Which of the following scenarios best describes how the Hawaiian Islands formed in the Pacific Ocean?
answer
Magma generated from a hot spot burned through the overlying plate to create volcanoes
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Which materials in Hawaii's lava help to keep it fluid for longer at the surface (as opposed to cooling and solidifying quickly), thus allowing extensive lava flows to develop?
answer
magnesium and iron
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Which of Hawaii's five volcanoes are still considered to be active?
answer
Kilauea and Mauna Loa
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Which of the following has the single most immediate effect on lava's ability to solidify?
answer
temperature
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What is piled up along the cone of SP Crater that causes it to be so steep?
answer
cinders
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What causes vesicles to form in lava?
answer
trapped gas bubbles
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What is the difference between aa lava and pahoehoe lava?
answer
Aa lava has a prickly texture; pahoehoe has a smooth, ropy texture.
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What is one way that cinder cones differ from composite and shield volcanoes?
answer
Cinder cones are smaller than composite and shield volcanoes.
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Which lava is thicker Basaltic or andesitic?
answer
andesitic lava
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What features at Yellowstone National Park is evidence for a magma chamber beneath the park?
answer
Geysers and hot springs (steam), Welded tuff, Rising (or bowing upward) ground near Yellowstone River
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What pieces of evidence for a past volcanic eruption are present at Yellowstone National Park?
answer
A caldera rim, Pyroclastic material, Lava flows
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Yellowstone is best described as an active, dormant, or extinct volcano?
answer
An active volcano that has erupted in the last 1 million years
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What was a stage in the formation of Yellowstone caldera?
answer
Crust bows upward above a magma chamber.
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How are igneous rocks formed?
answer
Igneous rocks are formed by the cooling and crystallization of molten rock.
question
Intrusive and extrusive igneous rocks are classified based on what criteria?
answer
How quickly the molten rock cools and crystallizes, and where this occurs with respect to Earth's surface
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What is required to generate an igneous rock with a fine-grained texture?
answer
rapid cooling and crystallization
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A phaneritic texture is characteristic of a(n) __________ igneous rock that cooled __________.
answer
intrusive; below the surface
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What does it mean if an igneous rock has an aphanitic texture?
answer
The igneous rock exhibits mineral crystals too small to see with the naked eye.
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Ultramafic rocks contain __________ and are commonly found in __________.
answer
olivine; mantle
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What is an accessory mineral?
answer
A mineral that makes up a relatively small portion of the total rock composition
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What is the difference between granite and rhyolite?
answer
Granite is phaneritic and rhyolite is aphanitic.
question
Andesite porphyry
answer
an intermediate rock with two distinct grain sizes
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What do pumice and scoria have in common?
answer
They both exhibit a vesicular texture.
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What factors describe the metamorphic conditions at a mid-ocean ridge?
answer
low pressure; hot, watery fluids; low temperature
question
What factors describe the metamorphic conditions in a subduction zone?
answer
high pressure and low temperature
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What is an example of a metamorphic rock?
answer
gneiss
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Which of the following is a temperature associated with metamorphism?
answer
400 degrees Celsius
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What role does hot ion-rich water play in the process of metamorphism?
answer
Water migrates into host rock carrying ions to stable minerals in order to facilitate growth of new metamorphic minerals.
question
By what process did the gabbro turn into amphibolite?
answer
The gabbro was heated to 500 °C and buried a few miles below the Earth's surface.
question
What is a mantle plume?
answer
hot mantle rock rising from deep within the Earth
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What kind of metamorphic texture results in the segregation of light and dark mineral bands?
answer
gneissic texture
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Why are garnets used in sandpaper?
answer
Garnets have a value of 8 or 9 on the Mohs Hardness Scale, making them very abrasive.
question
Define depositional environment?
answer
an area where sediment was deposited under certain conditions in Earth's past
question
What is a delta?
answer
A delta is a triangular landform created where a stream enters a body of water and deposits sediment.
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Other than sand dunes in a desert environment, where else would you expect to find well-rounded and sorted sand deposits?
answer
beach
question
Describe the distribution of sedimentary deposits you would expect to find on a delta.
answer
sand in channels, mud on floodplain
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If all the particles in a detrital sedimentary rock are nearly the same size, it is __________.
answer
very well sorted
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A smooth grain shaped like a cigar is __________ and shows __________.
answer
well-rounded; low sphericity
question
Wind-blown sand deposits would most likely be __________ and __________.
answer
very well-sorted; well-rounded
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Which of the following correlate to transport distance?
answer
grain size and rounding
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A conglomerate is poorly sorted with well-rounded grains. This rock was likely formed in what depositional environment?
answer
mountain stream
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Igneous rocks
answer
formed by the solidification of melts
question
Sedimentary rocks
answer
formed by cementing of grains from pre-
existing rocks, or precipitation of minerals from water solution
question
Metamorphic rocks
answer
formed when preexisting rock is changed by heat or pressure
question
Igneous rock classification is based on
answer
composition and texture
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Composition reveals
answer
melt source
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Texture reveals the
answer
cooling history
• Fast cooling—smaller crystals.
• Slow cooling—larger crystals.
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Felsic magma
answer
70% silica.
-Continental composition and light color.
50% silica.
-Ocean floor composition and dark color.
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Ultramafic magmas
answer
less than 50% silica.
-Mantle composition.
question
Bowen's Reaction Series
answer
Shows that mafic minerals form at higher temperatures than felsic minerals
question
Intrusive
answer
formed by freezing of magma below ground.
question
Extrusive
answer
formed by freezing of lava above ground.
question
Dike
answer
vertical, wall-like intrusion
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Sill
answer
horizontal, tabular intrusion
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Active volcanoes
answer
have records of historic eruptions.
question
Dormant volcanoes
answer
show evidence of activity in past hundred to thousand years, but no historical eruptions are known.
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Extinct
answer
eroded, has not erupted in thousands—if not millions—of years.
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Most volcanic hazards are associated with
answer
convergent plate tectonic boundaries.
(Think Pacific Ring of Fire)
question
Viscosity
answer
internal resistance to flow. Magma viscosity corresponds with silica content, as silica tends to polymerize.
question
Felsic and intermediate magmas
answer
higher silica, high viscosity, tend to explode.
question
Mafic magmas
answer
lower silica, low viscosity, tend to flow.
question
Tilt meters
answer
measure changes in ground surface as a result of moving magma
question
Seismographs
answer
measure earthquakes associated with magma movements.
question
Gas monitoring
answer
can indicate changes in magma composition.
question
Lava domes
answer
are small, bulbous masses made of high silica lava that does not flow easily.
question
Caldera
answer
large circular depression that forms following large explosive eruption and/or collapse of magma chamber
question
Flood Basalts
answer
broad, flat plains of volcanic rock.
(Low silica magmas may also erupt from fissures in continental settings.)
question
Cinder cones
answer
are small volcanic hills composed of tephra—fragments of volcanic material ranging in size from ash to boulders.
(Cinder cones usually one-time events)
question
Sediment
answer
loose fragments of rocks or minerals, mineral crystals that precipitate from water solution, and shells formed from organisms.
question
Sedimentary rock
answer
forms at or near surface from cementation of loose grains, precipitation of minerals from solution, or cementation of shell fragments.
question
Weathering
answer
processes that break up and/or corrode solid rock, eventually transforming it into sediment.
question
What are two categories of weathering
answer
physical and chemical
question
Physical (mechanical) weathering
answer
breakup of rocks into unconnected grains or chunks without changing the rock's chemistry.
question
Joints
answer
natural cracks formed in rocks due to cooling or removal of overburden
question
Exfoliation
answer
formation of onion-like sheets parallel to rock surface. Common in granites.
question
Talus
answer
accumulation of loose bedrock blocks forming an apron of rubble at the base of a slope
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Wedging
answer
expansion of a joint by external agent
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Frost wedging
answer
expansion of joint by ice
question
Root wedging
answer
expansion of joint by root.
question
Salt wedging
answer
expansion of joint by precipitated salt crystals.
question
Chemical weathering
answer
changes in a rock's mineral composition leading to breakdown of the rock.
question
Dissolution
answer
minerals dissolved by water
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Fastest Weathering has what kind of stability?
answer
Least Stable
question
Slowest Weathering has what kind of stability?
answer
Most Stable
question
Physical weathering aids chemical weathering by
answer
creating surface area.
question
Chemical weathering aids physical weathering by
answer
weakening the attachments between grains.
question
Clastic (detrital) sedimentary rock type is
answer
cemented-together fragments and grains derived from pre-existing rocks.
question
Chemical sedimentary rock type is
answer
composed of minerals that precipitate from water solutions. Usually carbonates, e.g., limestone.
question
Lithification
answer
compaction and cementation
-transforms loose sediment into rock.
question
Weathering that forms clastic rocks creates
answer
sediment
question
Erosion
answer
removes sediment from source
question
Transportation
answer
moves sediment by wind, water, or ice to a new location
question
Deposition
answer
allows sediment to settle from its transporting medium
question
Limestone
answer
rocks made from carbonate minerals, e.g., calcite.
question
Carbonate minerals precipitate in
answer
clear warm shallow water:
- Common in low latitudes.
- Common in shallow water.
- Not much clastic sediment.
question
Chert, a Chemical Sedimentary Rock, is composed of
answer
cryptocrystalline
question
Evaporites, a Chemical Sedimentary Rock, is formed by
answer
evaporation of saltwater.
question
Dolostone
answer
formed by replacing calcite in limestone with dolomite CaMg(CO3)2
question
Travertine
answer
calcite precipitated in layers
question
Coal
answer
Sedimentary rock with 50% or more organic material.
question
Acid
answer
is a proton donor
question
Foliation is in what direction to the differential stress
answer
perpendicular
question
What is the protolith of Quartz
answer
sandstone
question
What is the protolith of Marble
answer
Carbonate like limestone or calcite
question
What is the protolith of Hornsfell
answer
various rock types with high temp and low differential type
question
Metamorphic rock can be found
answer
local to the heat source
question
What are examples of volcanic glass?
answer
obsidian and pumice
question
Name the kind of volcanoes from largest to smallest
answer
Shield, Strata, Cinder
question
What is a lahar
answer
ash + water, mud flow
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