Connecticut Water Trails Association
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Connecticut Water Trails Association |
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Connecticut Water Trails Program Topographic Maps 101 The Basics The Five D's - Description
The description tells you about the area the map covers.
First there is the map title. This is found at the top and bottom margins of the topographic map. It is easy to find and printed in block lettering. This map title gives you the name of the map and the area or quadrangle it covers. There is also a map number.
You can also determine the location of the area on the globe from the information given. Each map has small numbers and lines along the top, bottom, and the side. These lines correspond to the lines on the globe.
The first line connects the top of the map to the bottom of the map. This line is called the meridian and is the true north-south line. The numbers found at the ends of these lines tell you the degree of longitude.
You can also draw a parallel line from side to side to connecting numbers
which will give you a true east-west line.
The numbers at the end of this line give you the degrees of
latitude.
The longitude translates into length while the latitude translates into width. The points you use to draw your meridian are called neat lines and appear all around the edge of the map at equidistant points.
Date Another important description found on maps is the date. This tells you the last time the map was updated. It also tells you when the map was first printed
Scale The next important piece of information on the
map is the scale. The scale helps
you to determine the relationship between the distance on the ground
as to the distance on the map.
Each topographic map has it's won specific scale.
What Is Scale?
Maps are made to scale. In each case, the scale represents
the ratio of a distance on the map to the actual distance on the
ground.
For example, if 2 cm on a map ...
Represents 1 km on the ground ...
The scale would be 2 cm = 1 km, or...
Here Are The Most Common Ones Used :
A. 1
: 25,000 - 1
Inch = 4 Miles B. 1
: 62,500 - 1
Inch = 1 Mile C. 1:
24,000
- 1 Inch = 2,000 Feet
Remember this scale when buying or ordering a
topographic map- the larger the fraction, the larger and clearer the
details on the topographic map. Also
the larger the fraction, the smaller the territory / area the map
covers.
1 Mile = 5280 Feet Or 1.609 Km 1 Nautical Mile = 1.15 Miles
Another important piece of
information which can be found on the map is the series. This helps
you to determine how a map is drawn.
Here Is How A Series Works: If the map is a 15" (minute ) series. Then this map covers a section of the earth’s surface 15" of longitude by 15" of latitude. Check the longitude and latitude marks on your map to confirm.
7 .5 " series. It takes four 7.5"
maps to equal a 15" map.
So In Summary: The
Information That You Find On A Map In The Margins Is As Follows:
1. Name Of The Map 2. Names Of Adjacent Maps 3. Location Of The Map On The Earth's
Surface A. Longitude Note
Meridians B. Latitude Note
Parallels 4. Date Of The Map 5. Map Scale
/ Series
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