Do Now:

When would knowing your altitude be important?

Today’s Objective:

Interpreting a Topographic Map

Isoline -

A term used to describe lines that connect points of equal value on a

map.

** Important Vocabulary **

Types of Isolines -

Isobars – equal pressures

Isotherms - equal

temperatures

Contour Lines -

equal elevations

Index Contour Line

Heavy lines spaced at a predetermined labeled elevations on

a topographic map.

Index Contour

Contour Interval

- The Distance between contour lines (what it is counting by).

Benchmark – tells the real elevation at that

point

What is the contour interval of this

map? 100

Estimating Elevation •Label the contour lines based on the map interval •Find the contour line before and after the point you are trying to determine •Your answer should be a point in between those lines

Contour Interval = 10 m

10

. a

20

30

. b . c

Give a possible elevation for

point “a”

Give a possible elevation for

point “b”

15 m

23 m

What is the highest possible elevation?

The highest possible point on a contour map will always be one unit less than the next possible contour line.

Contour Interval = 10 m

10

. a

20

30

. b . c

Give the HIGHEST possible elevation

for point “c”

39 m

What about the LOWEST possible point?

The lowest possible point on a contour map will always be one unit more than the lower contour line.

Contour Interval = 10 m

10

. a

20

30

. b . c

Give the LOWEST possible elevation

for point “c”

31 m

Where would it be easier to hike?

Why? A.

B.

B has a gentle slope, or gradient.

Closer contour lines = steep slopes.

Further contour lines = gradual slopes.

Gradient• Refers to the steepness of the land (slope)

Which side of the hill is the steepest?

WHY?

Gentle Steep

Contour lines will either

•Run off the map or

•Close on themselves to create circles

Contour lines will NEVER cross.

If contour lines touch they represent a very steep gradient, otherwise called a cliff.

Closed contours with hachure marks represent depressions (holes).

Hachure Contours

The contour line with the marks, or hachures , has the same elevation as the

line before it.

Same Elevation50 Meters

upstream

downstream

When a river or stream crosses a contour line, the contour line bends and points upstream.

River and Streams

• Upstream is where the river starts, higher elevation.

• Downstream is where the river ends, lower elevation.

1. What is the contour interval?

2. What compass direction is Eagle Mt. located?

3. What is the elevation at the edge of Wolf Pond?

4. What is the elevation of point B?

Point C? Point E?

10 m

Northwest

30 m

100 m 70 m 40 m

5. Place an “X” on the map where the steepest location would be.

6. What direction is the Creek flowing? Explain how your know.

x

upstream

V points upstream (in this case East).

So the downstream (direction of creek flow) is West.

What is the contour interval of this

map? 20

If given the contour interval, can you label the lines?

0

5

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