Erosion + Weathering + Mass Wasting

Question 1

Mechanical Weathering

Answer 1

Physical disintegration and
reduction in size of the rocks, but it doesn’t change the rocks chem. composition.

Question 2

Exfoliation w/ Mech. Weathering

Answer 2

When rock layers peel off in sheets due to temp changes. Kinda like the outer layer or skin of a brown onion

Question 3

Exfoliation Process w/ Mech. Weather

Answer 3

1. Daytime heat makes outer rock expand
2. Cool nights contract it
3. This repeats over time and the rocks outer layer eventually peels

Common in deserts/mountains, where temp. swings are common/large

Question 4

Process of Frost Wedging (sometimes Freeze-thaw weathering) w/ Mech. Weather

Answer 4

1. Water enters cracks in rocks
2. At night it freezes and expands (which expands the size of the crack)
3. It melts during the day, and more water can now enter that crack
4. Over time, this will eventually break the rock from the inside.

Question 5

Process of Salt Wedging w/ Mech. Weather

Answer 5

1. Salty water enters rocks cracks
2. When the water evaporates, it leaves salts behind
3. The salt crystals grow/expand (puts excessive pressure on the rock)
4. Over time, this will eventually break the rock from the inside.

Question 6

Process of Thermal Stress Weathering w/ Mech. Weather

Answer 6

1. The rocks expand when they get hot during the day
2. It contract as it cools during the night
3. The stress from this constant expansion + contraction weakens the rock.
4. Over time, pieces break off

Common in deserts/mountains, where temp. swings are common/large

Question 7

Process of Abrasion w/ Mech. Weather

Answer 7

1. Rocks grind against each other (from wind, gravity, or water movement).
2. From friction, fragments scrape off or edges become smoother.
3. Over time, rocks are worn down, broken, or rounded without any chemical change.

diff bw this and abrasion in erosion is this happens in the same spot, abrasion in erosion happens through other means

Question 8

Chemical Weathering

Answer 8

Chemical weathering decomposes, dissolves, alters, or weakens the rock through chemical processes, which changes their composition over time, forming residual materials

Question 9

Carbonation w/ Chem. Weather

Answer 9

When CO2 reacts w/ rainwater or moisture in the surrounding environment to produce carbonic acid, a weak acid that reacts w/ carbonic bedrock to form karst landscapes.

Question 10

Where does Carbonation (w/ Chem Weather) usually occur and why

Answer 10

Its more common in humid, warm climates because higher temperatures and moisture accelerate the chemical reactions, but it can also occur in wet, moist conditions where there is plenty of water to dissolve carbon dioxide.

Question 11

Hydrolysis w/ Chem. Weather

Answer 11

The breakdown of rocks and minerals due to interactions with water. The new compound tends to be softer/weaker than the original parent rock material.

Question 12

Hydrolysis Process w/ Chem. Weather

Answer 12

1. Water reacts with minerals in the rock
2. Chemical reactions occur, where water breaks down original minerals into new minerals
3. The rocks composition then changes, which weakens and breaks it down over time

Question 13

Whats some extra stuff to know ab Hydrolysis

Answer 13

1. It can also cause certain minerals to expand; facilitates mech. weathering
2. Usually affects igneous rocks (bc they’re composed of silicate materials) which readily combine with water

Question 14

Hydration Process w/ Chem. Weather

Answer 14

1. Water molecules combine with minerals in rocks.
2. The rock then expands or changes into a softer mineral.
3. Over time, the rock weakens and/or breaks apart.

Question 15

Whats the difference between hydration and hydrolysis.

Answer 15

In Hydration: - Water is added
- Minerals change from (swells/weaken)
In Hydrolysis: - Water reacts chemically
- New minerals are created

Question 16

Oxidation w/ Chem. Weather

Answer 16

Oxygen and water react with iron-rich minerals, weakening it. It accelerates rock decay.

Oxidation weakens the rock, then other weathering processes breaks down the rock fully.

Question 17

Hydraulic Action w/ Erosion

Answer 17

Water repeatedly hits like a rock or sum shit similar and over time, the waves wear down the rock into sediments.

Like a hose spraying at dirt on a wall, but over a long period of time

Question 18

Abrasion w/ Erosion

Answer 18

Movement agents (wind, water, ice) carries particles, which scrape against rocks surfaces, which ends up wearing and eroding the rock over time.
Sometimes, rocks are carried by waves/ the ocean, and they hit cliffs, eroding them over time.

Question 19

Corrosion w/ Erosion

Answer 19

Refers to chem. erosion, where water dissolves minerals from the rock, particularly in areas with soluble rocks, and ends up transporting them away

Question 20

Attrition w/ Erosion

Answer 20

A process where rocks and sediments become smaller, rounder, and smoother as they rub/collide/break down during transportation by water or wind.

Question 21

Biological Weathering

Answer 21

The disintegration/decay of
rocks and minerals caused by chemical or physical agents of organisms.

Question 22

Explain organic activity from Lichen and Algae w/ Biological weathering

Answer 22

Organisms (like lichen and algae) live on bare rock, extracting minerals from it through ion-exchange mechanisms. Because the rocks minerals has been leached off, it then weakens/breaks it down.

Question 23

Explain organic activity from Decaying plants w/ Biological weathering

Answer 23

The decaying of plant materials can also produce acidic compounds which dissolve the exposed rock

The presence of organisms growing/ expanding/moving across the surface of the rock exerts a small amount of abrasion and pressure, that gradually causes the mechanical weathering of the rock as the organisms extract various minerals.

Question 24

Biological Weather. w/ plant roots

Answer 24

When plant roots penetrate into cracks/crevices of rocks and causes it to split/break into smaller particles through mech. weathering.

Its the most common form of bio weather, its a very gradual process, and fairly effective at breaking rocks w/ pre-existing weakness (fracture, fault, joint)

Question 25

Biological Weather. w/ Organism Activity (Burrowing and Tunnelling)

Answer 25

Some organisms (small animals, worms, termites, and other insects) tunnel into rocks or cracks in rocks, causing it to breakdown and disintegrate.

Question 26

Biological Weather. w/ Organism Activity (Acid secretion)

Answer 26

Some organisms (snails, barnacles, limpets) attach themselves to rocks and secrete acids that chemically dissolves the rocks surface.

Question 27

Differential Weathering

Answer 27

Refers to the different rates of weathering due to different types of rocks, textures, or other characteristics. Contributes to unique formation of many landforms, like pedestals, waterfalls, and monadnocks

Question 28

What 3 factors cause differential in weathering

Answer 28

1. The type of weathering process (mechanical, chemical, biological) 2. The rock that is being weathered and its properties (some rocks are more durable/resistant to weathering than others) 3. Climate (if talking about same kind of rock) --> e.g Limestone weathers quicker in wet climates than in dry climates.

Question 29

Water (Fluvial) Erosion

Answer 29

Water erodes rocks + shapes the landscapes by removing and transporting weathered materials from their source, to another location where they are deposited, and either stored or transported to another location.

Question 30

Rain Splash Erosion w/ Fluvial Erosion

Answer 30

Occurs when the impact of a rain drop loosens and mobilises particles.

Question 31

Sheet Erosion w/ Fluvial Erosion

Answer 31

A process where particles loosened by rain-splash erosion are transported by runoff water down the slope of a surface.

Question 32

Rill/Gully Erosion w/ Fluvial Erosion

Answer 32

When water concentrates during sheet erosion and erodes small rills or gullies into the surface that channel the flow downslope.

Question 33

What landscapes are formed by Fluvial Erosion

Answer 33

V shaped River valley Fluvial forms pathways for surface and groundwater flow and carves v-shaped river valleys that continue to erode, transport, and deposit weathered sediments across the landscape.

Question 34

Wind (Aeolian) Erosion

Answer 34

Wind erodes materials by picking them up and temporarily transporting them from their source to another location where they are deposited, and either stored or re-mobilized and transported to another location.

Question 35

Deflation Erosion w/ Aeolian Erosion

Answer 35

Movement or transport of particles through the air or along the ground

Question 36

Abrasion Erosion w/ Aeolian Erosion

Answer 36

When wind-driven particles wear down and shape the landscape by scraping and grinding against rock surfaces. Has to be wind driven, otherwise it isn't aeolian erosion

Question 37

Ice (Glacial + Periglacial) Erosion

Answer 37

When particles are incorporated into glacial ice through plucking, then are transported downslope within the glacier. The friction + abrasion of the ice and rock moving across the bedrock erodes the surface of the bedrock and often leaves scrapes, grooves, striae, or polished rock surfaces.

Question 38

Gravitational Erosion

Answer 38

Gravity facilitates the down slope transportation of loosened, weathered materials and enables them to move without movement agents, However, these agents can act as catalysts for gravity related erosion.

Question 39

Rock Falls w/ Mass Wasting

Answer 39

Rocks dislodge b/c their ∆ potential energy is too much to maintain, so pot. energy --> kinetic energy, which causes the rock fragment to fall, restoring equilibrium. forms talus or scree.

Question 40

What aids/causes Rock Falls

Answer 40

The rocks may be loosened by a recent rainfall or snow melt-water event that facilitates the movement of the rock (before they fall from the force of gravity)

Question 41

Landslides w/ Mass Wasting

Answer 41

Mass-wasting events where large amounts of weathered rock material slide down a hill slope or mountain side primarily by gravity related erosion.

Question 42

What aids/causes Landslides

Answer 42

Nearly all landslides are triggered by an earthquake, or lubricant agent such as rainfall, or a snow or ice melt-water event. During intensive rainfall, soil and weathered rock material become unstable and loosened from the saturated conditions that separate the individual grains and other material fragments. The increased fluid pressures coupled with the loosened materials succumbs to gravity related erosion and the weathered materials plunge downhill as a powerful landslide.

Question 43

Debris and Mud Flows w/ Mass Wasting

Answer 43

When heavy rainfalls produce large amounts of runoff that transport eroded soils, sediments, and plant debris down slope where the flows eventually spreads out across valley bottoms. Sometimes the debris and mudflows follow existing drainage paths and other times they carve out new paths as they flow downhill

Question 44

Slump w/ Mass Wasting

Answer 44

A fairly common form of mass wasting where the rock or soil collapses, breaks off from the hill, rotates slightly, and slumps/falls downhill.

Question 45

Creep w/ Mass Wasting

Answer 45

Creep is the slowest mass-wasting process and involves a very gradual downhill movement of soil, bedrock, and weathered rock fragments. Usually, the entire slope is slowly creeping downhill as a complete unit. Creep processes occur to some degree on nearly every hill slope because of gravity

Question 46

With Creep, what accelerates it and what is it evidenced by

Answer 46

Creep is evident by bent or extended tree trunks that are adjusting to the slow movement of the soil, regolith, and weathered material they are rooted into. Freeze-thaw cycles and saturated conditions may accelerate creep processes but usually only for a short time-period.

Question 47

Deposition

Answer 47

Deposition is a constructive process that lays down or places weathered and eroded materials in a location that is different from their source. Its applied to any consolidated or unconsolidated materials that have accumulated as a result of some natural process or agent. Deposits can result from all kinds of weathering, and water, wind, ice, or gravity-related erosional processes