Geology 120 exam 2

Examine the diagram below. The lettered objects represent volcanoes formed on an oceanic plate above a hot spot. The arrow illustrates the direction of plate motion. Which volcano is the youngest?

A

What would the metamorphic rock shown below be called?

gneiss

What type of rock is shown in the image below?

igneous

how would you describe the composition of the rock shown below

intermediate

is the igneous rock shown below intrusive or extrusive

intrusive

Which of these would be chemical formulas of mafic silicate minerals?

Fe2SiO4 (Ca,Na)(Mg,Fe,Al)Si2O6

which of these terms would best describe the texture of the rock below?

phaneritic

The rock shown below contains fine-grained (too small to see with the naked eye) platy minerals such as mica. What would this rock be called?

phyllite

Which of these types of metamorphism would you most expect to have at a continental collision?

regional metamorphism

High Pressure/Low Temperature metamorphism is typically found at which tectonic environment?

subduction zone

The rock pictured below contains well-sorted, well-rounded, fine quartz sand, iron oxides and large cross-bedding. What is the most likely depositional environment for this rock?

- desert sand dune

The rock below fizzes when hydrochloric acid is dropped on it. What would this rock be called?

- limestone

The diagram below is a stratigraphic column for the Horsetooth Reservoir area. Examine the Dakota Group. It contains three rock members within the group, a sandstone on bottom, shale in the middle, and sandstone on top. What is the most likely interpretation of how sea level changed during the time that the Dakota Group was being deposited?

-A sea level rise (transgression) and then a sea level fall (regression)

At a subduction zone, what is the cause(s) of melting?

-Heating -Addition of water

Which of these minerals is the most resistant to weathering?

-Quartz

Based on your understanding of the defining characteristics of a mineral, which of these common substances would be classified as a mineral?

-ice -salt -diamond

Contact metamorphism occurs when rocks are exposed to________ temperature and_________

1)high 2)low

Put these metamorphic rocks in order of increasing metamorphic grade from 1 (lowest grade) to 4 (highest grade).

1)slate 2)phyllite 3)schist 4)gneiss

What does cross-bedding, such as shown in the image below, indicate about the environment in which the sand was deposited?

-The flow of a current of air or water in one direction.

Which of these are examples of chemical weathering?

-Which of these are examples of chemical weathering?

The rock below fizzes when hydrochloric acid is dropped on it. Which type of sedimentary rock is shown?

-biochemical

At a hot spot under ocean crust, which type of volcano would you expect to find?

-broad shield volcano

Examine the diagram below that shows oceanic and continental crust surrounding a plate boundary. Based on the current plate tectonic setting, location X is moving toward ____?

-c

The rock pictured below contains crystals of the mineral halite. It formed in a shallow evaporative sea. Which type of sedimentary rock would it be classified as?

-chemical

A black color in sedimentary rocks usually indicates

-deposition in an environment without much oxygen -the presence of organic matter

As sediment is transported it usually becomes more rounded, ______ sorted, and______ grain size.

1) more 2)better 3) smaller

Which of these rocks could be the parent rock of gneiss?

-mudrock (such as shale) -granite

in cooling magma, which of these minerals would crystallize first?

-olivine

The rock shown below contains large mica crystals and other platy minerals aligned in a parallel direction. What type of foliation does this rock display?

-schistosity

at an ocean-continent convergent boundary, what are the primary sources of magma >

-the mantle -continental crust

Volcano 1 is cone shaped and composed of a composite of andesite, ash layers, mudflow layers, and volcanic debris layers. Volcano 2 is broad and low-slope and composed of basalt. Which volcano would you be most concerned about low viscosity lava flows?

-volcano 2

Continental collisions are characterized by___________________.

-widespread shallow earthquakes -broad mountainous region

Is this rock foliated?

-yes

rank these magma composition form least viscous (1) to most viscous (3)

1) mafic 2)intermediate 3) felsic

What would the rock below be called?

conglomerate

Which of these is the LEAST likely depositional environment for the rock composed of clay-sized clasts pictured below?

beach environment influenced by waves

Which type of sedimentary rock is shown below?

clastic

at a mid-ocean ridge, what is the primary mechanism of melting ?

decompression

what is the igneous rock shown below

diorite

Which of the following is the most likely depositional environment for the rock pictured below?

floodplain

which of these magma compositions tend to be the least explosive?

mafic

at an ocean-continent convergent boundary, the extrusive igneous rocks that are produces are typically intermediate in composition

mafic magma produced in the mantle mixes with feldic magma produced by melting the continental crust

The metamorphic rock shown below is composed of medium-fine interlocking crystals that fizz when hydrochloric acid is dropped on them. What is this rock?

marble

What type of rock is shown in the image of an outcrop below?

metamorphic

The degree or intensity of metamorphism is known as

metamorphic grade

The two rocks pictured below were both deposited next to or under the Cretaceous Interior Seaway, when a shallow sea covered much of the mid-section of North America. Rock A (top) fizzes with hydrochloric acid and contains clam fossils. Rock B (bottom) contains sand-sized fragments of quartz. Which one would you predict was deposited in shallower water?

rock B

What type of rock is shown in the image of the landscape below?

sedimentary

at a mid-ocean ridge, what is the primary source of magma

the mantle

In the image below is sandstone and shale. Which rock is the sandstone?

upper rock

which of these villages would be the safest from volcanic mudflow?

village 1