Topographic Maps Gizmo 2.17.12
VOCABULARY:
Contour Interval: the change in elevation between adjacent contour lines
Contour Lines: a line connecting points of equal elevation on a map
Depression contour: a contour line with hachure marks to indicate a depression or hollow
-depression contours form closed curves
-the hachure marks distinguish depression contours from contour lines that indicate a hill or a mountain
Elevation: the height of a location above a fixed reference point, usually at sea level
Gradient: the slope of a surface or a line
-also called percent grade
-to calculate the gradient of a surface between two points, divide the change in elevation by the horizontal distance between the points
-gradient can also be estimated and compared using contour lines
Index Contour: a contour line that includes an elevation label
Relief: the difference in elevation between the highest and lowest points in a landscape
Part A
Prior Knowledge
1. Suppose it rained for a while, and the lake level rose up 5 meters. Would the house be safe? Explain.
Yes, because the house is more than 5 meters away from the lake.
2. What would happen if the lake level rose 10 meters?
The house would be underwater by then.
Observe: Select Add, and then click in the center of the landscape exactly four times. Click Horizontal View and use the Zoom In tool to magnify the landscape.
1. What feature have you created?
I have made a hill.
2. Look at each contour line on the horizontal view at left. What do you notice?
That the horizontal lines are parallel. The contour lines form circles around circles.
Calculate: Notice that one contour line is labeled with an elevation. This is an index contour. The elevation is given in meters above sea level. Because the contour intervalis 50 meters, each line above the index contour represents an elevation gain of 50 meters.
3. What is the elevation of the highest contour line on the hill?
The highest contour line of the hill is 700 meters.
4. What is the elevation of the lowest contour line you can see?
The lowest contour line of the hill is 0 meters.
5. What is the maximum height the hill could be? Explain.
The maximum height the hill could be is 700 because it can't grow any more.
6. What is the actual height the hill is?
The actual elevation of the hill is 570 meters.
Create: Reduce the Water level to 0 m, and click Flat. Select the Subtract button and click the center of the landscape exactly three times. Choose the Isometric view.
7. What feature have you created?
I have made a depression.
8. Based on the contour lines, what is the lowest possible elevation of the deepest point in the depression?
About 600 meters.
9. Check with the Water levelslider. What is the lowest elevation?
The water is 0 meters.
Part B
Create: Use the Add and Subtract tools to create an asymmetrical mountain similar to the one shown at right. The right side of the mountain should be steep, and the left side of the mountain should be gentle.
1. Compare the landscape to the map. How does the spacing of contour lines relate to the steepness of the mountainside?
The spacing of the lines relates to the steepness because the lines represent increase of height in the hill.
Apply: A hiker wants to climb a mountain. He is afraid of slopes that are too steep, however.
2. On the map, draw the gentlest route from the hiker to the top of the mountain.
Contour Interval: the change in elevation between adjacent contour lines
Contour Lines: a line connecting points of equal elevation on a map
Depression contour: a contour line with hachure marks to indicate a depression or hollow
-depression contours form closed curves
-the hachure marks distinguish depression contours from contour lines that indicate a hill or a mountain
Elevation: the height of a location above a fixed reference point, usually at sea level
Gradient: the slope of a surface or a line
-also called percent grade
-to calculate the gradient of a surface between two points, divide the change in elevation by the horizontal distance between the points
-gradient can also be estimated and compared using contour lines
Index Contour: a contour line that includes an elevation label
Relief: the difference in elevation between the highest and lowest points in a landscape
Part A
Prior Knowledge
1. Suppose it rained for a while, and the lake level rose up 5 meters. Would the house be safe? Explain.
Yes, because the house is more than 5 meters away from the lake.
2. What would happen if the lake level rose 10 meters?
The house would be underwater by then.
Observe: Select Add, and then click in the center of the landscape exactly four times. Click Horizontal View and use the Zoom In tool to magnify the landscape.
1. What feature have you created?
I have made a hill.
2. Look at each contour line on the horizontal view at left. What do you notice?
That the horizontal lines are parallel. The contour lines form circles around circles.
Calculate: Notice that one contour line is labeled with an elevation. This is an index contour. The elevation is given in meters above sea level. Because the contour intervalis 50 meters, each line above the index contour represents an elevation gain of 50 meters.
3. What is the elevation of the highest contour line on the hill?
The highest contour line of the hill is 700 meters.
4. What is the elevation of the lowest contour line you can see?
The lowest contour line of the hill is 0 meters.
5. What is the maximum height the hill could be? Explain.
The maximum height the hill could be is 700 because it can't grow any more.
6. What is the actual height the hill is?
The actual elevation of the hill is 570 meters.
Create: Reduce the Water level to 0 m, and click Flat. Select the Subtract button and click the center of the landscape exactly three times. Choose the Isometric view.
7. What feature have you created?
I have made a depression.
8. Based on the contour lines, what is the lowest possible elevation of the deepest point in the depression?
About 600 meters.
9. Check with the Water levelslider. What is the lowest elevation?
The water is 0 meters.
Part B
Create: Use the Add and Subtract tools to create an asymmetrical mountain similar to the one shown at right. The right side of the mountain should be steep, and the left side of the mountain should be gentle.
1. Compare the landscape to the map. How does the spacing of contour lines relate to the steepness of the mountainside?
The spacing of the lines relates to the steepness because the lines represent increase of height in the hill.
Apply: A hiker wants to climb a mountain. He is afraid of slopes that are too steep, however.
2. On the map, draw the gentlest route from the hiker to the top of the mountain.
3. What is the contour interval of this map?
The contour interval of the map is 50 meters
4. Calculate: The gradient of a mountainside is a measure of its steepness. Like the slope of a graph, gradient is calculated by dividing the vertical rise by the horizontal distance, or run. Because meters are divided by meters, there are no units for gradient.
A. What is the contour interval of the map at left?
The contour interval of the map is 80 meters.
B. What is the elevation of point A?
The elevation of point a is 320 meters.
C. What is the elevation of point B?
The elevation of point b is 880 meters.
D. What is the elevation change between A and B?
The elevation change between point a and b is 560 meters
E. If the horizontal distance between point A and point B is 2,800 m, what is the gradient?
The gradient of the horizontal distance is 320 meters.
The contour interval of the map is 50 meters
4. Calculate: The gradient of a mountainside is a measure of its steepness. Like the slope of a graph, gradient is calculated by dividing the vertical rise by the horizontal distance, or run. Because meters are divided by meters, there are no units for gradient.
A. What is the contour interval of the map at left?
The contour interval of the map is 80 meters.
B. What is the elevation of point A?
The elevation of point a is 320 meters.
C. What is the elevation of point B?
The elevation of point b is 880 meters.
D. What is the elevation change between A and B?
The elevation change between point a and b is 560 meters
E. If the horizontal distance between point A and point B is 2,800 m, what is the gradient?
The gradient of the horizontal distance is 320 meters.