Question 1

Almost all natural rocks are consolidated aggregates of minerals.

Accepted Answer

Most rocks are made up of different minerals that have been bonded together through geological processes, such as cooling and crystallization from molten lava or precipitation from water.

Question 2

A plutonic rock results from
A) hydrothermal activity.
B) volcanic activity.
C) clastic processes.
D) slow cooling beneath the earth's surface.

Accepted Answer

Plutonic rocks are formed from slow cooling and solidification of magma or lava deep beneath the earth's surface. The slow cooling results in the formation of large mineral crystals in the rock. This is in contrast to volcanic rocks, which solidify quickly on the earth's surface and have small mineral crystals. Hydrothermal activity and clastic processes can contribute to the formation of some types of rocks, but not plutonic rocks specifically.

Question 3

How can you tell the difference between plutonic and volcanic igneous rocks?
A) A volcanic rock is fine-grained; a plutonic rock is coarse-grained.
B) A volcanic rock experienced more pressure, so they are smaller; plutonic rocks are larger.
C) A volcanic rock has less silicate material than plutonic.
D) A volcanic rock is much hotter than a plutonic rock.

Accepted Answer

The texture of a rock (i.e. grain size) is determined by the rate of cooling. Volcanic rocks cool quickly and therefore have a fine-grained texture. Plutonic rocks cool slowly and therefore have a coarse-grained texture.

Question 4

Sedimentary rocks form
A) deep within Earth's crust.
B) at Earth's surface environment.
C) at elevated temperatures and low pressures.
D) from magma on the surface.

Accepted Answer

Sedimentary rocks form at or near Earth's surface environment through the accumulation and cementation of sediment or through the precipitation of minerals from water solutions.

Question 5

What is one situation in which a metamorphic rock results?
A) A volcano ejects a rock and it cools on the surface of the earth.
B) A sedimentary rock experiences the physical elements of the earth's surface.
C) An igneous rock breaks down to fragments and then experiences heat and pressure.
D) A sedimentary rock experiences intense heat and pressure.

Accepted Answer

Metamorphic rocks form when existing rocks (igneous, sedimentary, or other metamorphic rocks) are subjected to intense heat and pressure, which causes them to recrystallize and form new minerals and textures. This process occurs deep in the Earth's crust and is often associated with mountain building or tectonic activity. Sedimentary rocks (option B) can sometimes be involved in the process of metamorphism, but they do not result in metamorphic rock formation by themselves. Option A describes the formation of an igneous rock, and option C describes the breakdown of an igneous rock, neither of which necessarily leads to metamorphism.

Question 6

Why are Genetic classifications so helpful?
A) They classify genetics of the material, studying the mineral makeup to group types.
B) They group features or phenomena by noting similarities in the processes that create them.
C) They group rock types by the appearance of the material.
D) They study behaviors that processes exhibit.

Accepted Answer

Genetic classifications are helpful because they group features or phenomena by noting similarities in the processes that create them. This allows for easier understanding and organization of complex genetic information.

Question 7

All of the following are examples of descriptive classifications except
A) igneous vs. sedimentary vs. metamorphic rocks.
B) silica rich vs. silica poor vs. intermediate rocks.
C) dark-colored vs. medium-colored vs. light-colored rocks.
D) carbonate vs. mixed-carbonate vs. non-carbonate rocks.

Accepted Answer

Descriptive classifications typically categorize based on observable characteristics or composition. Choices B, C, and D are examples of such classifications based on composition or color. Choice A, however, classifies rocks based on their formation process (igneous, sedimentary, metamorphic), which is not merely descriptive but involves understanding the origin and history of the rocks.

Question 8

No rocks originate from observable processes that take place at earth's surface.

Accepted Answer

Rocks can originate from observable processes such as weathering, erosion, and sedimentation that occur at Earth's surface.

Question 9

A classification scheme that grouped plutonic and metamorphic rocks together and sedimentary and volcanic rocks together would be based on
A) the average grain size of the rocks.
B) the presence of glass in the rocks.
C) the location of the rock's formation.
D) the bulk composition of the rocks.

Accepted Answer

Plutonic and metamorphic rocks are both formed beneath the Earth's surface, while sedimentary and volcanic rocks are formed at or near the surface. This classification scheme is based on the location of the rock's formation.

Question 10

What must occur in order for a metamorphic rock to become a sedimentary rock?
A) weathering
B) solidification
C) melting
D) cooling

Accepted Answer

In order for metamorphic rock to become sedimentary rock, it must first undergo weathering, which breaks down the existing rock into smaller particles. These particles can then be transported and deposited, eventually undergoing cementation and lithification to become sedimentary rock. Solidification, melting, and cooling are processes more commonly associated with the formation of igneous rocks.

Question 11

How would a metamorphic rock become a sedimentary rock?
A) It could melt and crystallize.
B) It could eject from a volcano and cool on the earth's surface.
C) It could experience weathering or erosion, later precipitating and undergoing lithification.
D) It could be exposed to intense heat and pressure to form sedimentary rock.

Accepted Answer

A metamorphic rock could become a sedimentary rock if it goes through the processes of weathering, erosion, and lithification. This would involve the rock breaking down into smaller pieces through physical or chemical processes, being transported by wind or water, and eventually settling and compacting into a new sedimentary rock. The other options listed (melting and crystallizing, volcanic ejection and cooling, and exposure to heat and pressure) would result in the formation of igneous or metamorphic rocks, not sedimentary rocks.

Question 12

How would a chemical sedimentary rock form?
A) from the precipitation of minerals
B) particles of preexisting rocks liberate by physical weathering, then cement together
C) a metamorphic rock breaks down
D) a sedimentary rock is intensely heated

Accepted Answer

Chemical sedimentary rocks form by the precipitation of minerals from solution or the accumulation of organic material. Examples of this type of rock include limestone, halite, and chert.

Question 13

An igneous rock is fine-grained. What kind of rock is it, and how did it form?
A) a volcanic rock; it cooled quickly on the surface of the earth
B) a plutonic rock; it cooled quickly beneath the earth's surface
C) a hydrothermal rock; it cooled underwater
D) a chemical rock; it cooled by the mixing of certain chemicals

Accepted Answer

A fine-grained igneous rock indicates that it cooled quickly on the surface of the earth, as the lava had less time to cool and form larger crystals. This type of igneous rock is typically volcanic in origin.

Question 14

How did a coarse-grained inclusion that erupted from a volcano form by internal processes?
A) The material was precipitated from groundwater.
B) Intense heat and pressure formed the metamorphic rock in the inclusion.
C) Cooling lava erupted from a volcano.
D) Coarser rocks form from the slow solidification of magma beneath Earth's surface.

Accepted Answer

Coarse-grained inclusions that erupt from volcanoes are typically formed by the slow solidification of magma beneath Earth's surface. This slow cooling process allows larger crystals to form, resulting in a coarser texture compared to rocks that solidify quickly at the surface.

Question 15

How would a clastic sedimentary rock form?
A) A sedimentary rock is intensely heated.
B) Particles of preexisting rocks liberate by physical weathering, then cement together.
C) An igneous rock breaks down.
D) A metamorphic rock breaks down.

Accepted Answer

Clastic sedimentary rocks form from fragments of preexisting rocks that have been weathered and transported by wind, water, or ice. These fragments, or clasts, are then cemented together to form a rock.

Question 16

An example using a genetic classification of minerals is
A) The Metamorphic Minerals.
B) The Mohs Hardness Minerals.
C) The Silicate Structures.
D) The Rock Forming Minerals.

Accepted Answer

Metamorphic minerals are classified based on their formation process, which is a genetic classification.

Question 17

Why are descriptive classifications so useful?
A) They group items of similar appearance, making it easy to guess which rock type they are.
B) They describe classifications, making it easy to understand which classification the rock type falls into.
C) They are only used in Geology, so there is not much confusion.
D) They note similarities in creation, making it easy to understand formation processes.

Accepted Answer

Descriptive classifications are useful because they group items of similar appearance, making it easy to guess which rock type they are.

Question 18

It's wise to use the site of formation as the primary criterion for rock classification.

Accepted Answer

Rock classification is primarily based on composition and texture, not the site of formation. This approach helps in understanding the rock's origin, mineral content, and the conditions under which it was formed.

Question 19

A rock sample appears to have different layers, seemingly made of sand particles. How would you genetically classify this sample?
A) metamorphic
B) sedimentary
C) igneous
D) chemical

Accepted Answer

The presence of layered sand particles suggests that the rock sample is likely a sedimentary rock, formed through the accumulation and lithification of sedimentary particles.

Question 20

An igneous rock is weathered down to rock fragments; what happens to the fragments?
A) They undergo lithification to form sedimentary rocks.
B) They are transported and deposited into sediment banks, then undergoing lithification to form sedimentary rock.
C) They experience intense heat and pressure to form metamorphic rock.
D) They melt to form new igneous rock.

Accepted Answer

When fragments of an igneous rock are weathered down, they are transported and deposited into sediment banks where they can undergo lithification to form sedimentary rock. This process involves the compaction and cementation of the sediment, leading to the formation of a new rock. Therefore, option B is the best choice.

Quiz 3: Rocks and Rock-Forming Processes

Almost all natural rocks are consolidated aggregates of minerals.

A plutonic rock results from

How can you tell the difference between plutonic and volcanic igneous rocks?

Sedimentary rocks form

What is one situation in which a metamorphic rock results?

Why are Genetic classifications so helpful?

All of the following are examples of descriptive classifications except

No rocks originate from observable processes that take place at earth's surface.

A classification scheme that grouped plutonic and metamorphic rocks together and sedimentary and volcanic rocks together would be based on

What must occur in order for a metamorphic rock to become a sedimentary rock?

How would a metamorphic rock become a sedimentary rock?

How would a chemical sedimentary rock form?

An igneous rock is fine-grained. What kind of rock is it, and how did it form?

How did a coarse-grained inclusion that erupted from a volcano form by internal processes?

How would a clastic sedimentary rock form?

An example using a genetic classification of minerals is

Why are descriptive classifications so useful?

It's wise to use the site of formation as the primary criterion for rock classification.

A rock sample appears to have different layers, seemingly made of sand particles. How would you genetically classify this sample?

An igneous rock is weathered down to rock fragments; what happens to the fragments?