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Contour Lines Contour Lines

Contour Lines - PowerPoint Presentation

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Uploaded On 2017-07-26

Contour Lines - PPT Presentation

Contour lines are lines drawn on a map that connect points of equal elevation If you walk along a contour line you neither gain or lose elevation   Picture walking along a beach exactly where the water ID: 573326

lines contour contours elevation contour lines elevation contours line series slope level sea map closed shapes point spaced hill

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Slide1

Contour LinesSlide2

Contour lines are lines drawn on a map that connect points of equal elevation. If you walk along a contour line you neither gain or lose elevation.  

Picture walking along a beach exactly where the water

meets the land (ignoring tides and waves for this example).

The water surface marks an elevation we call sea level, or

zero.Slide3

As you walk along the shore your elevation will remain the same, you will be following a contour line.

If you stray from the shoreline and start walking into the ocean, the elevation of the ground (in this case the seafloor) is below sea level. 

If you walk in the other direction and walk up the beach your elevation will be above sea level. Slide4

Sea Level

Above Sea Level

Below Sea LevelSlide5

Why are contour lines useful?

Contour lines are useful because they allow us to show the shape of the land surface (topography) on a map.  Slide6
Slide7

Sea LevelSlide8

Rising WaterSlide9

Contour LinesSlide10

What is this?Slide11

CONTOUR MAPSlide12

10 characteristics of contour lines

1. Contour lines are continuous.

2. Contour lines do not cross each other- but there are 2 exceptions

3. A series of V-shape indicates a valley and the V’s point to higher elevation.Slide13

4. A series U shape indicates a ridge. The U shapes will point to lower elevation.

5. Evenly spaced lines indicate an area of uniform slope.

6. A series of closed contours with increasing elevation indicates a hill and a series of closed contours with decreasing elevation indicates a depression.

characteristics of contour lines cont.Slide14

7. Closed contours may be identified with a +, hill, or -, depression

.

8. Closed contours may include hachure marks. Hachure marks are short lines perpendicular to the contour line. They point to lower elevation.

9. The distance between contour lines indicates the steepness of the slope. The greater the distance between two contours the less the slope. The opposite is also true.

characteristics of contour lines cont.Slide15

10.

A different type of line should be used for contours of major elevations. For example at 100, 50 and 10 foot intervals. Common practice is to identify the major elevations lines, or every fifth line, with a bolder, wider, line.

characteristics of contour lines cont.Slide16

Some

contour lines may

complete full circles (connect) but

others will not.

In

this case, they will start at a boundary line and end at a boundary line

.

Contours

must either close or extend from boundary to boundary.

1. Contours are ContinuousSlide17

Two

exceptions:

They will meet at a vertical cliff

They will overlap at a cave or overhang.

When

contour lines overlap, the lower elevation contour should be dashed for the duration of the overlap.

2. Contour lines do not crossSlide18

3. Valleys and higher elevation

A

valley is shown by a series

of V-shapes

where

the V’s point to the higher

elevation.Slide19

4. U shapes and ridge

A

series of U shapes indicates a ridge. The U shapes will point to lower elevation.Slide20

5. Contour Spacing

Evenly spaced contours indicate an area of

the same slope

.

Unevenly spaced contours indicates an area with variable slope.Slide21

A series of closed contours with increasing elevation indicates a hill.

Hills may be identified with a “+” with the elevations

6 & 7 Hills and Depressions Slide22

A

series of closed contours with decreasing elevation indicates a depression

.

Depressions may be

identified with a “-”.

6 & 7 Hills and Depressions--cont.Slide23

8.

Hachures

Hachures

are short lines which are perpendicular to the contour line

.

Used

to indicate a hill or a depression

.

Not

used on modern maps.Slide24

9. Contour Spacing

Contours

spaced wider apart indicate

lower slope

.

Contours spaced close together

indicate a higher slope.Slide25

9. Contour Spacing-Intervals

Another

decision that must be made is the contour interval

.

The

“best” interval depends on the use of the data.Slide26

10. Contour line

The thicker contour is

Called the index line.Slide27

How do you make a contour map?

Contour lines never cross

Contour lines never end- unless they go off the map

There must be equal intervals between contour lines

When contour lines are closer together, the slope is steeper

When the contour lines are spaces farther apart, the land is less steepSlide28
Slide29

Contour MapSlide30

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