Geo Quiz 5-8

Why are igneous rocks composed of different types of minerals?

As the magma cools, different minerals form when it has different compositions.

What composition of bedrock is the most likely to be resistant to weathering?

Bedrock made up of quartz minerals.

What is an important result of partial melting of rocks?

The resulting magma has a different composition than the rock.

You identify that an area has a lot of metamorphic rock. What can you interpret?

There was a convergent plate boundary there in the past.

How are steam, wind, and flowing water similar in how they generate electricity?

They all spin the turbine blades which move magnets in the generator.

Which statement is true about igneous rocks that cool deep within the Earth's crust?

They are made up of large minerals.

As sediments are transported, what happens to them?

They become smaller.

How is the formation of chemical sedimentary rocks and igneous rocks similar?

They both start from liquid.

In what plate tectonic environment will you see the most weathering and erosion to form sediments?

convergent plate boundary

At which locations does magma form because water is added to mantle rock?

convergent plate boundary with subduction

When magma erupts on the seafloor at a divergent plate boundary, it cools to form rock. What characteristics does this rock have?

dark color, small minerals

Dikes and sills form when magma from a magma chamber fills cracks in the ground and then the magma cools to form rock. What is the main difference between a dike and sill?

dikes cut across rock types, sills follow sedimentary layers

Which of these lists are all associated with convergent plate boundaries?

felsic, explosive eruptions, high viscosity magma

Granite is an igneous rock. Based on that classification, how does granite form?

formed when magma cools and solidifies

Which is NOT a factor that influences the rate of chemical weathering? A) climate B) bedrock structure C) gravity D) bedrock type

gravity

What is a characteristic of many igneous rocks that makes them useful?

hard and resistant to weathering

Explosive volcanic eruptions tend to have magma with what viscosity?

high viscosity

What rock type tends to form at divergent plate boundaries?

igneous

What types of rock gives geologists clues about the locations of volcanoes and mountains?

igneous and metamorphic

What is a key feature that geologists look for to find reservoirs of oil and natural gas?

impermeable layers underground

Where does most rock melt at convergent boundaries with subduction?

in the mantle, where water is added

In mafic composition magma, what is usually the gas content and viscosity?

low viscosity and low gas content

If you identify many small spaces in a rock, what is the most likely interpretation of the rock type?

sedimentary

What type of rock does NOT tend to form at plate boundaries?

sedimentary

What is an ore resource?

A rock that contains metal that can be extracted and used.

Which layer of soil is the most valuable resource for farmers growing crops?

topsoil

Which soil horizon tends to have dark soil and nutrients from decomposing organic matter?

topsoil: This is the layer at the surface that is the first to erode away.

Which of these is useful in determining the frequency of the past eruptions of a particular volcano? a) historical records b) carbon-14 dates of plants killed during eruptions c) tree ring counting d) all of these

all of these

If you find and igneous rock that is dark in color and has small minerals, what is it?

basalt

What describes a shield volcano?

basalt lava

How do geologists classify rocks?

based on how the rocks form

You are looking at a building, and you notice when you look at it closely that the building is made up of a rock that is made up of little pieces. What type of sedimentary rock makes up that building?

clastic sedimentary rock

Where do stratovolcanoes form?

convergent boundaries

In what plate tectonic environment are you LEAST likely to form igneous rock?

transform plate boundary

Which of the following is the LEAST hazardous aspect of volcanic eruptions, for lives and property?

volcanic gases

Which of the following sediments were transported the furthest distance?

well-rounded, well-sorted sand

Which method of transportation carries only the smallest sediment sizes?

wind

Which of the following igneous rock cools and crystallizes deep within Earth's crust?

6.4 (answer is not basalt)

Why are pyroclastic flows and lahars dangerous? a) All of these are reasons. b) They have a relatively high density, so they can knock down buildings. c) They can travel very fast. d) They are unpredictable when they will happen during an eruption.

All of these are reasons.

How does the composition of magma affect the eruption style of a volcano?

Felsic magma results in explosive eruptions.

Which statement comparing felsic rocks to mafic rocks is true?

Felsic rocks have more silica and less iron and magnesium than mafic rocks.

How does the composition of hotspot volcanoes vary by location?

If they are in the ocean, they have a mafic composition; if they are within continental lithosphere, they can have a mafic, intermediate, or felsic composition.

You see an igneous rock with large minerals. What does this tell you?

It cooled slowly underground.

Which of the following statements describes the correct relationship between lava viscosity and composition?

Lava viscosity increases as the silica content of the lava increases.

Why does magma formed in the Earth's interior rise to the surface?

Magma is less dense than rock.

Why does magma formed in the Earth's interior rise to the surface? Magma is less dense than rock.

Magma is less dense than rock.

What is an example of a hotspot volcano?

Mauna Loa in Hawaii

What processes are necessary for metamorphic rocks to become sedimentary rocks?

Metamorphic rocks weather into sediments, then compact and cement into sedimentary rock.

What is the relationship between rocks and minerals?

Minerals are the pieces that make up rocks.

How are igneous rocks formed?

Molten rock cools and solidifies.

Which of these eruptions has had the highest Volcanic Explosivity Index?

Mount Tambora in 1815

Does the rock cycle have an end?

No, rocks continuously change.

Which answer correctly matches the melting location with the cause of melting?

convergent boundary with subduction, added water

Two students are discussing the locations of volcano types.

Student 1: Different volcano types tend to match with different plate boundaries. For example, stratovolcanoes tend to occur at convergent plate boundaries with subduction.

Two students are discussing how geologists identify eruptions in the past.

Student 1: Geologists look for deposits left behind by eruptions, such as solidified lava or ash.

Three students are discussing how large igneous rocks are when they first form.

Student 1: I think igneous rocks form as huge magma chambers or lava flows. Pieces break off, which is what we see.

Two students are discussing how rocks change.

Student 1: Rocks can change, like when they are weathered or melted, but it happens very slowly.

Two students are discussing which part of volcanic eruptions tend to be the most dangerous to people nearby.

Student 1: The pyroclasts tend to be the most deadly because when flowing quickly, they can knock down, suffocate, and burn whatever is in their path.

Why does most magma form at convergent plate boundaries with subduction?

Water is added to the mantle as minerals release water.

Which of these is useful in determining the extent of past eruptions for a particular volcano?

make a map of the lava flows and other deposits

A geologist wants to determine if there once was a volcano in a particular area by looking at the rocks there. What categories would it be most useful for a geologist to use for classifying those rocks?

method of formation

What is an advantage to using natural gas as an energy source?

much of our technology already uses it

Which of these is used to make plastic?

oil

Which of the following igneous rock formation tends to be the largest?

pluton

Which of the following igneous rock formations has a different shape than the others because magma does not squeeze through cracks in rocks?

pluton

What is the purpose of classifying rocks by their method of formation?

to learn clues about what Earth was like when the rocks formed in the past

Which of the following lists correctly ranks the size of volcanoes from largest to smallest?

shield volcano, stratovolcano, cinder cone

Igneous rocks are generally composed of which mineral type?

silicate minerals

What do oil and natural gas form from?

single-celled organisms in the ocean

What type of volcano is composed of mostly felsic and intermediate igneous rocks?

stratovolcano

What are two factors that affect soil formation?

the climate of the area and the bedrock type that is becoming the soil

Geologists work as a team to predict volcanic eruptions. What is NOT something these geologists look at? the phase of the moon the shape of the volcano the amount and type of gas coming out the number of earthquakes

the phase of the moon

What is the most important factor that controls the size of minerals in an igneous rock?

the rate of magma cooling