Deck 7: The Rock Cycle

Question 1

Explain the rock cycle. How is one rock the raw material for another rock?

Answer 1

The rock cycle is a continuous process that describes how rocks are formed, broken down, and reformed over time. It involves three main types of rocks: igneous, sedimentary, and metamorphic.

Igneous rocks are formed from the cooling and solidification of molten rock, either below the Earth's surface (intrusive) or on the surface (extrusive). These rocks can be broken down through weathering and erosion, forming sediment.

Sedimentary rocks are formed from the accumulation and compaction of sediment, which can come from the weathering and erosion of other rocks, or from the remains of organisms. Over time, these rocks can be subjected to heat and pressure, leading to their transformation into metamorphic rocks.

Metamorphic rocks are formed from the alteration of existing rocks through heat and pressure, typically deep within the Earth's crust. These rocks can then be melted to form new igneous rocks, completing the cycle.

Throughout this process, each type of rock can serve as the raw material for another. For example, igneous rocks can be weathered and eroded to form sediment, which can then be compacted and cemented to form sedimentary rocks. Similarly, any type of rock can be subjected to heat and pressure to form metamorphic rocks. This continuous cycle demonstrates how one type of rock can be transformed into another, serving as the raw material for the next stage in the rock cycle.

Question 2

88% of Earth's history is the Precambrian. Yet, as you look at the geologic time scale, you will note that we know very little about the Precambrian; there are not Period components as you see from the Paleozoic to the Cenozoic. Why is this? Why is Precambrian history more difficult to decipher than more recent geological history?

Answer 2

The lack of well-defined Period components in the geologic time scale for the Precambrian is largely due to the scarcity of preserved rock and fossil records from that time period. The Precambrian encompasses the vast majority of Earth's history, spanning from the formation of the Earth approximately 4.6 billion years ago to the beginning of the Cambrian Period around 541 million years ago.

During this immensely long time span, geological processes such as erosion, tectonic activity, and metamorphism have obscured or destroyed much of the original Precambrian rock record. Additionally, the simple, soft-bodied organisms that existed during this time period have left behind very limited fossil evidence, making it difficult to piece together a comprehensive understanding of Precambrian life and environmental conditions.

Furthermore, the lack of well-defined boundaries and distinct rock formations in the Precambrian makes it challenging to establish clear divisions and time periods comparable to those of the more recent geological history. As a result, our understanding of Precambrian history is more fragmented and incomplete compared to the more recent geological time periods, making it more difficult to decipher and study in detail. Despite these challenges, ongoing geological and paleontological research continues to provide valuable insights into the Earth's early history.

Question 3

The __________ involves the cycling of material through the geosphere as a result of the formation, breakdown, rearrangement, and reformation of rock.

Answer 3

rock cycle

Question 4

The end result of weathering on a global scale is the formation of __________ , he irregular blanket of loose, uncemented rock particles that covers the Earth's surface.

Question 5

__________ weathering is the decomposition of rocks and minerals as chemical reactions transform them into new chemical compounds.

Question 6

__________ weathering is the disintegration of rock as a result of physical breakup.

Question 7

Regolith that as undergone erosional transport is called __________ .

Question 8

__________ sediment is bits of broken rock and minerals that are moved as solid particles.

Question 9

__________ sediment is formed when substances that have been dissolved are transported in solution and then precipitated.

Question 10

The process by which sediment or regolith becomes rock is called __________ .

Question 11

Another way that lithification can occur is through __________ , in which mineral grains that were once separate can grow to become interlocked.

Question 12

To be classified as __________ , sedimentary rock must have clasts that are rounded and larger than 2 mm in diameter.

Question 13

An unusual but important kind of chemical sedimentary rock is called banded __________ formation.

Question 14

The study of sedimentary strata is called __________ .

Question 15

Stratigraphic __________ is the determination of equivalence in age of the succession of strata found in two or more different areas.

Question 16

An __________ unconformity implies that the older strata were deformed, uplifted, and partially removed by erosion.

Question 17

When discussing metamorphic rock, scientists use the term __________ instead of pressure.

Question 18

__________ has pronounced foliation and a very distinctive green color.

Question 19

__________ rock is transitional between igneous and sedimentary.

Question 20

One important factor that influences denudation rates is __________ activity, especially the clearing of forests, development of cultivated land, damming of streams, and construction of cities.

Question 21

The rock cycle is a process solely involving the movement of sedimentary rock from a mountain to a river.

Question 22

Rock is transformed into regolith through physical and chemical weathering, which work together.

Question 23

Regolith is sediment that has undergone erosional transport and deposition.

Question 24

Chemical sediment consists of broken rock and mineral particles.

Question 25

Landslides can be triggered by human activities that oversteepen or destabilize slopes.

Question 26

The locations where clastic sediment is deposited are largely controlled by plate tectonics.

Question 27

The first stage of lithification is burial and compaction.

Question 28

Limestone is the most important rock that forms from the lithification of biogenic sediment.

Question 29

Stratigraphy is based on the principle of absolute dating.

Question 30

The geologic column summarizes, in chronological order, the succession of known rock units.

Question 31

Conformities are breaks in the stratigraphic record.

Question 32

Metamorphic rock is igneous or sedimentary rock that has been changed in mineralogy and/or texture in the solid state.

Question 33

Igneous rocks form in the solid state under extreme heat and pressure.

Question 34

Mechanical deformation includes grinding, crushing, and the development of foliation.

Question 35

Metamorphic rocks are named on the basis of sediment size.

Question 36

The metamorphic conditions characteristic of greenschist occur where the crust is thickened by continental collision or heated by rising magma.

Question 37

Granite is an extrusive igneous rock.

Question 38

Volcanic rock is characterized by large grain sized crystals.

Question 39

Fractional crystallization does not contribute to the diversification of igneous rock types.

Question 40

Denudation begins as soon as a mountain range is uplifted, and continues long after active tectonic uplift has ceased.

Question 41

The dinosaurs became extinct at the end of what Period?

A) Cretaceous.
B) Jurassic.
C) Triassic.
D) Paleogene.

Question 42

Rocks formed at the Earth's surface from the breakup of other rocks are:

A) Metamorphic rocks.
B) Igneous rocks.
C) Sedimentary rocks.

Question 43

The class of rocks formed by subjecting existing rock to extreme heat and pressure (but not to the point of melt) is called:

A) Metamorphic rocks.
B) Sedimentary rocks.
C) Igneous rocks.

Question 44

What is the geologic time scale generally based upon?

A) The solar cycle.
B) The age of ocean water.
C) Major geological and/or biological events.
D) Dendrochronology.

Question 45

The principle variables of metamorphism are

A) Conformities and unconformities.
B) The size and shape of the parent rock.
C) Heat and pressure.
D) Heat and chemical composition.

Question 46

Sedimentary rocks provide clues about

A) Geologic activity at the time of deposition.
B) Past climates.
C) Surface conditions at the time of deposition.
D) All of these.

Question 47

Chemical sedimentary rocks are formed

A) From various solutions.
B) Only in wet or dry environments.
C) From weathered remains of igneous and/or metamorphic rocks.
D) Only in rivers and seas.

Question 48

If the rock pressure is about 1200 MPa, at about what temperature will high-grade metamorphism begin to occur?

A) 100 degrees Centigrade.
B) 200 degrees Centigrade.
C) 50 degrees Centigrade.
D) 400 degrees Centigrade.

Question 49

Which of the following properly lists low to medium to high grade metamorphic rocks?

A) Gneiss, Phyllite, Slate.
B) Phyllite, Slate, Gneiss.
C) Gneiss, Slate, Phyllite.
D) Slate, Phyllite, Gneiss.

Question 50

Which of the following factors can stabilize a slope and prevent mass wasting?

A) High density rocks on the mountain slope.
B) Water content in the rock.
C) Vegetation.
D) None of these.

Question 51

Mass wasting is material moved primarily due to

A) Ice.
B) Gravity.
C) Wind.
D) Running water.

Question 52

The process where dissolved minerals (such as quartz) precipitate within the pore spaces of sediment creating a gluey material leading to the binding of the sediment is called

A) Compaction.
B) Cementation.
C) Weathering.
D) Recrystallization.

Question 53

Stratification in a sedimentary rock

A) Is always horizontal.
B) Is generally vertical.
C) Is due to internal stresses from inside Earth.
D) Represents geologic, climatic, and biological conditions during the time of deposition.

Question 54

Clastic sedimentary rocks are classified based upon

A) Smell.
B) Composition.
C) Color.
D) Grain size.

Question 55

You will find fossil remains in what type of rock?

A) Igneous.
B) Sedimentary.
C) Metamorphic.
D) All of these.

Question 56

If one has an absolute age date for an intrusive igneous rock body that is intruding into a sedimentary rock, what does that reveal about the sedimentary rock?

A) You know the youngest possible age of the sedimentary rock.
B) You know the oldest possible age of the sedimentary rock.
C) You know the age of the next overlying stratum.
D) You know the absolute age of the sedimentary rock.

Question 57

Along what type of plate boundary is metamorphism the most common?

A) Transform.
B) Divergent.
C) Convergent.

Question 58

A metamorphic rock formed from granite is

A) Slate.
B) Marble.
C) Gneiss.
D) Quartzite.

Question 59

Which of the following metamorphic rocks is non-foliated?

A) Schist.
B) Gneiss.
C) Slate.
D) Marble.

Question 60

Which rock is the intrusive equivalent of rhyollite?

A) Basalt.
B) Diorite.
C) Gabbro.
D) Granite.

Question 61

Gabbro is coarser than basalt because

A) The magma that formed the gabbro cooled slower than the basalt magma.
B) Gabbro has contact metamorphism whereas basalt does not.
C) Gabbro contains much more silica than basalt.
D) Higher pressure formed the gabbro.

Question 62

What is obsidian?

A) An intrusive (plutonic) igneous rock.
B) An extrusive (volcanic) igneous rock
C) A piece of glass resulting from the melt of sediments.
D) A metamorphic form of shale.

Question 63

Intrusive igneous rocks are generally

A) Fine-grained.
B) Coarse-grained.
C) Vesicular.
D) None of these.

Question 64

In which environment would chemical weathering be most effective?

A) Cold and dry.
B) Warm and dry.
C) Warm and humid.

Question 65

Which rock is composed of alternating bands of light and dark minerals?

A) Gneiss.
B) Marble.
C) Phyllite.
D) Muscovite mica.

Question 66

For igneous rock formation, as the rate of cooling increases, the size of the crystals that form

A) Increases.
B) Decreases.
C) Stays the same.

Question 67

If you have an original sediment that is cube in shape with a length, width, and height of 1 unit each, then its overall exposed surface area will be 6 square units (1 square unit x 6 sides). If you were to break this sediment into 8 equal cubes by physical weathering, how much surface area would now be exposed?

A) 12 square units.
B) 15 square units.
C) 20 square units.
D) 30 square units.

Question 68

List the following sediments from largest to smallest:

A) Gravel, silty mud, sand.
B) Sand, gravel, silty mud.
C) Silty mud, gravel, sand.
D) Gravel, sand, silty mud.

Question 69

At the mouth of a rapidly flowing river, what type of sediment would you expect to see along the bed of the mouth of the river?

A) Moderately sorted.
B) Poorly sorted.
C) Well sorted, with only the smallest clasts.
D) Well sorted, with only the largest clasts.

Question 70

Which of the following areas has the highest sediment yields?

A) North Africa.
B) Central Australia.
C) Southeast Asia.
D) Northern Canada.

Question 71

What are the major attributes of "superposition"?

A) The assignment of relative age to the strata.
B) Younger rocks overlay older rocks.
C) Both of these

Question 72

The era that covers the longest time span is

A) The Paleozoic.
B) The Precambrian.
C) The Cenozoic.
D) The Mesozoic.

Question 73

Why do small sediments weather faster than larger sediments?

A) The small sediments have more surface area for chemical reactions.
B) The small sediments can be broken down quicker by bacteria in the soil.
C) The small sediments generally contain smaller minerals that are easier to break down.
D) All of these.

Question 74

What are the three most important kinds of metamorphism?

A) Contact, heat, pressure.
B) Contact, burial, and regional.
C) Burial, gravitational, contact.
D) Regional, gravitational, contact.

Question 75

Imagine you go hiking in the desert and happen upon large slabs of granite rock. All around you the ground is a flat, desert floor, except for these few, large slabs of granite. What does that tell you about the geologic history of the area?

A) The area used to be geologically active, complete with volcanic activity.
B) The area used to be geologically inactive. The granite rock is a result of mass movement due to wind and/or water.
C) The area used to be active with intrusive igneous processes. Over time, differential erosion led to the exposure of the once-underground granite rock.
D) Need more information.