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Chapter 2 Tools of Earth Science

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Section 1 Tools and Measurement

Section 2 Models in Science

Section 3 Mapping Earth's Surface

Section 4 Maps in Earth Science

Concept Map

Section 1 Tools and MeasurementChapter 2

Bellringer

What could you study with a telescope? What could you study with a microscope?

Write your answers in your Science Journal.

What You Will Learn

• Scientists use tools to make observations, take measurements, and analyze data.

• Scientists have determined standard ways to measure length, area, mass, volume, and temperature.

Tools for Science

• A tool is anything that helps you do a task.

• Different tools help scientists collect different kinds of data.

• There are tools for seeing, measuring, and analyzing.

Tools for Science, continued

Tools for Seeing

• Microscopes and magnifying lenses are tools that help you see things that are very small.

• Telescopes and binoculars help you observe things that are very far away.

• A reflecting telescope is made up of three major parts– a curved mirror, a flat mirror, and an eyepiece.

• Light enters the telescope and is reflected from a curved mirror to a flat mirror.

• The flat mirror focuses the image and reflects light to the eyepiece.

Tools for Measuring

• Stopwatches, metersticks, and balances are some tools that you can use to make measurements.

• Thermometers, spring scales, and graduated cylinders are also helpful tools.

Tools for Analyzing• Tools can help you to analyze data.

• Calculators can help you do quick calculations.

• Computers can help you to make neat figures and graphs. Computers can also collect, store, and analyze data.

Measurement

• Hundreds of years ago, different countries used different systems of measurement.

• Units were based on common objects, such as feet or grains of barley.

• In time, people realized they needed a simple and reliable system of measurement.

Measurement, continued

• In the late 1700s, the French Academy of Sciences set out to create a reliable system.

• Over the next 200 years, the metric system was developed.

• The system is now called the International System of Units, or the SI.

• Today, most scientists and almost all countries use the International System of Units.

• One advantage to the SI system is that they allow all scientists to share and compare results.

• Another advantage is that all units are based on the number 10.

• A meter (m) is the main SI unit of length.

• If you divide 1 m into 100 parts, each part equals one centimeter.

• In other words, 1 cm is one-hundredth of a meter.

• To describe the length of microscopic objects, use micrometers (m) or nanometers (nm).

• To describe the length of larger objects, use kilometers (km).

• Area is the measure of how much surface an object has.

• To measure the area of a square or rectangle, use the equation: area = length x width

• The units for area are square units, such as square meters (m2), square centimeters (cm2) and square kilometers (km2).

• Mass is the amount of matter that makes up an object.

• Scientists often use a balance to measure mass.

• The kilogram (kg) is the main unit for mass.

• The kilogram is used to describe the mass of things such as sacks of grain.

• The mass of smaller objects, such as an apple, can be described by using grams (g) or milligrams (mg).

• One thousand grams equals 1 kg.

• The mass of a large object, such as an elephant, is given in metric tons.

• A metric ton equals 1,000 kg.

• The amount of space that something occupies or the amount of space that something contains is called volume.

• The volume of a large, solid object is given in cubic meters (m3).

• The volumes of smaller objects can be given in cubic centimeters (cm3) or cubic millimeters (mm3).

• To find the volume of an irregularly shaped object, measure the volume of liquid that the object displaces.

• To calculate the volume of a box-shaped object, you can multiply the object’s length by its width and then by its height.

• The volume of a liquid is often given in liters (L).

• A cubic meter (1 m3) is equal to 1,000 L.

• 1,000 L will fit into a box measuring 1 m on each side.

• A milliliter (mL) will fit into a box measuring 1 cm on each side. So, 1 mL = 1 cm3.

• Graduated cylinders are used to measure liquid volume in milliliters.

• Temperature is a measure of the average kinetic energy of the particles that make up an object.

• You use degrees Fahrenheit (°F) to describe temperature. Scientists often use degrees Celsius (°C).

• Kelvin (K) is the SI base unit for temperature.

Writing Numbers in Scientific Notation

• Scientific measurement often involves numbers that are very large or very small.

• To make very large numbers and very small numbers more manageable, scientists use a shorthand called scientific notation.

Writing Numbers in Scientific Notation, continued• Scientific notation is a

way to express a quantity as a number multiplied by ten.

• The speed of light, 300,000,000 m/s, can be written as 3.0 x 108 m/s.

Section 2 Models in ScienceChapter 2

Bellringer

Describe as many models as you can think of.

Write your answers in your Science Journal.

What You Will Learn

• Physical models and mathematical models are two common types of scientific models.

• Theories and laws are models that describe how the universe works.

Types of Models

• A model is a representation of an object or a process that allows scientists to study something in greater detail.

• Models can represent things that are too small to see.

• Models can also represent things that are too large to see entirely, such as Earth.

Tools of Earth Science

Models

Chapter 2

Types of Models, continued

• Two common types of models are physical models and mathematical models.

• Physical models are models that you can touch.

• Physical models often look like the thing they represent, but they have limitations.

• For example, because Earth is nearly a sphere, a globe most accurately represents Earth.

• To make a map, you must make a flat model of Earth’s surface.

• In the process of making a map, you change the distance between points and the map becomes inaccurate.

• A mathematical model is made up of mathematical equations and data.

• Some mathematical models are simple.

• These models allow you to calculate things such as how far a car will travel in an hour or how much you would weigh on the moon.

• Other models are so complex that computers are needed to process them.

• Because so many variables affect population changes, scientists use computers to create mathematical models of population growth.

• Computer models can produce graphs to show predicted population growth.

• Powerful supercomputers that can make more than 30 trillion calculations every second help scientists process data.

• Computers are used to make these models because the models require many data sets.

• To calculate every variable by itself would take years.

• Scientists commonly use computers to build mathematical and physical models.

• For example, scientists use computers to run mathematical models that track the variables that affect Earth’s climate.

• To model climate change, researchers use information about current and past land and ocean-water temperatures around Earth.

• They also use information about weather patterns, ocean currents, and carbon dioxide levels in the atmosphere.

• These models do not make exact predictions about future climates, but they estimate what might happen if variables change.

Patterns in Nature

• It is possible to make models because events in nature often follow predictable patterns.

• Observing patterns in nature is the basis of science.

• These observations lead to explanations about the way the world works.

Patterns in Nature, continued

• Although these explanations are supported by observations, they may not be accurate.

• For example, the sun appears to move across the sky.

• For thousands of years, people observed this pattern and concluded that the Earth was the center of our solar system.

Theories and Laws

• Observing patterns in the natural world can lead to the development of scientific theories and laws.

• The words law and theory have special meanings to scientists.

• In science, a law is a statement or equation that reliably predicts events under certain conditions.

Theories and Laws, continued

• A theory is not a guess, or hypothesis.

• A theory is a scientific explanation that encompasses many scientific observations and may include many hypotheses and laws.

• Theories are very powerful explanations of the way the world works.

• Theories do not eventually become laws.

• Instead, theories are fully formed scientific explanations that are supported by evidence and data from many scientific disciplines.

• Like all scientific theories, the theory of an Earth-centered universe was supported by scientific evidence.

• However, over time, scientists observed movements of planets across Earth’s sky that did not fit the theory of an Earth-centered universe.

• Sometimes, planets appeared to be moving backward across Earth’s sky.

• Four moons were seen traveling around Jupiter.

• The movement of Jupiter’s moons showed that objects could revolve around objects other then Earth.

• Scientists developed a new theory to incorporate their new observations.

• They suggested that Earth and the other planets in our solar system travel around the sun.

• In 1665, Sir Isaac Newton discovered the law of universal gravitation.

• This law states that all objects in the universe, including the sun and planets, attract each other with a force called gravity.

• Gravity holds the planets in their orbits as they travel around the sun.

• Scientists used this law to strengthen the theory of the sun-centered solar system.

Limitations of Models

• Although models are important scientific tools, all models are limited because they are simplified versions of the systems they try to explain.

• Simplification makes a model easy to understand and use.

• However, information is left out when a model is made.

Limitations of Models, continued

• Models can change if a scientist finds new data or thinks about concepts in a different way.

• Scientists work continually to improve models that we use to understand the world.

• New technology may challenge existing models, or it may help create new models that help us understand the world differently.

Section 3 Mapping Earth's SurfaceChapter 2

Bellringer

Draw a map from your home to one of your favorite places. Clearly label all landmarks and include information that might be helpful to someone using the map.

Draw your map in your Science Journal.

What You Will Learn

• Maps can be used to find locations on Earth and to represent information about features of Earth’s surface.

• Most maps are made from data collected by a process called remote sensing.

Mapping Earth’s Surface

• The way in which people have seen the world has been reflected in their maps.

• A map is a representation of the features of a physical body such as Earth.

• Maps are used to find locations on Earth.

Finding Directions on Earth

• Although Earth’s shape is not a true sphere, it is best represented by a sphere.

• A sphere has no top, bottom, or sides to use as reference points for specifying locations on its surface.

• However, Earth’s axis of rotation can be used to establish reference points.

Finding Directions on Earth, continued

• The points at which Earth’s axis of rotation intersects Earth’s surface are the geographic North and South Poles.

• The poles are used as reference points for finding location.

Using a Compass

• Earth’s core generates a magnetic field that causes Earth to act as a giant magnet.

• Therefore, Earth has two magnetic poles that are located near the geographic poles.

• A compass is a tool that uses Earth’s natural magnetism to show direction.

Using a Compass, continued

• A compass needle points to the magnetic north pole.

• Therefore, a compass will show you which direction is north.

Finding Locations on Earth

• Every place on Earth can be located using latitude and longitude.

• The equator is a circle halfway between the North and South Poles that divides Earth into the Northern and Southern Hemispheres.

• Imaginary lines drawn parallel to the equator are called lines of latitude, or parallels.

Finding Locations on Earth, continued

• Latitude is the distance north or south from the equator.

• Latitude is expressed in degrees.

• The equator represents 0° latitude. The North Pole is 90° north latitude, and the South Pole is 90° south latitude.

• Longitude is the distance east or west from the prime meridian.

• Like latitude, longitude is expressed in degrees.

• The prime meridian represents 0° longitude.

• Lines of longitude, or meridians, are imaginary lines that connect both poles.

• Unlike lines of latitude, lines of longitude are not parallel.

• Lines of longitude touch at the poles and are farthest apart at the equator.

• Unlike the equator, the prime meridian does not completely circle the globe.

• The prime meridian runs from the North Pole through Greenwich, England, to the South Pole.

• The 180° meridian lies on the opposite side of the Earth from the prime meridian.

• Together, the prime meridian and the 180° meridian divide Earth into the Eastern and Western Hemispheres.

• East lines of longitude are found east of the prime meridian, between 0° and 180° longitude.

• West lines of longitude are found west of the prime meridian, between 0° and 180° longitude.

• Points on Earth’s surface can be located by using latitude and longitude.

• Lines of latitude and longitude cross and form a grid system on globes and maps.

• This grid system can be used to find locations north or south of the equator and east or west of the prime meridian.

• Lines of latitude and longitude can be used to find the locations of state capitols.

• Locate the star that represents a capitol on a map.

• Then, use the lines of latitude and longitude closest to the state capitol to estimate its approximate latitude and longitude.

Information Shown on Maps

• Maps provide information through the use of symbols.

• To read a map, you must understand the symbols on the map and be able to find directions and calculate distances.

• A map generally contains a title, indicator of direction, a scale, a legend, and a date.

Information Shown on Maps, continued

Modern Mapmaking

• Data used in many of today’s maps are provided by the process of remote sensing.

• Remote sensing is a way to gather information about an object without directly touching or seeing the object.

• Today, most maps are made from photographs taken by mapping cameras that are mounted on low-flying aircraft.

Modern Mapmaking, continued

• Mapmakers are beginning to use even more sophisticated instruments.

• These instruments are carried on both aircraft and Earth-orbiting satellites.

• Passive remote-sensing equipment records the amount of electromagnetic radiation that is emitted or reflected by objects.

• All objects give off electromagnetic radiation, such as heat or X rays.

• Data collected by passive remote-sensing equipment on satellites are recorded as a series of numbers.

• These numbers are beamed to ground stations and converted to satellite images of Earth’s surface.

• An active remote-sensing system produces its own electromagnetic radiation and measures the strength of the return signal.

• In an active remote-sensing system, radar is used to gather data.

• Radar gathers data using microwaves.

• An advantage to using microwaves for remote sensing is that they can penetrate clouds and water.

• Therefore, microwaves can be used to map areas that are difficult to study.

• The global positioning system (GPS) can help you find where you are on Earth.

• GPS is a system of orbiting satellites that send radio signals to receivers on Earth.

• The receivers calculate the latitude, longitude, and elevation of a given place.

• GPS was invented in the 1970s by the U.S. Department of Defense for military use.

• During the last 30 years, GPS has made its way into people’s daily lives.

• Mapmakers use GPS to check the location of boundary lines between countries and states.

• Airplane and boat pilots use GPS for navigation.

• Businesses and state agencies use GPS for mapping and environmental planning.

• Many cars now have GPS units. Some GPS units are even small enough to wear on your wrist.

• Geographic information systems (GIS) are computerized systems that visually present information about an area.

• A GIS organizes information in overlapping layers.

• Scientists can compare the layers to answer questions.

Section 4 Maps in Earth ScienceChapter 2

Bellringer

Draw a hill as it would look from above. Try to show the hill’s height and shape in your drawing.

Be prepared to share what method you chose to show shape and elevation in your drawing.

Draw your illustration in your Science Journal.

What You Will Learn

• Contour lines show elevation and landforms by connecting points of equal elevation.

• Geologic maps show the distribution of geologic features in a given area.

Topographic Maps

• A topographic map is a map that shows surface features, or topography, of an area.

• Topographic maps show both natural features, such as rivers, lakes, and mountains, and features made by humans.

Topographic Maps, continued

• Topographic maps also show elevation.

• Elevation is the height of an object above sea level.

• The elevation at sea level is 0 m.

Contour Lines

• On a topographic map, contour lines are used to show elevation.

• Contour lines are lines that connect points of equal elevation.

• For example, one contour line would connect points that have an elevation of 100 m. Another contour line would connect points that have an elevation of 200 m.

Tools of Earth Science

Topographic Maps and Contour Lines

Chapter 2

Contour Lines, continued

• The difference in elevation between one contour line and the next is called the contour interval.

• A map that has a contour interval of 20 m would have contour lines every 20 m of elevation change.

• A mapmaker chooses a contour interval based on the size of the area being mapped and the area’s relief.

• Relief is the difference in elevation between the highest and lowest points of the area being mapped.

• For an area of high relief, such as a mountain, a mapmaker would use a large contour interval, such as 100 m.

• For a flat area with low relief, a mapmaker would use a small contour interval, such as 10 m.

• The spacing of contour lines also indicates slope.

• Contour lines that are close together show a steep slope.

• Contour lines that are spaced far apart show a gentle slope.

• On most topographic maps, an index contour is used to make reading the map easier.

• An index contour is a darker, heavier contour line that is usually every fifth line that is labeled by elevation.

Reading a Topographic Map

• Topographic maps use symbols to represent parts of Earth’s surface.

• A legend on the map shows some of the symbols that represent features on the map.

• Colors are also used to represent features.

Reading a Topographic Map, continued

• In general, buildings, roads, bridges, and railroads are black.

• Contour lines are brown. Major highways are red.

• Bodies of water are blue and wooded areas are green. Cities and towns are gray or red.

The Rules of Contour Lines

• Reading a topographic map takes training and practice.

• The following rules will help you to understand how to read topographic maps.

• Contour lines never cross. All points on one contour line represent one elevation.

The Rules of Contour Lines, continued

• Contour line spacing depends on the slope of the ground.

• Contour lines that are close together show a steep slope.

• Contour lines that are far apart show a gentle slope.

• Contour lines that cross a valley or stream are V shaped.

• The V points toward the area of higher elevation.

• If a stream flows through the valley, the V points upstream.

• The tops of hills, mountains, and the bottoms of depressions are shown by closed circles.

• Depressions are marked with short, straight lines inside the circle that point downslope to the depression.

Geologic Maps

• Maps that show the distribution of geologic features in an area are called geologic maps.

Geologic Maps, continued

• Geologic features include different types of rocks and rock structures, such as folded, tilted, or broken rocks.

• Geologists make geologic maps by physically walking over an area.

• They record on a base map bodies of rock and geologic structures they see.

• A base map is often a topographic map.

• Geologists use the topographic map to identify features, such as hills, valleys, and streams.

• They use these features to help find their location and record information.

• The most important features shown on a geologic map are rocks seen at the surface of an area.

• Rocks of a given rock type and age range are called a geologic unit.

• On geologic maps, geologic units are identified by color.

• Geologic units of similar ages are given shades of colors in the same color family, such as different shades of blue.

• Geologists also give each geologic unit a set of letters.

• This set of letters is commonly a capital letter followed by two lowercase letters.

• The capital letter stands for the age of the rock.

• The lowercase letters represent the name of the unit or the type of rock.

• For example, a capital K stands for the Cretaceous Period on geologic maps.

• A lowercase ec is used to designate the El Capitan rock formation.

• Therefore, the pair Kec is used to indicate El Capitan Granite.

• Geologic units are not the only geologic features shown on geologic maps.

• A contact line shows places where two geologic units meet, called contacts.

• In addition, contact lines can be used to identify where rocks have been deformed

• The shapes of contact lines indicate where rock layers have been folded.

• Other symbols are used to show whether rocks are horizontal or tilted.

• Geologic maps also show the locations of breaks in rocks called faults.

Chapter 2 Tools of Earth Science

Use the terms below to complete the concept map on the next slide.

temperature

length

volume

balance

graduated cylinder

thermometer

meter stick

Concept Map

Tools of Earth ScienceChapter 2

Concept Map

Tools of Earth ScienceChapter 2

Concept Map

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