MappinMappingg

MAP PROJECTIONSMAP PROJECTIONS

Map ProjectionsMap Projections

• MercatorMercator - Shows - Shows the entire world the entire world on one on one continuous map continuous map (CYLINDRICAL (CYLINDRICAL Projection)Projection)

• Major problem is Major problem is that the higher that the higher latitudes are latitudes are very distorted very distorted (stretched)(stretched)

A mercator map shows Greenland & Africa as the A mercator map shows Greenland & Africa as the same size! Antarctica is also bigger than all the same size! Antarctica is also bigger than all the

continents put together! This type of map is HIGHLY continents put together! This type of map is HIGHLY DISTORTED!DISTORTED!

Greenland = 0.8 million square miles

Africa = 11.6 million square miles

Map ProjectionsMap Projections• GnomonicGnomonic - Made - Made

as if a sheet of as if a sheet of paper was put on a paper was put on a point on Earth’s point on Earth’s surface. (PLANAR surface. (PLANAR projection)projection)

• It can show the It can show the shortest route shortest route between two between two points, but points, but distances and distances and directions are directions are distorteddistorted..

Gnomonic projections accurately portray a Gnomonic projections accurately portray a specific latitude/longitude, but SEVERELY specific latitude/longitude, but SEVERELY

DISTORT as you go farther from the point of DISTORT as you go farther from the point of origin!origin!

Antarctica Antarctica is correct is correct in sizein size

Note the Note the distortion distortion

of S. of S. America & America & Australia!Australia!

Map ProjectionsMap Projections

* * ConicConic - used to - used to show small areas show small areas (CONICAL (CONICAL Projection)Projection)

* Nearly distortion * Nearly distortion freefree

* Used to make * Used to make topographic mapstopographic maps

Conic maps Conic maps show areas show areas in true in true proportion! proportion! N. America N. America is perfectly is perfectly representerepresented.d.

POLYCONIC POLYCONIC maps are maps are perfectly perfectly

proportioned for proportioned for BOTH BOTH

hemispheres.hemispheres.

Latitude and LongitudeLatitude and Longitude

• Latitude is the is the distance in degrees distance in degrees (0º - 90º) north and (0º - 90º) north and south of the equator south of the equator (0º). (0º).

• Lines of latitude are Lines of latitude are called called parallels. . – imaginary lines that imaginary lines that

circle the world from circle the world from east to west parallel to east to west parallel to the equator. the equator.

• One degree of latitude One degree of latitude on land is equal to on land is equal to 112 km (70 miles).112 km (70 miles).

• Longitude is the is the distance in degrees distance in degrees (0º - 180º) east and (0º - 180º) east and west of the prime west of the prime meridian (0º). meridian (0º).

• Lines of longitude Lines of longitude are called are called meridians. . – imaginary lines imaginary lines

that form half-that form half-circles and run circles and run between the North between the North and South Poles.and South Poles.

Longitude runs Longitude runs North-SouthNorth-South

LatitudLatitude runs e runs East-East-WestWest

magnetic declinationmagnetic declination• True NorthTrue North - a line from any point on - a line from any point on

the earth's surface to the north pole. the earth's surface to the north pole. All lines of longitude are true north All lines of longitude are true north lines.lines.

• Magnetic NorthMagnetic North - the direction to the - the direction to the north magnetic pole, as indicated by north magnetic pole, as indicated by the north-seeking needle of a magnetic the north-seeking needle of a magnetic instrument.instrument.

• DeclinationDeclination is the angular difference is the angular difference between any two norths.between any two norths.

True North & Magnetic North are different because True North & Magnetic North are different because of Earth’s shifting Magnetic Fields! In NYS the of Earth’s shifting Magnetic Fields! In NYS the

magnetic declination is approximately 12 degrees magnetic declination is approximately 12 degrees west of True Northwest of True North

Map ScaleMap Scale • the distance represented on the map compared the distance represented on the map compared

to the actual real-life distance to the actual real-life distance • the the ratioratio of distance on the map to distance on of distance on the map to distance on

EarthEarth• Map scales may be represented in three ways:Map scales may be represented in three ways:

– VerballyVerbally- example: “1 centimeter equals 10 - example: “1 centimeter equals 10 kilometers”.kilometers”.

– GraphicallyGraphically- usually a line divided into equal - usually a line divided into equal parts, with each part being a certain unit of parts, with each part being a certain unit of length (kilometers, miles, etc.).length (kilometers, miles, etc.).

– NumericallyNumerically- usually shown by writing a - usually shown by writing a fraction or ratio to show what part of real fraction or ratio to show what part of real distances the map distances are. Example: distances the map distances are. Example: 1/62500 or 1:62500, which means 1 unit on the 1/62500 or 1:62500, which means 1 unit on the map is equal to 62,500 units of real distance. map is equal to 62,500 units of real distance. 

The Bar The Bar Graph at Graph at the top the top

indicates indicates how long how long each mile each mile is on the is on the

mapmap

GRAPHIC GRAPHIC SCALESCALE

1:250,000 scale1:250,000 scale(one inch = about 4 (one inch = about 4

miles)miles)

NUMERCIAL SCALENUMERCIAL SCALE

Conversion is Conversion is written at top written at top

VERBAL SCALEVERBAL SCALE

Topographic Topographic MapsMaps

specialized maps which specialized maps which show the show the reliefrelief (highs (highs

and lows) of the and lows) of the Earth’s surfaceEarth’s surface

topo map parts…topo map parts…

• relief is shown with isolines (iso = same) called contour linescontour lines – connect points of the same elevation – show the shape of the land

• difference in elevation between two consecutive contour lines is called the contour intervalcontour interval

• An An index contourindex contour has has elevation noted on itelevation noted on it

Index Index contourcontour

Contour Contour lineslines

benchmarbenchmarkk

……topo map partstopo map parts

• A A benchmarkbenchmark is a point where the actual is a point where the actual elevation is knownelevation is known – elevation is shown on the map by the letters elevation is shown on the map by the letters

BM and the elevation next to it (ex. BM and the elevation next to it (ex. BM1078)BM1078)

• Depression contoursDepression contours show where the elevation show where the elevation decreases (a hole, volcano crater, etc.)decreases (a hole, volcano crater, etc.) – When reading the depression contour, the When reading the depression contour, the

elevation of the first one is the same elevation of the first one is the same elevation of the regular contour before it. elevation of the regular contour before it. The next one decreases the same amount as The next one decreases the same amount as the contour interval.the contour interval.

DepressioDepression contours n contours are shown are shown

with with dashed dashed

lines lines inside of inside of

the the contour contour

line circlesline circles

Landforms on Contour Landforms on Contour MapsMaps

• The The steepnesssteepness of an area is show by of an area is show by the closeness of the contour linesthe closeness of the contour lines – The closer the contour lines are The closer the contour lines are

together, the steeper the area (cliff, together, the steeper the area (cliff, etc.)etc.)

– When the contour lines are spread out, When the contour lines are spread out, the land is relatively flat. the land is relatively flat.

• A closed circle after a series of A closed circle after a series of increasing contour lines shows the increasing contour lines shows the top of a hill or mountain top of a hill or mountain

Hill top Hill top (circles)(circles)

Steep slope Steep slope

(close lines)(close lines)

Gentle slope Gentle slope

(spread out lines)(spread out lines)

Landforms on Contour Landforms on Contour MapsMaps

• contour line crosses a stream or river, contour line crosses a stream or river, the contour line bends and forms a “V” the contour line bends and forms a “V” shapeshape

• The point of the “V” shows the The point of the “V” shows the direction that the water is coming fromdirection that the water is coming from– The “v” points to the SOURCE of the The “v” points to the SOURCE of the

river!river!

Note the Note the “V” shape “V” shape

of the of the contour contour lines as lines as

they cross they cross the river!the river!

The “V” The “V” points to points to

the source, the source, so the river so the river is flowing is flowing in what in what

direction??direction????

The slope or gradient of the hill The slope or gradient of the hill can be determined by using your can be determined by using your

ESRTESRT

Gradient = difference in Gradient = difference in elevationelevation

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distancedistance

A profile (side view) of the hill/mountain can be drawn

using a contour map by plotting the elevations of certain points

on a vertical axis (LAB)

Place a paper Place a paper strip over the strip over the line you want line you want to draw a to draw a profile of. profile of.

Mark clearly Mark clearly each line of each line of contour of contour of your line.  your line. 

Below these Below these marks, write marks, write down the down the elevation of elevation of each line of each line of contour. contour.

Place your paper onto a graph. Copy each point. Place your paper onto a graph. Copy each point. Connect the dots! EASY!Connect the dots! EASY!