Landforms and Bodies of Water, Exogenic Processes Flashcards
A natural stream of water flowing in a channel to the sea, a lake, or another stream
River
An area of land that rises very
high above the land around it
and that is higher than a hill
Mountain
An area covered with sand or
small rocks that is next to an
ocean, sea, or lake
Beach
A large body of saline water
that separates continents
Ocean
An opening on the earth’s crust where pyroclastic
materials, lava, and gases come out
Volcano
Why do we have different landforms and bodies of water?
There are forces and processes that shape and change the structure of the earth and lead to the formation of these wonders.
- exogenic and endogenic processes
events that occur on the surface of the earth
- affected by external factors like solar energy (wind, water, etc.) and subsystems
- weathering, erosion, deposition, and sedimentation
Exogenic Processes
Events that are caused by the movement of materials in the Earth’s inner layer
- driven by Earth’s internal heat (geothermal energy)
- plate movement, magmatism, earthquakes, metamorphism, diastrophism
Endogenic Processes
the breaking down & changing of rocks as a result of exposure to the environment
weathering
Types of Weathering
- Physical/Mechanical - processes that break a rock or mineral into smaller pieces without altering its composition
- Chemical - accompanied by changing their chemical composition
Examples of Physical Weathering
- Exfoliation
- Frost Wedging
- Abrasion
- Plant/Root Wedging
- Animal and Human Activities
Cracking and peeling of the upper/outer rock
layers because it is weakened by:
- thermal expansion and contraction - repeated heating and cooling of materials cause rigid substances to crack and separate
- removal of overlying rocks - rocks underneath get exposed; there is less pressure on them, and they
expand. This causes the rigid layers to crack and sections to slide off
Exfoliation
cracking of rock mass by the expansion of water as it freezes in crevices and cracks
frost wedging/action
frost wedging in soil
permafrost
why does water expand when it freezes
When frozen, water molecules take a more defined shape and arrange themselves in six-sided crystalline structures. The crystalline arrangement is less dense than that of the molecules in liquid form which makes the ice less dense than the liquid water. When water freezes, the volume expands by approximately 9%.
Moving sediments or rock sections can break off
pieces from a rock surface they strike.
- The sediments can be moved by wind (in the desert), water, or ice, and the large rock sections by gravity.
- can be both weathering and erosion
Abrasion
As plants such as trees send out root systems,
the fine roots find their way into cracks in the
rocks. As the roots increase in size, they force the rock sections apart, increasing the separation and weathering.
plant/root wedging
how do human and animal activities cause physical weathering
- Some animals burrow themselves
on the ground. - Mining, construction, and
agriculture
Examples of Chemical Weathering
- Oxidation
- Carbonation
- Hydrolysis
Water mixes with carbon dioxide and forms carbonic acid. This dissolve minerals like limestone and calcite.
Carbonation/Leeching/Solution (uniform and dissolved)
Water mixes with carbon dioxide and forms carbonic acid. This dissolved minerals like limestone and calcite.
- results to the formation of majestic limestone
features in caves (stalagmites and
stalactites) and beaches, as well as, the development of dangerous sinkholes.
Carbonation/Leeching/Solution (uniform and dissolved)
a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings.
stalagmite
an icicle-shaped formation that hangs from the ceiling of a cave and is produced by the precipitation of minerals from water dripping through the cave ceiling
stalactite
Minerals may combine with oxygen to form
new minerals that are not as hard.
- When iron is exposed to oxygen forming iron oxide
- pyrite to limonite
Oxidation
When minerals chemically react with water to form new minerals. The newly formed minerals are not as hard as the original material
-Water splits the ion of the mineral usually resulting in clay, acidic solution, and
free ions or salts.
- feldspar to kaolinite (source of clay)
- silicate rich minerals
Hydrolysis
Factors affecting Weathering
- climate
a. hot and dry - less weathering (some wind abrasion)
b. hot and moist - more weathering (strong)
c. colder - frost action (more if more water) - mineral hardness - harder, less quick
- surface area - how much of an area is going to be exposed
e.g.sugar granules vs. sugar cubes
These water compositions enable what kind of weathering
- alkaline (>7)
- acidic (<7)
- w/ dissolved salts
- hydrolysis
- carbonation (carbonic acid)
- oxidation
the transportation of sediments that have been broken down by weathering
- Removal of rocks, sediments, and soil from their original location
- Usually occur after or together with weathering
erosion
Agents of Erosion (different processes that move sediments)
- gravity (mass wasting/movement)
- water
- wind
- ice/glaciers
What is it called when gravity moves sediments downhill
mass wasting/mass movement
erosion by gravity can be classified according to
speed, materials involved, and type of movement
mass movement
gradual downhill movement of soil
- slowest and most tame
- can take for weeks, months, years, decades, etc.)
soil creep
mass movement
gradual downhill movement of soil
- slowest and most tame
- can take for weeks, months, years, decades, etc.)
soil creep
mass movement
the rapid downslope flow of debris (anything)
debris flow/landslide
mass movement
the downward flow of fine particles (mud) & a large amount of water
- often associated with storms and rains
- fairly quick
- can engulf entire villages and communities
mud flow/slide
mass movement
- rapid falling of pieces of rocks from cliffs/steep slope
- violent
- solution - wrecking loose rocks off for control using wrecking ball
rock fall/slide
rock = ?
small rocks + big rocks = ?
small rocks + big rocks + plants = ?
rock
regolith
debris
difference of slide, fall, creep, flow
slide - move along a smooth surface while maintaining continuous contact with it (on a slope, leaves scar)
fall - move downward, typically rapidly and freely without control, from a higher to a lower level.
creep - slow
flow - with water
erosion by water
(Can happen during surface run-off or along the surface of riverbeds and/or sea floors)
surface run-off
- sheet erosion
- venous/stream flow erosion
- stream bank erosion
river transport systems/stream load
- traction (rolling of big rocks = smooth)
- saltation (bounce, smaller sediments)
- suspension (float, fine/light sediments)
- solution (dissolved, soluble materials)
erosion by water through surface run-off
occurs as a shallow ‘sheet’ of water flowing over the ground surface, resulting in the removal of a uniform layer of soil from the soil surface. (even removal of upper layers)
sheet erosion
erosion by water through surface run-off
- creates a channel
- small - rill
- big - ephemeral
- too big - gully
- areas where rocks and soils have less resistance to water
venous/stream flow erosion
erosion by water through surface run-off
a natural process that occurs when the forces exerted by flowing water exceed the resisting forces of bank materials and vegetation.
streambank erosion
erosion by wind
- creep (roll, big rocks)
- saltation (bounce, smaller sediments)
- suspension (float, fine/light sediments)
erosion by ice/glacier (nature’s bulldozer)
(thick deposition if new)
- freeze-thaw (frost wedging)
- plucking (removal)
- abrasion (scraping by moving rocks)
- transportation (downward movement)
- deposition (collection of rocks at the bottom of the hill/mountain)
the sediment deposited by a glacier. It blankets glacier forefields, can be mounded to form moraines and other glacier landforms, and is ubiquitous in glacial environments.
glacial till
the dropping off of sediments that have been weathered and eroded
deposition
