Geology Test 1

What is the category name for the largest division of time used on the geologic time scale?

Eon

Why is the geologic time scale more detailed in the Phanerozoic than in previous eons?

The Phanerozoic Eon is more detailed because of the presence of organisms with hard parts and the rapid increase in biodiversity.

The Jurassic Period lies in the _____ Era, which was dominated by large terrestrial vertebrates, or _____.

Mesozoic; dinosaurs

Using a calendar year as an analogy to the geologic time scale, when do the oldest anatomically modern humans appear on Earth?

The oldest human fossils show up at about eleven minutes to midnight on December 31st.

Name the epoch, period, era and eon in which we currently live.

We live in the Holocene Epoch of the Quaternary Period, which is part of the Cenzoic Era and Phanerozoic Eon.

A(n) ___ is a tentative explanation, whereas a(n) ____ has survived extensive scrutiny over many years.

hypothesis; theory

The layers of Earth are based on what two sets of characteristics?

Chemical composition and physical properties

What is the D" layer?

A partially molten layer above the outer core at the base of the mantle.

The upper mantle can be divided into the asthenosphere and lithosphere based on what physical properties?

The asthenosphere is solid, but mobile, while the lithosphere is solid and relatively rigid.

What are the two types of crust?

Oceanic and continental

What happens to the atmosphere as you move away from Earth’s surface?

The atmosphere thins.

What is the difference between magma and lava?

Magma is molten rock located below the surface; lava is molten rock erupted above ground.

What are the two most important driving forces of metamorphism?

High heat and pressure

_____ igneous rocks are those that cool below the surface.

Intrusive

What are the two important processes involved in lithification of sedimentary rocks?

Cementation and compaction

An igneous rock becomes buried, is subject to high heat and pressure, and recrystallizes. This rock then is eroded, transported, deposited and subsequently lithified. Which rock types—in order—did the original igneous rock develop into?

Metamorphic and sedimentary

Which of the following correctly states the order in which major features of North America were formed?

Canadian Shield, Appalachians, North American Cordillera

Which statement accurately describes continental shields?

Very old, stable regions composed of igneous and metamorphic rocks

If stable platforms represent sedimentary rocks that cover continental shields, then what statement must be true?

The sedimentary rock atop the stable platforms must be younger than continental shields.

The __________ is an example of an old mountain belt, while the Himalayas represent a(n) __________.

Appalachian Mountains; young mountain belt

Appalachian Mountains; young mountain belt

Age and degree of erosion

Which of the following statements best describes Wegener’s idea of continental drift?

Continents were formerly in different positions on the Earth and have shifted to their present locations over time.

How was the fossil record of ancient life used to support Wegener’s hypothesis about Pangaea?

Fossils of identical organisms were found on several continents, indicating the continents were once joined.

Late Paleozoic sedimentary rocks often contain extensive coal seams that were used to support the existence of Pangaea. What would the climate have been at that time and at the location where the coal deposits were formed, and what would it indicate about the continent’s past latitude?

Warm, humid climate near the Equator

When matching up once-joined continents such as South America and Africa, the coastlines do not fit together as nicely as the continental shelves. Why might this be the case?

The continental shelves are the edges of the continent. The shoreline simply shows where the sea level is in relation to topography.

What evidence supports that the glaciers on the southern continents were once part of a single, massive ice sheet?

Striations

The lithosphere is composed of material from the ________ and the rigid part of the ________.

Crust; Upper Mantle

A location where continental rifting is occurring today is ________.

East African Rift Valley

A typical rate of seafloor spreading in the Atlantic Ocean is ________.

2 centimeters per year

Which type of convergence will result in a volcanic island arc?

Oceanic-Oceanic

Where are the majority of transform faults located?

On the ocean floor offsetting segments of oceanic ridge

What two pieces of information would researchers need to have in order to calculate the rate of plate motion for seafloor spreading?

Distance from the rift and age of seafloor sample

Which factor contributes the most toward plate motion?

Slab Pull

Deep-ocean trenches are formed by _______.

the subduction of lithosphere into the asthenosphere

Which of the following is not part of the definition of a mineral?

Organic

Ionic Bond

Complete transfer of electrons between atoms

Carbonates

CO32

Silicates

SiO24

What are the two most abundant elements in Earth’s crust?

Oxygen and silicon

What minerals make up half of Earth’s crust?

Feldspars

What is an accurate description of the silicon-oxygen tetrahedron?

The silicon-oxygen tetrahedron is a four-sided figure with a silicon atom in the middle bonded to four neighboring oxygen atoms.

The micas (biotite and muscovite) exhibit what type of silicate structure?

Sheet

__________ SiO4 4- tetrahedra join with __________ ions to produce the mineral olivine in the rock peridotite.

Independent; Mg2+ and Fe2+

Two isotopes differ from one another because they have _____.

different numbers of neutrons

An ion with a surplus of electrons _____.

is negatively charged

Which of the following statements regarding a single silica tetrahedron is FALSE?

It has four silicon atoms.

Neutron

Particle found in the nucleus; no charge

How are igneous rocks formed?

Igneous rocks are formed by the cooling and crystallization of molten rock.

Intrusive and extrusive igneous rocks are classified based on what criteria?

How quickly the molten rock cools and crystallizes, and where this occurs with respect to Earth’s surface

What is required to generate an igneous rock with a fine-grained texture?

A fine-grained texture is the product of rapid cooling and crystallization of lava.

A phaneritic texture is characteristic of a(n) __________ igneous rock that cooled __________.

intrusive; below the surface

What does it mean if an igneous rock has an aphanitic texture?

The igneous rock exhibits mineral crystals too small to see with the naked eye.

Ultramafic rocks contain __________ and are commonly found in __________.

olivine; mantle

What is an accessory mineral?

A mineral that makes up a relatively small portion of the total rock composition

Which of the following best describes the difference between granite and rhyolite?

Granite is phaneritic and rhyolite is aphanitic.

What is the rock name of an intermediate rock with two distinct grain sizes?

Andesite porphyry

What do pumice and scoria have in common?

They both exhibit a vesicular texture.

At a subduction zone, melting is triggered by _____.

the introduction of water

What is the term used to describe increased temperature with depth in the Earth?

Geothermal gradient

Use your understanding of Bowen’s reaction series and crystal settling to determine which of the following mineral associations should not be found in nature.

Olivine, potassium feldspar, quartz

Once a source rock partially melts, what does it produce?

Felsic magma and mafic residue

According to Bowen’s Reaction Series, __________ is one of the first minerals to melt, but last to crystallize.

quartz

How is basaltic magma transformed into felsic magma?

Basaltic magma partially melts the continental crust, which is more felsic in composition.

What causes an elevated geothermal gradient in a divergent plate setting?

Decompression melting of the mantle

In a subduction zone, water driven from subducted oceanic crust causes __________.

the melting temperature of mantle rocks to decrease

What type of volcanism characterizes the ring of fire?

-volcanism caused by convergent oceanic-oceanic boundaries -volcanism caused by convergent oceanic-continental boundaries

What type of boundary is present along the eastern boundary of the North American plate?

divergent oceanic-oceanic

At what tectonic setting is Hawaii located?

oceanic hot spot

What drives melting at divergent boundaries?

decompression melting

Which of the following tectonic settings does NOT produce volcanism?

transform boundary

In order to cover such large expanses of seafloor, shield volcanoes erupt ________ lava.

Basaltic

Based on the structure of the cone and the rock making it up, what interpretations can be made about the gas content of eruptions from cinder cone volcanoes compared to those of shield volcanoes?

More gas than shield volcanoes

Which of the following are types of volcanoes?

-Composite volcano -Cinder cone -Shield volcano

What information do geologists use to classify volcanoes?

Shape and type of deposits

Cinder cones are made of________.

pyroclastic deposits

In general, how often do most cinder cones erupt?

Most cinder cones erupt once.

What are shield volcanoes generally made of?

Basalt flows

What is the range of shield volcano height?

300 to 10,000 meters

What are composite volcanoes made of?

Pyroclastic deposits

Why are shield volcanoes wider than composite volcanoes?

The lava that flows out of shield volcanoes is more fluid than the lava that flows out of composite volcanoes.

What type of magma erupts out of dome complexes?

Felsic magma

What type of volcanoes are the highest?

Shield volcanoes

What is the range of dome complex height?

500 to 2,000 meters

Lavas erupting from composite cones are generally ________-rich, making them very viscous.

Silica

How can the creation of ice result in physical weathering?

Water expands in volume when freezing, exerting pressure on a container.

How can plants physically weather a rock?

Plant roots exert outward pressures as they grow.

Which of the following climates would have the greatest degree of ice wedging?

cold in the winter, warm in the summer, and with moderate precipitation

How did weathering destroy New Hampshire’s Old Man in the Mountain?

Water migrated along fractures in the rock, where it froze and wedged the rock apart.

What is the definition of physical weathering?

Mechanical processes break substances into smaller pieces.

Which of the following is an example of chemical weathering?

a car fender getting rusty

How does physical weathering cause chemical weathering to be more effective?

When a rock is physically broken into smaller pieces, there is more surface area on which chemical weathering can occur.

Which of the following rocks would most likely experience sheeting?

granite

Which of the following scenarios best describes how sheeting will develop in an igneous rock?

A subterranean pluton is exposed at the surface, releasing confining pressure.

When sheeting develops in an igneous pluton, fractures will develop in an orientation __________ to the direction of expansion.

perpendicular

What changes are occurring in the igneous pluton that would result in sheeting?

volume increase

__________ is when various geologic materials exposed to the same environmental conditions will weather differently depending on their composition.

Differential weathering

Which of the following climates will have the highest rate of weathering?

warm, wet climates

Which of the following locations will weather a block of marble the most quickly?

Honolulu, Hawaii

Which soil horizon will contain the greatest amount of organic material?

O horizon

Where does the clay that accumulates in the B horizon come from?

A and E horizons

Which of the following components make up a healthy soil?

All of these choices are needed.

Approximately 75% of the planet’s landmasses are covered by sedimentary and sedimentary rocks.

True

________ are fragments of pre-existing materials that have been broken down through the processes of weathering.

Sediments

Conglomerate

Detrital

Chert

Chemical

Which of the following methods of transportation will result in the coarsest sorting (poorest sorting)?

Glaciers

Which of the following best describes the appearance and composition of a conglomerate?

Rounded fragments; poorly sorted

Detrital sedimentary rocks are classified according to clast size whereas chemical sedimentary rocks are classified based on their dominant minerals.

True

Which rock is the most abundant chemical sedimentary rock?

Limestone

________ processes such as evaporation and chemical activity can precipitate chemical sediments.

Inorganic

________ are tiny "seed" particles created when small sediments or shell fragments are rolled by waves in water supersaturated with calcium carbonate.

Ooids

The raw material for coal is dead marine organisms.

False

Alluvial Fan

Continental Environment

Graded bedding will display particle that are fine near the bottom of the layer and get progressively coarser toward the top.

False

When does the deposition of solid particles occur?

only when the fluid transporting the sediments slows down or when glacial ice melts

What is the main criterion for classifying detrital sedimentary rocks?

particle size

Volcanic activity in the early history of the Earth is believed to be responsible for much of the CO2 found in the atmosphere.

True

In the list below, indicate which of the environments fossilization is likely to occur in. Note that fossils contain organic matter.

-A swamp -In a floodplain -The ocean floor

There are no sediments on the deep sea floor.

False

Shale

Detrital

Which of the following is the parent rock for quartzite?

Sandstone

If clay minerals were buried at a depth where subsurface temperatures exceed 200°C, which mineral are they likely to become?

Muscovite

Which low-grade metamorphic rock will display fine rock cleavage and contains very fine grains of mica?

Slate

Which of the following lists of metamorphic rocks places the rocks in order from lowest metamorphic grade to highest?

Slate, Phyllite, Schist, Gneiss

Generally speaking, how is the chemical composition of most metamorphic rocks going to compare to that of the parent rock?

Chemical compositions will be nearly the same

How are metamorphic rocks formed?

Preexisting rock is altered through heat and pressure.

Do metamorphic rocks look like the preexisting rock from which they form?

sometimes, but not always

What is foliation?

banding in metamorphic rocks that results from the reorientation of minerals

How will foliation in continental metamorphic rocks formed during subduction be oriented?
perpendicular to the direction of plate movement

perpendicular to the direction of plate movement

What would you call a granite that has undergone metamorphism and now exhibits foliation?

gneiss

Physical rotation of platy minerals will contribute most to the development of foliation ________ grade metamorphism.

Low

Which style of metamorphism will be generated by a mantle plume?

Contact

________ is a widespread type of metamorphism typically associated with mountain building.

Regional metamorphism

Sillimanite

High Grade