Geology Midterm Flashcards
(91 cards)
1
Q
Stratigraphy
A
Geological time record
2
Q
Stratigraphic Unit
A
- Includes strata that are distinguishable by physical, chemical or paleontological properties
- Units of time based on age of strata can make up a unit
3
Q
Strata
A
- Layer of igneous or sedimentary rocks formed on the surface
- Characteristics distinguish it from other strata
4
Q
Correlation
A
Relationship between seperate parts of a stratigraphic unit
5
Q
Lithologic Correlation
A
Correlation based on rock type
6
Q
Temporal Correlation
A
Correlation based on age
7
Q
Time-Rock Unit
A
- All strata deposited at a certain time
- Geological system = time-rock unit (Chronostratigraphic Unit)
8
Q
Time Unit
A
Interval where a time-rock unit is formed (Geochronologic Time Unit)
9
Q
Geologic System
A
Section of the geologic time scale
10
Q
Erathem
A
- Groups of eras (time units)
- Erathems subdivided into series, then further subdivided into stages
11
Q
Epochs / Ages
A
Corresponding time units for subdivided time-rock units
12
Q
Boundary Stratotype
A
Boundary between two systems, series or stages
13
Q
Biostratigraphic Unit
A
- Defined by fossil content
- Based on stratigraphic range of fossil taxa
14
Q
Stratigraphic Range
A
Vertical range in which species show up in a stratigraphic unit
15
Q
Biozone
A
- Fundamental biostratigraphic unit
- Lower and upper boundaries of the biozone are determined by the ranges of taxa
16
Q
Taxa
A
Group of one or more populations of an organism or organisms that form a unit
17
Q
Index / Guide Fossil
A
- Taxa that provide a reliable source for defining biostratigraphic zones
- Exhibits some or all characteristics:
1. Found easily in stratigraphic record
2. Easily distinguishable
3. Widespread and can be used to correlate rocks over a wide area
4. Narrow stratigraphic range
18
Q
Magnetic Stratigraphy
A
Correlation based on magnetic properties of rocks
19
Q
Polarity Time-Rock Unit
A
Time-rock unit where the Earth’s polarity is either the same as it is now (Normal Interval) or the opposite as it is now (Reverse Interval)
20
Q
Chron
A
Polarity time-rock unit
21
Q
Rock Unit
A
- Groups, supergroups, formations and members
- Lithostratigraphic units
- Groups > Formations > Members
- Supergroups are made of multiple groups
22
Q
Lithology
A
Physical or chemical characteristics of a rock
23
Q
Stratigraphic Segement
A
- Vertical section of a rock unit
- May contain more than one rock unit
24
Q
Type Section
A
- Well-preserved section of a stratigraphic segment
- Defines the unit
25
Regression
Shoreline migrates seaward
26
Transgression
Sealine migrates shoreward
27
Facies
Characteristics of a body of rock that represents a depositional enivronment
28
Depositional Environment
Sediments, soils and rocks added to an environment
29
Nicolaus Steno
- Discovered how to relatively age rocks
| - His method only worked within stratigraphic segments
30
William Smith
Discovered that fossils can be used to determine relative ages of unrelated rocks
31
Baron George Cuvier
- First to discover species go extinct
| - Did not make the hypothesis that new species come
32
Geologic Systems
- Bodies of rock that contain specific fossils of flora or fauna
- Each geologic system corresponds to a geologic period
33
Relative Age Dating
Age of rocks in relation to other rocks
34
Absolute Dating
Actual numeric age of rocks
35
Fossil Succession
- Helps determine relative age of rocks
| - Vertical order of fossils in a stratigraphic segment
36
Fossil Record
Key to determining Geological Time Scale
37
Catastrophism
Belief that global floods were caused by supernatural forces
38
Actualism
- Events explained in terms of fact and physical processes
| - Replaced catastrophism in the nineteenth century
39
Abraham Gottlob Werner
- Supported catastrophism
| - Believed rocks formed from minerals that precipitated in a sea that occasionally flooded Earth
40
James hutton
- Promoted actualism
- Believed scientific processes created / destroyed rocks
- Theory focused on geologic time
41
Charles Lyell
- Popularized actualism with publication of 'Principles of Geology'
- What we see in the present is the key to the past
- Uniformitarianism
- Theory focused around geologic time
42
Plate Tectonics
-Used to be called continental drift
- Unifying theory of geology
- -Connects all current theories
- Predicts and explains geological phenomena
- Helps explain natural disasters, mountain formation, geography etc.
43
Lithospheric Plates
- Sections of the lithosphere that move
- Some carry oceanic crust, others carry continental crust
- Plate tectonics
44
Spreading Zones
- Plates move away from mid-oceanic ridges
- Forms new oceanic crust
- Plates move along the edges
- Also called Mid-Oceanic Rift
45
Mid-Ocean Ridge
Heat from asthenosphere causes spreading zone to swell and separate
46
Transform Faults
Surfaces where plates slide against one another
47
Mantle Convection
- Hot material rises from asthenosphere
- Cools as it rises
- Denser material drifts closer to the crust
48
Subduction Zones
- Places where plates descend (oceanic trenches)
- Caused by partial melting of upper mantle
- Subducted oceanic crust recycled
- Forms new sediment (accretionary prism)
49
Divergent Boundaries
- Plates move apart
| - Upwelling of magma creates new crust
50
Convergent Boundaries
- Plates move closer together
- One plate moves on top of another
- Oceanic crust descends into mantle
51
Plate Boundaries
- Associated with faulting
1. Normal faults - extension (divergent)
2. Reverse faults - compression (convergent)
3. Strike-Slip faults - plates sliding past one another (transform)
52
Continental Drift
- Now called plate tectonics
- Rotation of Earth caused Pangea to split apart and drift towards the poles
- Created by Alfred Wegener
- This theory was too incomplete and thus had little relevance
53
Crust
- Upper most layer of the Earth
- Hard
- Oceanic crust / mafic rock
- -High in iron / magnesium
54
Mantle
- Found below the crust
| - Slush-like consistency
55
Core
- Inner core is solid iron
| - Outer core is liquid iron
56
Moho Discontinuity
Boundary between the crust and the mantle
57
Lithosphere
Crust and solid, uppermost mantle
58
Asthenosphere
Upper, dutile mantle
59
Big Bang
- Occurred 10B years ago
- Expansion > redshift > increase in light wavelength > galaxies move apart
- ~ 2 Trillion galaxies
60
Our Galaxy
- ~ 100-400 Billion stars
- Formed <10B years ago
- Formed from gravitational collapse of dense gas clouds
- Stars form by condensing in spiral arms
61
Sun
Formed by the collapse of a star
62
Supernova
Exploding star
63
Planets
- Formed from rotating dust clouds shortly after the sun formed
- Inner planets: Mercury, Venus, Earth, Mars
- Asteroid Belt
- Outer planets: Jupiter, Saturn, Uranus, Neptune
- Oort Cloud
64
Meteorites
3 types:
1. Stony meteorites
2. Iron meteorites
3. Stony-iron meteorites
- Small asteroids
65
Comets
- Made of ice and rock
| - Come from Oort cloud beyond Neptune
66
Early Earth
- Denser core
- Mostly molten iron
- Many meteorite attacks
67
Earth Now
- Cooler
- Solid inner core, liquid outer core
- Slushy mantle and crust
68
Moon
- Formed when a Mars sized body hit Earth and created debris
- Formed 30-60M years after formation of Earth
- Small, metallic core
- No magnetic field
69
Mars
-Polar ice caps and dust storms
- Water in soil
- -Used to contain a lot of water
70
Atoms
- Electrons
- Nucleus (protons and neutrons)
- Neutral charge
71
Atomic Number
= Number of protons
72
Mass Number / Atomic Weight
= Protons + neutrons (nucleons)
73
Isotopes
- The same elements with different atomic weights
| - Vary in number of neutrons
74
Chemical Bonds
- 2 or more atoms form a molecule
| - Reaction: formation of molecule
75
Ion
- Charged atom
- Cation: positively charged
- Anion: negatively charged
76
Ionic Bond
Atom loses electron to other atom
77
Covalent Bonds
- Atoms share electrons
| - Stronger bonds
78
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!
79
Mineral Properties
Hardness, density, crystal habit (shape), colour etc.
80
Mineral Types
- Over 4500 types
- 2 dozen common types
- Silicates
- -Silicon, oxygen
- -Most common
-Carbonates, Sulfates, Halides etc.
81
Igneous Rocks
- Defined by composition and crystal size
- Created by cooling magma
- Cooling rate defines crystal size
- -Rapid: fine grain crystals
- -Slow: coarse grain crystals
- Composition:
- -Mostly silicates
- -Felsic (granite)
- -Mafic (basalt)
82
Sedimentary Rocks
- Produced by weathering, erosion, depositions etc.
- Contains skeletal and shell material
- Siliciclastic rock
- -composed of silicate minerals
83
Conglomerate
Made from pebbles
84
Clastic Rocks
- Rocks sorted by grain size
| - Poorly sorted = mixed grain sizes
85
Chemical Rocks
- Evaporites
- -From seawater
- -Halides and sulfates are common
-Chert / Silica (flint)
- Carbonate Rocks
- -Sediments
- -Mostly tropical / subtropical
86
Sedimentary Structures
-Ripples formed by wind or water
- Cracks (synsedimentary deformation)
- -desiccation
- -intrastratal shrinkage
- -sediment injection
- -convolute bedding
87
Lithification
- Process of sediments becoming rocks
| - Neomorphism, replacement and dissolution
88
Neomorphism
Recrystallization of CaCO3
89
Metamorphic Rocks
Created using high temperature and pressure
90
Metamorphic Grade
Level of pressure / temperature at time of alteration
91
Sedimentary Environments
- Sediments created, deposited and recorded in oceanic or continental environments
- Accumulate in sedimentary basins
- Characteristics of rock provide evidence on how / when the rock formed
- Can contain paleosols (fossil soils) and lake (lacustrine) deposits
