topographic maps topographic maps show the surface features of an area is about
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Contour Lines Equal elevationTRANSCRIPT
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