GEOL-1010 Exam

What would be a location where sediment is deposited, but not eroded?

A delta (where river meets the ocean and energy levels plummet) When sediment is deposited, it is because whatever was carrying it (ice, water, wind) no longer has the energy to do so.

What is one difference between a joint and a fault?

A fault displaces the rocks on one side relative to another.

Which of the following is m most likely to occur at shallow crustal levels (less than 15km depth)?

Brittle behavior

What is the main hazard of a rhyolitic caldera?

Burning, building collapse and suffocation from an eruption column and pyroclastic flows

Sedimentary rocks can form:

By the precipitation of minerals from water solution, by the cementing together of loose grains of preexisting rock, from shell fragments or carbon-rich relicts of plants The precipitation of minerals from water solution is called chemical sedimentary rock; the cementing together of loose grains of preexisting rock is called clastic sedimentary rock. Despite the fact organisms are involved, shell material and plant material do constitute biochemical and organic sedimentary rocks. (Pg. 164)

What was the direction of differential stress that this area experienced based on these features?

East to west

What is the main type of deformation that is observed at location X on the cross section from Loveland to Rocky Mountain National Park?

Folding, see both anticline and syncline

What is the main type of deformation that is observed in the cross section of Six Mile Area, north of Boulder?

Folding, see both anticline and syncline

What are some of the behaviors of a rock that undergoes compression?

Folds + reverse faults

The process by which mafic minerals freeze first i n a melt, leaving behind am ore felsic magma, is called:

Fractional crystallization

Which of the following is a way in which minerals can form?

Freezing/solidifying from a melt, precipitation from a liquid solution, through biological processes (e.g. a clam shell), precipitation from a gas

Which of the following igneous rocks has a texture consistent with a magma that cooled and solidified slowly at first, followed by more rapid cooling?

Large, early formed crystals are surrounded by smaller, later formed crystals

Which of the following is NOT involved in turning sediments into sedimentary rock?

Metamorphism

Which of the following is NOT one of the main families in the rock cycle?

Meteorites

New minerals form in the metamorphic rock that were not in the original protolith due to the increase of heat and/or pressure. This statement is describing which process?

Neocrystallization

Which of the following processes could result in a felsic magma?

Partial melting of a source with an intermediate composition, partial melting of continental crust, formation and settling of mafic crystals in an intermediate magma

When melting forms magma:

Partial melting produces a magma that is more felsic than the source

This specimen has a milky white color to it and a glassy sheen. There is no clear crystal shape or cleavage plane visible. It is a hard mineral though, a steel knife cannot scratch it.

Quartz

Considering both rock samples, what type of metamorphism (contact or regional) occurred? And what geologic processes could have created those events?

Regional metamorphism occurred because there is a lot of foliation, like you'd in a mountain building event or when continents collide.

Composite volcanoes are so called because they:

are composed of lava flows, pyroclastic material, and mudflows

Identify the false statement: Seismographs...

are sensitive enough to record ground movements down to only about one millimeter

Hazards associated with basaltic lava flows are:

burial of roads and neighborhoods by lava flows, house fires, flooding from catastrophic melting of ice, release of noxious gases (SO2)

Identify the FALSE statement: A metamorphic rock...

cannot be formed below 1200°C

Shield volcanoes commonly involve:

fluid lava flows + lava fountains

Lava is

molten rock that cools and hardens on Earth's surface.

Determining the location of an earthquake epicenter requires ____ seismograms.

3

Which of the following is least likely to be a volcano?

A hill capped by volcanic rocks

What kind of metamorphic rock is formed where rocks have been heated, but not deformed?

A rock with metamorphic minerals, but no foliation or lineation Contact metamorphism

Bowen's Reaction Series

Allows a geologist to predict what minerals will be grouped in igneous rocks Bowen's Reaction Series was deduced through laboratory procedures that cooled molten rock; the crystal formation in the igneous rocks produced always followed the same order (Section Box 4.1, pg. 106, pg. 115)

A very dark colored mineral, often found in igneous rocks. Does not form sharp crystal edges, typically granular. When it breaks, two planes that are not perpendicular to each can be seen. It can look glassy but at other times appears dull.

Amphibole

Which of the following acts to keep a rock solid (instead of melting)?

An increase in confining pressure

Which is NOT one of the major types of magma?

Assimilation magma

Igneous rocks are formed from magma that originates in the:

Asthenosphere

Uplift can occur during the rock cycle:

At any point after burial

At what depth do gas bubbles have the most effect on magma?

At very shallow levels, such as within the volcano

Rock containing aphanitic crystals of primarily pyroxene and Ca-rich plagioclase feldspar and a few olivine:

Basalt

This mineral is consistently dark with a glassy sheen to it and breaks apart easily.

Biotite

Formation of a clastic sedimentary rock involves five stages. Which of the following describes lithification?

Compaction and cementation of loose particles to form solid rock Distinegration describes weathering, compaction describes lithification, separation describes erosion, the process by which particles settle out of transport medium defines deposition, and the movement of sedimentary particles by water, wind, or ice defines transportation. Together, these are the five stages of clastic sedimentary rock formation. (Pg. 165-166)

This relatively large symmetrical volcano contains interlayer lava flow, pyroclastic deposits, and volcanic mudflows. What kind of volcano is it?

Composite or stratovolcano

What is the stress that most likely resulted in the feature observed at Six Mile Area?

Compressional differential stress

What type of stress most likely resulted in the deformation observed in location M?

Compressional differential stress

What type of stress is most likely observed at location Y?

Compressional differential stress Reverse faults: →←

What type of stress is most likely observed at location X? What was the direction of differential stress?

Compressional differential stress, east to west

Identify the FALSE statement: Felsic magma...

Contains about 50% silica Felsic magma is more viscous because the silicon tetrahedron link up in chains, which at the microscopic level tangle and impede smooth flow. (Pg. 101)

The San Andreas Fault zone in southern California is an example of a _____-plate boundary.

Continent to continent

Regional metamorphism results from:

Continental collision

What direction of differential stress did the area experience?

East to west

Which of the following is very common in oceanic crust?

Dark-colored silicate minerals

Melting that occurs due to a decrease in pressure is called:

Decompression melting

According to the rock cycle, sediment that is being transported by a river could become a metamorphic rock after:

Deposition and burial

Rock with phaneritic crystals of amphibole, shiny biotite, and some Na-rich plagioclase feldspar:

Diorite

Which of the following events is a warning sign of imminent eruption?

Earthquake activity, change in heat f low from the volcano's surface, bulges on the volcano's surface, increase in gas emissions and hydrothermal activities

What sentence down below best describes earthquakes that occur on transform plate boundaries?

Earthquakes at transform plate boundaries are located close or on the transform boundary and are shallow (< 33km depth).

Silicate mineral groupings with magma chemical composition:

FELSIC: Quartz, K-Feldspar, Biotite, Na-rich Plagioclase (70% or greater silica) INTERMEDIATE: Amphibole, Pyroxene, Biotite, Plagioclase Feldspar (52-66% silica) MAFIC: Pyroxene, Olivine, Ca-rich Plagioclase (45-52% silica) ULTRAMAFIC: Olivine, maybe some Pyroxene, not common at Earth's surface (<45% silica) (Pg. 101)

T/F: Short-term prediction of earthquakes is usually possible; short-term prediction of imminent volcanic eruption has had no proven success.

False

T/F: The intensity of earthquake damage is calculated by comparing measurements by seismographs.

False

What types of rocks would be most common in a composite volcano?

Felsic and intermediate lava flows and tephra

Igneous rocks that have visible coarse crystals less than 3cm in size indicate that they:

Grew due to slow cooling of magma at depth This will form large visible crystals, but just a long cooling period will not result in large pegmatitic crystals.

Which of the following is NOT a typical environment in which a sedimentary rock forms?

Heating next to magma Sedimentary rocks form by the weathering/breakdown of other rocks to form sediment, are then transported, then deposited in an area, and then finally buried to be compacted or cemented into rock. A rock being formed by high heat will be changed into a metamorphic rock. If the heat gets too high and it melts, it will form magma.

Which of the following conditions will m out likely form gneiss?

High pressure, high temperature

What locations would have weathering of bedrock or loose sediment?

High steep mountains, river

A shale can be metamorphosed into three rock types: (1) a banded gneissic rock; (2) phyllite, a rock with small mica crystals with a shiny aspect; (3) schist, a very shiny rock with large mica crystals; and (4) a dull slate with cleavage.

Increasing metamorphic grade: Slate, phyllite, schist, gneiss

Why is natural occurring glass not considered a mineral?

It doesn't have a crystalline structure

Rock sample of gneiss: What was the type of differential stress that occurred and what is the minimum depth in kilometers that the rock was at when it deformed based on its appearance?

It's ductile, the stress shown is compressional differential stress, and it was at depth of 15km or deeper

Which of the following volcanic phenomena can be triggered by a volcanic eruption under ice?

Jokulhaup

This mineral has a very distinct color and when broken will create pieces with 2 edge that are close to perpendicular to one another. No striations are visible on freshly broken sides. This is a hard mineral, but can be scratched by quartz.

K-Feldspar

Which of the following locations would volcanoes with intermediate or felsic magmas be a common event?

Location 1 Volcanoes typically originate at hot spots, divergent plate boundaries (rifts/mid-oceanic ridges) and convergent plate boundaries. Oceanic crust would produce a mafic magma, rather than felsic on continental crust.

Which of the following locations would you expect to find the hypocenter of really deep earthquakes (depth > 300km, in the mantle)?

Location 1 and 2 Deep earthquakes typically occur at convergent plate boundaries where Earth's crust is being subjected into the mantle.

Which of the location(s) present on the diagram has mountains above sea level?

Location 1, continent A Ocean to continent convergent plate boundary with subduction These are formed by subduction of an oceanic plate below a continental plate at a convergent plate boundary

Which of the location(s) present on the diagram has a deep ocean trench?

Location 2 Ocean to continent convergent plate boundary with subduction Deep ocean trenches occur where there is a convergent plate boundary

Which locations would you expect to have shallow earthquakes (less than 20km depth) on the topographical feature that indicates the plate boundary?

Location 2 and 3 Location 2 is indicating a trench, the beginning point of subduction

Which of the following locations would volcanoes or fissures with mafic magmas be a common event?

Location 3 Volcanoes typically originate at hot spots, divergent plate boundaries (rifts/mid-oceanic ridges) and convergent plate boundaries. Oceanic crust would produce a mafic magma, rather than felsic on continental crust.

Which of the location(s) present on the diagram has large ridges below sea level?

Location 3, mid-oceanic ridge Oceanic divergent plate boundary

Which of the location(s) present on the diagram is relatively flat with a thin layer of sediment over basalt?

Location 4

Which of the following locations would earthquakes be an uncommon event?

Location 4 and 5 Locations 4 and 5 aren't on plate boundaries of any kind

Which of the following locations would volcanic activity (volcanoes or fissures) be an uncommon event?

Location 4 and 5 Locations 4 and 5 aren't on plate boundaries of any kind

Which of the location(s) present on the diagram has a thick amount of clastic sediments resulting in a wide continental shelf?

Location 5, continent B Not a plate boundary, but a passive margin Part of the continent that is submerged in relatively shallow sea

Which of the following would NOT be directly involved in forming a sedimentary rock (weathering, transport, or burial)?

Magma

Identify the FALSE statement: Hot solid rock in the Earth...

Maintains uniform composition as it melts and becomes magma Magma composition evolves as rock melts due to partial melting and assimilation processes. (Section 4.2, pg. 102, pg. 112: Fig. 4.5)

Which of the following is NOT essential in defining a mineral?

Man-made

This rock is exposed on east facing side of Long Peak, known as the "Diamond". It has interlocking, randomly oriented, visible crystals of three mineral types: Mineral A: Black, shiny, and breaks into sheets Mineral B: Pink in color, opaque, with a rectangular crystal shape Mineral C: Translucent and very hard. Does not have any cleavage planes.

Mineral A: Biotite Mineral B: K-Feldspar Mineral C: Quartz Rock type: Igneous Name of rock sample: Granite Processes experienced: Slow crystallization deep in the continental crust

This is a picture of a rock commonly seen up Boulder Canyon, just west of the city. It as interlocking, visible crystals of the mineral: Mineral A: Black, shiny, and breaks into sheet Mineral B: Pink in color and hard. Mineral C: Clear in color and very hard, does not have a cleavage.

Mineral A: Biotite Mineral B: K-Feldspar Mineral C: Quartz Rock type: Igneous Name of rock sample: Granite Visible grain (phaneritic), solidified at depth (i.e. coarse grained crystals), most likely source to create the magma was continental crust

Near Highway 72, there is a shiny rock that breaks into plates. Layering is easily seen and there are three visible minerals that can be made out: A. A shiny mineral that is dark in color that can easily be peeled off into sheets. B. A second shiny mineral that can also be peeled off into sheets but is light in color C. A translucent mineral that is glassy and fractures.

Mineral A: Biotite Mineral B: Muscovite Mineral C: Quartz Rock type: Metamorphic Name of rock sample: Schist Processes experienced: Increase in heat and pressure

Interlocking, aligned minerals, give a layered appearance to the rock and a nice shine. Three different types of minerals are easily visible. Mineral A: Red in color and a well formed 12 sided crystal shape. Has a glassy luster to it. Mineral B: Black, shiny and breaks into sheets. Mineral C: Silver, shiny, and breaks into sheets.

Mineral A: Garnet Mineral B: Biotite Mineral C: Muscovite Rock type: Metamorphic Name of rock sample: Garnet schist Processes experienced: Increase in heat and pressure

Further west on the road, heading deeper into the canyon, there are rocks with alternating light and dark bands. The lighter bands consist of mineral A that is clear or whitish in color, hard, and does not react to acid. The dark color bands are made of mineral B that is black or dark green in color, rectangular in shape (long compared to their width) and is a silicate that cleaves in a non-perpendicular way.

Mineral A: Quartz Mineral B: Amphibole Rock type: Metamorphic Name of rock sample: Gneiss Processes experienced: Increase in heat and pressure

This is a picture of a rock that makes up the Flatirons. Loose pieces of varying sizes that touch each other, but do not interlock.Most of the grain size range from fine sand to course sand, with some gravel pieces. The visible crystals that can be seen are of mainly two mineral types: Mineral A: Clear, whitish in color. Hard to break but when it does, it fractures. Mineral B: Pink in color. Well-formed crystals have a rectangular

Mineral A: Quartz Mineral B: K-Feldspar Rock type: Sedimentary Name of rock sample: Sandstone, fountain formation Sediment is angular, poorly sorted, therefore hasn't undergone much weathering

Scattered larger crystals in a fine crystalline gray matrix (also known as groundmass). Contains way more Na-rich plagioclase feldspar than potassium feldspars for other rocks typically from this. Mineral A: Clear in color, no fracture Mineral B: White and light colored, with two planes of cleavage Mineral C: Black in color, shiny, layered in fine sheets

Mineral A: Quartz Mineral B: Plagioclase feldspar Mineral C: Biotite Rock type: Igneous Name of rock sample: Dacite Chemical composition: Felsic Rate of crystallization/cooling: Porphyritic texture with crystals varying in size, magma cooled below Earth's surface, then finished cooling quickly on the surface Formed from continental crust, intermediate magma, and resulted in a felsic rock

This crystalline rock has Interlocking, visible crystals of one type of mineral. The individual crystals are large and appear to have grown to become tightly packed. There does not appear to be any alignment of the recrystallized minerals, though faint lines that resemble bi-directional cross bedding can be seen. The mineral is clear or whitish in color, hard, and does not react to acid.

Mineral: Quartz Rock type: Metamorphic Name of rock sample: Quartzite Original rock: Quartz sandstone Processes experienced by the protolith: Because there is no alignment in the mineral grains, there was no significant pressure applied. Rock cycle events: 1. Older rock is uplifted and exposed at the surface and is weathered. The sediment has traveled a long distance from its original source and has become well rounded and well sorted. 2. Sediments are deposited on a beach where the waves move back and forth. Eventually the sediment is buried and lithified. 3. A magma body intrudes the rock and assimilates some of the rock into its magma composition and bakes the rock at its edges. 4. The rock is uplifted and brought up to the surface where it is exposed.

Earthquakes are caused by:

Movement on existing faults, magma moving through the crust, explosive volcanic eruptions, large landslides

Listing of detritus terms from smallest to largest:

Mud, silt, sand Clastic particle sizes range from smallest to largest: mud, silt, sand, pebbles, cobbles. (Pg. 164)

This mineral is often soft and silvery, and can be broken into think transparent sheets. It is a relatively soft mineral and can be scratched by a steel knife.

Muscovite

What are some of the behaviors of a rock that undergoes tension?

Normal faults

According to Bowen's Reaction Series, which of the following minerals has the highest melting temperature (i.e. would melt last)?

Olivine

Though the sample of this mineral that are transparent are highly sought after as gemstone, this mineral is can be often look more like green sugar in rock samples. Does not have a cleavage plane, but will fracture. Has a hardness greater than potassium feldspar. Typically found in very dark colored rocks.

Olivine

Tuff and volcanic breccia are both composed of a variety of igneous fragments. Their classification as either felsic, intermediate, or mafic therefore depends on the:

Overall mineral content the fragments in the tuff or the breccia

On a seismogram, which earthquake wave arrives first?

P-waves

This mineral is very hard and can scratch many other minerals. It does not break easily, and when it does often form jagged sharp edges.

Quartz

Andalusite is a white colored aluminum silicate mineral that forms at low pressures and temperatures. It can change into blue colored Kyanite, also an aluminum silicate, under higher temperature and pressures. Andalusite and Kyanite have the same chemical formula though they are different minerals. This statement is describing which process of metamorphism?

Phase change

This mineral has a blue-grey color to it. Sometimes on a freshly broken side you can see faint parallel lines. It is a relatively hard mineral, but softer than quartz and will form in rectangular shapes.

Plagioclase feldspar

White colored mineral that has a glassy luster to it. Faint parallel lines are visible on the side of the specimen and the sides are close to 90 degree to each other, though it can be hard to tell at times

Plagioclase feldspar

Imagine that well rounded, well sorted quartz grains were elongated due to the rock being "squeezed" under high pressure. This statement is describing what process?

Plastic deformation, due to compression

When wet rock is squeezed in one direction more than another, the edges of minerals grains can begin to dissolve. The ions then move through the water to precipitate elsewhere. This statement is describing which process of metamorphism?

Pressure solution

Which of the following are dangerous aspects of composite volcanoes?

Pyroclastic flows, landslides and mudflows, an eruption column

This mineral can come in a variety of colors, from dark brown to white. However it is usually dark green. It has cleavage at 90 degrees though the cleavage can be hard.

Pyroxene

According to Bowen's Reaction Series, which of the following minerals has the lowest melting temperature (i.e. would melt first)?

Quartz

What is the main type of deformation that is observed at location M on the cross section of Boulder, CO?

Reverse fault

What is the main type of deformation that is observed at location Y on the cross section from Loveland to Rocky Mountain National Park?

Reverse fault Foot wall is moving down, hanging wall is moving up

Dark colored rock, finely crystalline but no visible crystals. Igneous cuts through pre-existing continental sedimentary rock as a dike intrusion.

Rock type: Igneous Texture of rock: Aphanitic (not visible crystals) Rate of crystallization/cooling: Quickly on the surface, though not fast enough to become volcanic glass Chemical composition: Mafic Name of rock sample: Basalt The rock was created by a mafic magma and partial melting in the mantle.

This sample is found close Highway 36 on Lefthand Canyon Road and is also seen while hiking Mt. Sanitas. It contain clasts of only one mineral and feels sandy when touched. The mineral is light to clear in color, with a glassy appearance, very hard, and no cleavage planes.

Rock type: Sedimentary Mineral: Quartz Sorting: Well-sorted Level of rounding: Well-rounded Name of rock sample: Sandstone The rock has been weathered because of how well-sorted and well-rounded the sediments are

How does the strength of continental crust vary with depth?

Rocks become stronger with depth and then get weaker deep in the crust.

This volcano is relatively small and composed of volcanic cylinders. What kind of volcano is it?

Scoria cone or cinder cone

Sudden breaking of rock due to stress generates _____ waves, and the sliding of rock along the break results in a _____.

Seismic + fault

This volcano is broad and low, and is composed of basaltic lava flows. What kind of volcano is it?

Shield volcano

The most abundant minerals on Earth are from which class?

Silicates

The two elements most abundant in Earth's crust are:

Silicon, oxygen

Which of the following can occur within a magma chamber?

Sinking or floating crystals may change the composition of the resulting magma, wall rock can melt and become incorporated into the magma, if two magmas mix the resulting magma would be between the compositions of the two magmas

In transform plate boundaries, the plates:

Slide past one another horizontally

Identify the TRUE statement.

Surface waves arrive later and are generally more damaging than body waves.

What are the three main types of stress to cause deformation?

Tension, compression, shear

What is the term for an unconsolidated accumulation of any size of pyroclastic grains?

Tephra

The welded igneous texture of rhyolite means:

The ash and pumice were hot and became compacted

Factors that influence the chemical composition of magmas may include:

The chemical composition of the source rock, only partial melting of the source rock, melting and assimilation of some of the rock of the magma chamber walls, mixing of magmas brought together from different locations

What typically happens to the size, shape, and sorting of class as they are transported from steep mountains toward more gentle settings?

The clasts become more rounded

Which of the following characteristics are NOT used classify and name clastic sediments?

The climate in which the clasts are produced This is a clue about the type of weathering that will occur, but doesn't affect how we classify sediment.

What location would result in the formation of igneous rocks?

The cooling edge of a magma chamber

A lava solidifies into non-vesicular basalt instead of vesicular basalt because

The magma has a low gas content

What does a vesicular texture indicate about the formation of the rock?

The magma that created this rock had abundant dissolved gases

A glassy igneous texture indicates that:

The rock cooled quickly Volcanic glass occurs when the lava cools so quickly that crystals do not have time to form.

What's the main difference between conglomerate and breccia?

The shape of the clasts

Segments of the mid-ocean ridge system are offset. Between the offset segments we observe:

Transform faults

T/F: Pyroclastic flows bring instant death to any life caught in them.

True

T/F: Volcanic danger-assessment maps are valuable tools in protecting human life when volcanic eruption threatens.

True

T/F: When geologists say metamorphic grade, they're referring to the general degree of metamorphism of a rock; when they say facies, they mean a subset of the broad temperature and pressure conditions in which metamorphism can occur.

True

Schist is a medium-grade foliated metamorphic rock that should contain micas.

True Many different types of rocks are composed of atoms that can be metamorphosed into the mineral mica, which is a chief component of the metamorphic rock schist. (Section 7.3, pg. 194)

T/F: Wet igneous rock (rock that contains volatiles) melts at a lower temperature than does the dry version of the same rock.

True The presence of volatiles helps break chemical bonds, resulting in a lower melting temperature for the wet rock. (Section 4.2, pg. 101)

T/F: Recrystallization occurs because thermal energy causes atoms to vibrate rapidly, break existing chemical bonds, and migrate to new positions on the crystal lattice where they are more stable under the hotter conditions.

True This process doesn't change the identity or chemical composition of the mineral; it just produces larger crystals of the mineral. (Section 7.1, pg. 190)

What is NOT a type of seismic wave?

Tsunami wave

Which of the following does not describe the architecture of a volcano?

Vesicle

Which of the following are ways that viscosity affects gases in magma?

Viscous magma prevents gas from escaping easily + gas builds up in viscous magma and cause explosive eruptions

This relatively small volcanic feature consists of solidified lava and some volcanic ash. What kind of volcano is it?

Volcanic dome

The main cause of caldera collapse is:

collapse of the roof of a magma chamber as magma erupts

Volcanic mud-and-debris flows, composed of ash, debris, and water:

have often resulted in damage and death to humans and their property