114 LAND NAVIGATION FUNDAMENTALS Flashcards
explain sheet name and location
A map is named after the most prominent cultural or geographical feature.
Whenever possible, the name of the largest city on the map is used.
The sheet name is found in two places:
center of the upper margin.
either the right or left side of the lower margin
explain sheet number and location
Sheet Number
The sheet number is used as a reference number for that map sheet.
It is found in two places:
the upper right margin.
the lower left margin.
explain scale
The scale note is a representative fraction that gives you the ratio of a
distance on the map to the corresponding distance on the earth’s surface.
For example, the scale note 1:50,000 on many maps indicates that one inch
on the map equals 50,000 inches on the ground.
Maps with different scales will display different degrees of topographical
detail. For example, a map with a scale of 1:25,000 will give more detail than
a 1:50,000 map because one inch on the map represents only 25,000 inches
on the ground, rather than the 50,000 inches of the 1:50,000 map.
The scale is found both in the upper left margin after the series name and in
the center of the lower margin.
explain elevation guide and location
Elevation Guide
The elevation guide is a miniature characterization of the terrain shown.
The terrain is shown by bands of elevation, spot elevations, and major
drainage features.
The elevation guide helps you rapidly identify major land forms.
It is normally found in the lower right margin
explain Declination Diagram
Declination Diagram
This indicates the angular relationships of true north, grid north, and
magnetic north.
Recent edition maps have a note indicating how to convert azimuths from
grid to magnetic and from magnetic to grid next to the declination diagram.
The declination diagram is located in the lower margin.
explain bar scale and location
Bar Scales
Bar scales are used to convert map distance to ground distance.
Maps may have three or more bar scales, each in a different unit of measure.
Exercise care when using the scales, especially in the selection of the unit of
measure.
The bar scales are located in the center of the lower margin.
explain legend on map
Legend
The legend illustrates and identifies the topographic symbols used to depict
some of the more prominent features on the map, such as railroad tracks,
buildings, and swamps.
The symbols are not always the same on every map.
Always refer to the legend to avoid error when reading a map.
The legend is located in the lower left margin
explain grid lines
Grid Lines
Grid lines are a series of straight lines intersected at right angles and forming
a series of squares.
It furnishes the map reader with a system of squares similar to the block
system of most city streets.
Two digits are printed in large type at each end of the grid lines, and these
same two digits appear at intervals along the grid lines on the face of the
map. They are called principal digits.
They are of major importance to the map reader because they are the
numbers he will use most often for referencing points.
explain grid squares
These intersect at right angles of the horizontal and vertical grid lines.
The most common military map contains grid squares that measure 1000
meters by 1000 meters (not 1000 square meters as many people think).
Any point located within the grid square is considered to be part of the grid
square.
basic map reading rule
Basic Map Reading Rule
The designation of a point is based on the principle:
Read right then up.
Always read right on the vertical grid lines then up on the horizontal grid
lines.
grid square identification
Grid Square Identification
It is important that all of you understand how to apply the map reading rule to
identify a grid square and locate a point within a grid square.
The following grid coordinates will locate a point on a map within how many
meters: 4 digit
A four digit grid coordinate locates a point to within 1000 square meters, on the
map, which is called a grid square
The following grid coordinates will locate a point on a map within how many
meters: 6 digit
six digit grid coordinate will locate a point on a map within 100 meters.
The following grid coordinates will locate a point on a map within how many
meters: 8 digit
grid coordinate will locate a point on a map within 10 meters
explain true north
True North
The true north line is a line from any point on the earth’s surface to the North
Pole.
True north can be found at night by locating the North Star, which always
points towards true north.
Usually represented on the declination diagram by a line ending with a star.
Used almost exclusively when navigating without a compass.
explain magnetic north
Magnetic North
The earth has a magnetic field that is close to (but not exactly on) the North
Pole. The direction to this north magnetic pole is indicated by the northseeking arrow of your lensatic compass.
Magnetic north is usually symbolized on the declination diagram by a line
ending with a half arrowhead.
Anytime you use the compass to plan or follow an azimuth in the field, you
must work with azimuths measured from magnetic north.
explain Grid north
Grid North
This base line is established by using the vertical grid lines on the map.
Grid north may be symbolized on the declination diagram by the letters GN.
Anytime you use a protractor in conjunction with a vertical grid line to
determine or plot an azimuth on a map, you must work with an azimuth
measured from grid north.
explain hill
A hill is an area of high ground.
From a hilltop, the ground slopes down in all directions.
A hill is shown on a map by contour lines forming concentric circles.
The inside of the smallest closed circle is the hilltop.
explain ridge
A ridge is a series of hills that are connected to each other near the top.
A ridge line may extend for many miles.
It may be winding or quite straight.
It may have a reasonably uniform elevation along its top or it may vary
greatly in elevation
explain a saddle
Saddle
This is a dip or low point between two areas of higher ground.
A saddle is not necessarily the lower ground between two hilltops; it may be
simply a dip or break along a level ridge crest.
If you are in a saddle, there is high ground in two opposite directions and low
ground in the other two directions.
A saddle is normally represented as an hourglass or by figure-eight shaped
contour lines
explain finger/spur
A finger is a short, continuous sloping line of higher ground, normally jutting
out from the side of a ridge or hill.
A finger is often formed by two roughly parallel draws.
The ground slopes down in three directions and up in one.
Contour lines on a map depict a finger with the U or V pointing away from
high ground.
explain a draw
A draw is a short, continuous sloping line of low ground, normally cut into the
side of a ridge or hill.
Often, there is a small stream running down the draw.
In a draw, there is essentially no level ground. Therefore, little or no
maneuver room exists within its confines.
If you are standing in the middle of a draw, the ground slopes upward in
three directions and downward in the other direction.
Contour lines on a map depict a draw with the U or V pointing toward high
ground
explain a depression
Depression
This is a low point in the ground or a sinkhole.
It is an area of low ground surrounded by higher ground in all directions, or
simply a hole in the ground.
Usually only depressions that are equal to or greater than the contour interval
will be shown.
On maps, depressions are represented by closed contour lines that have tick
marks pointing toward low ground
no not your mental state
explain cover of compass
This protects the floating dial and the glass encasement.
It contains the sighting wire and two luminous sighting dots for night
navigation.
