DEFINITION AND PURPOSE - ANSWER--A map is defined as a graphic
representation of a portion of the Earth's surface drawn to scale, as seen
from above. It uses colors, symbols, and labels to represent features found
on the ground.
The ideal representation would be realized if every feature of the area being
mapped could be shown in true shape.
The purpose of a map is to provide information on the existence, location,
and distance between ground features, such as populated places and
routes of travel and communication. It also indicates variations in terrain,
heights of natural features, and the extent of vegetation cover.
All operations conducted require maps; however, the finest maps available
are worthless unless the map user knows how to read them.
MARGINAL INFORMATION - ANSWER--A map is considered equipment. To
use it properly, you should read the instructions.
These instructions on the outer edges of the map are called marginal
information.
All maps are different so examine the marginal information on each map
carefully.
MARGINAL INFORMATION TOP MARGIN - ANSWER--The top margin of
the map helps you to identify the specific area covered as well as the age
and scale of the map
Sheet Name - ANSWER--The sheet name is found in bold print at the
center of the top and in the lower left area of the map margin. A map is
generally named for the settlement contained within the area covered by
the sheet or for the largest natural feature located within the area at the
time the map was drawn.
Sheet Number - ANSWER--The sheet number is bolded in the upper right
and lower left areas of the margin and in the center box of the adjoining
sheets diagram, which is found in the lower right margin.
It is used as a reference number to link specific maps to overlays,
operations orders, and plans.
For maps at 1:100,000 scale and larger, sheet numbers are based on an
arbitrary system that makes possible the ready orientation of maps at scales
of 1:100,000, 1:50,000, and 1:25,000
Series Name - ANSWER--The map series name is found in the same bold
print as the sheet number in the upper left corner of the margin.
The name given to the series is generally that of a major political
subdivision, such as a state within the United States or a European nation.
A map series usually includes a group of similar maps at the same scale and
on the same sheet lines or format designed to cover a particular
geographic area.
It may also be a group of maps that serve a common purpose, such as the
military city maps.
Scale - ANSWER--The scale is found both in the upper left margin after the
series name and in the center of the lower margin.
The scale note is a representative fraction that gives the ratio of a map
distance to the corresponding distance on the Earth's surface.
For example, the scale note 1:50,000 indicates that one unit of measure on
the map equals 50,000 units of the same measure on the ground.
Series Number - ANSWER--The series number is found in both the upper
right margin and the lower left margin. It is a sequence reference expressed
either as a four-digit numeral (1125) or as a letter, followed by a three- or
four-digit numeral (M661; T7110)
Edition Number - ANSWER--The edition number is found bolded in the
upper right area of the top margin and the lower left area of the bottom
margin.
Editions are numbered consecutively; therefore, if you have more than one
edition, the highest numbered sheet is the most recent.
This date is important when determining how accurately the map data
might be expected to match what you will encounter on the ground
MARGINAL INFORMATION: BOTTOM MARGIN - ANSWER--This portion of
the map includes information that helps to interpret the map. It provides
correlation between actual terrain and man-made features and the map's
topographic symbols. Some information found in the bottom margin is
repeated from the top margin.
Boundaries - ANSWER--The index to boundaries diagram appears in the
lower or right margin of all sheets.
This diagram, which is a miniature of the map, shows the boundaries that
occur within the map area, such as county lines and state boundaries.
Adjoining Sheets - ANSWER--Maps at all standard scales contain a diagram
that illustrates the adjoining sheets. The diagram usually contains nine
rectangles, but the number may vary depending on the locations of the
adjoining sheets. All represented sheets are identified by their sheet
numbers. Sheets of an adjoining series of the same scale, whether
published or planned, are represented by dashed lines. The series number
of the adjoining series is indicated along the appropriate side of the
division line between the series.
Elevation Guide - ANSWER--This is normally found in the lower right
margin.
It is a miniature characterization of the terrain shown.
The terrain is represented by bands of elevation, spot elevations, and major
drainage features.
The elevation guide provides the map reader with a means of rapid
recognition of major landforms.
Declination Diagram - ANSWER--This is located in the lower margin of
large-scale maps and indicates the angular relationships of true north, grid
north, and magnetic north.
On maps at 1:250,000 scale, this information is expressed as a note in the
lower margin.
In new maps, there is a note indicating the conversion of azimuths from
grid to magnetic and from magnetic to grid next to the declination
diagram.
Bar Scale - ANSWER--These are located in the center of the lower margin.
They are rulers used to convert map distance to ground distance.
Maps have three or more bar scales, each in a different unit of measure.
Care should be exercised when using the scales, especially in the selection
of the unit of measure that is needed.
Contour Interval Note - ANSWER--This note is found in the center of the
lower margin normally below the bar scales.
It states the vertical distance between adjacent contour lines of the map.
When supplementary contours are used, the interval is indicated.
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