Midterm #1 Flashcards
1
Q
Geology
A
the study of the Earth
2
Q
scientific method
A
the derivation of an answer from a series of Qs
3
Q
scientific method steps (8)
A
- Q
- collect info
- generalize (eg. line of best fit)
- present an answer to hypothesis
- test it
- revise your answer
- theory
- law (rare)
4
Q
why study geo? (4)
A
- scientific curiosity
- env protection
- natural resources
- natural hazard awareness
5
Q
earth parts (4)
A
- crust
- mantle
- outer core
- inner core
6
Q
oceanic crust features (6)
A
- location: ocean basins
- mafic
- black
- 7-10km thick (thinner)
- melting point of about 1300 deg C (higher)
- higher density (about 3.0g/cm^3)
7
Q
continental crust features (6)
A
- location: emergent land masses
- felsic
- white
- 25-70km thick (thicker)
- melting point of about 700 deg C (lower)
- lower density (about 2.7g/cm^3)
8
Q
plate techtonics
A
the theory that the eths crust is broken up to pieces/plates that move
9
Q
mineral
A
a natural substance composed of a specific ratio of chem elements arranged in a reoccurring crystalline structure
10
Q
rock
A
an aggregate of one or more minerals
11
Q
magma
A
melted rock inside the eth
12
Q
lava
A
melted rock at or near the surface of the eth
13
Q
igneous rocks
A
form when melted rock cools and solidifies
14
Q
rock types (3)
A
- igneous
- sedimentary
- metamorphic
15
Q
sedimentary rocks
A
form when a pre-existing rock is weathered, eroded, transported, deposited, or precipitated, and then lithified
16
Q
weathering
A
how a rock falls apart/disintegrates
17
Q
erosion
A
the way rock fragments are set in motion
18
Q
transport
A
the way in which rock fragments move once they are in motion
19
Q
deposition
A
how a rock fragment stops moving
20
Q
precipitation
A
the creation of a new mineral crystal from elements in solution
21
Q
lithification
A
the transformation of loose sediment into solid rock
22
Q
metamorphic rock
A
form when a pre-existing rock is altered by heat and pres (w/ no sig melting)
23
Q
geological time scale (definition)
A
system of chronological measurement of the history of life (and extinctions) on eth
24
Q
anthropocene epoch (5)
A
- radiation (5:45am July 21 1945 first test of nuclear weapon)
- carbon
- charcoal
- concrete
- plastic
25
how fast do plates move?
about 1-6cm per yr
26
1500's
European exploration of the atlantic ocean (maps)
27
1700-1800's
industrial revolution; exploration for resources
28
1915
Alfred Wegener publishes The Origin of Continents and Oceans (continental drift)
29
continental drift theory was at first not well received b/c Wagener could not explain (2)
- the driving force btwn plate motion
| - what was going on in the oceans
30
1945-1960
improvements in tech and understanding -> today
31
the driving force behind plate motion
temp diffs
32
how plates move (4)
1. hot, liq rock rises by convection
2. rising body of rock cools as it approaches the surface (slows and is pushed sideways by rock beneath it)
3. cooler, heavier rock sinks back into the mantle
4. overlying crust is broken and pulled apart
33
convection currents
- cycle of moving rock in the mantle
| - driving force behind plate motion
34
4 types of plate margins
1. convergent
2. divergent
3. transform
4. passive
35
3 types of convergent plate margins
1. oceanic vs continental
2. oceanic vs oceanic
3. continental vs continental
36
continental vs oceanic convergent plate margin
- oceanic plate is subducted b/c it is heavier
- continental plate thickens
- mountains created
37
oceanic vs oceanic convergent plate margin
- chain of volcanic islands on the non-subducted plate is an island arc
- japan & aleutan islands in alaska
38
continental vs continental convergent plate margin
- no subduction, melting, or volcanism
| - himalayas
39
divergent plate margin
where plates pull apart
40
what happens at the rift between diverging plates?
as magma/lava is introduced into the rift and cools, new oceanic crust is created, which is then carried away by plate motion
41
transform plate margin
- plates move past each other side to side
| - no subduction melting or volcanism
42
passive plate margin
non active plate margin where 2 plates are joined and moving as a single unit
43
you can tell the orientation of the eths magnetic field by looking at what?
the arrangement of Fe in the rocks made at that time
44
what causes plate motion? (3)
1. convection currents
2. ridge push
3. slab pull
45
ridge push
as the ridge is pushed up, gravity pulls down and outward
46
slab pull
thick, old, heavy crust slides back into the mantle, pulling the rest of the plate w/ it
47
hot spots
areas of increased volcanism unrelated to plate margin (eg. volcanism in Hawaii)
48
asthenosphere
a layer of semi-liquid rock found in the lower crust and upper mantle over which continental crust can move
49
what is the asthenosphere based on?
density of mineral content
50
where does the asthenosphere form?
a depth where minerals begin to melt (between the mantle and crust)
51
what controls the melting of minerals?
heat and pres
52
heat
- geothermal grad
- causes minerals to melt
- inc w/ depth inside the eth
- near the surface the rate of temp inc is 25 deg C/km
53
pres
- prevents minerals from melting
- inc w/ depth inside the eth
- stops a rock from melting b/c if there is no room to expand they cannot melt
54
8 most common elements in the eths crust
1. O
2. Si
3. Al
4. Fe
5. Mg
6. Ca
7. Na
8. K
55
what % of the eths crust do oxygen and silicon make?
78%
56
8 most common minerals in the eths crust
1. quartz
2. plagioclase feldspar
3. potassium feldspar
4. muscovite
5. olivine
6. pyroxene
7. horneblende
8. biotite
57
felsic minerals contain more Al and are white. name 4
1. quartz
2. plagioclase feldspar
3. potassium feldspar
4. muscovite
58
mafic minerals contain more Mg + Fe and are black. name 4
1. olivine
2. pyroxene
3. horneblende
4. biotite
59
why are the 8 common minerals referred to as "silicate minerals"?
their bases and Si & O
60
crystalline structure
how a minerals grows
61
what shape is the basis for the crystalline structure in silicate minerals?
the tetrahedron
62
where are mafic minerals found?
oceanic crust
63
where are felsic minerals found?
continental crust
64
where are ultramafic minerals found?
mantle
65
oxides
based on O
66
sulfates
based on S + O
67
sulfides
based on S
68
native metals (3)
1. gold
2. silver
3. copper
69
carbonates
based on C + O
70
igneous intrusive rocks
form when magma cools and solidifies deep inside the eth
71
factors affecting the formation of magma (4)
1. heat
2. pres
3. presence of volatiles, such as w
4. type of minerals in the rock
72
which will form first, mafic or felsic minerals?
mafic (oceanic crust)
73
w (2)
1. promotes melting
| 2. deep inside the eth is superheated
74
felsic minerals melt at
lower temps (700 deg C)
75
mafic minerals melt at
higher temps (1300 deg C)
76
when magma cools, what forms?
rocks & minerals
77
Bowen's rxn series
a way of relating the 8 most common silicate minerals to explain how they form (olivine -> quartz)
78
pluton
solidified magma
79
country rock
what the pluton intruded into
80
the contact
the surface that separated the pluton from the country rock
81
the chill zone
- the outer layer of pluton next to eht country rock
| - small crystals b/c it cooled quicker
82
baked zone
- part of the country rock around the pluton
| - affected by the heat of the pluton -> changes colour
83
xenolith
a piece of country rock included in the pluton that was engulfed during formation
84
rocks and minerals formed from plutons typically have what size crystals?
coarse/large due to the long amounts of time it takes for the magma to cool and solidify into a pluton
85
decompression melting
a rock will melt when pres drops
86
when does decompression melting occur?
when a rock is moved closer to the surface, where pres is less
87
flux melting
melting inc when w is added
88
factors that affect magma once it forms (3)
1. partial melting
2. mixing magmas
3. assimilation
89
partial melting is when?
only part of the parent material melts
90
how do you know when magma is felsic in composition?
when it partially melts (felsic melts first)
91
magma mixing
magmas of diff mineral composition meet and mix to form a 3rd type
92
assimilation
the inclusion of other rocks/minerals, usually from the country rock, that will change the composition of the magma
93
crystal settling/fractional crystallization
the process whereby crystals form and settle to the bottom of the magma chamber to create diff textures and compositions
94
end result of crystal settling?
- a pluton/solid igneous intrusive rock that can have distinct layers of ultramafic, mafic, and felsic rock types
- coarse/large on the bottom & fine/small on the top
95
ultramafic rock contains
- olivine
- pyroxene
- horneblende
96
rock body definition
the shape and size of the rock once it is solid
97
2 types of rock bodies
1. deep
| 2. shallow
98
deep rock bodies
- large
- form slowly underground
- spherical (less affected by country rock)
99
shallow rock bodies
- form closer to the surface
- small
- more affected by nature of country rock
- faults, fractures, etc in the country rock determine shape of rock body (column, vertical dike, flat sill)
100
what are diamonds made of?
C
101
diamonds form
deep in the mantle under extreme pres
102
what differentiates it from its other C minerals?
crystalline structure
103
kimberlite
an ultramafic igneous extrusive volcanic rock that is the source of most diamonds
104
kimberlite eruptions
- small, short violent eruptions prod a small volcanic deposit onto the surface
- many occur w/in close proximity
105
do all kimberlites contain diamonds?
no
106
what type of crust are kimberlites found in?
only old archaean crust
107
kimberlite deposits in Canada
look for scratches on bedrock and find direction of glacial movement to map direction of potential kimberlite deposit
108
volcanic rocks are
igneous extrusive rocks
109
volcanic rocks form when (2)
1. lava cools and solidifies at or near the surface
| 2. rock fragments (plagioclastic debris) is ejected by a volcanoe
110
volcanoe
a hill/mountain that forms over a hole in the eths crust, out of which comes gas, lava, and plagioclastic debris
111
interior of a volcanoe (3)
1. crater
2. central vent
3. magma chamber
112
how are tsunamis created?
when a magma chamber/mountain collapses @ or beneath sea level
113
Plinian eruption
straight up
114
2 types of volcanoes
1. explosive (Krakatoa)
| 2. non-explosive (Hawaii)
115
non-explosive (7)
- location: oceanic plate
- mafic rock
- low lava viscosity
- low silicon content in rock (controls viscosity)
- low amount of trapped gas due to low viscosity
- common eruptions
- long eruptions
116
explosive (7)
- location: continental plate
- felsic rock
- high lava viscosity
- high silicon content (controls viscosity)
- high amounts of trapped gas due to high viscosity
- rarely erupts
- short eruptions
117
shield volcanoe
- low, wide, dome shaped
- a solid structure that forms when lava cools and solidifies
- eg. Hawaii
118
what are shield volcanoes created by?
a sustained outpouring of low viscosity lava
119
composite/strato volcanoe
- tall, steep sides feature that often stands out from flatter surroundings
- eg. Mt Baker
120
how are composite/strato volcanoes formed?
small amounts of lava and pyroclastic debris are ejected from the volcanoe by tiny eruptions
121
cinder cone
- small volcanic feature composed of pyroclastic debris
| - eg. Geribaldi volcanic complex
122
volcanic hazards (3)
1. volcanic gases
2. pyroclastic debris
3. columnar structure
123
most common volcanic gases (4)
1. w
2. CO2
3. sulfur dioxide (+ w forms sulfuric acid)
4. acid gases (hydrochloric & hydrofluoric)
124
pyroclastic debris (large)
explosive eruption will eject large rock fragments &cause local devastation
125
pyroclastic debris (ash)
ejected high in the atmos, affecting air travel and weather
126
lahar
mudflow associated w/ a volcanic eruption (liq cement; destructive)
127
glacial composite volcanoes
- were covered by glacier during formation
- prone to collapse after glaciers melt
- adds to landslides after eruption
128
columnar structure
hexagonal column of rock
129
what does the columnar structure mean for cooling?
- layer of hot uniform rock
- same thickness and type of rock
- shrinks/contracts, creating cracks
130
formation of the eth (7)
1. formed from the concentration of a nebula
2. heat was generated by radioactive decay + conversion of kinetic E to heat E
3. formed a hot, molten, homogenous mass (rocks mixed)
4. eth cooled and minerals started to separate into a core, mantle, and crust (heavy minerals sank, light floated to surface)
5. liq w on the surface came from degassing of the crust as it cooled + comets' impact
6. early atmos came from degassing crust (O came later from Photosynth activity by microorganisms)
7. life
