Geology Exam 1

Which of the following contributes to the sequestration of carbon dioxide? (check all that apply)

Burial of biomass (plants) Formation of limestone Photosynthesis

Sedimentary rocks are particularly important to humans because:

They contain resources such as water, oil and gas, uranium, and iron.

Which type of plate boundary is associated with most of the Earth's major mountain belts?

convergent

At which tectonic setting so most volcanoes exist?

convergent-subduction

Volatile-rich magmas are generated by melting due to addition of volatiles. At what plate tectonic setting does this occur?

convergent—subduction

Regional metamorphism is common at which of the following plate tectonic settings?

convergent—subduction zones convergent—collision zones

Continental crust is mainly composed of _________ , whereas oceanic crust is mainly composed of __________ .

granite basalt

What mineral makes up table salt?

halite

Why does a higher temperature cause the viscosity of a magma to decrease?

heat breaks bonds between atoms and allows them to move easily past one another

Hot material moves into a region with higher temperatures. than its melting temperature

heat-transfer melting

Wet mud and earthworm found on the edge of a lake would be considered to be part of which sphere?

hydrosphere geosphere biosphere

Which TWO of the following metamorphic agents combined can concentrate gold to form gold deposits?

hydrothermal fluids increase in temperature around a magma chamber

Metamorphism involving hot fluids like water is:

hydrothermal metamorphism

If you have a metamorphic rock, and you bury it and heat it until it melts, and then bring it closer to the surface where it cools and solidifies again, the resulting rock would be _______.

igneous

If a body of magma becomes more felsic (richer in Si), its viscosity will:

increase

The largest layer of the Earth (by volume) is the mantle , and it is composed primarily of peridotite .

mantle peridotite

What is an ion?

An atom that has gained or lost 1 or more electrons and is charged either positively or negatively.

Faults are examples of what kind of rock deformation?

Brittle

How old is the Earth?

4.6 billion years old

Nonsilicate minerals make up about ____ percent of Earth's crust.

8

Which of the following examples of cities experience the fast rate of weathering of roads (formation of potholes) in the wintertime?

A city with nightly average low temperatures of 15 degrees F, and average daytime highs of 40 degrees F.

The feature that may form where a stream enters a lake or ocean is called

A delta

A mineral, as geologists understand the term, is a naturally occurring solid substance with a definable chemical composition and...

A fixed crystalline structure

Which of the soil profile make up the topsoil? (select all that apply)

A horizon O horizon

______ is a feature of a divergent plate boundary. (select all that apply)

A rift valley An ocean ridge

In the Atlantic Ocean, where does the youngest oceanic crust occur?

Adjacent to the mid-ocean ridge.

Why is it important to know that every metamorphic rock has a protolith?

All metamorphic rocks form from a pre-existing solid rock, and the composition of the protolith will predict what new minerals will form during metamorphism.

Seafloor spreading is driven by volcanic activity that occurs:

Along mid-ocean ridges

Where would you expect to find volcanoes in an oceanic-continental convergence zone?

Always on the continental plate.

Based on what we learned about igneous composition and texture, which of the following statements is TRUE?

Any composition of magma/lava can cool to form any of the discussed textures, because the two �properties are independent from one another.

The collision of Africa and North America produced the _______________ Mountains.

Appalachian

Rainwater is often slightly acidic because:

CO2 combines with water to form carbonic acid.

What are the 8 most concentrated elements in Earth's crust? (choose all that apply)

Ca-calcium Al-aluminum O-oxygen K-potassium Na-sodium Mg-magnesium Fe-iron Si-silicon

The three most common volatiles in magma are:

Carbon dioxide, sulfur dioxide, and water vapor

Which of the following processes forms biochemical sedimentary rocks?

Cementing together of shell fragments

Recrystallization:

Changes the texture (shape and size of the grains)

Which of the following processes is most likely to form minerals?

Deposition of material by biological processes

A caldera forms by:

Draining of a magma chamber beneath a volcano during an eruption

True or False. Landslides can cause volcanic eruptions even in extinct volcanoes.

False

True or false, slightly acidic water is necessary for water to chemically erode a rock or material.

False

Which of the following is true of fractures, joints and faults?

Faults and joints are types of fractures. The difference is faults show displacement and joints do not.

Which of the following fits the definition of a mineral?

Gypsum, because it's crystalline

How can hot spots leave evidence of plate motion?

Hot spot tracks of volcanic islands are created as plates move over mantle plumes

Which of the follow is false about hot spot volcanism?

Hot spot volcanoes are always explosive

Identify the FALSE statement about pyroclastic flow hazards.

They can flow up to 100 km away from a volcano.

Where would you expect to get the thinnest O-layer in a soil profile?

In a desert

Based on the map image below, where do you think the spreading rate is greatest?

In the Pacific Ocean

As the silicate structures change from isolated silica tetrahedra to chains and frameworks of silica tetrahedra, the ratio of silicon atoms to oxygen atoms ________.

Increases

The crystallization of salt from evaporating sea water:

Is an example of precipitation from a solution

What makes CO2 gas hazardous to humans?

It can deprive the brain of oxygen and cause fainting and/or death it is denser than air so it will not rise rapidly and can easily be breathed in without one's knowledge of its presence it is colorless and odorless

Subduction zone metamorphism happens at temperatures ranging from ~200-450oC, why then do we call it "low temperature metamorphism?"

It is low temperature relative to other metamorphic processes that can occur up to ~850 degrees C.

What does grain size generally indicate about the cooling of a melt?

Larger crystals indicate that the melt cooled very slowly at depth

Which of these types of volcanic settings produced 70% of the Earth's surface?

Lavas erupted at mid-ocean ridges

In which of the following would you expect to see the least amount of change from the protolith to the metamorphic rock that forms during metamorphism.

Low grade metamorphism

Magnetic anomalies result from seafloor spreading in conjunction with:

Magnetic polarity reversals

Which of the following is not a category of sedimentary rocks?

Mechanical

How do rocks differ from minerals?

Minerals aggregate to form rocks, but rocks do not aggregate to form minerals.

As the map above shows, the oldest seafloor is generally less than 200 million years old. Why?

Most oceanic lithosphere eventually gets subducted beneath the continents by the time it is 200 million years old because the older it gets, the colder and denser it gets.

Why are rocks that formed in an oceanic environment found in the highest parts of the Himalayan Mountains today?

Ocean sediments were trapped and deformed during the continent-continent collisions that formed the Himalayan Mountains.

Coal is a form of ____________.

Organic sedimentary rock

_____ occurs when magnetic minerals in lavas align their magnetic fields with magnetic north, preserving a record of that pole's location at that moment in time.

Preserved magnetism

Which of the following are true of soils in rainforests? (select all that apply)

Removal of rainforests leads to soil erosion, leaving the soil fairly infertile. Removal of vegetation increases sunlight exposure to the soil, allowing it to become baked in the sunlight and essentially turned to a hard brick-like substance. Though they are some of the thickest soils, they are not particularly fertile because heavy rainfall leaches most of the nutrients from the top soil.

Which of the following rocks would be the most buoyant on Earth's mantle?

Rock A: Density 1.4 g/cm3

Which of the following is true of sedimentary rocks?

Sedimentary rocks are made of weathered and eroded bits of preexisting rocks. Sedimentary rock classification includes clastic, organic, and chemical types. Most of Earth's continents are covered in a thin veneer/layer of sedimentary rocks.

The major types of stress are _______.

Shear, tension, and compression

What is the main reason the mineralogy of a rock changes during metamorphism?

Some minerals are only stable under limited conditions of temperature and pressure, so they change when the conditions change

The relationship between stress and strain is:

Strain is the result of stress

Why is a swamp environment the best for accumulation of thick layers of organic material that eventually can become coal?

Swamps are stagnant and the decomposition of organic material impedes the growth of bacteria.

Which of the following is a mineral?

Table salt (NaCl)

Rhyolite lava:

Tends to erupt explosively due to pressure buildup from the high viscosity of the lava

What is the significance of the ages of the Hawaiian Islands in terms of plate tectonics?

The ages decrease toward the big island of Hawaii, showing that the Pacific plate is moving NW over a stationary hot spot.

The hotter the magma ...

The less viscous it becomes

Sedimentary Rocks are formed by:

The lithification of sediments Deposition from a solution

Which of the following influences the rate of weathering of rocks? (check all that apply):

The minerals that make up a rock. Presence of water. Temperature and climate of the region. Presence of vegetation and types of plants in a region.

Which of the following determines the chemical properties of an element?

The number of protons

Since temperatures in Earth increase with depth, why is the inner core solid?

The pressures in the core are immense and keep it in a solid state despite the temperature.

Many people say that California is going to fall off the face of the Earth, using what we know about plate tectonics, which of the following is most likely?

The western most edge of California and the Baja Peninsula will slowly move north relative to the rest of the North American continent.

The O and A horizons of the soil profile are important for what reason?

They are a mixture of sediments and organic matter than make up nutrient-rich topsoil

What defines the boundary between the lithosphere and asthenosphere?

This is a temperature boundary, where peridotite mantle is hot enough to behave more like a plastic than a rigid solid.

Which one of these processes does NOT contribute to plate motions?

Tidal forces

Why are mid-ocean ridges higher elevation than surrounding abyssal plains? (2 reasons)

Upwelling mantle at mid-ocean ridges causes these features to be elevated. Newly formed oceanic crust is more buoyant than older oceanic crust

Glaciers (ice) can pick up any sediment they flow over and transport that sediment long distances. The sediment is dropped out when the glaciers melt. Which of the following would best describe a glacial deposit?

VERY poorly sorted sediments

Water-induced melting at subduction zones come from where?

Water contained within minerals in the subducting plate is released during metamorphism.

Frost wedging occurs because:

Water occupies less volume than ice.

Tensional stress is most likely to occur at which type of plate boundary?

continental rift

The process of forming a clastic sedimentary rock is best described by which of the following?

Weathering, transportation, deposition, lithification

Which of the following issues initially prevented widespread acceptance of Alfred Wegener's continental drift hypothesis?

Wegener's lack of a good mechanism to explain why the continents moved

What is the smallest size classification of pyroclastic material?

ash

Mt. Vesuvius erupted in a very violent explosion in 79 C.E. and buried the residents of Pompeii in ash. On the basis of this information, which of the following would you LEAST expect to find at Vesuvius?

basaltic (mafic) lava

The character of a lava flow depends on the viscosity of the lava erupted. _____ lava is less viscous than _____ lava.

basaltic / rhyolitic

Mountains in the Basin and Range formed:

by continental rifting.

Which of the following is true about lahars:

can occur even if an eruption has not occurred recently can carry away people, buildings, and other structures high-density, fast-flowing, floods of water and tephra

Which of the following could cause rock to melt? (select all that apply)

change in composition increase in temperature decrease in pressure

Which of the following is the most important agent of metamorphism?

changes in temperature

Convection works because __________.

cold material is denser than the same material when it is hot

The grade of coal increases with:

compaction

Which of the following are true of dark colored silicate minerals? (Select all that apply)

contain iron and magnesium high density high melting temperature common in Earth's oceanic crust

Recall Earth's spheres (atmosphere, geosphere, hydrosphere, and biosphere), soil is considered an interface between spheres because:

contains water, air, rock, and organic matter.

Earth's lithosphere includes which of the following (select all that apply):

crust upper mantle

The melting temperature of hot material is lowered as the surrounding pressure decreases.

decompression melting

On Earth, chemical differentiation lead to the formation of layers in Earth based on the ______ of the materials that make up those layers.

density

What main hazard do lava flows pose to humans?

destruction of immovable property

Which of the following are examples of sedimentary rock structures that preserve features in the sedimentary record? (select all that apply)

dinosaur footprints mudcracks ripple marks

Folding of rocks occurs as a result of ________ deformation in the ________ crust. Folding generally _____________ .

ductile deep only occurs in compressional stress settings

The most common mineral in Earth's crust is __________.

feldspar

Why does a more felsic magma have a higher viscosity than a mafic magma at the same temperature?

felsic magmas contain more silica tetrahedrons which can link together in the melt and resist flowing past one another

Which of the following sediments have been transported the furthest?

fine grained, well rounded, well sorted

Which of the following describes sedimentary rocks?

formed by lithification of pre-existing rock

Which of the following describes metamorphic rocks?

formed by the heating and squeezing of pre-existing rock

Which of the following is the thickest sphere on Earth?

geosphere

Considering a felsic magma, what was the likely composition of the source of that magma, knowing that most magma forms by partial melting of a source rock?

intermediate

Which of the following are true of light colored silicate minerals? (Select all that apply)

low density low melting temperatures common in Earth's continental crust

In general a felsic magma will be _________ in temperature than a mafic magma.

lower

Effusive volcanoes are those with low viscosity lavas that are likely _____ in composition. A ______ volcano is usually effusive.

mafic / sheild

If I begin with a rock composed of clay and quartz and then I metamorphose it and form a rock with garnet and mica, what metamorphic process is taking place?

neocrystallization

Is glass a mineral?

no because it has no crystal structure

Elastic deformation:

occurs when a shape temporarily responds to stress, but returns to its original shape when the stress is removed

Between continental and oceanic crust, ______ crust is denser and ______ crust is thicker.

oceanic ; continental

In which of the following plate boundaries would you expect to find volcanism. Check all that apply.

oceanic-continental convergent boundary continental rift oceanic-oceanic convergent boundary mid-ocean ridge/spreading center

Which of the following minerals is an example of a silicate?

olivine- (Mg,Fe)2SiO4

Which layers in Earth's geosphere are liquid (check all that apply)?

outer core

Rigid lithospheric plates move _______.

over the more ductile asthenosphere

Cooled magma chambers form [ Select ] whereas cooled volcanic feeders form [ Select ] , which are both [ Select ] igneous features.

plutons dikes intrusive

Metamorphism of sandstone produces [ Select ] , whereas metamorphism of limestone produces [ Select ] .

quartzite marble

Which of the following is a chemical equivalent of granite?

rhyolite

Which of the following mountain building processes can have associated volcanoes?

subduction continental rifting

Compressional stress is most likely to occur at which type(s) of plate boundaries:

subduction zone collision zone

What is Uniformitarianism?

the idea that the present is key to the past since physical, chemical, and biological processes that operate today have also operated in the geologic past

Imagine a rock at high temperature and pressure that is solid in the Earth mantle. What will happen if water is added by a subducting oceanic plate?

the rock will partially melt

What is the basic molecule building block of all silicate minerals?

the silica tetrahedron

Transform faults are different from convergent and divergent plate boundaries because

there is neither the creation nor the destruction of lithosphere at a transform fault, and plate movement is parallel to the length of a transform fault.

Why does quartz have this pyramid shape?

this shape results from the ordered crystal structure of SiO2

Which of the following are examples of strain. Select all that apply.

thrust fault anticline reverse fault monocline

Water is added to a region with rocks at a temperature where they will melt if water is added.

volatile melting

Are the red or yellow lines the transform boundaries?

yellow