
Flow
type of mass wasting that results in the sliding of coherent rock materials along a curved surface
Slump
sliding of rock material down a mountain
more of a translational slide because it moves in a more uniform direction along a pre-existing plane, such as an underlying layer of rock
Rockslide
Fast movement
rate of movement (factor of mass wasting)
Slump
Rockslide
Debris flow
Earth flow
movement of water-laden mass of loose mud, sand, soil, rock, and debris down a slope. It is mainly coarse-grained rock fragments
Debris flow
downslope movement of soil that has been saturated with water to the extent that the debris moves as a fluid. It is mostly fine grained sediment particles
Earth flow
imperceptibly slow, downslope movement of soil and earth material
often only few cm/yr, but the inevitability of it can severely impact shallowly-placed structures
Creep
slow downhill flow of soil in arctic regions
occurs slowly and is measured in mm/yr or cm/yr
Solifluction
Slow movement
Rate of movement (factor of mass wasting)
Creep
Solifluction
Two ways glaciers flow
Plastic flow
Basil slip
movement within the ice
Plastic flow
occurs along the ground of the entire ice mass, the lowest portion of most glaciers are thought to move by sliding
Basal slip
generally quiet and slow
Glacial movements
some glaciers are characterized by periods of extremely rapid movements called __
Surges
wettest place in the world
average annual rainfall of 117cm/yr
Tutunedo, Colombia
Tutuendo, Colombia has an average annual rainfall of
117cm/yr
has most rainy days per year
has up to 350 rainy days annually
Moun Wai-ale’ale on Kauai, Hawaii
Moun Wai-ale’ale on Kauai, Hawaii has up to __ rainy days annualy
350 days
longest rainless period in the world was in __,__ which is __ years of no rain
Chile, Africa; 14