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OCR Geology A Level Definitions > Definitions > Flashcards

Definitions Flashcards

1
Q

Mineral

A

Naturally occurring chemical substance having a definite composition and crystalline structure.

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2
Q

Rock

A

An aggregate or mixture of one or more minerals.

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3
Q

Sublimation

A

Solid to gas

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4
Q

Lusture

A

Surface appearance of a mineral as light interacts with it

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5
Q

Crystal

A

Solid with plane faces formed when atoms are arranged in a structurally ordered pattern.

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6
Q

Glass

A

An amorphous solid with no crystalline structure.

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7
Q

Grain boundary

A

Line of contact between mineral crystals in a rock.

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8
Q

Igneous rock

A

Those that have cooled from magma

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9
Q

Phenocrysts

A

Large or clearly visible crystals on an igneous rock, much marger than groundmass

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10
Q

Essential mineral

A

This minerals used to classify igneous rock.

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11
Q

Accessory/secondary mineral

A

May be present but not used for classification

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12
Q

Felsic

A

Light coloured and silica rich

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13
Q

Mafic

A

Dark coloured, silica poor and rich in mg and fe

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14
Q

Magma

A

Molten rock below earth’s surface

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15
Q

Flow banding

A

Formed by friction as magma slows down near interfaces, aligning minerals.

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16
Q

Conchoidal

A

A fracture which results in a curved surface

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17
Q

Vesicular

A

Rock containing vesicles. Gas comes out of solution as a result of pressure release.

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18
Q

Porphyritic

A

Large phenocrysts are surrounded by groundmass

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19
Q

Equigranular

A

Crystals are approximately the same size

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20
Q

Amygdaloidal

A

Large vesicles fille din by secondary mineral

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21
Q

Lava

A

Molten rock cooled at surface

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22
Q

Ophiolites

A

Sections of earth’s oceanic crust that have been tectonically moved onto continental crust.

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23
Q

Isochemical

A

No elements added or removed

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24
Q

Granoblastic

A

He texture found in met rocks with interlocking equidimensional crystals

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25
Q

Foliation

A

Preferred alignment of flat minerals in met rocks

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26
Q

Slaty cleavage

A

The texture in fine grained, low grade, regional metamorphic rock. Perpendicular to pressure

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27
Q

Cataclasis

A

The brittle fracturing and grinding down of existing rock in fault zones

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28
Q

Porohyroblasts

A

Large crystals grown during recrystalisation in a met rock and surrounded by a finer grained ground mass.

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29
Q

Schistosity

A

Med and coarse grained met rocks formed by preffered alignment of flat/tabular minerals. Perpendicular to stress. No traces of original bedding remain

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30
Q

Gneissose banding

A

Segregation of light and dark minerals into bands. Light band is granoblastic and dark band shows schistosity.

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31
Q

Metamorphic grade

A

A measure of the intensity of metamorphism.

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32
Q

Country rock

A

Rock into which igneous rock is intruded

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33
Q

Metamorphic aureole

A

Region surround an igneous intrusion in which the country rocks have been recrystalised and changed by heat from the intrusion

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34
Q

Spotted rock

A

Formed by low grade metamorphism on the outer part of an aureole.

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35
Q

Index minerals

A

Metamorphic minerals which are stable under specific. Temp and pressures. They indicate grade.

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36
Q

Weathering

A

In situ chemical alteration, mechanical and biological breakdown of rocks by exposure to the atmosphere, water or organic matter

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37
Q

Carbonation

A

Reaction between carbon via acid and minerals

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38
Q

Hydrolysis

A

The reaction between minerals and water, causing the minerals to decompose.

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39
Q

Exfoliation

A

Occurs when sheets of rock split off due to differential expansion and contraction of minerals during diurnal heating and cooling.

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40
Q

Frost shattering

A

Caused by the expansion of freezing water in fractures by 9%.

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41
Q

Pressure release

A

Expansion and fracturing of rock due to removal of overlying rock.

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42
Q

Root action

A

Causes mechanical and chemical weathering by wedging open rojc by roots.

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43
Q

Burrowing

A

Animals bring rock and soil to the surface. Allows weathering at a greater depth.

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44
Q

Erosion

A

The wearing away of the land surface and removal of sediment by transport.

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45
Q

Abrasion

A

Wearing away of earth by wind, water ice dragging sediment over a surface

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46
Q

Attrition

A

Wearing down of sediment due to collisions with other grains.

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47
Q

Mineralogical maturity

A

Extent to which minerals have been destroyed by weathering and attrition

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48
Q

Solution

A

Transport of ions dissolved I. Water

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49
Q

Traction

A

The transport of material by rolling and sliding on a surface

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50
Q

Saltation

A

Bouncing

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51
Q

Suspensuon

A

Transport in water or air without touching earth’s surface

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52
Q

Roundness

A

How similar the outline of a grain is to a circle

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53
Q

Shape

A

Hwo similar it is to a sphere, rod, disc or blade

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54
Q

Phi scale

A

Grain size on a logarithmic scale

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55
Q

Textual maturity

A

Extent to which sediment is well sorted and well rounded.

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56
Q

Fossil

A

Any trace of past life. Parts or whole organisms as well as traces of them.

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57
Q

Organism

A

Individual life form.

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58
Q

Body fossil

A

Hard parts of an organism

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59
Q

Replacement

A

Atom by atom substitution of one mineral for another

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60
Q

Dissolution

A

Minerals that make up fossils are dissolved away and removed in solution.

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61
Q

Taphonomy

A

Study of fossilisation

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62
Q

Mould

A

Impression of the outside/inside of a fossil

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63
Q

Cast

A

An infilled fossil void, usually with another mineral.

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64
Q

Extant

A

Still alive

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65
Q

Extinct

A

No longer alive

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66
Q

Death assemblage

A

Collection of organisms found in a different place to where they lived

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67
Q

Disarticulated

A

Fragments of organisms

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68
Q

Life assemblage

A

Organisms fiund found within sediments in the same position as they they would’ve lived

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69
Q

Geopetal structures

A

Way up indicators

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70
Q

Derived fossils

A

Weathered out of one rock and deposited in another

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71
Q

Ornament

A

Surface features such as ribs, spines growth lines etc

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72
Q

Robustness

A

Ability to resist abrasion

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73
Q

Articulated

A

Whole or connected organisms

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74
Q

Luttoral zone

A

Area between high and low tide

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75
Q

Anoxic

A

Lack oxygen

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76
Q

Species

A

Group of organisms that can interbreed to poruce fertile offspring

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77
Q

Trace fossils

A

Formed by benthonic infaunal and benthonic epifaunal organisms.

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78
Q

Tracks

A

Footprints of an organism made when it moved along sediment e.g. Cruziana

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79
Q

Trails

A

Impressions of animals which were travelling.

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80
Q

Resting traces

A

A trail as the whole body of the organism has stopped

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81
Q

Bioturbation

A

Burrowing or working the sediment in a way that disrupts bedding caused by organisms

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82
Q

Substrate

A

Sediment or rock on sea floor.

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83
Q

Continental drift

A

Theory that the position of continents has changed. Convection currents moved continents like rafts.

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84
Q

Passive plate tectonics

A

Global seismic network set up and shows that lateral displacement of hundreds of kilometers had occurred.

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85
Q

Active plate tectonics

A

Evidence mounted that the passive model was neither machanically or thermodynamucally robust.

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86
Q

Tillites

A

Ancient glacial deposits preserved in a rock sequence

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87
Q

Evaporates

A

Formed by evaporation of hypersaline water, for example halite, gypsum and anhydrite.

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88
Q

Apparent polar wandering curve

A

A line on a map which joins up the apparent positions of the magnetic north pole over time.

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89
Q

Orogeny

A

A period of mountain building.

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90
Q

Geosycncline model

A

Continents fixed through time, lateral compression caused orogeny. Contraction theory - cooling of earth caused it to shrink
Random synclines.

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91
Q

Fossils found in SA and Aftrica

A

Mesosaurus and Glossopteris

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92
Q

Solar system

A

Consists of the sun, planets, moons comets and asteroids.

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93
Q

Sun

A

A star composed of hydrogen an helium. 98.8% of mass of solar system

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94
Q

Planets

A

Sizeable object orbiting star has its own grvaity

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95
Q

Moon

A

Natural satellite that orbits a planet

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96
Q

Asteroids

A

Rocky objects which failed to form planets

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97
Q

Meteorites

A

Rock fragments which fall to earth from space

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98
Q

Cmet

A

Composed of ice and dust. Outer layers metlt when closer to the sun.

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99
Q

Protoplanetory disc

A

Rotating disc of dense gas and dust surrounding newly formed star.

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100
Q

Planetessimala

A

Solid objects in protoplanetory discs

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101
Q

Protoplanet

A

Moon sized object that formed in protoplanetory disc.

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102
Q

Bed

A

A unit of sedimentation, which can vary considerably in thickness

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103
Q

Bedding plane

A

Mark a break between beds. They represent a break in sedimentation, a change in composition or grain size or change in colour.

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104
Q

Dip

A

The maximum inclination of a bed measured from horizontal

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105
Q

True dip

A

Angle measured at 90° to strike

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106
Q

Apparent dip

A

Dip that is measured to be less than the maximum inclination.

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107
Q

Strike

A

The horizontal line along a bedding plane. Measured as a bearing from north at 90° to dip.

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108
Q

Fault

A

A fracture in a rock along which there has been an observable amount of displacement.

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109
Q

Fault plane

A

A plane of fracture along which the rock has been displaced

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110
Q

Upthrow

A

The side of the fault where the movement is upwards, in relation to the other side.

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111
Q

Downthrow

A

The side of the fault where the movement is downwards in relation to the other side

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112
Q

Throw

A

The vertical displacement of rocks along the fault plane.

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113
Q

Footwall

A

Lies below the fault plane if it isn’t vertical

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114
Q

Hanging wall

A

Lies above the maximum inclination of the fault plane.

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115
Q

Normal fault

A

Crustal extension. Tensional forces.

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116
Q

Reverse fault

A

Crustal shortening. Comprwssional forces.

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117
Q

Thrust fault

A

Low angle reverse fault (<45°)

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118
Q

Grab and horst

A

Two normal faults which dip away from each other. Crustal extension.

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119
Q

Porosity

A

% volume of pore space

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120
Q

Permeability

A

Rate of flow of fluids through rock

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121
Q

Capillary pressure

A

The pressure between two immiscible fluids in narrow pore spaces. Resulting from interaction of forces between the fluids and grains.

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122
Q

Connate water

A

Trapped din pore spaces of a rock as it formed. It includes water trapped in the original sediment and water released during diagenesis.

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123
Q

Groundwater

A

Water occupying pores and other spaces in rocks and sediments which is derived mostly from rainfall percolating into underlying rock.

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124
Q

Water table

A

The surface separating unsaturated rock above from saturated rock below.

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125
Q

Hydrostatic pressure

A

The pressure at a point in a body of water due to overlying column of water.

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126
Q

Hydraulic gradient

A

The difference in hydrostatic pressure between two points divided by the distance between them.

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127
Q

Aquifer

A

A body of porus and permeable rock capable of storing and yielding significant amounts of water.

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128
Q

Recharge zone

A

The area of an aquifrr open to the atmosphere, allowing replenishment of water.

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129
Q

Artesian basin

A

A large synclinal confined aquifer under hydrostatic pressure.

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130
Q

Artesian well

A

Hold water under pressure which rises to a piezometeic surface.

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131
Q

Piezometeic surface

A

Imaginary level to which groundwater would rise to if under hydrostatic pressure.

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132
Q

Abstraction

A

The removal of water from any source.

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133
Q

Amplitude

A

Maximum displacement of an oscillation, measured from equilibrium.

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134
Q

Attenutation

A

The loss of energy experienced by a wave as it propigates through a material. Loss of amplitude

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135
Q

Moment

A

Turning force around a pivot

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136
Q

Geohazard

A

Geological condition that is dangerous or potentially dangerous to the environment and people who live within it.

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137
Q

Liquefaction

A

Saturated or partially saturated unconsolidated material losing strength and rigidity In response to applied stress eg earthquake.

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138
Q

Resonant frequency

A

Frequency at which amplitude of oscillation is at maximum

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139
Q

Intensity

A

Measure of surface shaking and damage caused by an earthquake. The mercalli scale measures intensity. Based on local accelerations.

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140
Q

Cratons

A

Stable portions of continental crust no longer tectonically active, mostly thick basement rock, thicker parts of the crust.

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141
Q

GOE

A

Great oxygenation event. Appearance of oxygen in atmosphere 2.3 BA

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142
Q

Snowball earth

A

Planet is frozen or frozen to very low latitudes.

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143
Q

Albedo

A

The fraction of solar energy reflected from earth back into space. Reflectivity of earth’s surface. Ice has high albedo.

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144
Q

Pannotia

A

A short lived super continent that formed at end of precambrian

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145
Q

Gondwanaland

A

Fomed 570-510ma. Includes most southern land masses.

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146
Q

Laurasia

A

Laurentia and Eurasia. North hemisphere continents

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147
Q

Variscan orogeny

A

Mountain building event caused by collision between gondwanaland and laurasia to form pangea.

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148
Q

Isostatic

A

Sea level change due to local events such has uplift or subsidence of crust.

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149
Q

Eustatic

A

Worldwide change. Volume of water oceans changes.

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150
Q

Which O isotope is more readily taken up by glaciers

A

O16 is more easily taken up. Leaving more O18 in oceans.

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151
Q

Which C isotope is more readily taken up by plants

A

C12 so during icehouse, it has higher % in ocean.

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152
Q

Marginal marine environment

A

Not marine or terrestrial, both due to tides.

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153
Q

Land mass

A

Continent/large body of land

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154
Q

Graptolites

A

Extinct marine organisms that lived in colonies, most of which floated freely in the sea, some may have been attached to the sea bed.

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155
Q

Avalonia

A

Microcontinent during the paleaozoic which contained Wales, Ireland, England and southern Scotland in the southern hemisphere.

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156
Q

Baltica

A

Microcontinent during paleaozoic containing baltic coutries (east of avalonia)

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157
Q

Laurentia

A

Microcontinent during paleaozoic which contained Scotland and Ireland, and north American continent

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158
Q

Iapetus

A

Ocean which existed in the lower paleaozoic wfhich closed due to collision between avalonia, baltic a and laurentia.

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159
Q

Caledonian orogeny

A

Mountain building era for scotland

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160
Q

Terranes

A

Fragments of crustal material broken from one tectonic plate and acreted onto another. The boundary is usually a fault.

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161
Q

Cations

A

Positively charged atoms

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162
Q

Anions

A

Negatively charged

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163
Q

Covalent bond

A

Sharing of a pair of electrons

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164
Q

Tetrahedron

A

4 sided object

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165
Q

Solid solution

A

One or more type of atoms may be substituted for the original atoms whilst in solid state, no change to strucutr as atomic radii are similar.

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166
Q

Bridging oxygen

A

An oxygen shared by two tetrahedra

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167
Q

Polymers

A

Repeating chains of small molecules

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168
Q

Twinning

A

Feature of feldspar where two or more crystals grow with different orientations from a common plane. One is a mirror of the other

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169
Q

Magma accumulation

A

Magma collecting in a magma chamber

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170
Q

Intrusion

A

Composed of igneous rock formed below earth’s surface. Forced into pre existing rock

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171
Q

Extrusion

A

Emission of magma onto surface where it forms a flow

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172
Q

Deposition

A

Laying down of sediment that occurs when transporting agent loses energy.

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173
Q

Transport

A

The means by which weathered material is moved from one place to another.

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174
Q

Uplift

A

The return of bhried rocks to earth’s surface by tectonic forces and erosion.

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175
Q

Single tetrahedra

A

Eg olivine
4- charge
1:4

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176
Q

Chains

A

E.g. Augite
2- charge
1:3

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177
Q

Double chains

A

E.g amphibole/hornblende
6- charge
4:11 charge

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178
Q

Sheets

A

E.g. Mica
-4 charge
2:5

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179
Q

Frameworks

A

E.g. Quartz
0 charge
1:2

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180
Q

Hypabyssal

A

Igneous rock intruded at relatively shallow depth ~1km - 10km

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181
Q

Plutonic

A

Rock intruded at >10km

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182
Q

Euhedral

A

Well formed with good crystal faces

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183
Q

Equant

A

All axis of crystals the same.

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184
Q

Prismatic

A

Four or more sides but elongated in one direction

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185
Q

Anhedral

A

Poorly formed crystal faces

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186
Q

Subhedral

A

Some well formed faces some poorly formed faces.

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187
Q

Pegmatite

A

Exceptionally large crystals of igneous rock.

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188
Q

Glassy

A

No crystals. Conchoidal fracture

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189
Q

Equicrystalline

A

All crystals the same size

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190
Q

Vesicular and amygdaloidal

A

Gas bubbles trapped in lava as it cools rapidly. Elongated in direction of flow. Vesicles filled in by minerals deposited by groundwater e. G. Calcite/quartz. Making an amygdale.

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191
Q

Flow banding

A

Separation of minerals in a lava flow by friction / viscosity

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192
Q

Porphyritic

A

Two stages of cooling. Two sizes of crystal. Groundmass and phenocrysts.

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193
Q

Ophitic

A

One mineral enclosed by another

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194
Q

Cumulated texture

A

Crystals settle out of magma on the floor of a magma chamber and accumulate in mutual contact.

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195
Q

Mechanically formed. (siliclastic)

A

Sedimentary rocks result from processes of erosion transport and deposition.

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196
Q

Siliclastic roxk

A

Formed from sediment compose dof silica ye material and rock fragments.

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197
Q

Matrix

A

The background material of small grans in which larger grains occur

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198
Q

Clay minerals

A

A group of sub-microscopic platy aluminium silicates called mica.

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199
Q

Plasticity

A

The ability of a material to permanently change shape without fracture

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200
Q

Fissile

A

Tendency of rock to split into thin layers

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201
Q

Rudaceous

A

Coarse >2mm

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202
Q

Arenaceous

A

2mm-0.0625mm medium

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203
Q

Argillacous

A

<0.0625mm fine

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204
Q

Ooliths

A

Spherical grains showing concentric banding of carbonate material. These are less than 2mm diameter

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205
Q

Pisolite

A

Very large ooliths in rock

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206
Q

Micrite

A

Microcrystaline calcite. Depositional matrix of lime mud

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207
Q

Sparite

A

Coarse grained crystalline calcite cement

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208
Q

Cement

A

Minerals precipitated between grains

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209
Q

Pellets

A

Carbonate material excreted by animals

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210
Q

Diagenesis

A

The changes that take place in sediments close to earth’s surface

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211
Q

Lithification

A

The process of changing u consolidated sediment into rock

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212
Q

Pressure dissolution

A

Minerals dissolve due to applied pressure between grains, resulting in reduced rock volume

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213
Q

Porosity

A

5he volume occupied by spaces in between grains

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214
Q

Peat

A

Partly decomposed plant remains with high water content

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215
Q

Coal

A

Carbon rich rock formed from fossil remains

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216
Q

Relict structures

A

E. G. Bedding partially preserved in metamorphic rock

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217
Q

Dalradian

A

Regionally metamorphised group of rocks deposited in precambrian found in Scotland and ireland

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218
Q

Inclusion

A

Early formed mineral enclosed by one which grew later

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219
Q

Unfoliated

A

Random orientation of minerals in metamorphic rock

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220
Q

Hornfels

A

Fine grained, hard, splintery, granoblastic metamorphic rock formed when shale is completely recrystallised close to contact with an intrusion. Index minerals are silimanite.

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221
Q

Slaty cleavage

A

Splits into thin sheets along cleavage planes. Formed from platy minerals, chlorite and mica.

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222
Q

Schistosity

A

In phyllites and schists. Aligned flat minerals at 90° to pressure. Granite porphyroblastoften present.

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223
Q

Gneissose banding

A

Light leucocratic minerals and dark melanocratic minerals separate into bands roughly 90° to pressure

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224
Q

Porphyroblastic fabric

A

Large crystals that grow and are surrounded by finer groundmass. Pyrite cubes found in slate, garnet found in schist

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225
Q

Granoblastic

A

Contact met only. Unfoliated. Randomly orientated equidimensional crystals

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226
Q

Crenulation cleavage

A

When there are two directions of max stress, creating a wavy pattern.

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227
Q

Catastrophism

A

The theory that changes in the earths crust have resulted from sudden, violent, short lived events.

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228
Q

Gradualism

A

Changes come gradually. E.g. Evolution

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229
Q

Uniformitariansim

A

Slow incremental changes created earth’s features. Processes observable now we’re acting in the same way in the past.

230
Q

Absolute dating

A

Specific dates for rock in ma

231
Q

Relative dating

A

Putting units into a sequential order

232
Q

Half life

A

The time taken for half the unstable parent nuclei to decay into stable daughter products.

233
Q

Closure temperature

A

The temperature at which a system has cooled so there is no diffusion of isotopes into or out of this system

234
Q

Closed system

A

When a mineral neither gains nor loses atoms. The higher the temperature, the more likely exchange of atoms or ions will be.

235
Q

Quaternary

A
  1. 6ma to present
236
Q

Neogene

A

2.6 to 23 ma

237
Q

Palaeogene

A

23-66 ma

238
Q

Cretaceous

A

66-145 ma

239
Q

Jurassic

A

145-201ma

240
Q

Triassic

A

201ma-252ma

241
Q

Permian

A

252-299ma

242
Q

Carbiniferous

A

299-359ma

243
Q

Devonian

A

359-419ma

244
Q

Silurian

A

419-444ma

245
Q

Ordovician

A

444-485ma

246
Q

Cambrian

A

485-541ma

247
Q

Stress

A

Force pr unit area

248
Q

Strain

A

Change in shape of an object due to stress

249
Q

Seismometer

A

Device which monitors seismic vibrations

250
Q

Seismogram

A

Paper or electronic record made by a seismometer

251
Q

Seismograph

A

A device which both writes and records seismic vibrations

252
Q

Focus

A

The point within tne earth at which the earthquake originates as movement occurs along a fault plane. Waves radiate in all directions from this point

253
Q

Epucentre

A

The point directly above the focus on earth’s surface

254
Q

Shadow zone

A

Area where earthquake waves are not recorded. 103-142°

255
Q

Intensity

A

Measure of surface damage caused by an earthquake

256
Q

Moho

A

Crust/mantle discontinuity.
Rock type change

257
Q

U mantle

A

35km-700km

258
Q

L mantle

A

700km-2900km

259
Q

Gutenberg

A

2900km
Phase and rock type change

260
Q

Outer core

A

2900km-5100km
Liwuid iron-nickel alloy

261
Q

Lehman discontinuity

A

5100km
Phase change

262
Q

Inner core

A

5100km-6371km
Solid nickel iron alloy

263
Q

Transform fault

A

A strike sli fplt whihh ends at the junction of another plate boundary or fault.

264
Q

Tear fault

A

A strike slip fault fail which dies out without a junction

265
Q

Transform plate boundary

A

A fault where no crust is created or destroyed.

266
Q

Sheeted dykes

A

For magma which usually does not reach the surface and usually composed of dolerite

267
Q

Pillow lava

A

Forms when lava erupts underwater. Made of basalt

268
Q

Island arc

A

Curved line of andesitic volcanic islands.

269
Q

Deep ocean trench

A

A long narrow linear submarine depression with relatively steep sides. Alongside island arcs into a subduction zone.

270
Q

Benioff zone

A

A zone of earthquake foci sloping down at 45° from the ocean trench

271
Q

Slickensides

A

The striations and polishing found on a fault plane indicating the direction of relative movement.

272
Q

Fault breccia

A

Composed of fragments produced by rocks fracturing during faulting. Found on fault planes.

273
Q

Fault gouge

A

Very finely groups particles, produced by grinding of rock during faulting. Often fused due to heat of friction.

274
Q

Mylonite

A

Rock produced by dynamic met on a fault plane.

275
Q

Antiform

A

Upward closing fold

276
Q

Synform

A

Downward closing fold :)

277
Q

Fold Hinge

A

Along the length of it. Measures the dip of the fold itself. Not the limbs.

278
Q

Overfold

A

Both fold limbs dipping in same direction by different amounts.

279
Q

Recent folds

A

Recumbent folds have axial planes which are close to horizontal

280
Q

Nappe

A

Recumbent fold whihh are broken along thrust planes

281
Q

Isoclinal fold

A

Parallel limbs whi b are nearly vertical.

282
Q

Gentle fold

A

180-120

283
Q

Open fold

A

120-70

284
Q

Closed

A

70-30

285
Q

Cone of depression

A

Lowering of water table around a well. Due to abstraction.

286
Q

Acid mine drainage

A

Water flows over sulfur bearing materials e.g. Iron pyrite. This causes acidification of the water by it reacting with water to form sulfuric acid.

287
Q

Ore

A

Rock containing valuable metals that is economic to mine

288
Q

Resource

A

Useful and valuable natural material

289
Q

Mineral resources

A

Can be metallic or non metallic industrial minerals

290
Q

Reserves

A

The amount of a resource which can be extracted at a profit using existing technology.

291
Q

Ore deposit

A

An accumulation of metal that may be economic to mine

292
Q

Average crustal abundance

A

The amount of metal in average crustal rock

293
Q

Concentration factor

A

The number of times a metal is concentrated above average crustal abundance.

294
Q

Ore mineral

A

A mineral containing valuable metals

295
Q

Gangue mineral

A

Low value waste mineral

296
Q

Grade

A

Concentration of valuable minerals within an ore

297
Q

Cut off grade

A

Grade below which an ore becomes uneconomical to mine.

298
Q

Secondary enrichment

A

Metals are leached from surface rocks and precipitated below the water table.

299
Q

Leaching

A

Where ions are dissolved from rocks and carried downwards in solution

300
Q

Gossan

A

A cap of iron oxides at the surface of a mineral vein

301
Q

Oxidising

A

Oxygen rich conditions, allowing elements to combine with oxygen to form oxides.

302
Q

Reducing

A

Anoxic, oxygen poor conditions.

303
Q

Enriched deposit

A

A zone of high grade ore just below the water table formed by secondary enrichment.

304
Q

Porphyry

A

Large igneous intrusion with porphyritic texture. Ores form from a wet magma at the top of the intrusion from hydrothermal fluid precipitating incompatible metals e.g. Copper.

305
Q

Resonance

A

The tendency to oscillate with greater amplitude at a buildings natural frequency.

306
Q

Geological hazard

A

A geological condition that is dangerous or potentially dangerous to the environment and people in it.

307
Q

Seismic risk

A

The possibility of suffering harm because of a seismic event in a particular time

308
Q

Probability

A

A measure of the likely hood an event occurs.

309
Q

Return period

A

The average time an earthquake of a given magnitude to occur again.

310
Q

Problems of abstraction

A

Lowered water table
Subsidence
Salt water encroachment

311
Q

Copper ore

A

Chalcopyrite

312
Q

Tin ore

A

Cassiterite

313
Q

Zinc ore

A

Sphalerite

314
Q

Anthropocene

A

Suggested name for current geological epoch. Human activity has been dominant.

315
Q

Holocene

A

Present epoch. 11700 years. Warm interglacial.

316
Q

Phyletic gradualism

A

Model of evolution which states speciation is slow, uniform and gradual.

317
Q

Genes

A

Sections of DNA that code for a protein.

318
Q

Adaptive radiation

A

Organisms diversify rapidly into many different forms, usually as a response to change in the environment or exploit a new niche.

319
Q

Morphology

A

Shape of orfanism

320
Q

Benthonic

A

Bottom of sea/river may have sediment on top of it

321
Q

Epifaunal

A

Living on top of sediment

322
Q

Substrate

A

Sedent or rock at sea floor

323
Q

Pelagic

A

Floating in water column

324
Q

Nektonic

A

Swimming in water column.

325
Q

Infaunal

A

Living in sediment maybe burrower.

326
Q

Anthropocene markers

A

Chicken bones as fossils
Radionuclides distributed 3T plutonium
Farming markers e.g. Fertiliser or plough marks
Plastics in oceans

327
Q

Nema

A

Extension of the sicula. Possibly to attach a floatation device

328
Q

Theca

A

Individual cup where a zooid lived

329
Q

Virgella

A

Spine at end of the sicula

330
Q

Sicula

A

Conical tube excreted by first zooid.

331
Q

Stipe

A

The stack of thecae built up to form a colony

332
Q

Viviparous

A

Producing live young instead of eggs

333
Q

Pycnofibres

A

Hair filaments

334
Q

Adiabatic

A

Thermodynamic process in which no heat enters or leaves the system during expansion or compression.

335
Q

Divergent plate bohndary

A

Two plates moving apart magma rising up between them.

336
Q

Hot spots

A

Formed by a fixed mantle plume bringing magma to the surface

337
Q

Convergent plate margin

A

Two plates colliding. Magma formed above a subduction zone or deep in the crust.

338
Q

Batholith

A

Very large igneous intrusion, plutonic in depth.

339
Q

Decompression metling

A

Decompression of peridot ite causes partial melting and produces mafic magma by decompression melting.

340
Q

Concordant

A

Parallel to the existing beds

341
Q

Discordant

A

Cut across existing beds

342
Q

Dyke

A

Discordant sheet like intrusion

343
Q

Minor intrusions

A

Cool at hypabyssal depth below earth’s crust, including sills and dykes.

344
Q

Sill

A

Concordant sheet like intrusion.

345
Q

Facies

A

Characteristics of a sedimentary rock that are produced by it’s environment.

346
Q

Lithofacies

A

Physical /chemical characteristics

347
Q

Biofacies

A

Paelaeontological characteristics of a rock.

348
Q

Varves

A

Annual lake clays and silts in thin layers

349
Q

Polymictic conglom

A

Many different rock types

350
Q

Monomictic conglom

A

One rock type

351
Q

Till fabric analysis

A

Tracking former movement direction of ic eby taking compass bearings of large clasts

352
Q

Fluvio glacial deposits

A

Melt water deposits

353
Q

Polymorphs

A

Same composition but different crystal forms

354
Q

Isograd

A

Line on map joining points of equal metamorphic grade.

355
Q

Metamorphic zone

A

Area between two isograds. Zone is named after the lower isograds. E.g. Silimanite.

356
Q

Barrovian zones

A

Regional Metamorphic zones in scotland

357
Q

Prograde

A

Recrystallisation in response to increase of metamorphism. Retrograde is as rocks are returned to surface.

358
Q

Dalradiam supergroup

A

Regionally metamorphised rock in Scottish Highlands. Due to close of Iapetus ocean. Caledonian orogeny.

359
Q

Relative dating methods lithologiaclly (4 principles)

A

Original horizontality
Cross cutting relationships
Principle of superposition
Included fragments.

360
Q

Lateral variation

A

Changes in thickness or lithology in beds laid down at the same time.

361
Q

Marker horizon

A

Bedding plane with a change of lithology easily distinguished from othe beds.

362
Q

Varve deposit

A

Alternating layers of light and dark layers in glacial deposit due to summer winter variations. Each pair =1 year

363
Q

Zone fossils

A

Fossils with ideal properties to identify a biozone

364
Q

Stratigraphic range

A

The time the fossil existed for

365
Q

Assemblage

A

The collection of fossils identified in a rock used to find its stratigraphic range

366
Q

Biozones

A

Intervals of strata which are defined by their characteristic fossils

367
Q

Coral phylum

A

Cndearia

368
Q

Trilobites phylum

A

Arthropoda

369
Q

Bivavle phylum

A

Molusca

370
Q

Brachiopod phylum

A

Brachiopoda

371
Q

Graptolite phylum

A

Hemi-chordata

372
Q

Dinosaur phylum and class

A

Cordata, dinosauria

373
Q

Ammonoid phylum. Examples

A

Cephalopod. Goniotite. Nautiloid. Ceratites. Belemnites. Ammonites.

374
Q

Transform fault

A

Strike slip fault which ends at junction with another plate boundary.

375
Q

Tear fault

A

Strike slip fault which stops when it reaches another fault. not plate boundary

376
Q

Transform plate boundary

A

A fault where no crust is created or destroyed.

377
Q

Sheeted dykes

A

At a mor magma that doesn’t reach the surface and cools as dykes.

378
Q

Pillow lava

A

When lava erupts under water cools rapidly in seawater. Basalt

379
Q

Island arc

A

Line of andesitic volcanoes which erupt due to partial melting of subducting oc plate.

380
Q

Ocean trench

A

Linear submarine depression, perpendicular to subducting plate.

381
Q

Benioff zone

A

Zone of earthquake foci sloping down 45 from ocean trench.

382
Q

Stress

A

Force over area applied to a rock

383
Q

Strain

A

Deformation in response to stress

384
Q

Competent

A

Strong and brittle. Joint and fault

385
Q

Incompetent

A

Weak and plastic. Tend to fold and develop cleavge

386
Q

Tension

A

Pulling force. Crustal extension. E. G. Normal fault

387
Q

Compression

A

Force trying to push rocks together

388
Q

Shear

A

Act along a plane and promote sliding along that plane

389
Q

Joint

A

A fracture in competent rocks along which no observable movement occurred.

390
Q

Tension joints

A

Form as a result of Folding and cause tension joints parallel to axial plane. Cross joints on limbs

391
Q

Cooling joints

A

Form as a result of contraction on cooling of igneous rocks.

392
Q

Unloading joints

A

Horizontal as well as vertical and form as a result of lower pressure near to the surface

393
Q

Dredging

A

Material scraped of river/sea bed

394
Q

Hydraulic mining

A

Using high pressure water to dislodge material.

395
Q

Geo chemical anomaly

A

A concentration of a metal above its normal background value

396
Q

Dispersion

A

Where small amounts of metal are spread out around it’s ore deposited by erosion and transport.

397
Q

Catastrophic dilution

A

Where tributaries meet and water and sediment from other sources are added.

398
Q

Forecast

A

A statement of the probable occurrence of an event based on information and data. Probability of an event occurring.

399
Q

Prediction

A

A statement about what you think will happen in the future. Includes more qualitative information such as when and where.

400
Q

Polyp

A

Soft body part of coral

401
Q

Mural pores

A

Connect multiple adjacent corralites together.

402
Q

Symbiotic relationship

A

Two organisms live together for mutual benefit.

403
Q

Zoozanthellae

A

The algea which live within a coral polyp

404
Q

Bleaching

A

Changes in temperature or pollution cause corals to expel their algae and they die.

405
Q

Strophic

A

Straight hinge line in a brachiopod

406
Q

Astrophic

A

Hinge line is not straight in a brachiopod.

407
Q

Commisure

A

Margin between two valves. Shape depending on environment

408
Q

Spatfall

A

Settling and attachment of juvenile brachiopods.

409
Q

Lobe finned fish

A

Have both lungs and gills. Four fleshy limbs supported by bones.

410
Q

Swim bladder

A

Filled with gas or fluid to control buoyancy of a fish.

411
Q

Lophophore

A

Gathers food and digests it and excretes it. Also respiration. Yuck.

412
Q

The 3 pyroclastic materials and sizes

A

Bombs >64mm
Lapilli 2-64mm
Ash <2mm

413
Q

Aa

A

Rough blocky jagged lava flows

414
Q

Pahoehoe

A

Smooth or ropy lava flow

415
Q

Nuée ardente

A

Pyroclastic cloud of magma droplets and ash.

416
Q

Pyroclastic flow

A

Mix of pyroclastic material and gas. E. G. Nuée ardente.

417
Q

Isostacy

A

The theoretical state of equilibrium between earth’s litho sphere and aesthenosphere such that the lithospher floats at an elevation that depends on its thickness and density.

418
Q

Subduction

A

One section of the lithospher is forced down beneath another.

419
Q

Slab pull

A

A process where cold dense section of lithosphere sinks intoantle.

420
Q

Hot spot

A

Area of high heat flow above mantle

421
Q

Thermal flux

A

Watts per square meter. Rate of energy transfer through a given surface per unit time.

422
Q

Advenction

A

Thermal energy transfered through a fluid

423
Q

Convection

A

Thermal energy is transfered by a substance due to buoyancy differences within the substances

424
Q

Conduction

A

Thermal energy transferred with no movement. Atom to atom

425
Q

Migmatite

A

Metamorphic rock e.g. Gneiss that melts to form an igneous rock

426
Q

Guyot

A

Flat topped seamount, usually eroded by wave action

427
Q

Seamount

A

A submarine mountain, often extinct volcano

428
Q

Diapir

A

A low density botany material rising upwards in the same way as a lava lamp

429
Q

Ridge push

A

A process where two sections of lithosphere are pushed apart by rising magma at the MOR

430
Q

Slab pull

A

A process where cold dense sections O lithosphere descend into mantle at subduction zone

431
Q

Cleavage

A

Planes of weakness in incompetent rock(e.g. Shale, made of clay minerals) and low grade metamorphic rocks along which these rocks will split forms perpendicular to maximum stress. At an angle to bedding planes.

432
Q

Sustainability

A

Using a resource so that it is not depleted or harmful to the environment. Supporting a long term balence in ecological and other systems.

433
Q

Non renewable resources

A

Do not renew themselves at a sufficient rate for sustainable economic extraction within a human lifetime.

434
Q

Open cast mining

A

Extracting ore from a surface quarry

435
Q

Shafts

A

Vertical openings to an underground mine

436
Q

Stope (mine)

A

Void where ore was once extracted form in underground mine

437
Q

Froth floatation

A

Aerate and agitate slurry to separate froth from tailings. Froth contains hydroponic minerals.

438
Q

Leachate

A

Liquid that drains from a landfill site. Containing dissolved chemicals and microbial contaminants.

439
Q

Pollution plumes

A

A zone of contamination produced by the flow of leachate through permeable rock into aquifers

440
Q

Transuranic elements

A

Elements with a higher atomic number than uranium, 92.

441
Q

Carbon sequestration

A

Co2 removed from atmosphere and held in alternative form, either solid or liquid.

442
Q

Placisity

A

The property of a substance has when deformed continuously under a finite force.

443
Q

Tilt

A

Change in elevation between two points divided by the distance between those points.

444
Q

Inflection point

A

A point in a curve where the curve changes from concave to convex

445
Q

Sinkholes

A

Hollows or holes in the ground caused by collapse of a surface layer, usually by dissolution of limestone.

446
Q

Dinosr

A

Mesozoic reptile with upright walking position

447
Q

Amniotic egg

A

Eggs with shells produced by birds and reptiles

448
Q

Pubis

A

Public bone

449
Q

Ornithischia

A

Bird hopped dinosaurs. Both hip bones point backwards.

450
Q

Saurischia

A

Reptile hipped. One bone points forward.

451
Q

Gastroliths

A

Stones swallowed by animals to help digestion.

452
Q

Olfactory lobes

A

The part of the brain which processes smell.

453
Q

Dinobird

A

Dinosaur with feathers

454
Q

Sternum

A

The breast bone

455
Q

Furcula/wishbone

A

Forked bone which strengthens the skeleton

456
Q

Sexual dimorphism

A

Means difference in size/appearance between sexes in animals

457
Q

Volcanoes

A

Vents at the surface of earth though which magma is erupted

458
Q

Fissure erpution

A

Where magma reaches the surface along long linear cracks or fissures

459
Q

Composite/strato volcanoes

A

Tall, conical shaped and composed of alternating layers of ash and lava

460
Q

Caldera

A

Volcanic crater that ha undergone collapse, following an eruption

461
Q

Effusive

A

Non explosive magma

462
Q

Vei

A

Volcanic explosivity index

463
Q

Hawaiian eruptions

A

Large amounts of low viscosity, basaltic lava

464
Q

Strombolian eruption

A

More explosive with less fluid basalt and andesite lava. Explosive and produce has and pryoclasts

465
Q

Plinian eruptions

A

Extremely explosive with andesitic and rhyolitic lava

466
Q

Isopachyte

A

Lines joining points of equal thickness of deposits such as ash on a pyroclastic distribution map.

467
Q

Flash floods

A

Brief but very high energy flows of water over a surface or down a river channel usually caused by heavy rainfall.

468
Q

Wadis

A

River channels in hot desert regions in whi h flow occurs very occasionaly

469
Q

Playa lakes

A

Temporary lakes formed by storm run off in deserts having inland drainage.

470
Q

Evaporites

A

Sedimentary rocks resulting from the evaporation of saline water

471
Q

Spring tides

A

Tides with greatest range. Happen every two weeks

472
Q

Longshore drift

A

Drift of sediment along a beach.

473
Q

Glauconite

A

Green coloured mineral. Formed on continental shelves

474
Q

Transgression

A

Sea spreads over land

475
Q

Regression

A

Sea retreats from land

476
Q

Macrofossils

A

Large fossils visible to the eye

477
Q

Microfossils

A

Can only be seen by microscope or hand lens

478
Q

Detrital mud

A

Fragments derived from mechanical weathering of rock

479
Q

Cryptocrystalline

A

Material is too fine grained to be distinguished with a microscope

480
Q

Radiolaria

A

Plankton ic animals with a silicic shell that form chert

481
Q

Calcerous ooze

A

Clay containing >30% skeletal material made of caco3

482
Q

Evaporite sequence

A

First
Calcite
Gypsum
Anhydrite
Halite
K minerals
Last

483
Q

CCD

A

Carbonate compensation depth.
Depth above which the supply of carbonate fossils is more than what dissolves in the water.

484
Q

Seismic tomography

A

A technique for 3D imaging of the subsurface of earth using seismic waves

485
Q

Mantle plume

A

Stationary area of high heat flow in the mantle. Rises from great depths and produces magma which feeds hot spot volcanoes such as hawaiian or iceland

486
Q

Curie point

A

Temperature above which magnetic minerals lose their permanent magnetism. 585 for magnetite.

487
Q

Remanent magnetism

A

Recorded in rocks due to the alignment of their magnetic minerals according to the earth’s magnetic field at the time of their formation

488
Q

Palaeomagnetism

A

Ancient magnetism preserved in rock.

489
Q

Magnometer

A

Instrument which detects field strength and direction of the magnetic field.

490
Q

Magnetic inclination

A

The angle of dip of the lines of a magnetic field it is the dip angle made with horizontal and the earth’s magnetic field. Can be used to find latitude

491
Q

Obduction

A

A process by which the edge of oceanic crust is scraped onto continental crust. Forming ophiolites

492
Q

Multi beam echo sounder

A

Sends out beams of sound in a fan from below a ship to make a transect.

493
Q

Side scan sonar

A

Towed at depths, a side view profile is made of the ocean floor.

494
Q

Adibiatic melting

A

Melting due to change in melting point due to a release in pressure

495
Q

Mush

A

A mixture of crystals and melt

496
Q

Continuous magma chamber

A

Continuous produces lava

497
Q

Discontinuous magma chamber

A

Produces lava periodically, with long periods of inactivity

498
Q

Black smoker

A

Hydrothermal vent ascociated with volcanic activity at Mor it emits dark clouds of sulfide particles

499
Q

Metasomatism

A

The hydrothermal alteration of rock

500
Q

Serpentine

A

A mineral formed by the hydration of olivine

501
Q

Serpentinite

A

A rock made of serpentine

502
Q

White smokers

A

Cooler hydrothermal vents which emit more silicic minerals

503
Q

Talus

A

Debris accumulating at the foot of a slope due to erosion of the rock face above.

504
Q

Translational slide

A

Several beds sliding down a slope together

505
Q

Isotropic clay

A

Equal properties in all driections
E.g. No particular cleavage

506
Q

Tsunamite

A

A tsunami deposit. Deposited onshore.

507
Q

Fabric

A

Spatial and geometric configuration of all the components of a rock.

508
Q

Confining pressure

A

The combined lithostatic and hydrostatic pressure

509
Q

Ductile deformation

A

Rock sufferers large strain without large scale fracturing.

510
Q

Brittle deformation

A

Causes the rock to fracture.

511
Q

Principle stresses

A

The direction of each stresses 01 02 and 03. Show the direction of maximum stress and median and minimum where they are all perpendicular.

512
Q

Lithostatic pressure

A

Vertical pressure due to the mass of the rock only.

513
Q

Asperity

A

The term mostly used to describe the roughness of the surface of a discontinuity

514
Q

Residual strength

A

The remaining resistance to movement after the rock has failed and been displaced

515
Q

Joint sets

A

Are fractures across which there is little displacement. They are mostly to dissapate the remaining stress left after Folding. As they are the result of regional stress they tend to form sub parallel sets.

516
Q

Traps

A

Large scale volcanism resulting in the formation of mafic igneous rock. (kinda shield volcanoes but massive)

517
Q

Shocked quartz

A

Grains showing deformation under high pressure. First descovered at nuclear testing sites.

518
Q

Iridium

A

Rare transition metal, but common in meteorites

519
Q

Tektites

A

Spheres or irregular shaped lumps of solidified molten rock, a few cm in diameter. Thought to have formed as a result of extremely high pressures and temperatures caused by meteorite impact.

520
Q

Biota

A

The plants or animals living in an area or environment.

521
Q

Low energy

A

Water not moving or moving very slowly. E.g. Lakes, deep sea.

522
Q

Anaerobic

A

Without oxygen. Conditions within a sediment.

523
Q

Anoxic

A

Water without oxygen. Bacteria and scavengers cannot live in these conditions.

524
Q

Reaction rim

A

One mineral surrounding another. As cooling of a melt occurs reactions between high temp minerals and the melt substitute the minerals and change the crystals composition. This is often incomplete as the magma may be erupted before it is complete.

525
Q

Liquidus

A

The phase boundary showing 5he temperature at which the last solid crystal melts

526
Q

Solidus

A

The phase boundary showing the temperature at which the first crystal melts when heated.

527
Q

Flocculation

A

When clay particles stick together. Therefore decreasing there depositional velocity. Clay are charged so this only happens in electrolitic sea water.

528
Q

Turbidity current

A

High velocity current that flows down gentle gradients because the sediment dispersed within it is more dense than sea water. Triggered by instability or earthquakes.

529
Q

Tirbidites

A

Upward fining deposit of greywacke deposited from turbidity current

530
Q

Bouma seauence

A

Sequence of deposits in a turbidite

531
Q

Climbing ripples

A

Form when deposition exceeds the migration of ripples.

532
Q

Tool marks

A

Pretty similar to flute casts

533
Q

Rip up clasts

A

Pieces of shale or mudsrone eroded by the turbidity current and included in the turbidite deoosit

534
Q

Silacous ooze

A

Containing biogenic skeletal material made of silica

535
Q

Plankton

A

Minute organisms living in the surface layers of the ocean. They die and sink to ocean floor forming calcerous and silicaous oozes.

536
Q

Diatoms

A

Plankton ic algae that secrete silicaous material.

537
Q

Pelagic fallout

A

The planktonic tests that fall from shallow water to the abyssal plane after they die.

538
Q

Inert

A

Chemically inactive. Unreactive

539
Q

Bioavailability

A

The proportion of metals that are available for incorporation into biota. E. G how badly metal pollution affects the environment.

540
Q

Ion exchange

A

Exchange of ions between two electrolytes. Used to describe the process of purification or decontamination of ion containing solutions.

541
Q

Adsorption

A

The process where clay removes heavy metals from ground water as a filter.

542
Q

Isomorphus subsitution

A

Replacement of one atom by another similarly sized during Crystal growth without changing the structure.

543
Q

North north Sea example and description

A

Piper oil field. Kimmerage clay is source, sandstone reservoir, clay caprock. Fault traps

544
Q

South North Sea basin example

A

Ekofisk gas field. Anticline trap. Kimmerage clay is source. Chalk reservoir. Mudsrone caprock.

545
Q

Fossil fuel

A

Hydrocarbon made from the remains of a once living organism.

546
Q

Source rock

A

Organic rich mudsrone or shale which contained plankton which died in anoxic marine conditions

547
Q

Reservoir rock

A

Porus and permeable rock capable of storing significant amounts of hydrocarbons.

548
Q

Caprock

A

I permeable rock preventing further migration of hudrocarbons

549
Q

Sapropel

A

Organic rich deposit which becomes source rock.

550
Q

Maturation

A

Converts plankton to hydrocarbons by the effect of temperature

551
Q

Oil/gas window

A

The narrow pressure and temperature conditions which allow oil/gas to be formed.

552
Q

Migration

A

The movement of hydrocarbons from source to reservoir rock

553
Q

Trap

A

Geological situations that concentrate hydrocarbons

554
Q

Frazctional crystalisation

A

Higher melting point crystals fork first. They are metal rich. This leaves the magma relatively depleted in metals and becomes more silicic.

555
Q

Gravity settling

A

Crystals are more dense than magma so sink to the bottom of the chamber. Combined with fractional crystalisatuon you get cumulate layers where the layers are more silicic upwards due to the depletion of metals in the magma over time.

556
Q

Filter pressing

A

When enough crystalisatuon has occurred and the magma is more of a mush, the combined weight of the crystals in the magma squeezes the liquid magma out where it forms a layer above the crystals.

557
Q

Contamination of magma

A

Stopping and assimilation of xenoliths changes the bulk composition of the magma.

558
Q

Cumulate

A

Igneous rocks formed by the accumulation of crystals due to gravity settling and are typical of layered intrusions.

559
Q

Drift

A

The superficial deposits of glacial or fluvio glacial material. Basically sediments above mapped rock that aren’t really considered important as they only formed very recently. Alluvium refers to river deposits.

560
Q

Seismic refraction surveys

A

Drop something heavy or blow something up and see how the seismic waves travel through the rock. Slow = low density, fast = high density

561
Q

Unknown affinity

A

Unrelated to any know organism. Living or extinct.

562
Q

Disarticulation

A

Separation of body parts such as shells after death.

563
Q

Arthropods

A

Invertibrate organisms with jointed apendages, segmented body and an exoskeleton.

564
Q

Necrolytic features

A

Features associated with dramatic cause of death. Death throes in a dying animal. Can show destruction of tissue and cells in the organism.

565
Q

Synsedimentaru faults

A

Show displacement over an extended time period usually within sediments during deposition.

566
Q

Distributary

A

A stream channel that takes water away from the main channel.

567
Q

Cyclotherms

A

Layers repeated due to cyclic sedimentation

568
Q

Topsets

A

Uppermost layers of delta containing coarse sandstone, coal, seat earth

569
Q

Foresets

A

The inclined layers formed on the delta front. Cross bedded sandstones

570
Q

Seat earth

A

A sandy or clay rich fossil soil found beneath the coal seam. Soil in which coal forming plants formed. Trace roots.

571
Q

Bottom sets

A

The lowest horizontal layers of a delta commonly made of marine shapes or limestone.

572
Q

Banded iron formations

A

Units of sedimentary rock of precambrian age consisting of alternating layers of iron oxides and chert

OCR Geology A Level Definitions (1 decks)

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