MAPPING OUR WORLD
cartography = science of map making
cartographers = map makers
Reference Points:
1. North and South Geographic Poles
2. equator = imaginary line the circles earth
dividing it into the Northern and Southern
Hemispheres
latitude = angular distance north or south of equator
1. parallels = circles that run east and west around
the world parallel to the equator
2. lines never meet or cross
3. areas are labeled as either N or S of the equator
4. equator = 0o latitude
5. all values fall between 0o to 90o
a. North Pole = 90oN
b. South Pole = 90oS
6. measured in degrees (more precise to give degrees,
minutes, and seconds)
a. 1 degree of latitude = about 111 km or 69 miles
b. each degree has 60 equal parts = minutes
(symbol: ‘)
1 minute of latitude = 1.85 km
c. each minute has to equal parts = seconds
(symbol: “)
1 second of latitude = 0.031 km (31m)
longitude = angular distance east or west of the
prime meridian
1. meridian = half circle (semicircle) running from
pole to pole
2. prime meridian = reference point for longitude
a. represents 0o longitude
b. passes through Greenwich, England
3. all values fall between
0o to 180o
4. can be expressed in degrees, minutes, and
seconds
a. distance covered depends on where the degree
is measured
b. farthest apart at equator and closest at the
poles
c. lines are not parallel
5. International Date Line = longitude opposite the
prime meridian
a. represents 180o longitude
b. where east lines of longitude
meet west lines of longitude
great circle = any circle that divides the globe into
halves
1. formed by two meridians on opposite sides of the
globe
2. equator is the only line of latitude which forms a
great circle
3. can run in any direction around the globe
4. shortest distance between two points on a sphere
Time Zones:
1. sun basis for measuring time
[12 noon - sun highest point in sky]
2. standard time zones = noon is set as time when
sun is highest over center of each zone
a. 24 zones - each 15o degrees wide
b. 1 hour difference in each
3. at 12 midnight (AM) calendar advances to the
next day in each time zone
4. crossing from one time zone to another causes
local time changes by one hour
a. traveling east → add one hour for each time
zone
b. traveling west → subtract one hour
5. International Date Line = transition line for
calendar days
a. traveling east across line → subtract one day
(gain one day)
b. traveling west across line → add one day (lose
one day)
6. daylight savings time = plan where clocks are set
one hour ahead of standard time for a
certain number of months
- usually begins first Sunday in April; ends last
Sunday in October
Finding Direction:
1. magnetic compass = indicates direction due to
earth’s magnetic properties
2. geomagnetic poles = points on earth’s surface
just above the poles
- different from geographic poles
3. magnetic declination = angle between the
direction of geographic pole and direction in
which compass needle points
a. true north = direction of geographic North Pole
b. determined for points all over earth
c. by adjusting measurement of magnetic north
one can determine geographic north for any
place on earth
globe = spherical model of earth
1. locations of surface features and relative areas
and shapes represented accurately
2. used in studying larger surface features
map = flat representation of earth’s curved
surface
1. areas shown may be distorted in size, shape,
distance and direction
2. larger the surface area
being shown, greater
the distortion
map projection = flat map
that represents threedimensional curved
surface of globe
TYPES OF MAP PROJECTIONS
1. Mercator projection
a. distorts regions of land and sizes of areas near
poles
b. shapes of land and water bodies are correct
c. both latitude and longitude lines are parallel and
intersect at right angles
d. used for navigation of ships and planes
2. conic projections: produce by projecting points &
lines from globe on a cone
a. produces accurate maps of small areas
b. areas near contact are least distorted
c. polyconic projections = series of projections
used to map neighboring areas which are
fitted together to
make a continuous
map
d. includes road maps
and weather maps
3. Gnomonic projection: produced by projecting points
& lines from globe onto a piece of paper that
touches the globe at a single point
a. little distortion occurs at the point of contact
b. distort both direction and distance increase as
distance from point of contact increases
c. used by navigators in plotting
routes used in air
& sea travel
d. great circles will appear
as straight lines
4. Robinson projection:
a. has accurate continent shapes and land areas
b. lines of latitude parallel while longitude is
curved
c. less distortion near the poles
5. polar projections:
a. latitude lines appear as circles with smallest
near the center
b. circular rather than rectangular
c. land areas near poles show in true proportions
while those at equator are distorted
d. used for countries around the Arctic Ocean
topography = shape of Earth’s surface
topographic maps = show changes in elevation of
Earth’s surface
1. natural features = mountains, hills, plains, lakes,
and rivers
- also called landscape features
2. cultural features (constructed) = roads, cities, and
other structures built by people
3. provide more detailed
information about the
surface of an area
4. elevation = height/distance of a location above or
below sea level
a. measured from mean sea level = point midway
between highest and lowest tide levels of
the ocean
b. mean sea level elevation = 0
c. all others are measured distances above or below
mean sea level
5. contour line = connect points of equal elevation
a. connect all points on a map that have the same
elevation
b. shape of line reflects shape of the land
c. never cross
d. will either close or extend to the edge of the
map
6. contour interval = difference in elevation between
two side by side contour lines
a. determined by size of map and relief
b. relief = difference in elevation between the
highest and lowest points of area being
mapped
1) high - large interval (50 m) [steep land]
2) low - small interval (5 m)
INTERPRETING TOPOGRAPHIC MAPS
1. topographic sheets (quadrangles) = detailed
maps of all the United States created by USGS
(United States Geological Survey)
a. first quadrangles covered 15’ of latitude and
15’ of longitude
b. new series covers 7.5’ latitude and 7.5’
longitude; smaller area but greater detail
2. symbols = show certain features
a. different colors used for different types
b. include: constructed features = black; major
highways = red; bodies of water = blue;
forested areas = green; contour lines = brown
3. direction
a. follow line of latitude and longitude
b. all parallels and meridians shown are labeled in
degrees and minutes
4. distance
a. refer to map scale
b. most common = 1:24,000 (1 in. on map =
2,000 ft. on surface)
c. can use ruler to measure
distances on map and
covert the inches to
feet or miles
5. elevation
a. index contours = lines marked with elevation
1) also called a bench mark
2) usually every fifth line, printed bolder than
others
b. points between two contour lines has an
elevation somewhere between two lines
c. exact elevations are
marked by an
“ x ” and labeled
6. landforms
a. can determine shape
b. lines far apart indicate gradual change, land
relatively level
c. lines close together indicate a rapid change in
elevation or steep slope
d. lines almost touching indicate a very steep slope
or cliff
e. lines evenly spaced shows slope increases about
the same over distances
f. lines bend to form V-shape indicate a valley
1) points toward higher end of valley
2) points upstream if river or stream flows through
valley (direction from which the water flows)
3) river always flow from higher to lower elevations
a) steep course of river - lines close together
when cross
4) width of valley shown by width of V
g. closed loops indicate a hilltop or depression
1) depression contours = marked with short,
straight lines
a) drawn on inside of loop and point toward
center
b) hachures = short lines at right angle to
contour line
c) always point toward the lower elevation
(Ex: pg. 34 text)
7. profile = line that shows changes in elevation
across a section of a topographic map
8. average slope, or gradient, between any two points
can be determined from contour map
average slope = change in elevation
distance
Ex: A trail is 4 miles long based on the map scale.
It begins at the 1060 ft. contour and ends at the
960 ft. contour. Calculate the average slope.
avg. slope = 1060 ft.- 960 ft. = 100 ft. = 25 ft./mi.
4 mi
4 mi.
READING A MAP:
1. map legend = list of the symbols and their meaning
2. determine direction
a. usually drawn with north at top, east at right,
west at left, and south at bottom
b. parallels run from side to side
c. meridians run from top to bottom
3. map scale = relationship between distances on map
and actual distances on Earth’s surface
a. graphic scale = printed line divided into equal
parts and labeled
1) line represents a unit of measure
2) to find actual distance between two points on
earth
a) first measure the distance between the
points on the map
b) compare that measurement with the scale
b. fractional scale = ratio of represented distance
on map to actual distance on surface
*two numbers must be in the same unit
Ex: 1:5000000 [1 cm on map = 5 million cm
(50 km) on earth]
c. verbal scale = equates two different units
Ex: 1 cm (map) = 1 km (on Earth)
remote sensing = process of collecting data about
Earth from far above Earth’s surface
1. uses electromagnetic spectrum = arrangement of
electromagnetic (EM) radiation based on
wavelength
a. frequency = number of waves that pass a
particular point each second
b. wavelengths, speeds, and frequencies of EM
wave determine how energy is used by different
satellites to map Earth
2. Landsat satellite = receives reflected wavelengths
of energy emitted by Earth’s surface
a. Earth’s surface features radiate warmth at
slightly different frequencies
b. features will show up different colors in map
images
c. scan entire surface of planet in 16 days
d. show landforms in great
detail; also used to
study plate movement,
rivers, earthquakes,
and pollution
3. Topex/Poseidon satellite = uses radar to map ocean
floor features
a. emitter sends outgoing signal to ocean surface,
receiver times returning signal, distance to
surface is calculated using know speed of light
and return time
b. used to study tidal
changes and global
ocean currents
4. Global Positioning System (GPS) = radio-navigation
system of at least 24 satellites that allows users
to determine their exact position on Earth
a. user’s receiver calculates user’s location by
processing signals emitted by multiple satellites
b. can also relay information about elevation,
direction, and speed
c. frequently used for
navigation by airplanes &
ships; popular among
hikers and backpackers
d. also used to detect
earthquakes, create
maps, track wildlife
5. Sea Beam = technology similar to Topex/Poseidon
satellite
a. located on a ship rather than on a satellite
b. uses sonar (sound waves) to detect and measure
objects underwater
c. used by fishing fleets, deep-sea drilling
operations, scientists
Mid-Atlantic
ridge