Topographic MapsTopographic MapsTopographic Maps show the surface

features of an area

is about…..

Contour LinesContour Lines• Contour Lines are

imaginary lines that join points of equal elevation above or below sea level

Contour Line Link

Contour LinesContour Lines

http://www.4orienteering.com

Equal elevation

Rules of Contour Lines Rules of Contour Lines • Never cross each otherNever cross each other

• Connect with themselvesConnect with themselves

• Get closer together as land gets steeperGet closer together as land gets steeper

• Get further apart as land gets flatterGet further apart as land gets flatter

Contour IntervalContour Interval

The distance

that separates contour intervals

The change in elevation from contour line to contour line is called the contour interval

Contour ProfileContour Profile• The shape you

would see if were sliced along a line

http://serc.carleton.edu/mathyouneed/slope/topoprofile.html

GradientGradient

• The gradient of a mountainside is a measure of its steepness

ReliefRelief• The relief of a

contour map is the difference between its highest and lowest points

500 m (950 m – 450 m) [Accept all reasonable estimates.]

500 m (950 m – 450 m)

Contour Interval = 50m

Important thing to remember ….Important thing to remember ….

Topographic maps can be used to identify land and erosional features

Let’s take a walk up a Let’s take a walk up a hill!hill!

We’re now at an elevation We’re now at an elevation of 100 meters.of 100 meters.

100m

Let’s keep going!Let’s keep going!

100m

Now we’re at 200m.Now we’re at 200m.

100m

200m

Shall we march on?Shall we march on?

100m

200m

We’ve made it to 300m!We’ve made it to 300m!

100m

200m

300m

On to the peak!On to the peak!

100m

200m

300m

We’re on the peak, but We’re on the peak, but what’s our elevation?what’s our elevation?

100m

200m

300m

Any ideas?Any ideas?

100m

200m

300m

Let’s add contour lines for every 50 meters and see if that helps.

100m

200m

300m

We know that we are above 350m, but less than 400m.

50m

150m

250m

350m

100m

200m

300m

Let’s head down the hill, it’s getting late!

50m

150m

250m

350m

100m

200m

300m

Now what’s our elevation?

50m

150m

250m

350m

If you said somewhere between 200m and 250m you are right!

100m

200m

300m

Let’s try this again!

50m

150m

250m

350m

100m

200m

300m

What’s our elevation now?

50m

150m

250m

350m

If you said 50m or just under, you’re right!

Let’s now look at the Let’s now look at the same hill, but the way same hill, but the way we might see it from we might see it from an airplane!an airplane!

Each color change represents a 50 meter increase.

Now, let’s try the same hike! Our elevation is 0 meters.

Now what is our elevation?

If you said more than 150 meters, but less than 200 meters you’re right!

Let’s go a little higher.

Think you know our elevation now?

More than 300meters

But less than 350meters

If we were standing on the peak, what would be our elevation?

• More than 350 meters, less than 400 meters

Let’s head down hill.

Know our elevation?

More than 100 meters, less than 150 meters

Let’s see what you know.Let’s see what you know.

400m 800m

1000m

1200m

A

B

C

D

E

F

600m

1. Could the elevation at the peak (B) be 1410 meters?

400m 800m

1000m

1200m

A

B

C

D

E

F

600m

No : The elevation must be under 1400 meters, but over 1300 meters.

2. What is the elevation at (E)?

400m 800m

1000m

1200m

A

B

C

D

E

F

600m

About 400 meters

3. If you walked a straight line from (D) to (C) would you walk over a ridge or

down a valley?

400m 800m

1000m

1200m

A

B

C

D

E

F

600m

Down a valley: If the contour lines point up the slope it’s a valley, if they point down the slope it’s a ridge.

4.Just looking at the map, would it be easier to head down from the peak going East, or going North?

400m 800m

1000m

1200m

A

B

C

D

E

F

600m

E

N

S

W

East: When contour lines are close together that means there is a steep slope, the further apart the lines, the more gentle the slope and therefore an easier walk! Go east!

What land feature is What land feature is represented in the picture represented in the picture

below?below?

DepressionDepression

What land feature is What land feature is represented in the picture represented in the picture

below?below?

ValleyValley

What land feature is What land feature is represented in the picture represented in the picture

below?below?

RidgeRidge

What land feature is What land feature is represented in the picture represented in the picture

below?below?

HillHill

Contour PracticeContour Practice1. What is the contour interval of the map at left?

2. What is the elevation of point A?

3. What is the elevation of point B?

4. What is the elevation change between A and B?

80 m80 m320 m320 m880 m880 m

560 m560 m

Close to Home Close to Home • Local maps

– http://www.topozone.com/states/Texas.asp?county=Bexar

– http://www.trails.com/topo.aspx?lat=30.50639&lon=-98.81861&s=50&name=Enchanted%20Rock

• Topo Map - http://www.youtube.com/watch?v=EqyfJMgFL-U