Rocks and Weathering

Question 1

What shape does the earth resemble due to its spin?

Answer 1

A geode

The earth is flatter at the poles and bulges at the equator.

Question 2

Which layer of the Earth is the thinnest?

Answer 2

Crust

The crust consists of two types: continental and oceanic.

Question 3

What is the thickest layer of the Earth?

Answer 3

Mantle

The mantle is composed of molten rock.

Question 4

What is the upper layer of the mantle called?

Answer 4

Lithosphere

The lithosphere is made up of solid crust and mantle and is broken into tectonic plates.

Question 5

What separates the colder, more rigid rocks from the hotter, more plastic rocks in the mantle?

Answer 5

Asthenosphere

The asthenosphere is a liquid layer of the mantle that tectonic plates float on.

Question 6

What are the main components of the outer core?

Answer 6

Liquid metals: iron and nickel

The outer core is in a liquid state.

Question 7

What is the state of the inner core and why?

Answer 7

Solid due to pressure

The inner core is the hottest layer of the Earth.

Question 8

What is the thickness range of oceanic crust?

Answer 8

6-10 km

Oceanic crust is thinner than continental crust.

Question 9

What is the age of oceanic crust?

Answer 9

Less than 200 million years

Oceanic crust is younger than continental crust.

Question 10

What is the average density of oceanic crust?

Answer 10

3.0 g/cm³

Oceanic crust is denser than continental crust.

Question 11

What is the composition of oceanic crust?

Answer 11

Basalt, silicon, magnesium, oxygen

Oceanic crust has a heavier composition.

Question 12

What is the thickness range of continental crust?

Answer 12

30-70 km

Continental crust is thicker than oceanic crust.

Question 13

What is the age of continental crust?

Answer 13

Over 1,500 million years

Continental crust is significantly older than oceanic crust.

Question 14

What is the average density of continental crust?

Answer 14

2.6 g/cm³

Continental crust is less dense than oceanic crust.

Question 15

What is the primary composition of continental crust?

Answer 15

Mainly granite, silicon, aluminium, and oxygen

Continental crust has a lighter composition compared to oceanic crust.

Question 16

True or False: Oceanic plates are denser than continental plates.

Answer 16

True

The density of oceanic plates increases due to the weight of the ocean compressing it.

Question 17

What are Constructive (divergent) plate margins?

Answer 17

Where two plates separate. This can occur in either oceanic areas or continental areas. O-O C-C

Question 18

What are Destructive (convergent) plate margins?

Answer 18

where two plates collide

Question 19

What are the 3 possible types of convergence?

Answer 19

• Oceanic meets continental
• Oceanic meets oceanic
• Continental meets continental (collision)

Question 20

What are Conservative (transform) plate margins?

Answer 20

where 2 plates slide past one another.

Question 21

What is a mid-ocean ridge?

Answer 21

Oceanic divergence leads to sea-floor spreading along either side of submarine mountain ridges thousands of kilometres long such as the Mid-Atlantic Ridge

Question 22

What is weathering?

Answer 22

The decomposition/decay and disintegration of rocks in situ

Question 23

What are the two main types of weathering?

Answer 23

physical/mechanical and chemical

Question 24

What does the efficiency of weathering processes depend on?

Answer 24

The interaction between climate, the properties of the rock and local factors such as relief.

Question 25

What is disintegration?

Answer 25

Disintegration occurs from physical (mechanical) weathering- breaking into smaller, angular fragments of the same type, resulting in scree.

Question 26

What is decomposition?

Answer 26

Decomposition affects of chemical weathering and changes the rocks substance, for example creating kaolinite (China clay) from granite

Question 27

What is weathering caused by?

Answer 27

changes in atmospheric conditions (such as temperature, moisture and wind) acting on a stationary object.

Question 28

What is regolith?

Answer 28

Loose material (soil + weathered rock) in a layer on top of solid bedrock.

Question 29

What do mass movements include?

Answer 29

any large-scale movement of the Earth’s surface that are not accompanied by an erosive agent such as a river, glacier or ocean wave.

Question 30

What is mass movement?

Answer 30

The downslope movement of rock and weathered debris by gravity alone.

Question 31

How can mass movements be classified?

Answer 31

- Speed of movement - Water content - Type of movement (heaves, flows, slides or falls) - Material involved e.g. - Very slow movements, such as soil creep - Fast movements, such as avalanches - Dry movement, such as rockfalls - Fluid movements, such as mudflows.

Question 32

What is sheer stress?

Answer 32

The force trying to move the mass down

Question 33

What is sheer stength?

Answer 33

The force trying to hold the mass on the slope.

Question 34

When does a slope 'fail'?

Answer 34

when it is too steep and unstable for existing materials and conditions or when shear strength < shear stress

Question 35

What are the most important factors that determine mass movement?

Answer 35

gravity, slope angle and water.

Question 36

Give examples of heaves

Answer 36

- Soil creep - Talus creep - Solifluction

Question 37

Give examples of flows

Answer 37

- Mudflow/ lahars - Earthflow

Question 38

Give examples of slides

Answer 38

- Landslide - Rockslide - Rotational slide

Question 39

Give an examples of a fall

Answer 39

Rock fall

Question 40

What is soil creep?

Answer 40

the movement of soil particles

Question 41

What is talus creep?

Answer 41

The slow movement of fragments on a scree slope

Question 42

What is solifluction?

Answer 42

Found in areas of permafrost, where summer thawing leads to waterlogged conditions and accelerated creep.

Question 43

When does surface run-off occur?

Answer 43

When the soil’s infiltration capacity is exceeded

Question 44

What is sheet wash erosion?

Answer 44

the un-channelled flow of water over a soil surface

Question 45

What are rills?

Answer 45

Relatively shallow channels (usually less than tens of cm deep) that are formed by water eroding channels on slopes and are common in agricultural areas following the removal of vegetation during harvest season.

Question 46

What is rainsplash erosion?

Answer 46

Soils are knocked into the air by the raindrop impact

Question 47

How do gulleys form?

Answer 47

if water becomes concentrated in rills for longer periods they may widen and deepen to form channels known as gullies.