Topographic MappingTopographic Mapping

Honors Earth ScienceHonors Earth Science

Parkland High SchoolParkland High School

Review of LatitudeReview of Latitude

Latitude describes locations north Latitude describes locations north and south of the Equator (0°)and south of the Equator (0°)

Lines of latitude are also called Lines of latitude are also called parallelsparallels

Ranges from 0° at the Equator to 90° Ranges from 0° at the Equator to 90° at the polesat the poles

Review of LongitudeReview of Longitude

Longitude describes locations east Longitude describes locations east and west of the Prime Meridian (0°)and west of the Prime Meridian (0°)

Longitude is represented by Longitude is represented by imaginary lines extending from the imaginary lines extending from the North Pole to the South PoleNorth Pole to the South Pole

Longitude ranges from 0° at the Longitude ranges from 0° at the Prime Meridian to 180° on the Prime Meridian to 180° on the opposite side of the world opposite side of the world (International Date Line)(International Date Line)

Minutes and SecondsMinutes and Seconds

Used when more precise descriptions Used when more precise descriptions of latitude and longitude are neededof latitude and longitude are needed

One degree is divided into 60 One degree is divided into 60 minutes (60')minutes (60')

One minute is divided into 60 second One minute is divided into 60 second (60")(60")

Importance of Latitude and Importance of Latitude and LongitudeLongitude

Accurately describes a unique Accurately describes a unique location on the Earthlocation on the Earth

Time ZonesTime Zones

Why do we have them?Why do we have them?• Telegraphs and trains brought about the Telegraphs and trains brought about the

need for standardized timesneed for standardized times• 24 standard time zones were 24 standard time zones were

established by international agreementestablished by international agreement• Time zones based on longitude and are Time zones based on longitude and are

in 15° incrementsin 15° increments

Time Zones of the USTime Zones of the US

International Date LineInternational Date Line

Located at 180° on the opposite side Located at 180° on the opposite side of the world from the Prime Meridianof the world from the Prime Meridian

When crossing the IDL going from When crossing the IDL going from west to east, it becomes the previous west to east, it becomes the previous dayday

When crossing the IDL going from When crossing the IDL going from east to west, it becomes the next dayeast to west, it becomes the next day

Time Zone ProblemTime Zone Problem

You leave New York City (75°W) at You leave New York City (75°W) at 1pm. What time is it in Seattle 1pm. What time is it in Seattle (120°W)?(120°W)?

Answer Answer

10am10am

Time Zone ProblemTime Zone Problem

You leave Easter Island (150°W) at You leave Easter Island (150°W) at 10am on Monday. What time is it in 10am on Monday. What time is it in Bikini Island (165°E)?Bikini Island (165°E)?

What day is it?What day is it?

AnswerAnswer

7am 7am TuesdayTuesday

Topographic MapsTopographic Maps

Topographic maps are important tools for studying the earth surface, not only for geologists, but for engineers, foresters, land use planners, hikers...virtually anyone who travels outdoors.  Topographic maps summarize the three dimensional topography of the earth's surface on two dimensional pieces of paper (or computer screens).

A topographic map is a map that shows A topographic map is a map that shows topography and features found on the topography and features found on the

Earth’s surface.Earth’s surface.

SymbolsSymbols Topographic maps use symbols to represent Topographic maps use symbols to represent

natural and human constructed features found natural and human constructed features found in the environment. The symbols used to in the environment. The symbols used to represent features can be of three types: represent features can be of three types: points, lines, and polygons. Points are used to points, lines, and polygons. Points are used to depict features like bridges and buildings. depict features like bridges and buildings. Lines are used to graphically illustrate features Lines are used to graphically illustrate features that are linear. Some common linear features that are linear. Some common linear features include roads, railways, and rivers. However, include roads, railways, and rivers. However, we also need to include representations of we also need to include representations of area, in the case of forested land or cleared area, in the case of forested land or cleared land; this is done through the use of color.land; this is done through the use of color.

Review Types of ScalesReview Types of Scales

Contour LinesContour Lines

What are they?What are they?• Imaginary lines that connect points of Imaginary lines that connect points of

equal elevation-if you walk along a line, equal elevation-if you walk along a line, you neither gain nor lose elevation.you neither gain nor lose elevation.

• Help understand and visualize the Help understand and visualize the topography of a surface using a maptopography of a surface using a map

Important Contour RulesImportant Contour Rules

Contour lines connect points of equal Contour lines connect points of equal elevationelevation

Contour lines NEVER crossContour lines NEVER cross Contour lines spaced far apart indicate Contour lines spaced far apart indicate

a gentle slope, contour lines spaced a gentle slope, contour lines spaced close together indicate a steep slopeclose together indicate a steep slope

Contour intervalContour interval is the difference is the difference between two successive contour linesbetween two successive contour lines

Contour lines that cross a valley or stream Contour lines that cross a valley or stream are V-shaped. The V points toward the area are V-shaped. The V points toward the area of higher elevation. If a stream or river flows of higher elevation. If a stream or river flows through the valley, the V points upstream.through the valley, the V points upstream.

Hills are represented by a concentric Hills are represented by a concentric series of closed contour linesseries of closed contour lines

A concentric series of closed A concentric series of closed contours with hachure marks on the contours with hachure marks on the downhill side represents a closed downhill side represents a closed depression.depression.

Widely Spaced Contours Widely Spaced Contours

Gentle SlopeGentle Slope

Closely Spaced ContoursClosely Spaced Contours

Steep SlopeSteep Slope

Index ContoursIndex Contours Contour line that is accentuated in thickness and is often labeled Contour line that is accentuated in thickness and is often labeled

with the appropriate measure of elevation. Index contours occur with the appropriate measure of elevation. Index contours occur every fourth or fifth contour interval and help the map user read every fourth or fifth contour interval and help the map user read elevations on a map.elevations on a map.

Elevations on one side of a contour line Elevations on one side of a contour line are higher than on the other sideare higher than on the other side

What is the elevation of A, B, C, D, E?What is the elevation of A, B, C, D, E?

Topographic ProfilesTopographic Profiles Allow us to see the changes in Allow us to see the changes in

elevation of the landscape along a elevation of the landscape along a lineline

Creates a side view of the landscapeCreates a side view of the landscape

How to Construct a Topographic How to Construct a Topographic ProfileProfile

Put a tick mark on your piece of Put a tick mark on your piece of paper where a contour line touches paper where a contour line touches the paperthe paper

Label this with the contour elevationLabel this with the contour elevation

How to Continued…How to Continued…

Line your piece of paper with a graph Line your piece of paper with a graph and place a dot above each tick mark and place a dot above each tick mark at the height that is labeled for that at the height that is labeled for that tick marktick mark

Connect the dotsConnect the dots

ElevationElevation

Elevation is the height of an object Elevation is the height of an object above sea levelabove sea level

The elevation at sea level is 0. The elevation at sea level is 0.

ReliefRelief

The difference in elevation between The difference in elevation between two pointstwo points

SlopeSlope

A way of describing elevation A way of describing elevation changes over a distancechanges over a distance

Difference in elevation between 2 Difference in elevation between 2 points divided by the horizontal points divided by the horizontal distance between the 2 pointsdistance between the 2 points

Calculating Slope from a Calculating Slope from a Topographic MapTopographic Map

1)1) Decide on an area for which you want Decide on an area for which you want to calculate the slope to calculate the slope

2)2) Once you have decided on an area of Once you have decided on an area of interest, draw a straight line perpendicular interest, draw a straight line perpendicular to the contours on the slope.  For the most to the contours on the slope.  For the most accuracy, start and end your line on, accuracy, start and end your line on, rather than between, contours on the map.rather than between, contours on the map.

3)3) Measure the length of the line you drew and, Measure the length of the line you drew and, using the scale of the map, convert that distance using the scale of the map, convert that distance to feet. to feet.

4)4) Determine the total elevation change along Determine the total elevation change along the line you drew (subtract the elevation of the the line you drew (subtract the elevation of the lowest contour used from the elevation of the lowest contour used from the elevation of the highest contour used).  You do not need to do highest contour used).  You do not need to do any conversions on this measurement, as it is a any conversions on this measurement, as it is a real-world elevation change.real-world elevation change.   

  5) Simply divide the elevation change in 5) Simply divide the elevation change in feet by the distance of the line you drewfeet by the distance of the line you drew

The EndThe End