Chapter 2: Mapping Our Chapter 2: Mapping Our WorldWorld

BIGBIG Idea: Idea: Earth Scientists use Earth Scientists use mapping technologies mapping technologies to investigate and to investigate and describe the world.describe the world.

I. Latitude and LongitudeI. Latitude and Longitude

How can I remember which How can I remember which lines are which?lines are which?

A. A. Latitude: Latitude: distance in degrees distance in degrees NORTH and SOUTH of the NORTH and SOUTH of the

EQUATOR (0EQUATOR (0°)°)

Think of latitude like the rungs of a ladder (ladder sounds a lot like latitude). Latitude lines run east and west, but they tell how far up (north) you can go or how far down (south) you can go.

Because lines of latitude Because lines of latitude never meetnever meet, they are also , they are also known as…known as…

Parallels:Parallels: circles around the circles around the globe N or S of the Equatorglobe N or S of the Equator

Each degree consists of 60 equal parts called Each degree consists of 60 equal parts called minutesminutes.. Each minute is divided into 60 equal parts called Each minute is divided into 60 equal parts called

secondsseconds..

D.C. is located at 38°53’51” North

B. B. Longitude: distance EAST and distance EAST and WEST of the PRIME MERIDIAN (0WEST of the PRIME MERIDIAN (0°)°)

When you think of longitude, think of long, tall telephone poles (because longitude lines run from pole to pole). Longitude lines run north and south, but they tell how far east you can go or how far west you can go.

Because the Prime Because the Prime MERIDIANMERIDIAN is the main line is the main line of longitude, they are also of longitude, they are also known as…known as…

Meridians:Meridians: semicircles running semicircles running from pole to pole. from pole to pole.

As with latitude, there are minutes and As with latitude, there are minutes and seconds: seconds: D.C. is 77°0’33” West

Great Circle:Great Circle: any circle that any circle that cuts the Earth into a perfect cuts the Earth into a perfect

half.half.

any 2 lines of longitude directly any 2 lines of longitude directly across from each other on across from each other on opposite sides of the globe, or opposite sides of the globe, or

the Equator (the only parallel of the Equator (the only parallel of latitude that forms a great circle)latitude that forms a great circle)

Using CoordinatesUsing Coordinates

Both latitude and longitude Both latitude and longitude are needed to locate are needed to locate positions on Earth precisely.positions on Earth precisely.

When giving coordinates, When giving coordinates, latitudelatitude is always given is always given firstfirst..

Do you know the coordinates Do you know the coordinates of Staunton, VA?of Staunton, VA?

Latitude: Latitude: 38° 8' 57" N38° 8' 57" N38 degrees, 8 minutes, 57 38 degrees, 8 minutes, 57 seconds Northseconds North

Longitude: Longitude: 79° 4' 18" W79° 4' 18" W79 degrees, 4 minutes, 18 79 degrees, 4 minutes, 18 seconds Westseconds West

DistanceDistance• The distance on Earth's surface The distance on Earth's surface

for each for each one degreeone degree of latitude of latitude or longitude = or longitude = 69 miles69 miles (111 (111 kilometers)kilometers)

• The distance between lines of The distance between lines of latitudelatitude remains constant. remains constant. Why?Why?

• What happens to the distance What happens to the distance between lines of between lines of longitudelongitude as as you move north or south of the you move north or south of the Equator?Equator?

Time ZonesTime Zones Earth is divided into 24 time Earth is divided into 24 time

zoneszones Why 24?Why 24?

Earth takes about 24 Earth takes about 24 hours to rotate once hours to rotate once on its axis (360°) on its axis (360°)

360° ÷ 24 hours = 360° ÷ 24 hours = 15° per hour15° per hour

Each time zone is 15° wideEach time zone is 15° wide Each time zone represents a Each time zone represents a

different hourdifferent hour

International Date Line International Date Line (IDL)(IDL)

180° meridian180° meridian gain or lose a daygain or lose a day travel travel WESTWEST across the IDL across the IDL ►►

advance one calendar day advance one calendar day ((add 24 hoursadd 24 hours))

travel travel EASTEAST across the IDL across the IDL ►► move back one calendar day move back one calendar day ((subtract 24 hourssubtract 24 hours))

Why is the IDL crooked?Why is the IDL crooked?

Wed. Feb. 2, 2011Wed. Feb. 2, 201103:05:5003:05:50

Tues. Feb. 1, 2011Tues. Feb. 1, 201103:05:5003:05:50

II. Types of MapsII. Types of Maps Maps are flat projections that Maps are flat projections that

come in many different formscome in many different forms

A. Map ProjectionsA. Map Projections Map projection: Map projection: a flat map that a flat map that

represents a 3-dimensional globerepresents a 3-dimensional globe

Distortions?

Cartography: Cartography: thethe science science of map makingof map making

1. 1. Mercator Projection:Mercator Projection: map that is map that is accurate at the equator and highly accurate at the equator and highly

distorted at the poles.distorted at the poles.

Mercator projections show Mercator projections show correct shapescorrect shapes of landmasses, of landmasses, but the but the sizes sizes are are distorteddistorted……

What’s wrong with this picture?What’s wrong with this picture?

2. 2. Conic Projections:Conic Projections: cone comes in cone comes in contact with one parallel of latitude.contact with one parallel of latitude.

Polyconic:Polyconic: a series a series of cones, each on a of cones, each on a different paralleldifferent parallel

Accurate along the Accurate along the parallel the cone is parallel the cone is in contact with.in contact with.

* The most accurate projection

3. 3. Gnomonic Projection:Gnomonic Projection: most most accurate at the poles and shows accurate at the poles and shows

great circles.great circles.

B. Topographic Maps: B. Topographic Maps: maps that maps that showshow topographytopography ( (surface surface

features and elevation changes)features and elevation changes)

What are some surface What are some surface features on Earth that you features on Earth that you might find on a topographic might find on a topographic map?map?

•mountainsmountains•hillshills•valleysvalleys• riversrivers• forestsforests•bridgesbridges•depressionsdepressions

ElevationA term that describes the height of a point on

Earth’s surface above (or below) sea level.This point is 6300 feet (1920 meters) above sea level.

http://www.math.montana.edu/~nmp/materials/ess/mountain_environments/novice/yosemite.jpg

Contour Lines:Contour Lines: lines on a map lines on a map that connect points of equal that connect points of equal

elevation.elevation.

Contour Interval:Contour Interval: the the difference in value between difference in value between adjacent contour lines on a adjacent contour lines on a

map.map.

Adjacent:Adjacent:

next tonext to adjoiningadjoining abuttingabutting borderingbordering

Contour Rules:Contour Rules: 1. Contours never cross or just 1. Contours never cross or just

stopstop

2. Contours never split2. Contours never split

3. The 3. The closercloser they are to each they are to each other, the other, the steepersteeper the land the land

4. The 4. The furtherfurther they are from each they are from each other the other the flatterflatter the land the land

5. If a contour line shows a “V”, the point of the V points UP hill

6. A river will always flow in the opposite direction of the V’s point (DOWN hill)

7. When contours close in a circle, that represents a hill top

Little ‘teeth’ (hachures) Little ‘teeth’ (hachures) show depressions (holes) in show depressions (holes) in

the landthe land

Rules for Successful ContouringRule #1

Every point along a contour line represents the same elevation.

This entire line represents 1200 feet above sea level.

Rules for Successful ContouringRule #2

Contour lines NEVER split or divide!

Can’t happen!

Rules for Successful ContouringRule #3

Contour lines cannot just stop. They must either form a closed loop, or run off the edge of your map.

What’s the elevation here???

1200

1250

1150

1100

?

This is fine!

?

Rules for Successful ContouringRule #4

Contour lines NEVER, EVER cross

What’s going on?? Is this area above or below 1200 feet?

?

Tip 1: What does contour line spacing indicate?

The closer togetherthe contour lines are, the steeper the hill is. The more spread apart they are, the gentler the slope.

Traveling along the red line would be much steeper than traveling along the green line.

Tip 2: Which way is the stream flowing?

When contour lines cross a stream or river, they form v-shaped kinks in the lines that always point upstream.

Also remember - Water always flows DOWNHILL! Blue Creek flow towards the East.

Tip 3: Finding the hill topsHill tops are easy to find. Just look for the

concentric closed contour lines that form the top of a hill. Notice the contour lines that form the two peaks below.

Tip 4: What do those funny hachure marks mean?

Some features, such as the Grand Canyon, lakes, mines, or sinkholes actually are holes in the ground. The hachured contours indicate a depression. Don’t confuse it with a hilltop!

60070

0

800

Depression Contour Lines

1. If you traveled from point A to point B, would you be going uphill or downhill?

2. What landform do you think this map depicts?

a. Valley

b. Mountain

c. Plain

X825

A

B

3. In which direction does Maple Creek flow?

a. Northeastb. Southwestc. Can’t tell from

information given4. What is the contour

interval of this map?a. 50b. 100c. 400

5. What is the approximate elevation at the top of this hill?

a. 1240

b. 1300

c. 1000

6. Which hike would be steeper, from A to B or from C to D?

1200

1150

1100

C D

A

B

7. What is the contour interval of this map?

a. 20 feet

b. -20 feet

c. 60 feet

8. What type of landform is depicted here?

a. a mountain

b. a depression

c. a valley

Topographic ProfileTopographic Profile The side-view of a surface The side-view of a surface

featurefeature

Reading a MapReading a Map

Legend: list of symbols list of symbols and their meaningsand their meanings

Scale: ratio between ratio between distances on a map distances on a map and actual distances and actual distances on Earth’s surfaceon Earth’s surface

1:25,000 - one unit on one unit on the map equals 25,000 the map equals 25,000 units on Earth’s units on Earth’s surfacesurface

Finding DirectionFinding Direction Geomagnetic poles:Geomagnetic poles: points on the points on the

Earth’s surface just above the poles Earth’s surface just above the poles of the imaginary magnetof the imaginary magnet

Magnetic Declination:Magnetic Declination: angle between angle between geographical North Pole and where a geographical North Pole and where a compass points to (magnetic north pole).compass points to (magnetic north pole).

True North:True North: Geographic North Pole Geographic North Pole