Sedimentary system Flashcards

(36 cards)

1
Q

Why is sedimentology important?

A
  • earth history
  • origins of life
  • mineral and fuel resources
  • Geohazards
  • sedimentary processes
  • Impacts of climate change
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2
Q

What is a rock?

A

Any mass of mineral matter weather consolidated or not which forms part of the earths crust

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3
Q

What is a mineral?

A

A structurally homogeneous solid of definite chemical composition, formed by the inorganic processes of nature

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4
Q

What is a crystal?

A

A 3D body with symmetrical bounding surfaces, constant angular relationships, arising from the inherit regular atomic structure of the substance.

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5
Q

Examples of physical weathering? (4)

A
  • Freeze thaw
  • Differential expansion of minerals as they heat in the sun
  • action of plant roots and micro-organisms
  • Abrasion (wind, wave etc)
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6
Q

Examples of natural zones of weakness: (2)

A
  • Jointing

- Bedding planes

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7
Q

What controls a rocks resistance to weathering in relation to it’s chemistry? (2)

A
  • atomic structure

- chemical stability

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8
Q

What is an ION?

A

When atoms or molecules gain or loose an electron

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9
Q

What is the formula for the ions halite go to when disolved in water?

A

NaCl= Na+ +Cl-

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10
Q

What is an ANION?

A

Atom/molecule gains an electron and so becomes negatively charged i.e Cl-

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11
Q

What is a CATION?

A

Atom/molecule looses an electron and so becomes positively charged i.e Na+

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12
Q

CaCO3+H2O+CO2 ->

A

Ca2+ +2HCO3-

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13
Q

Calcium carbonate +water + Carbon dioxide

A

Calcium Cation + bicarbonate anion

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14
Q

State the order in witch the minerals in granite weather

A

1) biotite mica
2) Plagioclase f’spa (white)
3) Orthoclase f’spa (pink)
4) Quartz

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15
Q

What minerals are present in Arkose?

A

Othoclase feldspar and Quartz

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16
Q

What is there no Plagioclase feldspar in Arkose?

A
  • It reacts with acid in rain water
  • some atoms are dissolved and turned to clay
  • fine clay particles are washed away large quartz and orthoclase are left behind
17
Q

What is the relationship between the level a climate supports life and chemical weathering?

A

the more a climate supports live the higher the weathering

18
Q

What climate would you expect a)fast b) slow chemical weathering?

A

a) warm and humid b) cold and dry

19
Q

what is mass wasting?

A

Mass wasting is the down slope movement of a mass of sediment and/or rock due mainly to the force of gravity

20
Q

Mass movement of consolidated rock:

A
  • Rock fall
  • Rock slide
  • Rock avalanche
21
Q

Mass movement of unconsolidated material:

A
  • Creep
  • Slump
  • Debris slide
  • Debris avalanche
  • Earthflow
  • mudflow
  • solifluction
  • Debris flow
22
Q

What is a rock slide?

A

Mass of rock slides down as one unit

23
Q

What is Rock avalanche? Where do these happen?

A

Rocks flow downhill, Himalayas

24
Q

What is creep?

A

Slow movement of soil or other debris (1-10mm/year)

-Cause issues interperating dip of rocks

25
What is slump?
Slow slide of unconsolidated material mooving as an unit
26
what is a mudflow?
Mud flows move very fast and contain large amounts of water
27
what is debris flow?
Contain material coarser than sand and move at afew tens of km/hour
28
What makes a slope a) stable b) unsatble?
a) Driving force < /=Resting force | b) driving force > resting force
29
What are the driving forces of a slope?
Shear stress: Steepness of slope, mass of material
30
What are the resisting fores of a slope?
Slope material, water content
31
What 3 factors determine weather a slope will undergo mass movement?
1) slope materials- loose unconsolidated material is more susceptible than solid bedrock 2) water content- a small amount of water can bind sediments together, to much water will allow sediments to flow 3) steepness of slope- 'angle of repose' the maximum angle at which a slope is stable
32
What can trigger mass movements? (4)
1) earthquakes- liquefaction: shaking saturated sediments transforming them into a fluid state 2) heavy rain: saturates slope material 3) Damn construction- saturate slopes 4) Steep road cuttings- cut steeper than angle of repose
33
Vaiont damn reservoir 1) Where was it? 2) When was it built? 3) what indicaters were there before the mass movement? 4) when did the mass movement occur? 5) how many people were killed? 6) what kind of mass movement was it and what did it trigger?
1) Alpine valley italy 2) 1959 3) Cracked and deformed limestone and shale valley walls, aincient slide scar above resevoir, small rockslide in 1960 4) 1963 5) 3,000 6) landslide water spilled over damn (200m wave)
34
describe a laminar flow? | What size particles can it carry?
streemiles do not cross; no mixing between layers, slow flow, high viscosity, thin sheet of fluid. Carrys only clay size particles
35
describe a turbulent flow?
Streams cross with extensive mixing of fluid, fast flow, low viscosity thick body of water. Can carry clay size up to cobble size
36
What are the two ways current flowing over sand and silt can carry water?
in a 'suspended load' or in the 'bed load' sliding and rolling along the bottom