Geology Midterm (Chapter 7 + 8)

Which of the following can form sedimentary rocks?

the cementing together of shell fragments or carbon-rich relicts of plants

Pieces of broken rock produced by physical weathering

are collectively called clasts or detritus.

Which of the following processes is associated with the formation of travertine?

precipitation

If you find quartz sandstone in the place where it formed, you know you are looking at an ancient

beach

Gypsum and halite

are evaporite minerals

Which of the following classes of sedimentary rocks is produced by weathering and erosion of pre-existing rocks?

clastic

Formation of a clastic sedimentary rock involves five stages. Of these stages, erosion is the

separation of rock or regolith from its substrate

As sediment is transported downstream, away from its point of origin, the particles become

smaller

How are rocks that are formed predominantly from the calcium carbonate shells of marine organisms classified?

biochemical

Which of the following features is a bed-surface marker, meaning that it appears on the surface of a bed as a result of events during or soon after sediment deposition?

mud cracks

Which of the following sedimentary structures indicates that the sediments were deposited in a moving fluid?

ripple marks

Which of the following sedimentary features is the surest indicator that the past environment was subaerial (under air), not submarine (underwater)?

mud cracks

What is the most logical ancient environment to have produced a deposit consisting of layers of well-sorted sandstone with cross beds several meters high?

sand dunes

What is the most logical past environment to have produced a deposit consisting of layers of unsorted, unstratified sedimentary clasts, clay-sized to boulder-sized?

glacial valley

When the sea level rises (as illustrated here), the shoreline migrates inland, flooding the land and depositing coastal sediments over pre-existing terrestrial sediments. This process is called

transgression

According to the diagram, which sediment sample is considered immature, and why?

Sample 1, because it contains both resistant and nonresistant minerals.

A metamorphic rock

may have preferred mineral orientation caused by differential stress

Which of the following is a common process by which metamorphic rocks are formed?

pressure solution

Normal stress

is a push (compression) or pull (tension) perpendicular to a surface

Recrystallization

changes the texture (shape and size) of the grains

According to this phase diagram, which of the following conditions will lead to the formation of kyanite?

550°C, 7 kbar

What is the protolith of marble?

limestone

The extremely high heat of metamorphism

is necessary to form migmatite

Which of the following rocks is classified as non-foliated?

hornfels

Quartzite

is basically a solid mass of interlocking quartz grains

What type of foliation does slate, a common material used for roof shingles, exhibit?

cleavage

Which of the following locations could possibly be part of a shield?

Canada

Shock metamorphism

can be caused by meteorite impact

Shields are

composed of some of the oldest rock on the Earth

According to this metamorphic facies diagram, which of the following statements is true?

Blueschist facies rocks form at high pressures and low temperatures

A high-grade metamorphic rock that exhibits significant compositional banding, such as the one shown here, is most likely

a foliated rock called gneiss