specialized maps which specialized maps which show the highs and show the highs and lows (relief) of the lows (relief) of the

Earth’s surfaceEarth’s surface

topo map parts…topo map parts…

Field : A region in which similar quantities can be measured at every point or location (ex. temperature in a room or depth of snow)

Isolines: Connect points of equal values on a map

Contour line: Connect points of equal elevation

• Index contour: A contour line that has has elevation noted on it. Typically a multiple elevation noted on it. Typically a multiple of five or ten (example: 300, 320, etc)of five or ten (example: 300, 320, etc)

• Contour interval: The difference in the height between two contour lines that are next to each other. NOTE: A contour interval shows a difference in vertical height and a map scale shows horizontal distance

Contour Interval = 5 feet

Contour interval = (Index Contour 2-Index Contour 1)/ Number of Lines between

Ex.: (320-300)/4= 20/4= 5 ft contour interval

……topo map partstopo map partsA A benchmarkbenchmark is a point is a point where the actual elevation is where the actual elevation is knownknown elevation is shown on the elevation is shown on the map by the letters BM and map by the letters BM and the elevation next to it (ex. the elevation next to it (ex. BM1078)BM1078)

..

Depression contours show where Depression contours show where the elevation decreases (a hole, the elevation decreases (a hole, volcano crater, etc.)volcano crater, etc.) When reading the depression When reading the depression contour, the elevation of the first contour, the elevation of the first one is the same elevation of the one is the same elevation of the regular contour before it. The regular contour before it. The next one decreases the same next one decreases the same amount as the contour intervalamount as 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

Index Index contourcontour

Contour Contour lineslines

benchmarbenchmarkk

Landforms on Contour Landforms on Contour MapsMaps

The The steepnesssteepness of an area is shown of an area is shown by the closeness of the contour linesby the closeness of the contour lines The closer the contour lines are The closer the contour lines are together, the steeper the area together, the steeper the area (cliff, etc.)(cliff, etc.)

When the contour lines are spread When the contour lines are spread out, the land is relatively flat. out, 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 contour line crosses a stream or river, the contour stream or river, the contour line bends and forms a “V” line bends and forms a “V” shapeshape

SUPER IMPORANT!!!!!!!!!!!:SUPER IMPORANT!!!!!!!!!!!:The point of the “V” shows the The point of the “V” shows the

direction that the water is coming direction that the water is coming fromfromThe “v” points to the SOURCE of The “v” points to the SOURCE of the river or upstream the river or upstream

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????

Escarpments and SlopeEscarpments: Another word for cliff

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 elevationGradient = difference in elevation --------------------------------------------------------------------------------------------------------------------------------------------------------------

distancedistance

Some important pointsContour lines are circles within circles

Contour lines never cross each other, but they may touch

Contour lines are darker every 5th line and has elevation printed

Contour lines are not spaced evenly.

The closer the lines, the steeper the slope

The smaller the circle towards the middle, the closer you are to the top of a hill

Some important pointsHachured/dashed lines show a depression

or a hole (decrease in elevation)The first contour line of a depression is

the same elevation as the contour line which surrounds it

When lines cross a stream, they bend making a “V”

The “V” points upstream, opposite the direction of flow.

Profile: side view of the hill/mountain; drawn by using a contour map and by plotting the elevations of certain points on a vertical axis

Making a Profile from a Topographic Mapa. Lay a piece of scrap paper along the line

where the profile is to be constructed.b. Make a mark on the scrap paper at the

exact place where each contour line, stream and hill top crosses the profile line.

c. Label each mark with the elevation of the contour it represents.

d. On the graph provided, label the horizontal lines with matching elevations, if not already completed for you

e. Place the scrap paper with the labeled contour lines at the bottom of the graph and project each contour to the horizontal line of the same elevation. Make a dot at this location

f. Connect the dots.g. Round out hills and valleys- do not draw lines

straight across

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!