The document discusses topographic maps and how to read them. It defines a topographic map as a map that shows elevation, and explains that contour lines connect points of equal elevation. It describes how to calculate gradient by finding the change in elevation over the change in distance between two points. It also explains how to create a topographic map profile by tracing contour lines to show what the landscape would look like if viewed directly.

1. LESSON 4 – TOPOGRAPHIC MAPS
Learning Objective: We will learn how
to read and analyze a topographic map
Do Now: Fill in the heading for
Lesson 4
Ms. Sgambati 9/16/11
Earth Science

2. What is a Topographic map?
LO: We will learn how to read and analyze a topographic map
● Topographic map - a map that shows the
elevation of an area of Earth

3. What is an isoline?
●Isoline - a line that connect points of equal value
●Examples:
●Isotherms – An isoline that connects points of equal temperature
●Isobars – An isoline that connects points of equal pressure
●Contour lines – An isoline that connects points of equal elevation
LO: We will learn how to read and analyze a topographic map

4. Topographic map
LO: We will learn how to read and analyze a topographic map

5. What is the Contour Interval?
●Contour interval - the amount or value in between
each contour line
●Usually listed at bottom of map
LO: We will learn how to read and analyze a topographic map

6. What is the contour interval?
LO: We will learn how to read and analyze a topographic map
20 meters

7. What is the gradient?
●Gradient = the slope of an
area
LO: We will learn how to read and analyze a topographic map

8. Gradient = change in field value
change in distance
●Field value = the value of the contour line of each point
●Distance = the distance between the 2 points on the map
● Use map scale on bottom
LO: We will learn how to read and analyze a topographic map
How do we calculate Gradient?

9. How do we calculate Gradient?
● “Change in field value”:
1. Locate the 2 points of interest (ex. A and B)
1. Subtract these 2 values to get the “change in field value”
LO: We will learn how to read and analyze a topographic map

10. How do we calculate Gradient?
●“Change in distance”:
1.Put scrap paper up against the 2 points so the paper creates a
line between them
1.Mark both points on scrap paper
1.Put the scrap paper up to the “map scale” & read distance
LO: We will learn how to read and analyze a topographic map

11. How do we calculate Gradient?
Gradient = change in field value
change in distance
LO: We will learn how to read and analyze a topographic map

12. Other important facts
●The closer that contour lines are to each other,
the steeper the slope
●The further that contour lines are to each other,
the flatter the slope
LO: We will learn how to read and analyze a topographic map

13. Steepest area =
Flattest area =
LO: We will learn how to read and analyze a topographic map
A
B
C
C
B

14. ●Rivers always flow into lakes or oceans
●Rivers always
flow downhill
LO: We will learn how to read and analyze a topographic map
Other important facts

15. What is a Topographic Map Profile?
●A topographic map profile
is what the land looks like
when looking directly at it
(from the ground)
LO: We will learn how to read and analyze a topographic map

16. Creating a Topographic Map Profile
1. Locate the 2 points of interest
2. Put the edge of the scrap paper up against the 2 points
(creating a line)
3. Mark wherever the paper crosses a contour line.
4. Label each “mark” on the scrap paper with its value
5. Put the scrap paper at the bottom of the profile paper.
6. Mark with an “x” where each value should go on the profile
paper.
7. Connect all of the x’s to create your profile.
LO: We will learn how to read and analyze a topographic map