We will discuss planet Earth's structure and resources in this chapter.
According to the College Board, about 10% of the test will be on the material that's contained in this chapter, so consult your textbook for more information about subjects that don't look familiar.
We will discuss the components of the solid Earth, how long it has existed, and why we have earthquakes and volcanoes.
This will be followed by a discussion of how soil is formed, what it's made of, and why it's important to humans.
We'll discuss the structure of the atmosphere and how it produces the weather.
The atmosphere, hydroosphere, and biosphere are intricately related.
We'll go through everything you'll need to know about the systems for test day after we break them down into neat sections.
We will review oceans and freshwater bodies and refresh your memory about environmental issues related to Earth's water supply.
Earth's history is the first thing you should know.
The planet is thought to be between 4.5 and 4.8 billion years old.
The geologic time scale on the following page will help you understand the amount of time that has passed since Earth was formed.
You don't have to memorize all of the eons, eras, periods, and epochs, but you should be familiar with the major ones.
Our solar system contains eight planets, including Earth, which is the third planet from the Sun.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, and Neptune can be seen from the Sun.
Earth and the other planets are in an elliptical pattern around the Sun.
It takes Earth about a year to complete its circle of the Sun.
Planet Earth has three zones of rocks that are either solid or liquid.
The core is the innermost zone.
A solid inner core and molten outer core make up the core.
The inner core is made of nickel and iron and is solid.
The outer core is composed mostly of iron and sulfur and is semi-solid.
The mantle is made mostly of rock.
The asthenosphere is a slowly flowing area on the mantle.
The outer layer of the earth is called the lithoosphere.
The solid surface of Earth is contained in the rigid upper mantle.
The continents were joined together and formed a supercontinent called Pangaea.
Pangaea began to break apart 200 million years ago.
The word pan meant whole in ancient Greek, while the word gaia meant land.
It is believed that the earth's crust is composed of several large pieces that move slowly over the mantle of the earth.
There are at least a dozen plates that move independently of one another.
The plates are made from the same material.
The majority of the land is above six giant plates, while the rest is under the ocean and the continents.
The Nazca plate, which lies off the west coast of South America, is one of the plates that only contains ocean floor.
The United States is located in the North American plate, which extends out to the mid-Atlantic ridge.
The boundaries of the plate are almost identical to those of Turkey.
The largest plate is the Pacific plate, which includes Mexico's Baja Peninsula and southwestern California.
The major plates of Earth are shown on the map.
The places where two plates abut each other are called plate boundaries and are where events like sea floor spreading and earthquakes occur.
There are three different types of plate boundary interactions.
Two plates are pushed towards each other.
The plate will be pushed into the mantle.
Two plates are moving away from each other.
New crust is formed when a gap is filled with magma.
Two plates slide from side to side relative to each other, like when you rub your hands back and forth.
These are called transform boundaries.
It depends on where the plates collide.
Subduction is when a heavy ocean plate is pushed below the other plate and melted as it encounters the hot mantle.
The Himalayas were created by a collision between the plate carrying India and the Asian plate, as well as the Alps, the Urals, and the Appalachian Mountains.
The creation of volcanoes and earthquakes is a result of plate movement.
A volcano is a mountain formed from Earth's interior.
Active volcanoes are those that have erupted within recorded history, while dormant volcanoes have not been known to erupt.
It is thought that extinct volcanoes will never erupt again.
There are volcanos where tectonic plates meet.
There are breaks in Earth's crust at these junctures.
Pressure builds up until it is relieved in a volcanic eruption if no outlet is available.
The kind of tectonic event that produces active volcanoes are categorized.
Plates move away from each other in a valley.
The plates have separated and the ocean floor is formed.
basaltic magma rising from rift valleys.
It forms pillow lava when it touches the ocean water.
Subduction zones occur when plates collide and the denser plate is subducted beneath the less dense plate.
Hot spots don't form at the margin of plates.
Instead, they are found over "hot spots," which are areas where magma can rise to the surface through the plates.
The Hawaiian Islands formed over a hot spot.
The magma can be basaltic or rhyolitic, which is associated with continental hot spots.
Shield volcanoes have slopes.
They form over hot spots and have eruptions with slow lava flow.
When water enters the vent, it can form a fluidized mixture of hot ash and rock.
The volcano has a broad base but steep slopes.
They are formed at subduction zones and are associated with violent eruptions.
Cinder volcanoes form when molten lava erupts and cools quickly in the air, and then becomes rock that breaks as it hits Earth's surface.
They form near other types of volcanoes.
Earthquakes are caused by the release of energy from deep in the earth.
Earth's tectonic plates move at about the same pace as fingernails, but earthquakes are very sudden.
Two plates slide past each other at a transform boundary.
The epicenter of the earthquake is the location at which it begins within the earth.
The seismograph was invented in 1935 and is used to measure the size of earthquakes.
The highest S-wave of an earthquake is measured on the Richter scale.
An S wave, also known as a shear wave, is a wave that shakes the ground back and forth as it moves.
The nation of Haiti was struck by an earthquake in January of 2010.
The epicenter of the earthquake was in the boundary region between the Caribbean plate and the North American plate.
There were 222,570 people killed, 300,000 injured, 1.3 million displaced, 97,289 houses destroyed, and 188,383 damaged in the earthquake in Haiti.
At least 4 people were killed by a local wave in the Petit Paradis area.
During an earthquake or volcanic eruption, large waves, or chains of waves, can be caused by the movement of the earth and can be very destructive.
The eastern coast of Japan was hit by an earthquake in March of 2011.
The wave was 33 feet high.
Many buildings, roads, and railways were destroyed, major fires occured, villages, thousands of homes, and people were washed away, and at least three nuclear power plants were 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217 800-273-3217
Our buildings, the soil, and the rocks used in industry are all around us.
Other rocks is the answer.
The oldest rocks on the planet are 3.8 billion years old.
Rocks have to be recycled.
The rock cycle is the process that does this.
Three basic types of rocks are created when time, pressure, and the earth's heat interact.
When rock is melted into a liquid, it resolidifies.
The molten rock (magma) comes to the surface of the earth, and when it emerges it is called lava.
An example of a rock is basalt.
As the remains of plants and animals build up, the rocks are formed.
A stream bed or ocean floor contains dissolved minerals that form under the water.
As more material is deposited, they are compressed.
Limestone is an example of a rock.
Pressure and heat are applied to the rock.
The high temperatures found in the earth's mantle can cause this to happen.
Slate is a product of the transformation of shale.
The diagram on the next page shows the rock cycle.
The soil is an important player in Earth's interdependent systems.
The life of the plants, animals, and other organisms that live in the biosphere is dependent on the soil, and it is an essential link between the abiotic and the biotic.
In the next chapter, we'll see that soil plays a role in the cycling of nutrients.
You will be expected to know the major characteristics of the soil for the test.
We may be tempted to think of soil as just a dirt, but it's actually a complex, ancient material teeming with living organisms.
In a gram of soil, there may be as many as 50,000 organisms.
Mineral materials make up half of the volume of soil, while organic matter makes up 5 percent.
The size of the particles that make up the soil determines the size of the pores between the soil particles.
The physical and chemical features of the soil can be categorized.
The United States Department of Agriculture divides the soil into three large groups, and the clay category has the smallest particles.
Sand is the coarsest soil with particles less than 2.0mm in diameter.
Sand particles are too large to stick together, and sandy soils have larger pores, which means they can hold more water.
Clays are easy to adhere to, and there is little room between particles for water.
The soil's acidity or alkalinity is an important characteristic.
The concentration of hydrogen ion is a measure of the pH of a substance.
Most soils range in pH from being neutral to slightly acidic.
It's important that the soil's pH is right because it affects the ability of plants to absorb certain vitamins and minerals.
If the soil in the region is acidic or basic, the plants won't be able to use certain soil nutrients.
The College Board wants you to know that when the pH of the soil gets more acidic, heavy metals can get into the ground water.
Plants and aquatic life can be harmed by ion travel.
The gills of fish can be damaged by aluminum ion.
The combination of organic material and rock that has been broken down by chemical and biological weathering is called soil.
The identity of the base rock of the region will affect the types of minerals found in the soil.
Water, wind, and living organisms are all prominent agents of weathering, and all weathering processes are placed into the following three broad categories.
Any process that breaks rock down into smaller pieces without changing the chemistry of the rock is called physical weathering.
The forces that cause physical weathering are wind and water.
When iron and other metallic elements come in contact with water, they form rust.
The activities of living organisms, such as tree roots growing and expanding through rocks, are what cause biological weathering.
Different layers make up the soil.
There are different layers of soil known as horizons.
The O horizon is the uppermost horizon of the soil.
It is made up of waste from organisms, decomposing organisms, and live organisms.
The A horizon is made up of weathered rock and organic material that has traveled down from the O layer.
The A layer is an important part of plant growth.
This is the part of the body that oxidizes.
The E horizon is between the A and B horizon and is made of clay, iron, or aluminum oxides.
The B horizon is below the A horizon.
The B layer gets all of the minerals and organic materials that are washed down from the top of the A horizon.
The zone of illuviation is this one.
Illuviation is the movement of dissolved material from higher soil layers to lower soil layers due to the downward movement of water.
The C horizon is the bottommost layer of soil.
The C horizon is composed of larger pieces of rock.
The bedrock is referred to as the R horizon.
Understand the different types of weathering processes and the order of the soil layers.
We need enough arable land and suitable soil to grow all of the food we consume.
Nitrogen, K, and P are essential to plants and are provided by soil fertility.
The types of soil that are considered the best for plant growth are composed of the same amount of clay, silt, and sand.
The extent to which the soil clumps is an important characteristic.
The texture of the soil can be changed by certain agricultural activities, for example, repeated plowing can break down soil aggregates, leaving "plow pan" or "hard pan," which is unfertile soil.
In modern agriculture, the monoculture or the planting of just one type of crop in a large area is more preferred than the traditional planting of many different types in a field.
There has been a decrease in the genetic diversity of crop species.
There are a lot of problems created by this.
Crops are more susceptible to pests and diseases because of a lack of genetic variation.
The consistent planting of one crop in an area eventually causes the soil in that area of the specific nutrients that the plant needs to grow.
Crop rotation, in which different crops are planted in the area in each growing season, is one way to prevent this phenomenon.
Polyculture is a practice that farmers will use to increase their sustainable practices.
This increases the number of animals.
The reliance on large machinery and the fact that agriculture is a huge consumer of energy are some of the problems with modern agriculture.
Fossil fuels are used to run farm machinery, as well as in the production of pesticides and fertilizers.
The mechanization of farming that resulted from the Industrial Revolution has resulted in a huge increase in worldwide agricultural productivity over the past 50 years.
The Green Revolution, a boom in agricultural productivity, has had detrimental effects on the environment.
The emergence of a new variety of pesticide-resistant insects was a result of the use of chemical pesticides.
The introduction of genetically modified plants has made it possible for researchers to solve the problem of pesticide-resistant insect species.
The increase in irrigation worldwide resulted in over-irrigated soils.
Salt forms a layer on the surface of the soil when it dries out.
This leads to land degradation.
In order to combat this problem, researchers have developed drip irrigation, which only gives an area as much water as is necessary and delivers it directly to the roots.
The small rock fragments that result from weathering may be moved to new locations in the process of erosion, and bare soil is more susceptible to erosion than soil that's covered by organic materials.
The constant movement of water and wind on Earth's surface causes the erosion of soil.
It can become a problem for humans when soil is deposited in undesirable places.
Farmers who need healthy soil for planting and people who rely on bodies of water to be uncontaminated with soil runoff are at risk of being in bodies of water.
Slash-and-burn agriculture, which is characterized by cutting down and burning trees to clear land for agricultural purposes, is the most significant portion of erosion caused by humans.
The removal of plants makes the soil more vulnerable to erosion.
The levels of erosion in the upper layers of soil have been increased by human activities such as the over-cultivation of agricultural fields.
Farmers searching for arable land will continue to face problems until new techniques that preserve the integrity of the soil are introduced.
Several best management practices have been developed to conserve soil resources.
These practices return organic matter to the soil, slow down the effects of wind, and reduce the amount of damage done to the soil by plowing.
Some of the more common methods are listed here.
The amount of organic matter in the soil can be increased by using animal waste, compost, and plants.
A method of farming that utilizes compost, manure, crop rotation, and non-chemical methods to manage soil fertility and pest control is called organic agriculture.
Chemicals, pesticides, and genetically modified organisms are not used by organic producers.
Modification of practices to reduce the amount of erosion.
These include plowing and strip planting.
Trees and other wind barriers can be used to reduce the force of the wind.
Much of what we know about soil is new.
The creation of the Soil Conservation Service was made possible by the Soil Conservation Act of 1935.
The Dust Bowl of the 1930s was a period of unprecedented dust storms caused by severe drought and ill-advised farming practices.
The program was led by Hugh Hammond Bennett and was created to conserve soil and restore the nation's ecological balance.
The federal government was aware of the need to protect this resource.
There are two laws related to preserving soil.
The halfway point of this chapter is almost here.
Next, we will look at the atmosphere.
The atmosphere is a layer of gases held close to Earth by the force of gravity.
The troposphere is a layer of gases that extends from Earth's surface to about 10 miles away.
The majority of atmospheric water vapor and clouds can be found in the troposphere, which is where all of the weather takes place.
The troposphere is mixed vertically and gradually becomes colder with an increase in altitude.
You've probably heard about the troposphere before, because of the greenhouse effect.
H 2 O and CO 2 are the most important gases in the troposphere.
Greenhouse gases in the troposphere absorb a lot of the solar radiation that is reflected back into space.
We'll look at the greenhouse effect further in Chapter 9.
The tropopause is a layer that protects the troposphere from the next layer up.
The temperature begins to increase with altitude in this buffer zone.
The stratosphere is on top of the tropopause and extends up to 50 km above Earth's surface.
As in the tropopause, the temperature in the stratosphere increases as the distance from Earth increases, but its gases are not very well mixed.
This warming effect is caused by a thin band of ozone.
The ozone protects the troposphere and Earth's surface from the high-energy radiation of the Sun.
The mesosphere and the thermoosphere are above the ground.
The mesosphere is 80 km above Earth's surface and is where most meteorites burn up.
The thermoosphere is the most dense gas layer above Earth and is where the Auroras occur.
Most of the charged particles from the Sun are absorbed by the thermoosphere, which is also known as the ionosphere.
Long distance radio communication is possible because the thermoosphere reflects radio waves.
You will need to know how the climates on Earth are created by the atmosphere.
Earth's atmosphere has physical features that change day to day as well as patterns that are consistent over time.
The day-to-day properties such as wind speed and direction, temperature, amount of sunlight, pressure, and humidity are referred to as weather.
Climate is the pattern that is constant over many years.
Average temperature and precipitation amounts are the most important factors in describing the climate.
Scientists who study weather and climate are called meteorologyologists.
The weather and climate of any given area is the result of the Sun warming Earth and the gases above it, as well as Earth's rotation.
Solar heating, the rotation of Earth, and the physical properties of air, water, and land all contribute to the motion of air around the globe.
There are three reasons why Earth is not evenly heated.
More of the Sun's rays hit the earth at the equator than at the poles.
The areas that are pointed toward the Sun receive more intense light than those that are pointed away.
The seasons are caused by this.
The equator is moving faster than the poles.
The motion of air in major prevailing winds is changed by this.
The winds that move north from the equator in the Northern Hemisphere are diverted to the right or east, while the winds that move south from the equator in the Southern Hemisphere are diverted to the left or west.
This pattern is known as the Coriolis effect.
Radiation heating transfers heat to the atmosphere.
The warmed gases expand, become less dense, and rise, creating vertical currents called convection currents.
The warm currents can hold a lot of water.
Cool air travels along Earth's surface into the area where the warm air was located.
There are ways in which surface winds are created.