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physical geology Flashcards

1
Q

Soil

A 
Mixture of:
minerals (ca. 45%) (dominated by clay minerals and quartz, along with minor amounts of feldspar and small fragments of rock.
organic matter (ca. 5%)
empty space (ca. 50%, filled with varying degrees of air and water)
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2
Q

Factors that affect the nature of soil and the rate of its formation

A

Climate (especially average temperature and precipitation amounts, and the consequent types of vegetation)
The type of parent material
The slope of the surface
amount of time available

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3
Q

Residual soil

A

Soil developed on bedrock

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4
Q

Transported soil

A

Soil developed on transported material such as glacial sediments. Misleading term.

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5
Q

Typical soil horizons

A

O - the layer of organic matter
A - the layer of partially decayed organic matter mixed with mineral material
E - the eluviated (leached) layer from which some of the clay and iron have been removed to create a pale layer that may be sandier the the other layers
B - the layer of accumulation of clay, iron, and other elements from the overlying soil.
C - the layer of incomplete weathering
Caliche - Another type of layer that develops in hot arid regions. It forms from the downward (or in some cases upward) movement of calcium ions, and the precipitation of calcite within the soil. When well developed, caliche cements the surrounding material together to form a a layer that has the consistency of concrete.

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6
Q

Caliche

A

A mineral deposit of gravel, sand, and nitrates, found in dry areas of America.
Other term for calcrete.

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7
Q

Types of Soils (Canada System of Soil Classification)

A

Forest soils
Grass-land soils
Other important soils

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8
Q

Forest soils (Canada System of Soil Classification)

A

Podsol
Luvisol
Brunisol

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9
Q

Grassland soils (Canada System of Soil Classification)

A

Chernozem

Solonetzic

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10
Q

Other important soils (Canada System of Soil Classification)

A

Organic

Cryosol

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11
Q

Podsol

A

Well-Developed A and B horizons.

Coniferous forests throughout Canada

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12
Q

Luvisol

A

Clay rich B horizon

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13
Q

Brunisol

A

Poorly developed or immature soil, that does not have the well-defined horizons of podsol or luvisol.

Boreal-forest soils in the discontinuous permafrost areas of central and western Canada, and also in southern B.C.

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14
Q

Cherozem

A

High levels of organic matter and a A horizon at least 10 cm thick.

Souther prairies (and parts of British Columbia’s southern interior), in areas that experience water deficits during the summer.

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15
Q

Solonetzic

A

Clay-rich B horizon, commonly with a salt-bearing C horizon.

Southern prairies, in areas that experience water deficits during the summer.

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16
Q

Organic (Soil)

A

Dominated by organic matter, mineral horizons are typically absent.

Wetland areas, especially along the western edge of Hudson Bay, and in the area between the prairies and the boreal forest.

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17
Q

Cryosol

A

Poorly developed soil, mostly C horizon

Permafrost areas of northern Canada.

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18
Q

The steps of the Geological Carbon Cycle

A

A: Organic matter from plants is stored in peat, coal, and permafrost for thousands to millions of years.

B: „Organic matter from plants is stored in peat, coal, and permafrost for thousands to millions of years.“

C: Dissolved carbon is converted by marine organisms to calcite, which is stored in carbonate rocks for tens to hundreds of millions of years.

D: Carbon compounds are stored in sediments for tens to hundreds of millions of years; some end up in petroleum deposits.

E: Carbon-bearing sediments are transferred to the mantle, where the carbon may be stored for tens of millions to billions of years.

F: During volcanic eruptions, carbon dioxide is released back to the atmosphere, where it is stored for years to decades.

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19
Q

Mechanical Weathering

A

Rocks weather when they are exposed to surface conditions, which in most case are quite different from those at which they formed. The main processes of mechanical weathering, including exfoliation, freeze-thaw, salt crystallization and the effects of plant growth.

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20
Q

Chemical Weathering

A

Chemical Weathering takes place when minerals within rocks are not stable in their existing environment. Some of the important chemical weathering processes are: hydrolysis of silicate minerals to form clay minerals, oxidation of iron in silicate and other minerals to form iron oxide minerals, and dissolution of calcite.

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21
Q

Two main types of sedimentary rocks

A

Clastic:
Mainly composed of material that has been transported as solid fragments (clasts).

Chemical:
Mainly composed of material that has been transported as ions in solution.

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22
Q

clast

A

a fragment of rock or mineral, ranging in size from less than a micron to as big as an apartment block.

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23
Q

Large Boulder (Udden-Wentworth grain-size scale)

A

1024mm - no limit.

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24
Q

Medium Boulder (Udden-Wentworth grain-size scale)

A

512-1024mm

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25
Q

Small Boulder (Udden-Wentworth grain-size scale)

A

128-256mm

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26
Q

Large Cobbe (Udden-Wentworth grain-size scale)

A

128-256mm

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27
Q

Small Cobble (Udden-Wentworth grain-size scale)

A

64-128mm

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28
Q

V. Coarse Pebble (Udden-Wentworth grain-size scale)

A

32-64mm

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29
Q

Coarse Pebble (Udden-Wentworth grain-size scale)

A

16-32mm

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30
Q

Medium Pebble (Udden-Wentworth grain-size scale)

A

8-16mm

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31
Q

Fine Pebble (Granule) (Udden-Wentworth grain-size scale)

A

4-8mm

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32
Q

V. Fine Pebble (Granule) (Udden-Wentworth grain-size scale)

A

2-4mm

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33
Q

V. Coarse Sand (Udden-Wentworth grain-size scale)

A

1-2mm

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34
Q

Coarse Sand (Udden-Wentworth grain-size scale)

A

500-1000 microns

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35
Q

Medium Sand (Udden-Wentworth grain-size scale)

A

250-500 microns

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36
Q

Fine Sand (Udden-Wentworth grain-size scale)

A

125-250 microns

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37
Q

V. Fine Sand (Udden-Wentworth grain-size scale)

A

63-125 microns

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38
Q

V. Coarse Silt (Udden-Wentworth grain-size scale)

A

32-63 microns

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39
Q

Coarse Silt (Udden-Wentworth grain-size scale)

A

16-32 microns

40
Q

Medium Silt (Udden-Wentworth grain-size scale)

A

8-16 microns

41
Q

Fine Silt (Udden-Wentworth grain-size scale)

A

4-8 microns

42
Q

V. Fine (Udden-Wentworth grain-size scale)

A

2-4 microns

43
Q

Claly

A

0-2 microns

44
Q

Discharge (of a stream)

A

The volume of flow passing a point per unit time. It’s normally measured in cubic metres per second (m3/s).

45
Q

Bedload

A

The sediment transported by a river in the form of particles too heavy to be in suspension.

46
Q

Soil Compaction

A

soil compaction is the process in which a stress applied to a soil causes densification as air is displaced from the pores between the soil grains.

47
Q

Lithification

A

Term used to describe a number of different processes that take place within a deposit of sediment to turn it into solid rock.

  • Burial by other sediments, which leads to compaction of the material and removal of some of the intervening water and air. After this stage, the individual clasts are all touching one another.
  • Cementation
48
Q

Cementation

A

The process of crystallization of minerals within the pores between small clasts, and also at the points of contact between the larger clasts (>= sand size). Depending on the pressure, temperature, and chemical conditions, these crystals might include calcite, hematite, quartz, clay minerals, or a range of other minerals.

49
Q

Types of clastic sedimentary rocks

A 
Mudrock
Coal
Sandstone
Conglomerate
Breccia
50
Q

Mudrock (Examples and Characteristics)

A

Mudstone / > 75% silt and clay, not bedded
Shale / >75% silt and clay, thinly bedded

If it is dominated by clay, it is called claystone.

Mudrocks form in very low energy environments, such as lakes, river backwaters and the deep ocean.

51
Q

Coal (Characteristics)

A

Dominated by fragments of partially decayed plant matter, often enclosed between beds of sandstone or mudrock.
Moast coal form in fluvial or delta environments where vegetation growth is vigorous and where decaying plant matter accumulates in long-lasting swamps with low oxygen levels.

52
Q

Sandstone (Examples and Characteristics)

A

Quartz Sandstone / Quartz

Arenite (cleans sandstone) / < 15% silt or clay.

Quartz Arenite / > 90% quartz.

Wacke / > 15% silt and clay

Arkose / Dominated by sand, > 10% feldspar

Lithic Wacke (greywacke) / Dominated by sand, > 10% rock fragments, > 15% silt and clay

53
Q

Conglomerate (Characteristics)

A

Dominated by round clasts, pebble size and larger.

Form in high-energy environments where the particles can become rounded, such as fast-flowing rivers.

54
Q

Breccia (Characteristics)

A

Dominated by angular clasts, pebble size and larger.

55
Q

Common chemical sedimentary rocks

A

Limestone (most common)
Chert
Bandediron formation
Variety of rocks that form when bodies of water evaporate

56
Q

Limestone

A

Forms almost always in oceans.
Mostly forms on the shallow continental shelves (below 4000m calcite is soluble so limestone does not accumulate), especially in tropical regions with coral reefs.
Reefs are populated by a wide range of organisms that use calcium and bicarbonate ions in sea water to make carbonate minerals (especially calcite) for their shells and other structures. E.g Corals, green and red algae, urchins, sponges, molluscs, crustaceans.

57
Q

Dolostone

A

Rock composed of the mineral dolomite

58
Q

Dolomitization

A

Magnesium replacing some of the calcium in the calcite in carbonate muds and sands.
Thought to take place where magnesium-rich water percolates through the sediments in carbonate tidal flat environments.

59
Q

Chert

A

Some organisms like radiolaria or diatoms use silicate to make their hard parts. When they die their tiny shells (or tests) settle slowly to the bottom where they accumulate as chert.

60
Q

Banded Iron Formation (BIF)

A

A deep sea-floor deposit of iron oxide that is a common ore of iron.
BIF forms when iron dissolved in sea water is oxidized, becomes insoluble, and sinks to the bottom in the same way that silica tests do to form chert.
The prevalence of BIF in rocks dating from 2400-1800 Ma is due to the changes in the atmosphere and oceans that took place over that time period.
Photosynthetic bacteria (ie cyanobacteria aka blue green algae) first evolved around 3500 Ma. They consume carbon dioxide from the atmosphere and use solar energy to convert it to oxygen.
For the next billion years, almost all of that free free oxygen was used up by chemical and biological processes, but by 2400 Ma free oxygen levels started to increase in the atmosphere and the oceans. Over a period of 600 million years, that oxygen gradually converted soluble ferrous iron (Fe2+) to insoluble ferric iron (Fe3+), which combined with oxygen to form the mineral hematite (Fe203), leading to the accumulation of BIFs. After 1800 Ma, little dissolved iron was left in the oceans and the formation of BIF essentially stopped.

61
Q

Evaporites

A

In arid regions, lakes and inland seas have no stream outlet, water is removed by evaporation. Thus water becomes increasingly concentrated with dissolved salts. Eventually, some of these salts reach saturation levels and start to crystallize.

62
Q

Important evaporite minerals

A

Gypsum (precipitates at about 20% of the original volume)
Halite (precipitates at 10%)
Sylvite
Borax

63
Q

Principle of original horizontality

A

States that sediments accumulate in essentially horizontal layers. The implication is that tilted sedimentary layers observed to day must have been subjected to tectonic forces.

64
Q

Principle of superposition

A

States that sedimentary layers are deposited in sequence, and that, unless the entire sequence has been turned over by tectonic processes, the layers at the bottom are older than those at the top.

65
Q

Principle of inclusion

A

States that any rock fragments in a sedimentary layer must be older than the layer. For example, the cobbles in a conglomerate must have been formed before the conglomerate.

66
Q

Principle of faunal succession

A

States that there is a well-defined order in which organisms have evolved through geological time, and therefore the identification of specific fossils in a rock can be used to determine its age.

67
Q

Bedding

A

The seperation of sediments into layers that either differ from one another in textures, composition, color or weathering characteristics, or are separated by partings.

68
Q

Partings

A

Narrow gaps between adjacent beds. They may represent periods of non-deposition that could range from a few decades to a few centuries.

69
Q

Bedding is an indication of ….

A

Changes in depositional processes that may be related to seasonal differences, changes in climate, changes in locations of rivers or deltas, or tectonic changes.

70
Q

Cross-Bedding

A

Bedding that contains angled layers and forms when sediments are deposited by flowing water or wind.
Cross-beds in streams tend to be on the scale of centimeters to tens of centimeters.
Those in in aeolian sediments can be on the scale of meters to several meters.

71
Q

Graded bedding

A

Characterized by a gradation in grain size from bottom to top within a single bed. “Normal” graded beds are coarse at the bottom and become finer toward the top, a product of deposition from a slowing current.

72
Q

Imbrication

A

A sedimentary deposition in which small, flat stones (boulders, cobbles, pebbles) are tiled in the same direction so that they overlap.

73
Q

Mud cracks

A

form when a shallow body of water (eg a tidal flat or pond), into which muddy sediments have been deposited, dries up and cracks.

74
Q

Formation (Stratigraphy)

A

The main stratigraphic unit
A series of beds that is distinct from other beds above and below and is thick enough to be shown on the geological maps that are widely used within the area in question.

75
Q

Group (Stratigraphy)

A

A series of formations can be classified together to define a group.

76
Q

Member (Stratigraphy)

A

A formation might be divided in to members, where each member has a specific and distinctive lithology. Fe a formation that includes both shale and sandstone might be divided into members, each of which is either shale or sandstone.

77
Q

Metamorphism

A

The change that takes place within a body of rock as a result of it being subjected to conditions that are different from those in which it formed.
In most cases this is where it is subjected to higher temperatures and pressures.
Typically have different mineral assemblages and textures from their parent rock.

78
Q

Factors that control metamorphic processes

A

Mineral composition of the parent rock
Temperature at which metamorphism takes place
The amount and type of the pressure during metamorphism
The types of fluids (mostly water) that are present during metamorphism
The amount of time available for metamorphism

79
Q

Types of foliated metamorphic rocks (listed in order of the grade of metamorphism and the type of foliation)

A

Slate
Phyllite
Schist
Gneiss

80
Q

Amphibolite

A

aka amphibole gneiss

A gneiss that originated as basalt and is dominated by amphibole.

81
Q

migmatite

A

Restulting rock from a burial to a great depth and encountering temperatures close to its melting point, so it will partially melt. Includes both metamorphosed and igneous material.

82
Q

Contact metamorphism

A

The heat for the metamorphism comes from a body of magma that has moved into the upper part of the crust.
Some examples of non-foliated metamorphic rocks are marble, quartzite, hornfels.

83
Q

Hornfels

A

A non-foliated metamorphic rock that normally forms during contact metamorphism of fine-grained rocks like mudstone or volcanic rock.
In some cases, it has visible crystals of minerals like biotite or andalusite.

84
Q

Retrograde metamorphism

A

Metamorphism that takes place at temperatures well below the temperature at which the rock originally formed.

85
Q

Glaucophane

A

Amphibole mineral. Blue. Major component of a rock known as blueschist.

86
Q

Zeolite

A

A silicate mineral that typically forms during low-grad metamorphism of volcanic rocks.

87
Q

Terrane

A

A distinctive block of crust that is now part of a continent, but is thought to have come from elsewhere, and was added on by plate-tectonic processes.

88
Q

Aureole

A

A ring around an igneous intrusion. Deep magma bodies cool very slowly and turn into coarse-grained, plutonic rocks like granite and gabbro. During this time they bake a zone, or aureole, of contact metamorphism in the country rock. Prolonged heat doesn’t always melt the country rock, but it does mobilize the elements and allow new minerals to form and grow that are stable in the high temperatures. It also may help the existing minerals recrystallize into larger grains.

89
Q

Metasomatism

A

Metamorphism in which much of the change is derived from fluids passing through the rock.

90
Q

Hydrothermal Alteration

A

Metamorphism where hot water contributes to changes in rocks, including mineral alteration and formation of veins.

91
Q

Principle of cross-cutting relationships

A

States that any geological feature that cuts across, or disrupts another feature must be younger than the feature that is disrupted.

92
Q

Unconformity

A

Represents an interruption in the process of deposition of sedimentary rocks.

93
Q

Angular unconformity

A

A boundary between two sequences of sedimentary rocks where the underlying ones have been tilted (or folded) and eroded prior to the deposition of the younger ones.

94
Q

Disconformity

A

A boundary between two sequences of sedimentary rocks where the underlying ones have been eroded (but not tilted) prior to the deposition of the younger ones

95
Q

Paraconformity

A

A time gap in a sequence of sedimentary rocks that does not show up as an angular conformity or a disconformity.

96
Q

sialic

A

silicon and aluminium dominated

97
Q

simatic

A

silicon and magnesium dominated

geology (1 decks)

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