FOCUS ON EARTH SCIENCE (4)

Earth’s Structure and Plate Tectonics The Unique Planet Earth The structure of our planet, both inside and out, makes it the only place in our solar system that harbors intelligent life 30 Million Years Ago 1562 1777 North American Plate first touches the Pacific Plate, eventually causes the San Andreas Fault Diego Gutierrez makes first map of Baja California San José was established as the first city in California 10 Million Years Ago San Andreas Fault first moves A.D 42 (bkgd)Chris Collins/CORBIS 1500 1700 1750 c 150 1746 Claudius Ptolemy writes book on geography that includes color maps based on knowledge of Earth’s surface at the time Jean Etienne Guettard presents first map of minerals in France to French Academy of Sciences To learn more about mapmakers and their work, visit ca6.msscience.com Interactive Time Line To learn more about these events and others, visit ca6.msscience.com 1800 December 1849 1932 Bird’s-eye-view map, popular at the time, shows Sacramento City, established as the capital of California in 1854 The first time the Olympics are held in Los Angeles 1850 E6C Earth’s surface can be represented in many ways Maps provide twodimensional views of Earth’s three-dimensional surface } > *VÌÕÀi 7.f ì> LESSON Reading Maps ,i>`} >Êì> Maps repre- iV sent large areas of Earth at a size we can easily see and study 7.b, 7.c, 7.f, 7.h Topographic and } > Geologic Maps *VÌÕÀi ì> LESSON >Êì> Specialty maps,i>`} are used to show iV specific features such as changes in elevation and geologic characteristics > ì> } *VÌÕÀi ,i>`} iV Where would you build your home? Do you wish to live close to the beach? A single centimeter on this satellite image of the San Francisco Bay area might represent a long distance on land Can you tell from this image how steep or flat the ground is? If you look more closely, you can see the San Andreas Fault Where would it be safe to build your home? -ViViÊÊ+PVSOBM List some kinds of information you might get from maps if you were planning to build a new home 44 WorldSat International Start-Up Activities How might you map your neighborhood? What would your neighborhood look like from the air? How would you draw it on paper? Types of Maps Make the following Foldable to organize information about different types of maps STEP Fold a sheet of paper in half from top to bottom and then in half from side to side Think About This • Consider What would you see on the ground if you flew in a plane over your neighborhood? • Determine Think about where objects are in relation to other objects STEP Unfold the paper once Cut along the fold of the top flap to make two flaps Procedure Make an empty two-column table In the left column, list ten objects you would include in a map of your neighborhood In the right column, draw each object as it might appear from above Make a list of six symbols to represent objects such as trees, houses, and roads Draw a map of your neighborhood using a ruler, grid paper, and colored pencils STEP Label the flaps as shown /«}À>«V i}V >«Ã >«Ã 7.f ELA6: R 2.4 Monitoring Your Comprehension As you read this chapter, list details about each type of map Include information about how each map looks, what information it contains, and how it is used Visit ca6.msscience.com to: ▶ ▶ ▶ ▶ view explore Virtual Labs access content-related Web links take the Standards Check 45 Horizons Companies Get Ready to Read Preview Learn It! If you know what to expect before reading, it will be easier to understand ideas and relationships presented in the text Follow these steps to preview your reading assignments Look at the title and any illustrations that are included Read the headings, subheadings, and anything in bold letters Skim over the passage to see how it is organized Is it divided into many parts? Look at the graphics—pictures, maps, or diagrams Read their titles, labels, and captions Set a purpose for your reading Are you reading to learn something new? Are you reading to find specific information? Practice It! Take some time to preview this chapter Skim all the main headings and subheadings With a partner, discuss your answers to these questions • Which part of this chapter looks most interesting to you? • Are there any words in the headings that are unfamiliar to you? • Choose one of the lesson review questions to discuss with a partner Apply It! Now that you have skimmed the chapter, write a short paragraph describing one thing you want to learn from this chapter 46 Target Your Reading Use this to focus on the main ideas as you read the chapter r, s chapte i h t w e i rev As you p can the illustra s o be sure t s, and graphs ble tions, ta ns e captio h t m i k S Before you read the chapter, respond to the statements below on your worksheet or on a numbered sheet of paper • Write an A if you agree with the statement • Write a D if you disagree with the statement After you read the chapter, look back to this page to see if you’ve changed your mind about any of the statements • If any of your answers changed, explain why • Change any false statements into true statements • Use your revised statements as a study guide Before You Read A or D Statement After You Read A or D Latitude lines run north to south Degrees, minutes, and seconds can be used to measure distance on maps A map legend is a historic map Longitude lines run north to south A meridian is a longitude line that forms a semicircle Contour lines run up and down on hillsides Print a worksheet of this page at ca6.msscience.com Contour intervals indicate horizontal distance on topographic maps A map scale is used to measure the weight of heavy maps Geologic maps use color to indicate the different ages of rocks 10 Geologic cross sections can be used to visualize the slope of geologic formations beneath Earth’s surface 47 LESSON Science Content Standards 7.f Read a topographic map and a geologic map for evidence provided on the maps and construct and interpret a simple scale map Reading Guide What You’ll Learn ▼ Define latitude and longitude ▼ Explain how latitude and longitude are used to determine a location on Earth ▼ Demonstrate how map scales are used Why It’s Important Being able to get from one place to another or to determine your exact location is an important life skill Vocabulary longitude latitude map view profile view map legend Review Vocabulary pole: either end of an axis of a sphere, especially of Earth’s axis (Grade 5) 48 Chapter Reading Maps >Êì> Maps represent large areas of Earth at a size we can easily see and study Real-World Reading Connection Have you ever pretended to find a map to lost treasure? Was the treasure buried somewhere on a deserted island? Look at Figure 1, and use your imagination to hypothesize why pirates would bury and make treasure maps } > their treasure ì> *VÌÕÀi Understanding Maps ,i>`} iV Maps have been used for many centuries, and there are countless types of maps All show where things are on Earth or where things are in relation to each other For example, a street map shows the locations of streets in relation to other streets, towns, and landmarks Other maps may show the position of a weather system A single map is like a picture of the location of things at a given time However, a series of maps drawn over many years can show how Earth’s surface and interior change over time Because Earth is large, humans need a way to determine where they are located on the planet Imagine telling someone your exact position on the snow-covered continent of Antarctica It would be difficult to describe Ships’ captains and airplane pilots experience the same problems as they plot their courses across Earth Figure How might pirates have indicated the locations of their buried treasure? A Grid System for Plotting Locations Mapmakers created a system for identifying locations on Earth This system uses an imaginary grid of lines that encircles the globe The intersection, or crossing, of these lines can be used to pinpoint a location Latitude and Longitude Two sets of lines, called latitude and longitude, make up this imaginary grid Longitude is the distance in degrees east or west of the prime meridian The prime meridian, shown in Figure 2, is a longitude line that runs from the north pole to the south pole and passes through Greenwich, England This line represents zero degrees longitude If you were to travel 180° east or west from the prime meridian, you would reach another longitude line called the 180° meridian It lies exactly opposite of the prime meridian, on the other side of Earth Separately, each of these lines is a semicircle Together, they form a complete circle that divides Earth into two imaginary halves—the eastern and western hemispheres The 180° meridian also forms part of the International Date Line Latitude is the distance in degrees north or south of the equator Earth’s equator, shown in Figure 2, represents zero degrees latitude It is a latitude line that runs perpendicular to the longitude lines The equator also divides Earth into two halves—the northern and southern hemispheres Latitude lines form complete circles The equator forms the largest circle All remaining latitude lines form smaller and smaller circles as they approach Earth’s poles Degrees Lines of latitude and longitude are labeled in units of degrees (°) Because Earth is spherical, each set of the lines of latitude and longitude make up 360° The north pole is located at 90° north latitude (90°N) and the south pole is located at 90° south latitude (90°S) There are an infinite number of latitude and longitude lines on Earth However, on a globe, they are generally labeled every 10° Minutes and Seconds Because Earth is so large, it is necessary to make this location system more precise So, the lines of latitude and longitude are divided into smaller units Each degree of latitude or longitude is divided into 60 minutes ( ' ) Each minute is divided into 60 seconds ( " ) The degrees, minutes, and seconds of a line of latitude or longitude can be used to pinpoint a precise location on a map WORD ORIGIN meridian meri– prefix; from pre-Latin; means mid –dian from pre-Latin dies; means day Figure Latitude lines run east to west, but longitude lines run north to south Observe Why you think latitude lines are called parallels, but longitude lines are called meridians? &*%L &-%&*%: &'%L &'%: LZhiZgc ]Zb^he]ZgZ %L %: :VhiZgc ]Zb^he]ZgZ +%: +%L (%L % (%: Eg^bZbZg^Y^Vc Longitude +%C (%C %C +%C Cdgi]Zgc ]Zb^he]ZgZ (%C %:fjVidg (%H +%H Hdji]Zgc ]Zb^he]ZgZ %H (%H +%H Latitude Lesson • Reading Maps 49 Figure The tiny marks on the x-axis and y-axis are called tic marks California occupies land from 32°N to 42°N, and from 114°W to 124°W )% (- AViîjYZYZ\gZZh ( (, (+ (* &'* &') &'( &'' &'& &'% Adc\îjYZYZ\gZZh Treasure Map &')L &''L &'%L &&-L &&+L &&)L )%C CZkVYV JI Which is listed first—latitude or longitude—when describing a location? (-C Different Views 8Va^[dgc^V (+C Plotting Locations The lines of latitude and longitude intersect, or cross each other at an infinite number of places on Earth These intersections describe precise locations on Earth A location on Earth’s surface is described by the intersection of the nearest lines of latitude and longitude The combination of the latitude number and the longitude number is referred to as a coordinate Latitude always is listed first when describing a location For example, Sacramento, California is located near 38°N latitude by 121°W longitude The coordinates of California’s State Capitol Building in Sacramento, however, is 38°34'33" north (N) latitude by 121°29'29" west (W) longitude Practice finding locations by describing the location of the treasure in Figure Then try to determine the latitude and longitude of your hometown 6O E68>;>8 D8:6C ()C BZm^Xd California Map Figure The terms map view and plan view mean the same thing Infer Why you think geographers use the term map view but architects use the term plan view? EaVck^Zl Egd[âZ k^Zl Most maps are drawn in map view, which means they are drawn as if you were looking down on an area from above Earth’s surface Map view may also be referred to as plan view Lines of latitude and longitude usually are drawn on a map-view map Cross sections are drawn in profile view, which is a drawing showing a vertical section of the ground A profile view is like a side view of a house To help you visualize this concept, a map view and a profile view of a house are shown in Figure Map views and profile views will be used to describe topographic maps and geologic maps in Lesson Also, you will use profile views when you study models of the inner structures of volcanoes in Chapter How is a profile view related to Earth’s surface? Map Scales and Legends Maps have two features to help you read and understand the map They are a map legend and and a map scale Map Legends Maps use specific symbols to represent certain features on Earth’s surface These symbols allow mapmakers to fit neatly many details on a map All maps include a key, called a map legend, so you can interpret the symbols A map legend lists all the symbols used on the map and explains what each symbol means Figure shows an example of a map legend Map Scales When mapmakers draw a map, they need to decide how big or small to make the map They need to decide on the map’s scale The map’s scale tells you the relationship between a distance on the map and the actual distance on the surface being mapped The scale can be written as a phrase such as, “1 centimeter is equal to kilometer.” The scale also can be written as a ratio, such as 1:100 Because this is a ratio, there are no units Verbally, you would say, “Every unit on the map is equal to 100 units on the ground.” If your unit were cm on the map, it would be equal to 100 cm on the ground If you drew a map of your school on a scale of 1:1, your map would be as large as your school Scale bars also are shown on maps to help determine distance First, you use a ruler to measure the distance on the map Then you compare that distance to the scale bar There are many kinds of scale bars Some examples of scale bars are shown in Figure SCIENCE USE V COMMON USE legend Science Use an explanatory list of the symbols on a map or chart You can use the legend to interpret the different symbols Common Use a story that is popularly regarded as historical but not verifiable; a popular myth Everyone loved the many legends of the western frontier ACADEMIC VOCABULARY ratio (noun) the relationship in quantity or size between two or more things The ratio of boys to girls in Ms Smith’s class was 2:1 Figure On a map scale, the map distance is listed before the actual distance ;djciV^c EVg` EVg`h]ZaiZg H^YZlVa` Hl^bb^c\edda IVWaZ IgVâ IgZZ % % *b &% '% &%bZiZgh (% )%[ZZi &/*%% &Xb2*b Lesson • Reading Maps 51 Figure The map key below can be used to locate geologic formations in the geologic map of the Grand Canyon to the right FJ6I:GC6GN AVcYha^YZhVcYgdX`[Vaah R G^kZghZY^bZcih E:GB>6C 0K @V^WVWA^bZhidcZ 0T IdgdlZVe;dgbVi^dc 0C 8dXdc^cdHVcYhidcZ 0H =ZgbîH]VaZ 0E :heaVcVYZHVcYhidcZ E:CCHNAK6C>6C 0S HjeV^;dgbVi^dc B>HH>HH>EE>6C -R GZYlVaaA^bZhidcZ 9:KDC>6C $TB IZbeaZ7jiiZA^bZhidcZ 86B7G>6C #M BjVkA^bZhidcZ #BA 7g^\]i6c\ZaH]VaZ #T IVeZVihHVcYhidcZ NDJC6C 0#I 9^VWVhZhâahVcYY^`Zh 0#S H]^cjbdFjVgioîZ 0#H =V`ViV^H]VaZ 0#B 7Vhh;dgbVi^dc DA9:GEG:86B7G>6C 0#GR OdgdVhiZg

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