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Flashcards in Geology Chapter 2 Deck (66):
1

Igneous Rocks

-Classified by composition and crystal size

-Created when magma cools

-Rapid cooling creates fine crystals, slow creates coarse crystals

-Mostly made of silicates

2

Felsic Rock

-Igneous rock

-Found in continental crust

-Mostly silicon and aluminum

3

Mafic Igneous Rocks

-Igneous rock

-Found in oceanic crust

-High in magnesium and iron

4

Sedimentary Rocks

-Produced by weathering, erosion etc,

-Contains a lot of skeletal / shell material and other sediments (clays, sand etc.)

5

Siliciclastic Rocks

-Sedimentary rocks

-Composed of silicate minerals such as quartz, feldspar and mafic

6

Conglomerate

Made from a variety of pebbles

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Clastic Rocks

Sorted by size

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Chemical Rocks

-Formed by evaporation of seawater

-Rich in halides and sulfates

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Carbonate Rocks

-Made from sediments

-Mostly tropical or subtropical

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Sedimentary Structures

-Ripples formed by wind and water

-Cracks

-Synsedimentary deformation (convolute bedding)

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Symmetrical Current

Ripples made by wind or water moving in two directions

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Asymmetrical Current

Ripples made by wind or water moving in one direction

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Desiccation

-Type of crack

-Extreme drying of rock

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Catastrophism

Belief that supernatural forces caused global floods that influenced rock

15

Actualism

-Belief that geological events should only be explained in terms of fact and recorded events

-Replaced catastrophism in the 19th century

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Abraham Gottlob Werner

-Supported catastrophism

-Believed rocks formed from minerals that precipitated in a sea that flooded the Earth

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James Hutton

-Promoted actualism

-Believed scientific processes created / destroyed rocks

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Charles Lyell

-Popularized actualism with publication of "Principles of Geology"

-Controversial ideas

-Believed in uniformitarianism

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Uniformitarianism

The belief that changes in the crust are due to chemical and biological processes

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Plate Tectonics

-Called continental drift

-Unifying theory of geology

-Predicts and explains geological phenomena (natural disasters, mountain formation, geography etc)

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Lithospheric Plates

-Sections of the lithosphere that move

-Some carry oceanic crust and others carry continental crust

-Movement of these plates is called plate tectonics

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Spreading Zones

-Plates move away from mid-oceanic ridges

-Forms new oceanic crust

-Plates move along the edges

-Also called Mid-Oceanic Rift

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Mid-Ocean Ridge

Heat from asthenosphere causes the spreading zones to swell and separate, causing a trench

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Transform Faults

-Plates slide along one another

-Strike-Slip fault

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Mantle Convection

Slow, creeping movements made by solid, uppermost mantle caused by heat currents coming from the Earth's surface

26

Subduction Zones

-Places where plates descend into trenches

-Partial melting of upper mantle

-Oceanic crust gets recycled

-Accretionary prism is formed

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Accretionary Prism

Welling of scraped up sediment piled on the upper plate in a subduction zone

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Divergent Boundaries

-Plates move apart

-Upwelling of magma from crust

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Convergent Boundaries

-Plates move together

-Descent of oceanic crust into mantle

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Plate Boundaries

-Associated with faulting

1. Normal faults - extension (divergent)

2. Reverse faults - compression (convergent)

3. Strike-Slip faults - sliding past (transform)

31

Continental Drift

-Created by Alfred Wegener

-Rotation of Earth caused Pangea to break apart and spread toward the poles

-Theory was incomplete and had no evidence

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Crust

-Upper most layer of Earth

-Oceanic crust / mafic rock

-High in iron and magnesium

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Mantle

-High in olivine

-Slushy consistency

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Core

-Solid iron inner core

-Liquid iron outer core

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Moho Discontinuity

Boundary between the crust and the mantle

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Lithosphere

Crust and solid uppermost mantle

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Asthenosphere

Upper, dutile mantle

38

Big Bang

-Occurred about 10b years ago

-Expansion > redshift > increase in light wavelength > galaxies move apart

-Around 2t galaxies

39

Our galaxy

-100-400b stars

-Formed less than 10b years ago by gravitational collapse of dense gas clouds

-Stars form by condensing in spiral arms

40

Sun

Formed by the collapse of a star

41

Supernova

Exploding star

42

Planets

-Formed from rotating dust clouds shortly after formation of the sun

-Inner planets: Mercury, Venus, Earth, Mars

-Asteroid Belt

-Outer planets: Jupiter, Saturn, Uranus, Neptune

-Oort Cloud

43

Meteorites

-3 types:

1. Stony

2. Iron

3. Stony-Iron

44

Comets

-Formed by ice and rock

-Come from Oort Cloud beyond Neptune

45

Early Earth

-Denser core

-Mostly molten iron

-Many meteorite attacks

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Earth now

-Solid / liquid core

-Cooler

-Formation of crust and mantle

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Moon

-Mars sized body of rock struck Earth; formed moon

-30-60m years after formation of Earth

-Small, metallic core

-No magnetic field

48

Mars

Polar ice caps, dust storms and water in soil

49

Atom

-Electrons

-Nucleus (protons and neutrons)

-Neutral charge

50

Atomic Number

= Number of protons

51

Mass Number / Atomic Weight

= Protons + Neutrons

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Isotopes

-Different atomic weight of same element

-Vary in number of neutrons

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Chemical Bonds

2 or more atoms forming a molecule

54

Covalent Bonds

-Electrons are shared

-Strongest bond

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Ionic Bond

One atom loses electrons to another

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Ion

-Charged atom

-Cation: positive charge

-Anion: negative charge

57

Crystal Lattice

-3D molecular structure of molecules

-Configuration related to size and number of ions

Note: some minerals (such as sapphires and rubies) are chemically the same, but impurities in their lattice will make them present as different minerals!

58

Mineral Properties

Hardness, density, crystal habit (shape), colour etc.

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Mineral Types

-Over 4500 known, but 2 dozen common types

-Silicates (olivine, feldspar, quartz etc.)

-Carbonates, sulfates, halides etc.

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Silicates

-Most common mineral

-Mostly formed from silica and oxygen

61

Lithification

-Process of sediments becoming rocks

-Neomorphism (recrystallization of CaCO3)

-Replacement (mineral transfer)

-Dissolution

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Metamorphic Rock

-Formed by high temperature and pressure

-Fluid composition

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Metamorphic Grade

Level of pressure / temperature at time of formation

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Regional Metamorphism

Formed by high pressure and temperature

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Contact metamorphism

Formed by high temperature with igneous intrustion

66

Sedimentary Environments

-Sediment created, deposited and recorded in marine or terrestrial environments

-Accumulation in sedimentary basins

-Characteristics provide evidence on how / when rock was formed

-Can contain paleosols (fossil soils) and lake (lacustrine) deposits