chapter 6 and 7

The Jurassic Period lies in the _____ Era, which was dominated by large terrestrial vertebrates, or _____.

Mesozoic; dinosaurs Submit

In general, how often do most cinder cones erupt?

Most cinder cones erupt once.

Distinguish between numerical and relative dates.

Numerical dates specify the actual number of years that passed since an event, whereas relative dates determine the order of events in relation to one another.

How is triangulation method used to locate the epicenter of an earthquake?

On a map, a circle is drawn around each of three recording stations, with the radius being the distance from the station to the epicenter of the earthquake. The epicenter is located where the three circles intersect.

Name two types of body waves.

P waves and S waves

As the distance between the epicenter of an earthquake and a seismograph station increases, so does the difference in the arrival times of the P and S waves. What causes this?

P waves are faster than S waves.

__________ in the sandy layer causes the ground to subside after sand volcanoes form.

Tighter packing

A container holds 100 atoms of an isotope. This isotope has a half-life of 1.5 months. How many total atoms will be in the container after 3 months?

100 atoms

On average, how many damaging earthquakes occur each year?

1000

A container holds 100 atoms of an isotope. This isotope has a half-life of 1.5 months. How many atoms of the radioactive isotope will be in the container after 3 months?

25 atoms

What is the range of shield volcano height?

300 to 10,000 meters

Which principles of relative dating did you use to answer the previous question?

Superposition and Cross-Cutting Relationships

Why is the geologic time scale more detailed in the Phanerozoic than in previous eons?

The Phanerozoic Eon is more detailed because of the presence of organisms with hard parts and the rapid increase in biodiversity.

Which of the following statements best represents the relationship between magma and crystals formed from that magma?

The crystals are denser than the magma.

false

The dike is older than the inclusion.The inclusion formed originally in the sandstone country rock.

Cinder cones are made of________.

pyroclastic deposits

Which of the following types of magma has the highest viscosity?

rhyolitic

Choose the correct order of magmas from the highest to lowest silica content.

rhyolitic magma, andesitic magma, and basaltic magma

How long does it typically take for the first earthquake waves to arrive at a seismograph that is some distance away from the epicenter after the earthquake occurs

several minutes

What are the two primary types of waves generated by earthquakes?

surface waves and body waves

What is the scientific definition of half-life?

the amount of time over which the number of parent isotopes decreases by half

What zone on Earth has the greatest amount of seismic activity?

the circum-Pacific belt

What is the range of dome complex height?

500 to 2,000 meters

Distinguish among a conduit, a vent, and a crater.

A conduit is the circular path through which magma ascends to the vent, which is the surface opening of the conduit. A crater is a funnel-shaped depression around the vent.

What is the underlying principle of seismograph construction?

A heavy weight suspended within a moving box needs to overcome inertia, resulting in a slight delay in the motion of the weight after the box moves. Submit

What is an earthquake?

A sudden shaking of the ground that is caused by the rapid release of energy from the slipping of crustal blocks along a fault.

Describe how sand volcanoes form.

An earthquake causes loose, saturated sandy material to liquefy, shoot upward through fractures of a confining unit, and eventually erupt at the surface.

What is the significance of an unconformity?

An unconformity represents an interval of time that is missing from the rock record.

What are shield volcanoes generally made of?

Basalt flows

Where do body waves and surface waves travel?

Body waves travel within Earth, and surface waves travel along Earth's surface.

What do vertical and horizontal surface waves have in common?

Both waves travel along Earth's surface and decrease in amplitude with depth below the surface. Submit

Which of the following are types of volcanoes?

Composite volcano, Cinder cone and Shield volcano

Why does magma composition change during fractional crystallization?

Different elements in the magma form crystals at different rates, leaving behind more of the unused elements.

What is meant by elastic rebound?

Elastic rebound refers to how the slippage along a fault (i.e., earthquake) allows the deformed rock to regain its original shape in a new location. Submit

What is the category name for the largest division of time used on the geologic time scale?

Eon

Are volcanoes in the Ring of Fire generally described as effusive or explosive?

Explosive, as most of these volcanoes are composite cones which eject andesitic lava.

A series of layers of rocks are cut by two faults. Fault B breaks through to the surface, while Fault A does not. Which of the following statements about Faults A and B is correct?

Fault A is older than Fault B, and Fault A is older than the surface layer.

Five layers of rock are cut by two faults. Both faults cut through all five layers of rock. Fault A breaks through to the surface, whereas fault B does not. Which of the following statements about faults A and B is most accurate?

Fault A is younger than fault B, and both are younger than the five layers of rock.

What type of magma erupts out of dome complexes?

Felsic magma Submit

What is the principle of fossil succession?

Fossil organisms succeed one another upward through rock layers in a definite and determinable order; therefore, any time period can be recognized by its fossil content.

Which of the following events allows rocks on either side of a fault to rebound elastically, causing an earthquake?

Friction along the fault plane is overcome.

What is the principle of cross-cutting relationships?

Geologic features that cut through rocks must form after the rocks that they cut through.

The Principles of ___________ and __________ were used to determine relative ages in the previous question.

Inclusions, Cross-Cutting Relationships

What happens during radioactive decay?

Parent isotopes turn into daughter isotopes.

Which method of fossilization listed below is correctly described?

Permineralization is the process where pores in bones and wood are permeated by mineral-laden water.

1. The _______can be used to determine the relative ages of the sedimentary rocks versus canyon formation.

Principle of Cross-Cutting Relationships

The __________says that folded sedimentary beds have been disturbed since deposition.

Principle of Original Horizontality

What are composite volcanoes made of?

Pyroclastic deposits and andesitic lava

Which statement accurately describes a pyroclastic flow?

Pyroclastic flows, which consist of incandescent ash and lava fragments, can reach many miles away from their sources because they are nearly frictionless and are driven by gravity.

Which of the following statements about relative and absolute age dating is most accurate?

Relative age dating places rocks and events in chronological order but does not provide information about absolute age.

Which of the following statements about relative and absolute age dating is correct?

Relative age dating places rocks and events in chronological order, but does not provide information about absolute age.

Choose the correct description of viscosity. Under what conditions does magma have high viscosity?

Resistance to flow. Magma has a higher viscosity if it has a lower temperature, is rich in silica, and contains very few dissolved gases. Submit

How does rock within Earth change as S waves pass?

Rocks within Earth are displaced up and down as S waves pass.

How do rocks within Earth change as P waves pass?

Rocks within Earth both expand and contract as P waves pass. Submit

Which of the three basic types of seismic wave is likely to cause the greatest destruction to buildings?

S waves

How are hypocenters and epicenters related?

The hypocenter is the exact point underground along a fault where the slippage of the two blocks of rock occurs. The epicenter is the point on Earth's surface that is directly above the hypocenter.

How are S waves and vertical surface waves different?

S waves are body waves, whereas vertical surface waves are surface waves. The amplitude of S waves does not decrease with depth, but the amplitude of vertical surface waves does decrease with depth. Submit

What is the Principle of Original Horizontality?

Sedimentary rocks are close to horizontal when deposited.

What is the principle of original horizontality?

Sedimentary rocks are close to horizontal when deposited.

Which of the below choices supports the concept of crustal uplift?

Seismic tomography has shown a superplume centered below the southern tip of Africa. This is thought to explain the high topography of the area, which consists of an expansive plateau with an elevation of 1500 kilometers.

What information do geologists use to classify volcanoes?

Shape and type of deposits

What type of volcanoes have the greatest total height?

Shield volcanoes

A fault (F) breaks three layers of sedimentary rock (S). An igneous intrusion (I1) has broken through the bottommost layer of rock. A second igneous intrusion (I2) has moved up the fault and pooled on top of the uppermost layer of rock. Which event would be considered the youngest?

The intrusion of I1 or I2 is the youngest event. Without more information, we cannot know which igneous rock is youngest. Submit

Why are shield volcanoes wider than composite volcanoes?

The lava that flows out of shield volcanoes is more fluid than the lava that flows out of composite volcanoes.

The storm-disrupted layer identified in this model at annotation #1 contains abundant fossils (bioclasts) as evidence of storm wave action. The layers above that storm layer do not contain any clasts to indicate wave action. What can you conclude about these layers in terms of whether they were deposited in calmer water with little to no wave energy or deposited in high wave energy water?

The layers above the storm layers have horizontal and parallel bedding surfaces that were not disrupted by any kind of activity.

Using a calendar year as an analogy to the geologic time scale, when do the oldest anatomically modern humans appear on Earth?

The oldest human fossils show up at about eleven minutes to midnight on December 31st. Submit

What conditions favor the preservation of an organism as a fossil? PLEASE SELECT ALL THAT APPLY.

The organism has or is made of hard parts.The organism is rapidly buried.

Which of the following responses best describes the epicenter of an earthquake?

The point on Earth's surface directly above the focus of an earthquake.

Which of the geologic principles listed here is incorrectly defined?

The principle of cross-cutting relationships states that the fault or intrusion that cuts across several rock layers is older than these layers.

Two containers hold the same radioactive isotope. Container A contains 1000 atoms, and container B contains 500 atoms. Which of the following statements about containers A and B is true?

The rate of decay of atoms (half-life) in container B is the same as the rate of decay of atoms (half-life) in container A

true

The sandstone country rock is older than the dike. The intrusive igneous rock making up the dike is the youngest in age.

How is magma generated along convergent plate boundaries?

The subducting slab drives water and carbon dioxide into the mantle, which reduces the temperature at which it melts, allowing mantle rock to melt and rise. Submit

What are the two primary factors that determine the manner in which magma erupts?

Viscosity of magma and the amount of gasses in magma. An increasing in either or both of those factors makes eruption more explosive.

How do volcanic bombs differ from blocks of pyroclastic debris?

Volcanic blocks are made of hardened lava, whereas volcanic bombs are made of incandescent lava.

Volcanism at divergent plate boundaries is most often associated with which magma type?

Volcanism at divergent boundaries is most often associated with basaltic magma, which is created by decompression melting.

Name the epoch, period, era and eon in which we currently live.

We live in the Holocene Epoch of the Quaternary Period, which is part of the Cenozoic Era and Phanerozoic Eon. Submit

What is the principle of superposition?

Within a sequence of rock layers formed at Earth's surface, rock layers lower in the sequence are older.

What type of magma would you expect to see after crystallization of minerals containing significant amounts of iron?

a magma depleted in iron

When will the first earthquake waves arrive at a seismograph station?

a short time after the earthquake occurs

In addition to viscosity, which of the following parameters has an influence on whether a volcanic eruption will be effusive or violent?

amount of gas in the magma

What is a seismograph?

an instrument used to record earthquake waves Submit

Which of the following types of lava will most likely lead to a volcanic eruption of an effusive nature?

basaltic

Which type of plate boundary is associated with Earth's most destructive earthquakes?

convergent boundaries

Which of the pairs below are both examples of a trace fossils?

coprolite and burrow

What is fractional crystallization?

crystallization of part of a magma, leaving behind melted rock with a different composition from the original magma Submit

Isostatic adjustment

dam construction mining

Most earthquakes are the result of movement along which of the following features?

faults

The point within Earth from which earthquake wave energy radiates is known by which of the following terms?

focus

The sedimentary beds were initially deposited in a(n)_______ orientation.

horizontal

Structures built on __________ will become unstable during an earthquake.

loose, saturated sediments Submit

The sedimentary layers are ________than both folding and stream incision.

older

In calculating the location of the epicenter of an earthquake, which of the following factors is most useful?

the difference in arrival time of P and S waves Submit

What information does a time-travel graph provide?

the distance from the earthquake to the recording station Submit

Which principle of relative age dating is important for determining the relative age of igneous rock that has intruded into overlying rock?

the principle of cross-cutting relationships

Which of the following best describes liquefaction?

the transformation of stable soil into loose, liquefied material that is able to rise toward Earth's surface

In addition to a travel-time graph, at least how many seismograph stations are needed to determine the location of the epicenter of an earthquake?

three

What is the goal of correlation?

to gain a more comprehensive view of the geologic history of a region

Pore water pressure

wastewater injection groundwater extraction

The process of stream incision is _______compared to the folding of the rock units.

younger