HS Studying Earth’s Surface
Dana Desonie, Ph.D.
Erica Restum
Say Thanks to the Authors
Click http://www.ck12.org/saythanks
(No sign in required)
www.ck12.org
Chapter 1. HS Studying Earth’s Surface
C HAPTER
1
HS Studying Earth’s
Surface
C HAPTER O UTLINE
1.1
Isolines
1.2
Topographic Maps
1.3
Interpreting Topographic Maps
1.4
Profiles and Gradients
1.5
Chapter 3-Summary
1.6
References
1
1.1. Isolines
www.ck12.org
1.1 Isolines
Making sense out of data
Lesson Objectives
• Understand that an isoline is a line connecting points of equal value
• Construct a isolines map
Vocabulary
• Isoline
• Contour Lines
Introduction
Isolines are ways to connect data and make sense of what you are seeing. Isoline is a general category for a strategy
to understand data.
Fields and Isolines
A field is is a type of map that shows some sort of data. This data could be anything from air pressure, to temperature,
to pollution, to elevation. To make field maps easier to read, we often draw isolines, which are lines that connect
points of equal value. Different types of isolines has different names.
• Air Pressure isolines- Isobars
• Air Temperature Isolines- Isotherms
• Elevation Isolines- Contour Lines
When drawing isolines, you must follow these guidelines
• All isolines must be smooth and curving, separating larger values from smaller values
• Isolines can never touch or cross
• Isolines can never end in the middle of a map, they must either run to the edge, or close on themselves
Tips
• Circle all of the numbers that are the same as the isoline you are drawing
• Make a line between sets of numbers where your number fits
• Connect the circles together following the lines
Practice
Use the animation to try drawing several isolines. Draw the 40,50,60,70,80 lines, and reveal the answers.
2
www.ck12.org
Chapter 1. HS Studying Earth’s Surface
1.2 Topographic Maps
Contour Lines
Lesson Objectives
• Explain how to read and interpret a topographic map.
• Describe what a geologic map shows.
Vocabulary
• contour interval
• contour line
• topographic map
Introduction
Maps are extremely useful to Earth scientists to represent geographic features found above and below sea level and
to show the geology of a region. Rock units and geologic structures are shown on geologic maps.
What is a Topographic Map?
Mapping is a crucial part of Earth science. Topographic maps represent the locations of geographical features, such
as hills and valleys. Topographic maps use contour lines to show different elevations on a map. A contour line is
a type of isoline; in this case, a line of equal elevation. If you walk along a contour line you will not go uphill or
downhill.
Contour Lines and Intervals
Contour lines connect all the points on a map that have the same elevation and therefore reveal the location of hills,
mountains, and valleys. On a contour map:
• Each contour line represents a specific elevation and connects all the points that are at the same elevation.
• The contour lines run next to each other and NEVER cross. After all, a single point can only have one
elevation.
• This difference between contour lines is called the contour interval. The map legend gives the contour
interval.
Recognizing Landforms
Hills
3
1.2. Topographic Maps
www.ck12.org
FIGURE 1.1
A topographic map of Stowe, Vermont.
FIGURE 1.2
View of Swamp Canyon in Bryce Canyon
National Park.
On a topographic map, hills are represented by a series of closed circles. For a hill the elevation of each contour line
increases as you move towards the center of the circle
Maximum Possible Elevation
The highest point on any hill, is inside the inner most circle. To figure out what the Maximum Possible elevation is,
we need to follow a simple procedure:
1. Find the highest contour line
4
www.ck12.org
Chapter 1. HS Studying Earth’s Surface
2. Figure out what the next line up would be
3. Maximum Possible Elevation = Next line -1
Minimum Possible Elevation
The lowest point in a depression is inside the inner most circle. To find the Minimum Possible Elevation we need to
follow another simple procedure:
1. Find the lowest contour line
2. Figure out what the next line down would be
3. Minimum Possible Elevation = Next line down + 1
5
1.3. Interpreting Topographic Maps
www.ck12.org
1.3 Interpreting Topographic Maps
Interpreting Topographic Maps
Rules of Contour Lines
How does this map reveal the terrain of the location? You must know a few rules in order to read a topographic map.
1.Contour lines show the shape of the land. What does the spacing of the contour lines indicate?
• Closely-spaced contour lines indicate a steep slope, like a mountain for sides of a hill
• Broadly spaced contour lines indicate a shallow slope, like a flat area, or plain.
FIGURE 1.3
The N is the steepest part of the hill. The L is the flattest.
2. Circles indicate a hill. When contour lines form closed loops all together in the same area, this is a hill. The
smallest loops are the higher elevations and the larger loops are downhill.
3. Hatched circles indicate a depression. The hatch marks are short lines inside the circle. A depression means the
elevation is going down, like a pit or a crater. So instead of counting up by the contour interval, you count down.
FIGURE 1.4
4.V-shaped contour lines indicate streams or a river. Where a stream crosses the land, the Vs in the contour lines
point uphill. To find which way a stream is following you can use two strategies.
• a. Find the V, remember a V points UPHILL, a river cannot flow up a hill (thats against gravity!) so the stream
must be flowing the other way.
• b. Use the contour lines to determine where the higher elevation is, remember rivers cannot flow up a hill, so
pick the direction with the lowest elevation
6
www.ck12.org
Chapter 1. HS Studying Earth’s Surface
1.4 Profiles and Gradients
Profiles and Gradients
Lesson Objectives
• Calculate gradient on a topographic map
• Construct a topographic profile
Vocabulary
• gradient
• profile
Introduction
Now that we can identify areas with steep slopes, the next thing we want to be able to do is measure exactly HOW
steep it is.
Gradient
This is done by measuring the GRADIENT between two points. To find the gradient we need to know several
things:
• the elevation of two points
• the distance between two points
Profiles
FIGURE 1.5
The illustrations above are all drawn in profile, which means that they are
drawn to show us the side view of the subjects face.
Follow the directions on the video , to create your first profile.
Materials needed:
7
1.4. Profiles and Gradients
-Piece of scrap paper
-Pencil
8
www.ck12.org
www.ck12.org
Chapter 1. HS Studying Earth’s Surface
1.5 Chapter 3-Summary
Lesson Summary
• Topographic maps are 2-dimensional representations of the 3-dimensional surface features of an area.
• Topographic maps have contour lines that connect points of identical elevation above sea level.
• People use topographic maps to locate surface features in a given area, to find their way through a particular
area, and to determine the direction of water flow in a given area..
Post Reading Tasks
Transfer vocabulary to your Earth Science dictionary
Answer Reading Comprehension questions
1. On a topographic map, contour lines create a group of concentric, closed loops. Which of the following
features could this indicate?
1.
2.
3.
4.
a stream channel
a hilltop
depression
a cliff
Describe the pattern on a topographic map that would indicate a stream valley. How do you determine the
direction of water flow?
3. On a topographic map, five contour lines are very close together in one area. The contour interval is 100 ft.
2.
What feature does that indicate? How high is this feature?
4. On a topographic map, describe how you can tell a steep slope from a shallow slope.
5. On a topographic map, a river is shown crossing from Point A in the northwest to Point B in the southeast.
Point A is on a contour line of 800 ft and Point B is on a contour line of 900 ft. In which direction does the
river flow?
•
•
•
•
•
•
Isolines connect values of equal values
Contour lines express elevation
Topographic maps can be used to determine highest point, stream direction, and highest point.
Gradients help you determine slope
Profiles give you a unique perspective
You can make predictions based off topographic maps
Post Reading Tasks
Transfer vocabulary into Earth Science dictionary.
Answer Reading Comprehension questions.
9