Earth’s Earth’s TopographyTopography

TopographyTopography

►TopographyTopography refers to the shape of the refers to the shape of the Earth’s surface, including an area’s Earth’s surface, including an area’s elevation, relief, and landformselevation, relief, and landforms

►The surface of the Earth is changed byThe surface of the Earth is changed by►Weather conditionsWeather conditions►Running waterRunning water►Earthquakes and volcanoesEarthquakes and volcanoes►PeoplePeople

Earth’s topography is made up Earth’s topography is made up of different kinds of landformsof different kinds of landforms

► LandformsLandforms are the physical features of the are the physical features of the Earth’s surface formed by processes that Earth’s surface formed by processes that shape the Earth’s surfaceshape the Earth’s surface

► Landforms are defined by theirLandforms are defined by their►Elevation-Elevation- Height above sea levelHeight above sea level►Relief-Relief- The difference in a region’s elevationThe difference in a region’s elevation

► There are three main types of landformsThere are three main types of landforms►MountainsMountains►PlainsPlains►PlateausPlateaus

North American Landforms

MountainsMountains

►Natural landforms that reach high Natural landforms that reach high elevationselevations

►Rise at least 600 meters above the Rise at least 600 meters above the surrounding landsurrounding land

►Have narrow summits, steep slopes, Have narrow summits, steep slopes, and high reliefand high relief

Shaping MountainsShaping Mountains

►Mountains result from the folding and Mountains result from the folding and breaking of Earth’s surface due to breaking of Earth’s surface due to movements of portions of the crustmovements of portions of the crust

►Can be created when hot magma from Can be created when hot magma from within the Earth breaks through the within the Earth breaks through the surfacesurface

►Streams and rivers often Streams and rivers often

carve valleys in mountainscarve valleys in mountains

Groups of MountainsGroups of Mountains

►Mountain range-Mountain range- A roughly parallel A roughly parallel series of mountains that have the series of mountains that have the same general shape and structuresame general shape and structure

►Mountain system-Mountain system- A group of A group of mountain ranges in an areamountain ranges in an area

►Mountain belt-Mountain belt- A large group of A large group of mountains which includes mountain mountains which includes mountain ranges and mountain systems ranges and mountain systems

PlainsPlains

►Plains are flat areas that have very Plains are flat areas that have very small differences in elevationsmall differences in elevation

►Areas of low reliefAreas of low relief►Characterized by broad rivers and Characterized by broad rivers and

streamsstreams

Coastal PlainsCoastal Plains

►Coastal plainsCoastal plains are low, flat areas are low, flat areas located along a coastlocated along a coast

►Formed when soil and silt were Formed when soil and silt were deposited on the edge of a continentdeposited on the edge of a continent

►The fertile soil makes farming a major The fertile soil makes farming a major activityactivity

Interior PlainsInterior Plains►Interior plainsInterior plains are low flat areas are low flat areas

found inland on a continentfound inland on a continent►Elevations are higher above sea level Elevations are higher above sea level

than coastal plainsthan coastal plains►Sediments deposited by rivers and Sediments deposited by rivers and

streams make the soil good for streams make the soil good for farmingfarming

PlateausPlateaus►PlateausPlateaus are broad, flat areas of land are broad, flat areas of land

that rise more than 600 meters above that rise more than 600 meters above sea levelsea level Surfaces are fairly flatSurfaces are fairly flat Have low reliefHave low relief

►Most are located inland in dry, almost Most are located inland in dry, almost desert like locationsdesert like locations

►Often have the same landscape for Often have the same landscape for thousands of kilometersthousands of kilometers

Introduction to MapsIntroduction to Maps

►Map-Map- A drawing of the A drawing of the Earth, or part of the Earth, or part of the Earth, on a flat surfaceEarth, on a flat surface

►Globe-Globe- A spherical, or A spherical, or round, model of the Earthround, model of the Earth The most accurateThe most accurate representation of the representation of the

entire surface of the Earthentire surface of the Earth Shows the shapes, sizes, Shows the shapes, sizes,

and locations of all the and locations of all the Earth’s landmasses Earth’s landmasses

and bodies of waterand bodies of water

Map ScalesMap Scales

►Both maps and globes are drawn to Both maps and globes are drawn to scalescale

►The scale compares distances on a The scale compares distances on a map or globe to actual distances on map or globe to actual distances on the earth’s surfacethe earth’s surface

►The more closely the map approaches The more closely the map approaches the land in size, the larger the scale the land in size, the larger the scale will bewill be

WaysWaysto to show show scale scale on a on a mapmap

VerbalVerbal

FractionFractionalal

GraphicGraphic

ParallelsParallels

►Parallels-Parallels- Lines going from east to Lines going from east to west across a map or globewest across a map or globe

► Imaginary lines that Imaginary lines that

completely circle the Earthcompletely circle the Earth

►Used to measure latitudeUsed to measure latitude

LatitudeLatitude► Latitude-Latitude- Measure of distance north and Measure of distance north and

south of the equatorsouth of the equator►Numbered in degrees from 0Numbered in degrees from 0° at the equator ° at the equator

to 90° at the polesto 90° at the poles► Labeled as being either north orLabeled as being either north or

south of the equatorsouth of the equator►One degree of latitude is equal One degree of latitude is equal

to approximately 69 land milesto approximately 69 land miles

MeridiansMeridians►Meridians-Meridians- Lines running between Earth’s Lines running between Earth’s

North and South poles North and South poles

► Each meridian represents half of an imaginary Each meridian represents half of an imaginary circle around the Earthcircle around the Earth

► Prime Meridian-Prime Meridian- Runs through Runs through

Greenwich, England (0Greenwich, England (0° longitude)° longitude)

► Used to measure longitudeUsed to measure longitude

LongitudeLongitude► Longitude-Longitude- Measure of distance east and west of Measure of distance east and west of

the prime meridianthe prime meridian

►Numbered in degrees from 0Numbered in degrees from 0° at the prime ° at the prime meridian to 180° at the international date linemeridian to 180° at the international date line

► Labeled as being either east or west of the prime Labeled as being either east or west of the prime meridianmeridian

► Unlike lines of latitude, meridiansUnlike lines of latitude, meridians are not parallel (farthest apart at are not parallel (farthest apart at the equator and get closer as they the equator and get closer as they near the poles)near the poles)

Time ZonesTime Zones► Time zone-Time zone- A longitudinal belt on the Earth in A longitudinal belt on the Earth in

which all areas have the same local timewhich all areas have the same local time

► The Earth has been divided into 24 time zones The Earth has been divided into 24 time zones that are 15that are 15° wide ° wide Why 15° wide?Why 15° wide? 360° (deg. in a circle)360° (deg. in a circle) 24 (hrs in a day)24 (hrs in a day)

► There are 4 time zones in There are 4 time zones in the contiguous Unitedthe contiguous United States (eastern, central,States (eastern, central, mountain, & pacific)mountain, & pacific)

= 15° (movement per hour)= 15° (movement per hour)

Determining Local TimeDetermining Local Time

►When you cross from one When you cross from one timetime zone to another, the local time zone to another, the local time changes by one hourchanges by one hour

► Traveling east-Traveling east- add oneadd one hour for each time zonehour for each time zone you crossyou cross► Traveling west-Traveling west- subtractsubtract one hour for each time zone one hour for each time zone you crossyou cross

Crossing the International Date Crossing the International Date LineLine

► The international date line is a special meridian The international date line is a special meridian (180(180° E or ° E or 180180° W)° W)

►Not only do you change the time when you Not only do you change the time when you cross it, you also change the daycross it, you also change the day

Traveling east-Traveling east- add one hour, add one hour,

but subtract a daybut subtract a day Traveling west-Traveling west- subtract one hour, subtract one hour,

but add a daybut add a day

MapsMaps

►Maps show locations and distancesMaps show locations and distances►Since the Earth is not flat, all maps Since the Earth is not flat, all maps

have some distortionhave some distortion Causes changes in the shapes and sizes Causes changes in the shapes and sizes

of landmasses and of landmasses and oceansoceans The smaller the,The smaller the, area mapped area mapped the less distortionthe less distortion

Projecting Our Globe Onto A Projecting Our Globe Onto A Flat SurfaceFlat Surface

►Globes are the most accurate way to Globes are the most accurate way to represent the surface of the Earthrepresent the surface of the Earth

► Since it’s not practical to carry a globe into Since it’s not practical to carry a globe into the field, projections are used to represent the field, projections are used to represent the round Earth on a flat piece of paperthe round Earth on a flat piece of paper

Mercator or Cylindrical Map Mercator or Cylindrical Map ProjectionsProjections

► The most common type of map that we seeThe most common type of map that we see

► It’s like projecting an image of the globe on a It’s like projecting an image of the globe on a movie screen that’s been wrapped around it movie screen that’s been wrapped around it

► Areas near the equator Areas near the equator have very little distortionhave very little distortion

► The closer to the poles, The closer to the poles, the more distorted the mapthe more distorted the map becomesbecomes

Conic ProjectionsConic Projections

► Created by placing a cone shaped screen on Created by placing a cone shaped screen on a globea globe

► Produces a fairly accurate representation of Produces a fairly accurate representation of the portion of the Earth’s surface being the portion of the Earth’s surface being mappedmapped

► Used for making Used for making

topographic mapstopographic maps

Gnomonic or Plane Gnomonic or Plane ProjectionProjection

► Created by placing an imaginary screen Created by placing an imaginary screen directly above, or below a globedirectly above, or below a globe

► Used to plot the shortest distance between Used to plot the shortest distance between two pointstwo points

► Since it distorts both directionSince it distorts both direction

and distance, this type of mapand distance, this type of map

projection is seldom usedprojection is seldom used

Interrupted ProjectionInterrupted Projection► There are many different types of There are many different types of

interruptedinterrupted

projection mapsprojection maps

►Depict the continents as accurately as Depict the continents as accurately as possible by leaving blank space in the less possible by leaving blank space in the less important areas of the map, such as in the important areas of the map, such as in the oceansoceans

Equal-Area ProjectionEqual-Area Projection

► For equal-area projections the meridians For equal-area projections the meridians and parallels are placed on the map so that and parallels are placed on the map so that every part of the Earth is the same size on every part of the Earth is the same size on the map as it is on the globethe map as it is on the globe

► Correctly shows the Correctly shows the

amount of area aamount of area a

landmass covers, landmass covers,

but distorts its shapebut distorts its shape

Computer MappingComputer Mapping►With computers, cartographers can store, process, With computers, cartographers can store, process,

and display maps electronicallyand display maps electronically► Computers produce maps using data from many Computers produce maps using data from many

sources, including satellites and the Global sources, including satellites and the Global Positioning System Positioning System

► Satellite imagesSatellite images- - Pictures of the land surface Pictures of the land surface based on computer data collected from satellites based on computer data collected from satellites in spacein space

►Global Positioning System (GPS)Global Positioning System (GPS)- - Method of Method of finding latitude, longitude, and elevation of points finding latitude, longitude, and elevation of points on Earth’s surface using a network of satelliteson Earth’s surface using a network of satellites

Topographical MapsTopographical MapsTopographic Topographic mapsmaps shows:shows: different shapes different shapes

and sizes of land and sizes of land surfacessurfaces

small details of small details of the topography the topography of an areaof an area

the location of the location of landscape and landscape and cultural featurescultural features

thethe reliefrelief, or , or elevation elevation change, of the change, of the landland

Contour LinesContour Lines►Most topographic maps use contour lines to Most topographic maps use contour lines to

show the relief of the landshow the relief of the land► Contour line-Contour line- A line that passes through A line that passes through

points on a map that have the same points on a map that have the same elevation elevation (height above sea level)(height above sea level)

► Index contour-Index contour- A bolder/wider brown line A bolder/wider brown line that has the elevation value marked at various that has the elevation value marked at various intervals as a part of the lineintervals as a part of the line Typically occur every fifth lineTypically occur every fifth line Find an index contour near the point Find an index contour near the point

for which you are trying to find the for which you are trying to find the elevation, then count up or down fromelevation, then count up or down from

there to determine the elevationthere to determine the elevation

Contour IntervalContour Interval► Contour interval-Contour interval- The difference in The difference in

elevation from one contour line to the nextelevation from one contour line to the next The size of the interval depends on the The size of the interval depends on the

relief of the land (mountains will need a relief of the land (mountains will need a bigger interval than a plain)bigger interval than a plain)

► To calculate the contour interval- To calculate the contour interval- determine the distance between two determine the distance between two successive index contours and then divide successive index contours and then divide that number by 5that number by 5

Step 1: 800 ft – 700 ft = 100 ft

Step 2: 100 ft ÷ 5 = 20 ft

The contour interval would be 20 ft

Rules for using contour Rules for using contour lineslines

1.1. Contour lines never cross or intersectContour lines never cross or intersect2.2. Closely spaced lines represent a steep slopeClosely spaced lines represent a steep slope3.3. Contours spaced far apart represent a gentle Contours spaced far apart represent a gentle

slopeslope4.4. Contour lines form V’s that point upstream, or Contour lines form V’s that point upstream, or

in a direction opposite the flow of the streamin a direction opposite the flow of the stream5.5. Contours form closed loops around hilltops or Contours form closed loops around hilltops or

depressionsdepressions6.6. Short dashes called Short dashes called hachureshachures are used to are used to

indicate a depressionindicate a depression7.7. All contour lines either close or extend to the All contour lines either close or extend to the

edge of a mapedge of a map

Mapping EtiquetteMapping Etiquette

To make reading and using a map easier, To make reading and using a map easier, all maps should have a:all maps should have a: TitleTitle-- to know what you’re looking at to know what you’re looking at Compass rose or north facing arrow- Compass rose or north facing arrow- to to

determine directiondetermine direction Map scale- Map scale- to determine distanceto determine distance Map key (or legend)- Map key (or legend)- to explain symbols to explain symbols

usedused A way to determine the contour interval on A way to determine the contour interval on

topographic maps topographic maps

Bel IsleBel Isle