BJU Life Science Chapter 8

Give the two different views about where the earth's internal heat comes from.

Secular geologists believe that about 20% of the heat is left over from the old earth's formation, when planetesimals collided and melted to build up the earth. The remaining 80% comes from radioactive decay. Young-earth geologists believe that the earth's internal temperatures are part of God's design. They think that radioactive decay also may contribute to the heat.

Sills, dikes, and batholiths are examples of what kind of volcanism?

Sills, dikes, and batholiths are examples of intrusion volcanism.

Name three kinds of plutons from smallest to largest.

Stocks, laccoliths, and batholiths

How does the amount of silica in lava affect its viscosity and the temperature at which it melts?

The amount of silica in lava affects its viscosity because lava with low amounts of silica are runny and melt at higher temperatures. Lava with high percentages of silica are very viscious but melt at lower temperatures

The term pyroclastic refers to all the different types of solid volcanic emissions.

True

Contrast hot springs and geysers.

A hot spring is a place where heated water rises to the surface as a liquid. A geyser is a hot spring that forcefully ejects its water from the ground at regular intervals.

Why is a volcano an extrusive igneous feature rather than an intrusive feature?

A volcano is an extrusive igneous feature rather than an intrusive feature because extrusive means above ground.

Which kind of igneous structure is a volcano?

A volcano is an extrusive igneous structure.

How would you classify a volcano that has no record of erupting but has evidence of a nearby ancient village partly buried in lava from it?

An active volcano

Why are hydrothermal features often found near volcanoes?

Both hydrothermal features and volcanoes exist because of the presence of magma.

(True or False) Nearly all scientists agree that building on or near a dormant volcano is not a good idea.

False

(True or False) The temperature of rocks rises at a constant 72 °F/mi with depth to the center of the earth.

False

Flowing lava is the most dangerous hazard from volcanoes.

False, a pyroclastic flow is the most dangerous hazard from volcanoes.

Pillow lava forms from the action of pyroclastic flows near the crater of a volcano.

False, it forms from water erupting under water.

Hawaii, in the middle of the Pacific Ocean, is an example of a volcano that rises from a mid-ocean ridge system.

False, it is an example of a volcano that formed over a hot spot in the middle of a tectonic plate.

Cinder cones are among the largest volcanoes in the world.

False, they are composite cones.

Geothermal energy has only recently been discovered and put to use.

False,it has been put to use for many years.

Why is geothermal energy not more wisely used?

Geothermal energy is not more widely used because you have to have a spot where the geothermal is near the Earth's surface.

Why does heated groundwater easily create special mineral deposits like travertine and geyserite?

Heated groundwater can easily create special mineral deposits like travertine and geyserite because the algae and bacteria in hot water makes the heat stay.

How are sills and dikes arranged in relation to the surrounding rocks?

How are sills and dikes arranged in relation to the surrounding rocks?

In general, how is the energy of a volcanic explosivity index (VEI) number related to the energy of the next lower value?

It is related to the energy of the next lower value because each number on the VEI scale represents an explosivity ten times greater than the number below it (except VEI 2). In other words, ten times as much tephra is ejected from a volcano with a given VEI than one with a VEI one less than that.

Evaluate the basis for old-earth and young-earth geologists' theories for the origin of the Earth's interior heat.

The Old-Earth's interior heat theory are mostly atheists, so their theory doesn't match the Bible or Christianity; The young-earth geologists are Christians, so they believe it is a part of God's design.

What is the Pacific Ring of Fire?

The Pacific Ring of Fire is a chain of volcanoes around the Pacific Ocean, or it can also be known as the Circum-Pacific Belt.

Explain how the Volcanic Explosivity Index rates volcanic eruptions.

The VEI rates volcanic eruptions by the volume of ash produced, height of the eruption cloud, the duration of eruption. They rate the eruption from 0-8 based upon tephra volume.

As you get closer to the center of the earth, how does the temperature of rocks change?

The closer you get, the warmer it gets.

From a young-earth view of Earth's history, what is the difference between an active volcano and a dormant one? What may be a safer way of classifying a volcano's activity?

The difference between an active volcano and a dormant volcano is an active volcano is currently erupting or has been observed to erupt in historical times and a dormant volcano is an inactive but uneroded volcano. A safer way of classifying a volcano is using better technology to stay safe when you're observing a volcano.

If there were more than forty VEI 8 or greater eruptions around the world that likely occurred during or shortly after the Flood, how would these events have affected the earth's climate right after the flood?

The earth was most likely dark and freezing and an ice age could have occurred.

Explain what causes the geothermal gradient.

The geothermal gradient is caused by the Earth's core having an estimated temperature of 500° C, while the Earth's surface temperature averages about 30° C.

What is the main difference between the types of solid volcanic emissions?

The main difference between the types of solid emissions is particle size.

What are the main volcano belts in the world? Briefly describe their geographic extent.

The main volcano belts are the Alpine-Himalayan, and the Circum-Pacific. The Alpine-Himalayan volcano belt lies above the collision boundary of the African, Indo-Australian, and southern Eurasian plates. The Circum-Pacific volcano belt surrounds most of the Pacific Ocean. This is where the tectonic plates that make up the Pacific basin are subducting beneath adjacent continental plates.

What is the most common type of volcano? Describe its structure.

The most common type of volcano is a strata volcano. It's structure consists of alternating layers of ash and overflowing pahoehoe and a'a craters.

How did earth scientists help prevent deaths from the 2010 Eyjafjallajokull volcano eruption? Why is this important?

The scientists carefully monitored the area and made accurate predictions. This is important because this proves we can make accurate predictions and it saved lives.

Evaluate the statement, "From a biblical view of history, almost all volcanoes are active according to the USGS definition of volcanic activity."

The statement is true because humans have been around since the beginning and could have possibly witnessed the eruption.

Name the three main types of volcanic emissions. Briefly describe or list the most common forms of each type

The three main types of volcanic emissions are liquid emissions, gaseous emissions, and solid emissions. Liquid emissions are lava and include basaltic magma, and esitic magma, and rhyolitic magma. Gaseous emissions include glowing avalanches/pyroclastic flows, lahars, and gases that escape from fumaroles. Solid emissions include pyroclastic material cinders, bombs, and tephra.

Describe the three general categories of volcanoes based on structure and indicate what materials make up each.

The three main types of volcanoes are cinder cones, composite cones, and shield cones. Cinder cones are the smallest kinds of volcanoes and are formed by bursts of gasses, mostly that of pyroclastic material. Composite cones are volcanoes formed by the ejections of both lava and pyroclastic materials and are larger than cinder cones but much smaller than shield cones. Shield cones are formed by lava and these are the largest volcanoes.

Describe the general features of a volcano.

There is at least one crater, neck, magma chamber, vent, and tephra.

Why were there no deaths from the Eyjafjallajökull volcano eruption in 2010?

There were no deaths in the 2010 Eyjafjallajökull volcano eruption because scientists were carefully monitoring and predicting where it would create hazards. Atmospheric models helped predict where the ash clouds would travel, so aircraft could be warned.

What do the number and extent of volcanoes and flood basalt zones indicate about conditions during the Flood?

These indicate the hellish conditions that occupied the earth both before and after the flood.

(True or False) A glowing avalanche is a downhill rush of hot volcanic gases carrying volcanic rocks and cinders.

True

Even though no VEI 8 eruption has ever been observed, we can see geologic evidence for past volcano explosions that could have been rated with a VEI of 8 or more.

True

Most volcanoes erupt from a magma chamber relatively near the Earth's surface.

True

On a contour map, hatched contour lines indicate lower elevations completely enclosed by higher elevations.

True

The geothermal gradient is often higher near tectonic plate borders than at the interior of the plates.

True

The number of active and extinct volcanoes around the world and the extent of flood basalts suggest that the Flood event was far more horrific than "just" a global flood with heavy rains and tsunamis.

True

Why do we find volcanoes near active tectonic zones?

We find volcanoes near tectonic zones because volcanoes are often byproducts of convergent boundaries.

What kind of igneous formations are sills, dikes, and plutons?

intrusive igneous formations.

Compare the source (s) of Earth's interior heat as suggested by old-earth and young-earth geologists.

Old-Earth geologists believe that the source of the Earth's interior heat is that there are two main heat sources; Young-earth geologists believe the heat is just a part of God's design.