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Geography Shared > Second Batch: 2.2-2.7 > Flashcards

Second Batch: 2.2-2.7 Flashcards

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1
Q

2.1: About the North Antrim Coast:

A
  • Predominantly rocky coastline
  • History of volcanism - slow cooling of molten basalt erupted 60 million years ago has preserved softer sedimentary rocks underneath
  • Subsequently covered by ice sheets during Quaternary
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2
Q

2.1: About Igneous:

A
  • Very slow rate of erosion
  • Igneous rocks are crystalline; interlocking crystals make for strong, hard erosion-resistant rock
  • Have few joints so there are limited weaknesses to be exploited by erosion
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3
Q

2.1: Types of Igneous rocks:

A

Granite
Basalt
Dolerite

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4
Q

2.1: About Metamorphic:

A
  • Slow rate of erosion
  • Crystalline
    Many metamorphic rocks experience foliation:
    – When crystals are oriented in 1 direction allowing for some weaknesses
  • These rocks are often folded and fractured
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5
Q

2.1: Types of Metamorphic rocks:

A

Slate
Schist
Marble

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6
Q

2.1: About Sedimentary:

A
  • Moderate to fast rate of erosion
  • Most sedimentary rocks are clastic and erode faster than crystalline rocks
  • Younger sedimentary rocks tend to be weaker
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7
Q

2.1: What does it mean to be clastic?:

A

As being composed of consolidated sediments formed by the accumulation for fragments derived from pre-existing rocks

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8
Q

2.1: Why are ancient sedimentary rocks more resistant to erosion?

A

They have been compressed and compacted over millions of years and so are significantly more resistant

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9
Q

2.1: How can permeability affect rock strength?

A
  • Permeability is important as groundwater can weaken rocks

- It can lead to high pore water pressures reducing stability

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10
Q

2.1: Define permeability?

A

A rock that allows water to pass through it

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11
Q

2.2: What is the structure of rock?

A
  • The arrangement of rock and its bedding planes

- Determines strength and surface area exposed to waves/ subaerial erosion

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12
Q

2.2: Define jointing:

A

Cracks/ fracture present in layers/ body of rock

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13
Q

2.2: Define dipping:

A

Which way a column of rock leans:

  • Seaward
  • Landward
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14
Q

2.2: Define faulting:

A

Fracture or zone of fractures between 2 blocks of rock

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15
Q

2.2: Define folding:

A

Stack of originally level surfaces that are bent or curved during permanent deformation

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16
Q

2.2: Stability of different cliff dips:

A

Seaward dip is typically more unstable than a landward dip

17
Q

2.2: Define colonnade and entablature:

A

Entablature is layer of rock that sits above the colonnade

  • Entablature is made of laterite and is more permeable
  • Colonnade consists of basalt columns with joints present horizontally and vertically
18
Q

2.2: What about entablature overhanging?

A
  • When water reaches overhanging entablature, it causes it to become saturated
  • So heavier
  • Some water can escape into colonnade leading to further breakdown
  • Most water stays in the entablature which leads to mass movement of it
  • It topples down
19
Q

2.2: How can extrusive igneous basalt rock be formed?

A

When volcanic lava flows over ground

20
Q

2.2: How can intrusive igneous basalt rock be formed?

A

Through volcanic lava funnelled through tunnels

21
Q

2.4: Describe the process of cave/arch/stack/stump:

A
  • Starts with headland
  • Causes waves to refract
  • Erosion concentrated in weak points on side of headland
  • Hydraulic action/ abrasion causes caves to form on sides
  • Caves meet forming tunnel
  • Tunnel becomes arch which increases in size
  • Top of arch collapses leaving stack
  • Waves erode and cut into base of stack
  • Stack becomes unstable collapses
  • Leaves a stump, submerged at high tide
22
Q

2.5: Describe areas dominated by marine erosional processes:

A
  • Often at headland sites
  • Wave cut notch and platform formation
  • Rate of erosion varies over time
  • Steep face
23
Q

2.5: Describe areas dominated by sub-aerial erosional processes:

A
  • Often at backshore of bays
  • Refractions means lower marine energy
  • Cliff degradation increases from above
  • Curved slope profile
24
Q

2.6: What are the 3 main types of sub-aerial processes?

A

Mass Movement

Rock Breakdown:

  • Mechanical
  • Biological
  • Chemical
25
Q

2.6: Example of biological weathering:

A

Molluscs

26
Q

2.6: Example of chemical weathering:

A
  • Chemical Reactions

- Seaweed Acid

27
Q

2.6: Example of mechanical weathering:

A
  • Frost shattering & Freeze Thaw

- Salt Crystallisation

28
Q

2.6: How do Frost Shattering & Freeze Thaw contribute to rock breakdown?

A
  • Temp has to change daily - expansion and contraction of rocks
  • During Freeze-Thaw, water seeps into cracks, freezes and expands by 9%
  • Rock is left angular, cliff face would be jagged and material would accumulate at bottom as scree slope
29
Q

2.6: How does Salt Crystallisation contribute to rock breakdown?

A
  • Waves break and splash water against cliff
  • Water evaporates, leaving sodium and magnesium behind
  • Once they’re in cracks and joints, the salt crystal grow
  • Exerting pressure and force the rock apart
30
Q

2.6: How does Oxidation contribute to rock breakdown?

A
  • Chemical reactions via iron minerals in rock
  • Leaves red-orange rusty colour
  • Rock crumbles away
31
Q

2.6: How does Carbonation contribute to rock breakdown?

A
  • Slow dissolution of limestone due to rainfall
32
Q

2.6: How does Hydrolysis contribute to rock breakdown?

A
  • Minerals breakdown to form new clay minerals, and new materials in solution
  • Due to water/ dissolved CO2
33
Q

2.6: How does Seaweed Acid contribute to rock breakdown?

A
  • Have sulphuric acid, so if cells break, it can lead to rock being dissolved
  • Rock minerals aren’t bonded together so rock crumbles
34
Q

2.6: How do Molluscs contribute to rock breakdown?

A
  • Live on rocks and scape away to get food
  • Leaves hole in the rock
  • Holes become weak points for weathering to act
35
Q

2.7: Define Hydraulic Action:

A

Force of water hitting cliffs and squeezing air into cracks in the rock

36
Q

2.7: Define Abrasion:

A

Force of bits of rock carried in the water blasting off the cliff

37
Q

2.7: Define Attrition:

A

Process of rocks hitting each other and breaking into smaller rocks

38
Q

2.7: Define Corrosion:

A

Chemical reaction between sea water and minerals in the rocks

Geography Shared (6 decks)

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