GEO 101 – Mapping Basics Laboratory
Student Name:________________________________
Purpose
The purpose of this lab is to become familiar topographic maps. To understand a map grid
represented by latitude and longitude, to read and understand and interpret contour maps and the
features on them, including creating topographic profiles and measuring contour gradients.
Learning Objectives
After doing this lab you will be able to:
1. Explain latitude and longitude and how it can be used to determine any location on the
planet.
2. Explain different map scales.
3. Explain how a contour maps turn three-dimensional features into two-dimensional ones.
4. Explain how to depict mountains, valleys, slopes, depressions on a contour map.
5. Explain how to make a topographic profile and calculate a contour gradient.
Map Locations
Latitude lines, or parallels, are parallel to the equator and measure distances north and south of
the Equator. Longitude lines, or meridians, pass through the North and South Poles (Fig. 1). They
measure distances east and west of the Prime Meridian, which passes through Greenwich,
England. Any point on the Earth's surface can be represented as an intersection of a line of latitude
and a line of longitude. Since all of North America is north of the Equator and west of the Prime
Meridian, all latitudes in the continental United States are north and all longitudes are west.
Latitude and longitude are expressed in degrees, minutes, and seconds. 1 degree (˚) = 60 minutes
('), 1 minute = 60 seconds (") 360˚ makes a complete circle.
Figure 1. Lines
of latitude and
longitude
.
Direction
The four directions north, south, east and west commonly denoted by their initials N, E, S, and W.
East and west are at right angles to north and south, with east being in the clockwise direction of
rotation from north and west being directly opposite east (Fig. 2).
Figure 2. The
four directions
north, south,
east and west.
The direction of geographic north is toward the top of the map (and it is always parallel to the
lines of longitude). However, compasses do not point to the geographic North Pole, but to the
magnetic north pole. The angle formed between the direction of geographic north and the
direction of magnetic north is known as the magnetic declination (Fig. 3).
Figure 3. A
representation of
magnetic north
compared to
geographic north.
[CC BY-SA 3.0
(http://creativecommons.o
rg/licenses/by-sa/3.0/)]
It is usually indicated in diagrammatic form in the margin of a topographic map. The magnetic pole
moves very slowly through time, so the declination is exact only for the year listed on the map.
Tables are available from which you can calculate correct declination for any quadrangle and year.
Topographic Maps
Topographic maps represent the Earth’s three-dimensional features, such as elevation, on a twodimensional surface. Features on a map include:
Relief: mountains, valleys, slopes, depressions as defined by contour lines.
Hydrography: lakes, rivers, streams, swamps, rapids, falls.
Vegetation: wooded areas.
Transportation: roads, trails, railways, bridges, airports.
Culture: buildings, urban development, power transmission line, pipelines, towers.
Boundaries: international, state, geographical.
Toponymy: place names, water feature names, landform names, boundary names.
Map colors: colors on maps relate to different features.
Black shows cultural features such as buildings, railways and power transmission lines. It is
also used to show geographical names (toponymy), certain symbols, geographic coordinates
and precise elevations.
Blue represents water features including lakes, rivers, swamps and marshes. Magnetic
declination and UTM grid information are also blue.
Green indicates vegetation such as woods.
Brown indicates contour lines.
R. Davies Mapping Basics Laboratory
2
Contour lines on topographic maps connect points of equal elevation and illustrate relief on a
map. They are imaginary lines that show the height of ground above mean sea level (MSL). They
help to depict the steepness of a terrain. Contour lines that are close to one another indicate hilly
or mountainous terrain, while lines that are further apart indicate a gentler slope. When far apart
they indicate flat terrain.
The zero contour is the shoreline of the ocean halfway between high tide and low tide (mean sea
level). All points 10 feet above sea level would lie on the 10-foot contour line and so on. In figure 4,
the contour interval, which is the difference in elevation between two adjacent contours, is 20
feet. A contour interval is chosen to fit the relief of the landscape and the scale of the map; to show
as much relief as possible without cluttering the map with lines bunched too closely together.
Contour Rules
Listed below are some rules summarizing the basic nature of contour lines which should be used
when constructing or interpreting a topographic map:
Figure 4. A
topographic map
showing a mountain
summit, a river
valley, ridges, and a
pass.
1. The spacing of contours reflects the gradient or slope: Contour lines that are far apart
indicate a gentle slope. Contours that are close together indicate a steep slope
2. Contour lines never cross.
3. All solid-line contours are multiples of the contour interval
4. Contour lines crossing stream valleys form a V-shape that points uphill.
5. Mountain summits have a circle.
6. Depression contours enclose areas and are marked by hachures on the inside.
7. Depression contours have the same elevation as the adjacent normal contour which
encloses the depression.
8. Hilltop elevations may be estimated as being greater than the highest contour shown but
less than the next contour (imaginary) above. Similarly, the bottoms of drainages will be
below the lowest contour shown in the immediate area, as will the bottoms of depressions.
9. All contours close a space that’s higher than them (unless hatchures).
Drawing Contour Lines
Interpolation is a way to find unknown values from known within their min and max values. On the
map below (Fig. 5), min and max values are 0 and 50 feet. Therefore, if we draw contour lines with
10-foot interval, they will consist of five contour lines 0, 10, 20, 30 and 40.
R. Davies Mapping Basics Laboratory
3
Figure 5. Contour
lines drawn with a 10
foot interval.
Map Scales
Maps are representations of vast areas reduced into a small space such as phone or piece of
paper. Maps are made to scale which represents the ratio of a distance on the map to the actual
distance on the ground. To interpret a map we must know how much the area has been reduced.
There are two types of scales. (1) Verbal or descriptive map scale indicate a ratio such as
1:24,000 scale which means that any one linear unit measured on the map is equal to 24,000 of
those units on the ground. The larger the number on the right, the greater the area on the map
(Fig. 6).
Figure 6. The first number (map distance) is always 1. The second number (ground distance) is
different for each scale; the larger this second number is, the smaller the scale of the map (source
USGS).
(2) A bar scale is a ruler for measuring map distances (Fig. 7). This scale will be valid if the map
on which it is printed is reduced or enlarged.
Figure 7. Three
equivalent bar
scales found on
USGS maps.
Exercises
R. Davies Mapping Basics Laboratory
4
Part 1. Mapping Basics — ENGAGE
Figure 8.
Question 1. In the Figure 8 above what does the top image represent?
Question 2. What does the bottom image represent?
Question 3. How are the two images related?
Question 4. How does the spacing of the lines on the lower map relate to the steepness of the
slope?
R. Davies Mapping Basics Laboratory
5
Watch this video on how to interpret contour lines:
https://www.youtube.com/watch?v=zqPMYGDxCr0&t=11s
[Skip This] Part II. Constructing Contour Lines and Topographic Profiles — EXPLORE
Maps allow for land features to be reduced to a scale that can be studied, and take a 3dimensional feature and turn it into a 2-dimensional one. In this activity you will make a contour
map and a topographic profile of a volcano.
Materials: Model of volcano, plastic tub and lid, transparency paper, marker pens, rulers, blue dye,
water, beakers, graph paper.
Step 1. Mark units of equal distance (1 inch) on the
side of the tub and place the volcano model in the
tub. Tape the transparent film onto the lid of the
plastic tub.
Step 2. Fill the tub to reach the level of one unit of
water. Look straight down and trace the line at the
boundary between the water and the volcano on the
transparency.
Step 3. Fill the tub to reach the level of one unit of
water. One the transparency trace the line at the
boundary between the water and the volcano. Repeat
until the basin is nearly full (about 6-7 units of water).
Step 4. EXPLAIN Using graph paper at the back of the lab packet (page 18), construct a
topographic profile of your contour map. View the diagram on page 5 and the following video
before you start: https://www.youtube.com/watch?v=rJru71-b61Y
Part III. Latitude and Longitude
Figure 9. Lines of latitude and longitude on a world map. The prime meridian runs through
Greenwich, England.
R. Davies Mapping Basics Laboratory
6
Question 1. What direction do latitude lines go?
a. North-South
b. West –East
Question 2. What direction do longitude lines go?
c. North-South
d. West –East
Question 3. Why do you think lines of latitude and longitude might have been drawn on the map?
Question 4. On the world map (Figure 9), approximate the location of New York City and mark it
with a dot and read from the map the approximate latitude and longitude at this location.
Latitude:_____________________, Longitude:___________________________
Question 5. What do you do if your location is not on a line but in between lines?
Question 6. On the world map, mark the these locations with an X on the world map: (1) 30˚S and
150˚E and (2) 30˚N and 150˚ E.
Question 7. The map of the United States of America (Fig. 10) shows lines of latitude (horizontal
lines across) and longitude (vertical lines up and down). Mark the location 28 degrees N, 105
degrees W with an X. What country is this location? __________________________
Question 8. Mark the location 35 degrees N latitude, 75 degrees W longitude with a Y. Is this in
the Atlantic or Pacific Ocean? __________________________
Question 9. On the map label 43 degrees N, 75 degrees W with a Z. What state is part of this
location? __________________________
Question 10. Use your internet browser and google maps to locate the latitude and longitude of
Queensborough Community College https://www.google.com/maps
_____________________________________________
R. Davies Mapping Basics Laboratory
7
Figure 10. Lines of latitude and longitude on map of the United States.
Part IV. Contour Maps
Notice in Figure 12 that a 500-foot contour line has been drawn through all the points that have an
elevation of 500 feet above mean sea level. This is connecting points with the same elevation. On
Figure 12 we see that minimum value is 482 and maximum value is 515. Therefore we can
interpolate between these values.
Question 1. Practice and finish contouring both maps using a contour interval of 10 feet, i.e. make
contour lines with values 490, 500, 510.
Figure 12.
Question 2. On Figure 13, create contour lines from elevation points using a10-foot interval
Before you start, answer these useful questions:
a. What is minimum elevation?
________
b. What is maximum elevation?
________
c. How many 10-foot contour lines can you make?
___________
R. Davies Mapping Basics Laboratory
8
Figure 13.
Question 3. The map shown in Figure 14 shows spot elevations and drainage lines. Draw
contours with a 20 feet contour interval that to reveal the topography.
Figure 14.
R. Davies Mapping Basics Laboratory
9
Part IV. Topographic Maps — ELABORATE
Figure 15. Contour maps (left) and topographic profiles (right).
Question 1. Match the contour map (left) to the correct topographic profile (right) from Figure 15.
Question 2. Using the elevations and streams given in Figure 16 below, construct a topographic
map with a contour interval of 20 feet along the line labeled A-B.
Question 3. Indicate with arrows on the map in which direction the streams flow.
Question 4. What is the maximum elevation of the area? ________________
Question 5. If standing at point a could one see point b? ________________
R. Davies Mapping Basics Laboratory
10
SKIP: Figure 16.
Map Scales:
R. Davies Mapping Basics Laboratory
11
Question 6. How many miles correspond to one inch at map scale 1: 94,000,000?
Step 1: Think about your scale as: 1 inch = 94,000,000 inches
Step 2: 1 inch = 1.58 x 10-5 miles.
Step 3: Convert 94,000,000 inches into miles: 94,000,000 in * 1.58 x 10-5 = 1,485
Step 4: Write down the answer: 1 inch = __________ miles
Question 7. On a scale 1 centimeter = 10 kilometers (km) what distance on a map represent
20,000 meters (m) of terrain?
Step 1: Convert 10 km into m. 10 km = 10,000 m. Thus 1 cm on the map = 10,000 m of terrain.
Step 2: Using ratio 1 cm = 10,000 m we can calculate that 20,000 m will be represented by:
20,000 / 10,000 = ____________ cm
Base your answers to the following questions on the topographic map in Figure 17 below. Points A,
B, C, D, and X represent locations on the map. Elevations are measured in feet.
Figure 17.
Question 8. What is the elevation of each of the following points?
A. _____________ B. _____________ C. _____________ D. _____________
Question 9. What is the contour interval of this map? _________________________ feet
Question 10. Calculate the Gradient between C and D. (note. Gradient =
elevation/distance)________________ _feet/miles
Question 11. In what direction does Fish Creek Flow? _______________________
Question 12. What is the elevation of Point X? ____________________
Question 13. Which side of Rock Mountain has the steepest slope? (compass direction)
____________________
R. Davies Mapping Basics Laboratory
12
Question 14. Which side of Rock Mountain has the gentlest slope? (compass direction)
__________________
Question 15. Which cross section below (Fig. 18) best represents the profile along straight line AB
in Figure 17. _____________
Figure 18
Part V. Questions — EVALUATE
Question 1. In the three maps of Mt Rainer (Fig. 7), which map has the smallest scale indicating
the greatest distance per unit?
a. 1: 24,000 scale
b. 1: 100,000 scale
c. 1:250,000 scale
Question 2. A scale of 1:1000 on a topographic map indicates that
a. 1 unit on the map is greater than 1 unit in the real world
b. the map represents the entire Earth
c. 1000 units on the map equals 1 unit in the real world
d. 1 unit on the map equals 1000 units in the real world
Question 3. On a topographic map, the closer the contour lines the
a. lower the elevation
b. flatter the land surface
c. gentler the slope
d. steeper the slope
Question 4. If the contour interval on a topographic map is 10 feet, and one contour line is labeled
50 feet
a. the adjacent contour line would represent 150 feet in elevation
b. the adjacent contour line would represent 10 feet in elevation
c. the adjacent contour line would represent 60 feet in elevation
d. the adjacent contour line would represent 20 feet in elevation
R. Davies Mapping Basics Laboratory
13
Question 5. When you observe contour lines with hachures on a topographic map, this indicates
that
a. you have crossed a stream
b. the elevation of this area is increasing
c. a depression is located in this part of the map
d. you are entering a mountainous area
Question 6. How are streams indicated on a topographic map?
a. by contour lines that form v's which point downstream
b. by contour lines that form u's which point upstream
c. by contour lines that form u's which point upstream
d. by contour lines that form v's which point upstream
Question 7. On a topographic map, how would you determine if a feature was a hill or a valley?
a. a hill would have contour lines that are close together and form ovals or circles
b. a valley would have close together contour lines with hachures
c. a valley would have contour lines that are close together and form ovals or circles
d. a hill would have V-shaped contour lines which are close together
Question 8. How would a sink hole be identified on a topographic map?
a. by contour lines with hachures
b. by contour lines which show higher elevation at the center of the formation
c. by contour lines with v's pointing toward the center of the formation
d. by contour lines that are very close together and the highest elevation at the center
Question 9. The distance between contour lines on a topographic map is called the
a. contour index
b. contour interval
c. elevation
d. gradient
Question 10. A set of circles inside circles on a topographic map indicate a
a. Stream
b. Hill
c. Valley
d. Depression
Question 11. Calculate the gradient if the change in elevation is equal to 100 feet and the distance
is equal to 50 miles. (note. Gradient = elevation/distance)
a. feet/miles
b. 20.0 feet/miles
c. 2.0 feet/miles
d. 0.5 feet/miles
R. Davies Mapping Basics Laboratory
14
Appendix 1
Select two points (A – A`) and draw a line of topographic profile
Place the edge of the paper strip along profile and mark contours
Place the edge of the paper strip along graph paper boundary, make
vertical elevation scale, mark elevation values as dots and connect
R. Davies Mapping Basics Laboratory
15
R. Davies Mapping Basics Laboratory
16
Purchase answer to see full
attachment