Midterm Flashcards
1
Q
What is the process by which Earth formed from the gas and dust of the protoplanetary disk?
A
Accretion
2
Q
What is the process by which Earth became divided into layers?
A
Differentiation
3
Q
From the surface to the center, Earth’s chemical (compositional) layers are
A
Answer 1:
continental crust
Answer 2:
oceanic crust
Answer 3:
mantle
Answer 4:
core
4
Q
From the surface to the center, Earth’s mechanical (physical) layers are
A
Answer 1:
lithosphere
Answer 2:
aesthenosphere
Answer 3:
mesosphere
Answer 4:
outer core
Answer 5:
inner core
5
Q
lithosphere
A
crust and mantle
6
Q
asthenosphere
A
mantle
7
Q
mesosphere
A
mantle
8
Q
outer core
A
core
9
Q
inner core
A
inner core
10
Q
Which elements make up most of the continental crust?
A
aluminum
silicon
calcium
sodium
potassium
oxygen
11
Q
Which elements make up most of the oceanic crust?
A
aluminum
calcium
oxygen
silicon
iron
12
Q
Which elements make up most of the mantle?
A
magnesium
oxygen
iron
silicon
13
Q
Which elements make up most of the core?
A
nickel
iron
14
Q
What are the three properties of the lithosphere that affect isostasy, or how it floats on the asthenosphere?
A
temperature
density
thickness
15
Q
describes large-scale sweeping beds that cut each other at angles
A
cross bedding
16
Q
form in a water current running one direction
A
asymmetric ridges
17
Q
form in wind-blown sand dunes
A
cross bedding
18
Q
form in a water current moving back and forth
A
symmetric ripples
19
Q
form in coastal environments
A
symmetric ripples
20
Q
form in river environments
A
assymetric ripple
21
Q
rift basins
A
Lithosphere stretches horizontally, thus thinning vertically
Typically narrow, often asymmetrical
Bordered by tall, thin mountain ranges
22
Q
Foreland basin
A
A fold-thrust belt develops at an ocean-continent subduction zone and its weight depresses the crust
Very asymmetric, deepest part of basin runs along base of mountains
Similar to a rift valley (asymmetric shape, bordered by tall mountains) but much wider
23
Q
Passive margin basin
A
Edge of a continental rift that has become an ocean basin
Subsidence caused by cooling of crust (cold rocks are denser and sink down into the asthenosphere) and weight of sediment
Very deep and very expansive – 90% of sedimentary rocks form in passive margin basins
24
Q
A relative rise in sea level is known as ____________ which results in clast sizes getting ____________, while a relative drop in sea level is known as ____________ and results in clast sizes getting ____________.
A
transgression, smaller, regression, bigger
25
mountain river environment.
large (boulder to gravel) clasts
immature clast composition (arkosic/lithic)
moderately rounded clasts
moderate sorting of clasts
26
deposited in sand dunes.
sand-sized clasts
well rounded clasts
well sorted clasts
crossbedding
27
crossbedding
mud-sized clasts
mature clast composition (quartz/clay)
well rounded clasts
well sorted clasts
28
29
deposited on beaches.
sand-sized clasts
mature clast composition (quartz/clay)
well rounded clasts
well sorted clasts
symmetric ripples
30
deposited in tidal flats.
sand-sized clasts
mud-sized clasts
mature clast composition (quartz/clay)
crystals composed of gypsum or halite
well rounded clasts
well sorted clasts
symmetric ripples
31
too much water from a long period of rain or snowmelt
seasonal flood
32
relatively quick development and short duration
flash flood
33
water comes too quickly to soak into ground, or for rivers to move away
flash flood
34
relatively slow development and long duration
seasonal flood
35
can linger for months before floodwaters recede
seasonal flood
36
can occur too quickly for a person to escape
flash flood
37
Where does flooding occur in a meandering river system?
The flood fills the entire river valley
38
What can be done to protect against seasonal floods?
build dams to regulate water flow
build dikes and levees
breach levees and flood less valuable areas to protect more valuable areas
39
What can be done to protect against flash floods?
get to high ground if it rains
watch the weather forecasts and avoid flood-prone areas if rain is forecast
get to high ground immediately if river flow increases or turns muddy
build flood control basins
40
What is monitored to predict flooding?
predicted precipitation
current snowpack
ground saturation
current streamflow
41
rich in Na, K, Al
felsic
42
associated with high temperatures
mafic
43
rich in Mg, Fe
mafic
44
viscous (thick and sticky)
felsic
45
associated with lower temperatures
felsic
46
light colors
felsic
47
low silica content
mafic
48
low viscosity (thin and runny)
mafic
49
high silica content
felsic
50
dark colors
mafic
51
Which of the following are the processes by which magma is melted from the mantle?
decompression, flux, heat transfer
52
Which of the following are the processes that modify the composition of magma after it is produced, as it travels through the crust?
assimilation, fractional crystalization
53
Decompression melting occurs at
----------
plate boundaries and mantle
---------- .
Flux melting occurs at
-----------
zones.
divergent
plumes
subduction
54
andesite/diorite
intermediate
55
rhyolite/granite
felsic
56
basalt/gabbro
mafic
57
peridotite
ultramafic
58
dacite/granodiorite
felsic
59
Igneous rocks with no visible crystals
phaneritic
60
igneous rocks with all visible crystals
aphanitic
61
Igneous rocks with a mix of microscopic and visible crystals
porphyritic
62
Which of the following are the diagnostic features we use to tell minerals apart?
color
crystal habit (shape)
streak
cleavage
luster
hardness
density
63
True or False: a mineral with cleavage planes can also break not along a cleavage plane.
True
64
olivine?
olive green
Silicate
Vitreous
conchoidal fracture
6.5 to 7
65
pyroxene?
dark green to dark brown or black
Silicate
Vitreous to dull
two directions of cleavage that intersect at approximately 87o and 93o.
5 to 7
66
amphibole?
Chemical Classification Silicate
Color Usually black, dark green, dark brown
Streak White, colorless – (brittle, often leaves cleavage debris behind instead of a streak)
Luster Vitreous
Diaphaneity Translucent to nearly opaque
Cleavage Two directions intersecting at 124 and 56 degrees
Mohs Hardness 5 to 6
67
calcium plagioclase feldspar?
Usually white or gray. Also colorless, yellow, orange, pink, red, brown, black, blue, green.
Silicate
translucent
Perfect in two directions that intersect at approximately 90 degrees.
6 to 6.5
68
sodium plagioclase feldspar?
Usually white or gray. Also colorless, yellow, orange, pink, red, brown, black, blue, green.
Silicate
translucent
Perfect in two directions that intersect at approximately 90 degrees.
6 to 6.5
69
potassium feldspar?
70
mica (both light and dark)?
Color Purple, rosy, silver, gray (lepidolite)
Dark green, brown, black (biotite)
Yellowish-brown, green-white (phlogopite)
Colorless, transparent (muscovite)
Cleavage Perfect
Fracture Flaky
Mohs scale hardness 2.5–4 (lepidolite)
2.5–3 biotite
2.5–3 phlogopite
2–2.5 muscovite
Luster Pearly, vitreous
Streak White, colorless
Specific gravity 2.8–3.0
Diagnostic features Cleavage sheets
71
quartz?
Quartz occurs in virtually every color. Common colors are clear, white, gray, purple, yellow, brown, black, pink, green, red.
Streak Colorless (harder than the streak plate)
Luster Vitreous
Diaphaneity Transparent to translucent
Cleavage None - typically breaks with a conchoidal fracture
Mohs Hardness 7
72
What are the three types of plate boundary?
What are the three types of plate boundary?
73
Lithosphere is created at
-
plate boundaries.
divergent
74
Lithosphere is destroyed at
-
plate boundaries.
convergent
75
Lithosphere is neither created nor destroyed at
-
plate boundaries.
transform
76
What does the orientation of mid-ocean ridge segments tell you about the direction of plate motion?
Plate motion is perpendicular to mid-ocean ridge segments
77
What are the three different types of convergent plate boundary?
ocean-continent subduction zone
continental collision
ocean-ocean subduction zone
78
In order from the front of the forearc to the backarc, the features of a standard ocean-continent subduction zone are:
trench
Answer 2:
accretionary prism
Answer 3:
forearc basin
Answer 4:
volcanic arc
Answer 5:
fold and thrust belt
Answer 6:
foreland basin
79
How do the thickness of the crust and mantle lithosphere change at convergent plate boundaries?
the crust thickens and the mantle lithosphere thickens slightly
80
How do the thickness of the crust and mantle lithosphere change at divergent plate boundaries?
the crust becomes thinner by collapsing and the mantle lithosphere pinches out
81
The force of moving water plucks up and tears away material from the channel, including solid rock
scouring
82
Sediment carried by the river acts as sandpaper, scouring away material from the channel bottom
abrasion
83
Slightly acidic river water dissolves the rock of the river channel
dissolution
84
steep gradient
carries large, sand-sized, and mud-sized clasts; deposits large clasts
deep, narrow valleys
primarily vertical erosion
deep, narrow valleys
straight river
high energy
low sinuosity
straight river
85
wide, shallow valleys
high sinuosity
primarily horizontal erosion
carries finer sand-sized and mud-sized clasts, deposits finer sand-sized and mud-sized clasts
low energy
gentle gradient
meandering river
86
medium energy
carries coarser sand-sized and mud-sized clasts, deposits sand-sized clasts
transition from steep to gentle gradient
braided river
87
How can superposed drainage come to be?
change in river gradient
uplift of mountains around a river
differential weathering of rocks around a river
88
The base level of a river is
the elevation at the river's mouth
the lowest elevation a river can erode to
89
A drop in base level ____________ a river's energy, leading to an increase in ____________, while a rise in base level ____________ a river's energy, leading to an increase in ____________.
increases, erosion, decreases, deposition
90
List the three categories of sedimentary rock discussed in the powerpoint slides:
Answer 1:
clastic
Answer 2:
biogenic
Answer 3:
chemical
91
The four properties of clastic sedimentary rocks that we study are:
Answer 1:
size
Answer 2:
composition
Answer 3:
roundness
Answer 4:
sorting
92
Biogenic rocks that have visible fossil fragments are described as
-
, whereas biogenic rocks that are made of microscopic fragments or calcite crystals are described as
-
Answer 1:
fossiliferous
Answer 2:
muddy
93
Which conditions are necessary for the life that produces biogenic rocks to flourish? In other words, when you see a biogenic rock, what does it tell you about conditions when the rock formed?
warm water, not too hot
shallow water
clear water
not too salty
94
Chemical sedimentary rocks are
minerals that grow out of water as the water evaporates
95
large clasts (gravel or larger)
conglomerate
96
medium clasts (smaller than gravel but large enough to see)
sandstone
97
small clasts (too small to see)
mudstone
98
broad, gentle slopes
dark, mafic lava
effusive (gentle) eruptions
very large overall size
shield volcano
99
explosive eruptions
steep slopes
relatively small overall size
light, felsic to intermediate lava
composite volcano
100
What are the two factors that determine whether a volcano erupts effusively or explosively?
magma composition and water content
101
Shield volcanoes usually occur where
-
melting occurs in the mantle, which occurs at
-
plate boundaries and
mantle
-.
Composite (strato) volcanoes usually occur where
-
melting occurs in the mantle, which occurs at
-
zones.
Answer 1:
decompressing
Answer 2:
divergent
Answer 3:
mantle
Answer 4:
flux
Answer 5:
subduction
102
What is a phreatic eruption?
an explosive eruption powered by magma coming in contact with water or ice
103
True or false: phreatic eruptions are common at mid-ocean ridges
False
104
true or false: Calderas are much larger than normal volcanic craters. They form during explosive eruptions when the ground collapses into the empty magma chamber
true
105
Which of the following are the volcanic hazards discussed in class?
pyroclastic flows
lahars
lava flows
toxic gasses
ash clouds
ash fall
earthquakes and landslides
volcanic blast
106
Four things that can be mointored on a volcano to try and predict an eruption are
Answer 1:
earthquake activity
Answer 2:
heat flow
Answer 3:
movement
Answer 4:
shape
Answer 5:
gas emissions
107
The two general types of weathering are
physical
Answer 2:
chemical
108
Chemical weathering will dominate in
wet climates
109
The three types of wedging we discussed are
Answer 1:
root
Answer 2:
salt
Answer 3:
frost
110
Cracks in rocks that form from pressure on the rock are called ____________.
joints
111
____________ is the process by which phaneritic igneous rocks crack into rounded layers when exposed at the surface.
exfoliation
112
What are the products of chemical weathering listed in the powerpoint?
clay minerals
quartz
dissolved ions
hematite (rust)
113
True or false: Not all the minerals in a rock dissolve during chemical weathering. Some are left over, mixed with the weathering products.
True
114
A valley formed by the weathering and erosion of a softer rock layer is called a ____________ valley.
strike
115
Continental crust
25-70 km
116
Oceanic crust
5-10 km
117
Mantle
2900 km
118
Core
32 km
119
Lithosphere
15-300 km
120
Aesthenosohere
100-700 km
121
Mesosphere
35 km
122
Outer core
2200 km
123
Inner core
1250
124
