Chapter 8 APES

Can you name each of the horizons in the figure below?

1-O horizon, 2-A horizon or topsoil, 3-B horizon or subsoil, and 4-C horizon.

What minerals or elements is basalt primarily composed of?

It is composed of minerals with high concentrations of magnesium, iron, and calcium.

Why is the movement of lithospheric plates significant?

It predicts where certain natural hazards are likely to be found such as volcanoes and earthquakes.

What are some possible detrimental aspects of volcanic activity?

Obviously great loss of life can occur during and after a volcanic eruption. Air travel can even be disrupted by volcanic eruptions. Air travel across the Atlantic Ocean was disrupted during the spring of 2010 due to ash from an Icelandic volcano.

According to the figure below, the island of Kauai was probably over the hot spot approximately how many million years ago?

Anywhere from 3 to 5.5 million years ago.

What are the important elements that are abundant in the mantle?

Is composed of magnesium, aluminum, silicon (materials a bit less dense than the core).

Where do deep sea trenches form? Why?

A deep-sea trench normally forms at a subduction boundary where a more dense oceanic plate is being pulled beneath a less dense continental plate. A deep-sea trench normally forms at the boundary between the two converging plates.

Where do deep-sea trenches form?

A deep-sea trench normally forms at a subduction zone boundary.

What is clay sometimes used for?

A good liner for a landfill is made of clay. The clay has such a small particle size that it is virtually impermeable. The clay effectively acts as a barrier so that liquids in the landfill do not percolate into the ground.

What are some benefits of hybrid vehicles?

A hybrid car has the potential to use only half as much gasoline as an internal combustion car so they are less dependent on fossil fuels. Hybrid cars have lower emissions and better mileage during operation. They often have lower maintenance than internal combustion engine vehicles. They are quieter to drive so there is less noise pollution.

What is the complete definition of a mineral?

A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. A rock, by comparison, is an aggregate of minerals and need not have a specific chemical composition. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms. By definition, minerals must have a definable crystal structure, be inorganic, naturally occurring (not manmade), and solid.

What is a soil profile?

A soil profile is a vertical section of the soil from the ground surface downwards to where the soil meets the underlying rock.

The Earth is generally considered to be how old?

About 4.5 to 4.6 billion years old

How does acid deposition relate to chemical weathering?

Acid rain is destructive (via chemical weathering) to limestone gravestones and to marble statues and buildings. Acid rain reacts with the calcium carbonate present in rocks like limestone and marble and over time, many gravestones become unreadable.

Should nuclear power plants be operated in seismically active areas?

After the 2011 Fukishima earthquake that devastated part of Japan, the world has been rethinking its love affair with nuclear energy, especially in seismically active regions of the world. Nuclear power plants are programmed to shut down if ground movement above a certain threshold occurs but this didn't stop the meltdown of the Fukishima-Daiichi nuclear disaster.

What evidence did Alfred Wegener present for claiming that the continents have not always been positioned where they are today?

Alfred Wegener was a German meteorologist who also studied what we used to call "continental drift". Some of the research and data that he used to support his ideas included: the continents look like they could "fit" together (much like the puzzle pieces that have drifted apart), the rock layers that form the Appalachian mountains of the eastern U.S. matched quite well with those in Scotland, fossils found on the east coast of Brazil match quite nicely with fossils found in western South Africa (Mesosaurus - a small freshwater reptile), and he also noticed that a lot of the fossilized life found in the rock record didn't fit in the climates they were found in.

What causes earthquakes?

An earthquake is MOST directly caused by the creation of a fault (fracture in rock) or shifting along an existing fault.

What is an ore?

An ore is a metal-yielding material that can be economically extracted.Ores may form when igneous rock is deposited, as a precipitate when magma comes into contact with water, in veins within rocks, or as a result of physical separation from other materials.

What are nonrenewable mineral resources? Give some examples.

Are concentrations of solid, liquid, or gaseous materials in or on the Earth's crust that can be converted to useful materials at an affordable price. Solid nonrenewable mineral resources include both metallic and nonmetallic resources. See below.

How do organisms sometimes respond to changes caused by plate movement?

As plates move, organisms must respond to changes such as speciation, extinction, alterations in behavior of predators and prey.

What is base saturation?

Base saturation of soil is a measure of the proportion of soil bases to acids. The soil that yields the greatest productivity for agriculture has more bases than acids.

What math do you need to be able to do for the Chapter 8 Test?

Be able to do problems like questions 1, 4, and 6 from your "Chapter 8 Review: Math Practice". These problems have been worked out and are posted for you to compare your answers to on Dropbox.

What is cation exchange capacity?

Cation exchange capacity refers to the nutrient holding capacity of the soil. Soils with high cation exchange capacities have the potential to provide essential cations to plants and are therefore desirable for agriculture. The cation exchange capacity in clays is high, meaning that it adsorbs and releases positively charged ions. The problem is, if a soil has too much clay, its water retention can become too great for most crops and waterlogging can occur that deprives the roots of oxygen.

Why is chemical weathering important?

Chemical weathering is part of the cycle that allows nutrients to be renewed to the soil. The weathering of certain granitic rocks consumes (uses up) carbon dioxide from the atmosphere and may reduce atmospheric carbon dioxide that would otherwise contribute to climate change.

What is the primary difference between chemical and physical weathering of rock?

Chemical weathering results in new substances and physical weathering just breaks big rocks into smaller pieces (their composition or make-up stays the same).

How does continental crust compare with oceanic crust?

Continental crust is made up primarily of granite (it is the dominant or primary rock type) and is less dense than oceanic crust. Oceanic crust is composed of basalt and is more dense than continental crust. Earth's crust is thickest beneath the continents and thinnest under the oceans. Oceanic crust underlies the ocean basins and covers around 71% of the Earth's surface.

Where does crust return to the mantle for recycling?

Crust returns to the mantle in subduction zones.

Which lettered position indicates where new ocean floor is being created?

D.

Describe what happens at diverging plate boundaries.

Diverging plate boundaries are areas where Earth's lithospheric plates are moving apart in opposite directions. Stated another way, tectonic plates move apart in opposite directions at a divergent plate boundary.

Which lettered position indicates a subduction zone?

E.

Which plate boundary has the largest probability of having the most violent and explosive type of volcanism?

E.

What are the main characteristics of Earth's crust?

Earth's crust is made up of the least dense minerals (which is why the crust is the outermost layer).

What is full-cost pricing and how does it relate to mining?

Environmentalists and some economists call for phasing in full-cost pricing that includes the cost of environmental harm done in the price of goods made from minerals. Right now we don't pay the full cost of the damage that is done to our environment as a result of mining. If we were to include all of the environmental costs associated with mining - air pollution, land pollution, water pollution, exploiting people in developing countries, etc. - the cost of our metals would be much higher.

What minerals is granite primarily composed of?

Feldspar, mica, and quartz.

Know the layers inside Earth. Know the order they go in.

From the Earth's surface to the middle of the Earth: Crust, Mantle (be sure to spell correctly, not like below), Outer Core, and Inner Core.

Why are we not actively mining the rich hydrothermal deposits that are found in the deep-ocean floor and around black smokers?

Hydrothermal ore deposits form when mineral-rich superheated water shoots out of vents in solidified magma on the ocean floor. After mixing with cold seawater, black particles of metal ore precipitate out and build up as chimney-like ore deposits around the vents. Rich hydrothermal deposits of gold, silver, zinc, and copper are found as sulfide deposits in the deep-ocean floor and around black smokers. Currently, it costs too much to extract these minerals even though some of these deposits contain large concentrations of important metals.

How is it possible for earthquakes with lower magnitudes on the Richter scale to be more damaging than some higher magnitude earthquakes?

If there are more people living in an area that is struck by even a low magnitude earthquake, there can be considerable damage to the infrastructure. If a high magnitude strikes a remote area with little human habitation, there can be less damage that affects humans directly.

What are some reasons igneous rocks are important?

Igneous rocks are an important source of many non-fuel mineral resources.As a stone, igneous rock is dense, crystalline, and durable, and therefore is often used for both building stone and as decorative rock material. Some igneous rocks are host to certain kinds of metallic mineral deposits, including iron and platinum (for instance).

What are igneous rocks? How do they form?

Igneous rocks form either below Earth's surface or on the Earth's surface when molten rock wells up from the Earth's upper mantle or deep crust and then cools and hardens. Igneous rocks form from liquid magma or lava.

How do igneous rocks that form beneath the surface compare to rocks that form outside of the crust?

Igneous rocks that form from magma that cools inside of Earth are known as intrusive igneous rocks. Granite is an example of an igneous rock that cooled slowly giving large crystals a chance to develop. Igneous rocks that form on Earth's exterior cool more quickly and therefore they are often fine-grained without visible crystals. Basalt, pumice, and obsidian are examples of extrusive igneous rocks.

After cooling, lava would be considered an example of what type of rock?

Igneous.

What type of rock makes up the bulk of Earth's crust (even though it may be covered by other rocks or soil)?

Igneous.

What is cyanide heap leaching and what is it used to extract?

In Australia and North America, a mining technology called cyanide heap leaching is cheap enough to allow mining companies to level entire mountains containing very low-grade gold ore. Cyanide - a highly toxic chemical - is used to separate about 85% of the world's gold from waste ore.

What is the definition of a rock?

In geology, rock is a naturally occurring aggregate (combination) of minerals. The Earth's lithosphere is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic. Summary - a rock is basically a solid combination of one or more minerals.

What has been the most important volcanic eruption in North America in recent times?

In the continental (48) states, the most important volcanic eruption in recent times was Mt. St. Helens in 1980. Mt. St. Helens if part of the Cascade Mountain Range that runs from Washington down to Northern California. The volcanic activity of the Cascades are related to the subduction of the Juan de Fuca Plate under the North American Plate.

What are mantle plumes?

In this process mantle rock flows slowly upward in a column, like smoke from a chimney on a cold, calm morning. When the moving rock reaches the top of the plume, it moves out in a radial pattern, as if it were flowing up an umbrella through the handle and then spreading out in all directions from the tip of the umbrella to the rim.Mantle plumes are thought to be the cause of volcanic centers known as hotspots and flood basalts.

What can predict the damage an earthquake causes?

Its magnitude on the Richter Scale. The proximity of its epicenter (the location on Earth's surface directly above the focus of the earthquake beneath Earth's surface) to densely populated areas. The quality of building construction close to the earthquake zone is also a good predictor of potential damage.

What is limestone sometimes formed from?

Limestone is a common sedimentary rock that formed from the compacted shells, skeletons, and other remains of dead organisms in shallow marine environments. Limestone is composed of the mineral calcium carbonate.

What type of soil is best for growing plants?

Loam is generally considered to be the best type of soil for growing most plants. Loam soils are a mixture of sand, silt, and clay that promotes water drainage and retention.Sandy soils drain well but they don't hold on enough water. Clay soils are relatively impermeable but they retain their soil moisture for quite a while.

What are the environmental impacts of mining low grade ores?

Low-grade ores are those where there is very little of the mineral we are want that is present and it is surrounded by lots of waste rock. The environmental impacts of mining for low-grade ores can be substantial. First of all, it is very expensive to mine low-grade ores because so much volume has to be processed just in order to get a little of metal we want. Many of the low-grade ores also require large amounts of water to process them and the ores themselves are located in arid or semiarid regions. This can lead to destroying a water resource already in short supply. Finally, the environmental impact of increased land disruption, waste material, and pollution produced during mining and processing make low-grade ores a definite environmental problem.

What occurs at a hot spot eruption?

Magma rises to the surface of Earth's crust.As a plate moves across this hot spot, volcanic activity takes place. The hot spot remains stationary but as the plate moves, it creates a record of the volcanic activity.

What is obsidian?

Obsidian is a great example of an extrusive igneous rock that is smooth and very fine-grained. It hardened so rapidly that crystals didn't have time to develop.

What are metamorphic rocks?How do they form?

Metamorphic rocks are rocks that have been transformed as a result of their subjection to high heat and pressure.

Name a famous example of a diverging plate boundary.

Mid-ocean ridges are good examples of diverging plate boundaries. The Mid-Atlantic ridge is a good example of a diverging plate boundary.

A geologist finds a substance with uniform solid crystalline structure and composition throughout. In the lab it is determined that the substance consists of more than one element. The term which properly identifies the substance is?

Mineral.

What constitutes a small earthquake on this scale?

Minor and moderate earthquakes are 1 -4.

Where do most earthquakes and volcanic eruptions occur? Why?

Most earthquakes and active volcanoes occur and are associated with plate boundaries. The constant bumping, grinding, and lateral movement along crustal boundaries can create sudden movements that result in earthquakes. As plates diverge at mid-ocean plate boundaries magma wells up and creates volcanic activity. As plates subduct under other plates the tension and pressure cause friction and heat that creates both deep earthquakes and explosive volcanoes.

What does mountaintop removal of minerals involve?

Mountaintop removal is a type of mining primarily used in the extraction of coal. Is extremely disruptive to ecosystems and entire habitats are lost. This type of mining leaves the land so changed that any rehabilitation is a mere shadow of what of the habitat once was.

Where is new ocean floor created?

New ocean floor is created by seafloor spreading in the rift zone of diverging plate boundaries.

What constitutes a large, devastating earthquake on this scale?

Noteworthy and high damaging earthquakes have Richter values of 6 through 10. The Chilean earthquake of 1960 at 9.5 is perhaps the largest earthquake ever and is associated with the subduction of the Nazca Plate beneath the South American Plate.

What can cause soil degradation?

One way soil is degraded by man is through the compaction of soil caused by the use of heavy equipment. If soil is not held into place by roots, it can succumb to water and wind erosion. Agriculture and also deplete the soil of its organic matter and nutrients.

How is open pit mining accomplished?

Open pit mining is where machines dig holes and remove ores (such as iron and copper), sand, gravel, and stone (such as limestone and marble). Big holes in the ground are left after the desired mineral or rock has been removed. Open pits are sometimes filled back in or they sometimes fill with water to become lakes (very deep lakes).

What is overburden? What are spoils and spoil banks?

Overburden refers to the layer of soil and rock overlying a mineral deposit. Surface mining removes this layer. Spoils are what the waste material removed as overburden are called. Area strip mining leaves a wavy series of highly erodible hills of rubble known as spoil banks.

The crustal abundance of four (4) elements makes up greater than 88% of the Earth's crust. What are these elements? Rank them from high to low.

Oxygen, silicon, aluminum, and iron. Know that oxygen and silicon are by far the most abundant followed by aluminum and iron.

What is physical weathering?

Physical or mechanical weathering is when a large rock mass is broken down into smaller fragments. The most important agent of physical weathering is frost wedging in which water collects in the pores and cracks of rock, expands upon freezing, and splits off pieces of rock. Also, when minerals within a rock respond differently to temperature changes, it results in physical weathering due to the differential cracking of the rock.The "freeze-thaw" or hot-cold change in rocks is an example of physical weathering.When minerals within a rock respond differently to temperature changes, it results in both physical weathering and the differential cracking of the rock.

How do plant roots weather rock?

Plant roots wedge rocks apart as they grow into rock crevices. Lichens are very important in both physical and chemical weathering because they produce weak acids that help to weather the rock.

Why do Earth's plates continue to move on Earth's surface?

Plates are moved (pushed and pulled) by convection currents within the mantle. This causes the asthenosphere to flow very slowly. Material expands and rises upon heating but contracts and sinks upon cooling. Plates are pulled apart where convection cells are rising. Plates are being pulled back into the Earth and are being remelted where convection currents are sinking. In other words, sinking convection currents are associated with lithospheric plates that are moving together like at subduction boundaries. Ridge push and slab pull also assist plate movements. Magma circulates in convection cells in the asthenosphere. Convection cells in the asthenosphere are a contributing reason as to why Earth's lithospheric plates move.

How can rich deposits of gold and silver be formed?

Rich deposits of gold and silver may be concentrated when water dissolves them and they precipitate out to form veins in a rock.

What minerals have been found around volcanic hot springs and hydrothermal vents?

Rich hydrothermal deposits of gold, silver, zinc, and copper are found as sulfide deposits in the deep-ocean floor and around black smokers.

What are some ways we can know that a volcanic eruption is possibly imminent?

Scientists are actively studying phenomena that precede an eruption in order to better predict when an eruption is likely. One indicator that is often used to indicate an imminent (likely to happen at any time in the near future) volcanic eruption is the tilting or swelling of the volcanic cone. Other examples include changes in magnetic and thermal properties of the volcano, changes in gas composition, and increased seismic activity.

What are sedimentary rocks?How do they form?

Sedimentary rocks form primarily in three (3) different ways - by the consolidation of rock fragments, from organic materials (once living organisms, and by precipitation (chemicals settling out of water usually). Sedimentary rock may be formed by sediments deposited on an ocean floor, by sediments deposited in a stream, by sediments deposited on a lake bottom, and as a result of compression by overlying sediments.

What type of rock is where fossils, formed from plant or animal remains are found?

Sedimentary rocks.

What can we do to promote the sustainable use of nonrenewable minerals?

See chart.

What are soil horizons?

Soil horizons are stratified layers in soil. To see the horizons, a soil profile is dug and used to classify the soil.

What causes soil to be more fertile?

Soil is more fertile when the parent material has a high calcium carbonate content.

What effect do temperature and rainfall have on soil?

Soil is nutrient poor in the humid tropics because of the warm temperatures and high rain creating conditions most able to weather rock and leach nutrients from the ground.

What is soil?

Soil is the weathered portion of the Earth's crust that can sustain life. Soil is an anchor for plants, a habitat for many different organisms, is a place where organic matter is recycled, and it also serves to filter water and atmospheric chemical compounds. The layer of soil on the surface of Earth is at the top of the crust.

What is soil porosity?

Soil porosity refers to how much space exists between soil particles.

What kinds of soils develop from granitic rock?

Soils that develop from granitic rock tend to be more permeable. This is because much of granite is composed of the relatively hard mineral quartz that weathers down into sand-sized particles. Sand, with its large pores, tends to be very permeable. Soil drains most rapidly when it is made up of primarily sand.

What are some examples of sedimentary rocks?

Some common sedimentary rocks include sandstone, limestone, coal, shale, conglomerate, halite, etc.

What are some examples of metamorphic rocks?

Some examples of metamorphic rocks include marble, slate, schist, gneiss, etc.

What are some important secondary effects of earthquakes?

Some secondary effects from earthquakes include: urban fires from broken gas lines, damaged coastal areas, death due to diseases from poor sanitation (such as cholera), mass wasting, tsunamis, lack of food, clean water, shelter, and medical facilities. Some economic effects might include job losses and loss of communication networks.

What is strip mining?

Strip mining is a form of surface mining in which "strips" of soil and rock are removed to expose ore.In surface mining, mechanized equipment strips away the soil and rock that lies on top of the mineral deposits being removed.

Describe what happens at subduction boundaries.

Subduction boundaries are places where oceanic lithosphere is carried downward (subducted) under another plate at a convergent boundary. A trench ordinarily forms at the boundary between the two converging plates.

What creates acid precipitation?

Sulfur dioxide and water vapor combine to create sulfuric acid. Sulfur and oxygen combine to create sulfur dioxide. Sulfur dioxide comes the burning of coal.

What is the A horizon?

The A horizon, or topsoil, is below the O horizon and is frequently rich with accumulated humus.

What is the B horizon?

The B horizon or subsoil, is typically a zone of illuviation for the leached material from the A and E horizons. It may be rich in humus, clay, or iron. Mineral nutrients are primarily present in the B horizon or subsoil.

What is the C horizon?

The C horizon, or regolith contains weather rock and sits upon the parent material. The least weathered zone in a soil is the C horizon.

What is the E horizon?

The E horizon (eluviated) is a heavily leached soil area that sometimes develops between the A and B horizon. The E horizon is a zone of eluviation which means that materials are leached from it. It is the zone through which iron and aluminum pass from overlying soil horizons.

What are the main characteristics of Earth's inner core?

The Earth's inner core is composed of iron and nickel just like the outer core, the main difference is that it is solid because of the tremendous pressure it is under.

What are the main characteristics of Earth's outer core?

The Earth's outer core is composed primarily of liquid (molten) iron and nickel. Most scientists believe that one of the main reason we have such a strong magnetic field is because of the Earth's rotation and the molten iron that makes up the outer core.

What is the O horizon?

The O horizon is the organic material on the surface of the soil.

What is its significance?

The asthenosphere is the region that the lithospheric plates are moving on.

What is the asthenosphere?

The asthenosphere is the upper region of the mantle composed of very hot, partly melted rock that flows slowly and can be deformed like soft plastic.

What are the important rocks that make up the crust?

The crust is made up primarily of two rocks, granite and basalt. The crust is the only layer of the Earth we have drilled into and is the source of all the elements and minerals we extract through mining.

What is erosion? How does it compare to weathering?

The difference between weathering and erosion is that weathering refers to the breakdown of the rock; erosion refers to the removal of the rock from its landscape.We can think of erosion as carrying rock fragments to a new location.Erosion is caused by wind, water, gravity, glaciers, burrowing animals, etc.

What are the energy sources primarily responsible for Earth's external geological processes?

The energy sources primarily responsible for Earth's external geological processes are energy from the sun and gravity.

What causes the high temperatures at the center of the Earth?

The high temperatures at the center of the Earth are primarily the result of radioactive decay.

How can sandy soils affect the infiltration of pollutants?

The infiltration of pollutants into groundwater is common in areas with sandy soils because water flows through them easily.

What is the lithosphere? Describe what makes up the lithosphere.

The lithosphere is the outer shell of the Earth, composed of the crust and the rigid outermost part of the mantle outside of the asthenosphere. So, the lithosphere includes all of the crust (both continental and oceanic crust) and the rigid upper part of the mantle.

What are the main characteristics of Earth's mantle?

The mantle is just above the outer core of the Earth. The outermost part of the mantle is rigid and the region under this is partially melted rock.

What region of our planet has the most volume and mass of any Earth layer?

The mantle.

How are the elements of Earth separated?

The most dense elements are in the center, known as the core. The elements making up the other layers are increasingly less dense as you approach Earth's outer layer, the crust.

How are igneous, sedimentary, and metamorphic rocks related through the rock cycle?

The rock cycle has no beginning and no end. Igneous rocks and sedimentary rocks can both be put under heat and pressure to form metamorphic rocks and weathered to form sedimentary rocks. Metamorphic rocks can also be remelted to form igneous rocks. In other words, the rock cycle is a group of changes where one type of rock can be altered to form another type. Study the rock cycle below to see how many ways rocks can be converted into other types of rocks.

What is the rock cycle?

The rock cycle refers to the constant formation and destruction of rock. The rock cycle is the slowest of all Earth's cycles. Environmental scientists are most often concerned with the part of the rock cycle that occurs at or near Earth's surface.

How is the strength of earthquakes measured?

The strength of earthquakes is measured with the Richter Scale. The Richter Scale is logarithmic, in other words, each level is 10 times stronger. An earthquake that measures 8.0 on the Richter Scale for example would be 1000 times stronger than an earthquake that measures 5.0.

What is soil texture?

The texture of soil is determined by the relative amounts of different sized inorganic soil particles. The three particle sizes of soil are sand, silt, and clay (from large to small).

What does the theory of plate tectonics state?

The theory of plate tectonics states that Earth's lithosphere is divided into plates which move.

How does the upper mantle compare with the region of mantle just below the upper mantle?

The upper mantle is rigid and along with ocean and continental crust forms Earth's lithospheric plates. The Asthenosphere is a region of partly melted rock that flows very slowly.

About how many major rigid plates make up Earth's surface?

There are about 15 major rigid lithospheric plates that make up Earth's surface.

What are metallic resources? Give some examples.

These include important metals such as iron, copper, nickel, aluminum, etc.

What are nonmetallic resources? Give some examples.

These include important resources that are nonmetals such as salt, clay, sand, phosphates, and soil.

What is the Surface Mining Control and Reclamation Act of 1977?

This is legislation that mandates that land should be minimally disturbed during the mining process and reclaimed after mining is completed.

What is the U.S. Mining Law of 1872?

This law encourages the extraction of minerals from public lands, almost free of charge.

What are some environmental trade-offs that hybrid electric cars come with?

To mine the elements needed in hybrid electric cars acids have to be pumped into deep boreholes to dissolve surrounding rock. There is considerable ground disturbance which enables air and water to react with other minerals in the rock. The natural habitat experiences fragmentation. Acid mine drainage flows over the land as a result of underground disturbances in the mining process.

Describe what happens at transform boundaries.

Transform faults are areas where the Earth's lithospheric plates are moving in opposite but parallel directions along a fracture (fault) in the lithosphere. The San Andreas Fault is a famous transform fault on land. Diverging plate boundaries are also the site of many transform faults.

What is ejecta?

Volcanic activity can release ejecta (debris ranging from large chunks of lava rock to ash that may be glowing hot).

What are some possible benefits of volcanic activity?

Volcanic soils are some of the most fertile soils on Earth. Volcanic rocks are composed of minerals that contain elements important to plant growth. When volcanic rocks break down, they form soils that contain many nutrients that plants can use. They can also form new land masses and islands. Volcanoes can provide geothermal energy can be useful for heating. Our atmosphere got much of its components from the eruption of volcanoes. Places like Mt. St. Helens are also great tourist destinations and that can be an economic benefit to local communities.

Where can volcanoes be found?

Volcanoes can be found at or near plate boundaries where subduction, divergence, convergence and seafloor spreading are occurring.

How can we reduce loss of life from volcanic activity?

We need to use historical records and geologic measurements to identify high-risk areas so that people can try to avoid living in them. We should develop effective evacuation plans and try to invent new devices that can take measurements to warn us more accurately when volcanoes are likely to erupt.

What is weathering? What are the basic types of weathering and how do they operate?

Weathering consists of the physical (mechanical or disintegration), chemical (decomposition), and biological processes that break down rocks and minerals into smaller particles that can be eroded.

How is rock weathering associated with surface area to volume relationships?

When the surface area to volume ratio of rock is increased, the rock weathers more rapidly because there are greater surfaces on which chemicals can work

Describe what happens at converging boundaries where both plates have the same density.

When two plates composed of continental crust collide, both plates get pushed upwards to form some of the tallest mountains in the world such as the Himalayas, the Urals, and Alps.

Name an important example(s) of where this is happening today.

Where the Indian plate (Indo-Australian plate) is slamming into the Eurasian plate the tallest mountains on Earth are continuing to grow taller into the Himalayas.

Rocks comprise (are made up by) primary minerals that erode to secondary minerals and then to ionic forms of these minerals. An example is:

granite ->feldspar->clay->potassium ions