Reading Maps & Globes

Reading maps is not unusually difficult because there are some rules
that are generally followed when creating and reading maps:
North, South, East, and West are the four main "cardinal" directions.
On a map, North is at the top, South at the bottom, West to the left, and East to the right.
Every map has a Map Scale which relates distance on the map to the world.
For example, one inch equals one mile.
Using the scale of a map, you can tell the actual distance between
two points for real. Maps use map symbols to represent real-world things,
such as buildings, trails, roads, bridges, and rivers. Maps use
colors to share more information. Blue often means water, green means forest, and white means bare land.
A map has a Legend which lists the symbols it uses and what they mean.
A grid of imaginary lines wrap around and over the earth. These lines are called Latitude
and Longitude and can identify the exact location of any point on earth.
Keeping those things in mind, you can read pretty much
any map and especially learn how to read a topographic or TOPO map for navigation
in the back country.

This simple road direction map contains a lot of information:
North is marked in the upper-left corner so you know which way this map relates to the world.
The Scale is marked. One inch equals 5 miles, so you can tell it is about 15 miles from Seattle to
Woodinville. Main roads are included so you can find the best route direction between two locations.
Roads are labeled so you know what to look for when navigating.
Bodies of water are colored blue. So, you can see even a simple road
map is packed with good direction and navigation information. The maps we
use for hiking are even more packed with details.





The TOPO map on the bottom represents the land
in the Google aerial photo above it. Notice the buildings
and roads on the map can be seen in the photo. 




Latitude
If you could stand at the center of the earth, you could
look out at the surface of the earth all around you. With the North Pole
directly above your head, if you looked straight ahead in any direction, you would be
looking at the equator. This imaginary line is exactly halfway between
the north and south poles and has a latitude of 0 degrees because you are looking straight ahead at
an angle of 0 degrees. If you look up a bit, maybe at an angle of 30 degrees, you have
increased your latitude to 30 degrees North. Continue to look up higher and higher
until you are looking straight above you at the north pole
which is 90 degrees North.




Longitude
Longitude is the angle east or west around the earth, just like latitude
is the angle north and south. Longitude lines
are called meridians.
For latitudes, we have two fixed points - the north and south poles -
that we use as end points. But, going around the earth, there is no start
or stop, it just keeps spinning and spinning. So, an arbitrary spot was chosen to be
the Start point for longitudes. This spot is the Royal Observatory in Greenwich, UK. The longitude
line that runs through it is called the Prime Meridian and is longitude
zero degrees. ( it’s also the place where Greenwich mean time starts.)
Notice that longitude lines are not parallel. The closer to the poles you get,
the shorter the distance between meridians until they all actually converge at the poles.




Map Scale
Any scale can be used for a map, but a few common scales
have been settled on for use by most organizations:
1:24,000 - primary scaled used by USGS for mapping the United States in topographic form.
1 inch on the map equals 24000 inches in the real world,
which is the same as 2,000 feet. This scale is used on the over
54,000 quadrangle maps covering the entire country. They are also called 7.5 minute
quadrangles because the area covered by one map is 7.5 minutes of latitude high
by 7.5 minutes of longitude wide on paper that is about 29 inches high and 22 inches wide.
1:63,360 - 1 inch equals 1 mile
1:50,000
1:250,000
1:1,000,000







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