Flashcards in Land Nav- Map reading Deck (63):
What publication covers MAP READING and Land Navigation?
What is the definition of a map?
A map is a graphic representation of a portion of the earth's surface drawn to scale as seen from above.
What does a map provide?
Information on the existence, the location of, and the 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.
Who is responsible for securing maps for the unit.
The G2/S2 section.
How many different sizes of maps are there?
What are the different map sizes?
1) Small; 1:1,000,000
2) Medium; Larger than 1:1,000,000 but smaller than 1:75,000
3) Large; 1:75,000 and Larger
Where would you find useful information that will help you read a map.
In the Marginal Information.
Where will you find information about the symbols found on a map?
In the Marginal Information
What should a soldier do prior to using a particular map?
Read the instructions; orient
Where will you find the sheet number of a map
In bold print in BOTH 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.
Where will you find the series name of a map?
In the SAME bold print as the sheet number, upper left corner of the margin.
Where will you find the scale of a map, and what does it represent?
In the upper left margin, after series name, and in the center of the lower margin, and it a representative fraction that gives the ratio of a map distance to the corresponding distance on the earths surface.
Where will you find the series number of a map?
In both the upper right margin, and the lower left margin
Where will you find edition number of a map?
In bold print in the upper right area of the top margin and the lower left area of the bottom margin.
Where will you find the index to boundaries of a map, and what does it represent?
The index to boundaries diagram (which is a miniature of the map) appears in the lower or right margin of all sheets, shows the boundaries that occur within the map area such as county lines and state boudaries.
What is the adjoining sheets diagram of a map, and what does it represent?
It consists of as many rectangles representing adjoining sheets as are necessary to surround the rectangle that represents the sheet under consideration.
Where will you find the elevation guide of a map, and what does it represent?
In the lower right margin, and it is a miniature characterization of the terrain shown.
where will you find the declination diagram of a map, and what does it represent?
In the lower margin of large scale maps and indicates the angular relationships of true north, grid north and magnetic north.
Where will you find the bar scales of a map and what does it represent?
In the center of the lower margin, and 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.
Where will you find the grid reference box of a map, and what does it represent?
Center of the lower margin, contains instructions for composing a grid reference.
Where will you find the unit imprint and symbol of a map, and what does it represent?
Left side lower margin. It identifies the agency that prepared and printed the map with its respective symbol.
Where will you find the legend of a map, and what does it represent?
Lower left margin. It illustrates and identifies the topographic symbols used to depict some of the more prominent features on a map.
What are topographic symbols used to represent?
The natural and man made features of the earth, military personnel requires some method for showing identity, size, location, or movement of soldiers, military activity and installations.
What are the colors of a military map?What does each color represent?
Black-Man made features
Red/Brown- Contour lines (red light readable)
Blue- Water Features
Brown- all relief features, man made (cultivated)
Red- Cultural features, populated areas, main roads, boundaries.
How many colors on a military map?
What direction do lines of latitude run?
East to West
What are the rings around the earth parallel to the equator called?
How do you read a map with a protractor to determine a gird?
Right and Up.
What is the universal transverse mercator grid? (UTM)
Designed to cover the part of the world between latitude 84 N and latitude 80 S, and as it's name implies, is imposed on the transverse mercator projection.
What does UTM stand for?
Universal Transverse Mercator grid
How are distances always measured?
Right and up
How many grid zones is the world divided into?
60 grid zones.
How close will a six digit grid be to a location>
within 100 meters.
How close will an 8 digit grid be within a location
within 10 meters
How close will a four digit grid be to a location?
Within 1,000 meters
What does the graphic bar scale do?
A ruler printed on a map, used to convert distances on the map to actual ground distances.
how many units of measure are used for direction?
What are the 3 units of measurement used for direction?
1) degree ( most common)
2) mil ( used mainly in artillery, tank, and mortar gunnery)
3) grad ( metric unit of measure, found on some foreign maps.)
How many baselines are on a military map?
What are the 3 baselines (Versions of North) on a military map?
2) Magnetic North
3) Grid North
What are the most common "Norths" used on a military map?
What is true north?
A line from any point on the earth's surface to the North pole. (longitude lines) True north is usually represented by a star.
What is magnetic north?
The direction to the north magnetic pole as indicated by the north seeking needle of a magnetic compass. Magnetic north is usually symbolized by a line ending with half of an arrow head.
What is grid north.
The north which is established by using vertical grid lines on a map. Grid north may be symbolized by the letters "GN" or the letter "Y"
What is an azimuth?
Horizontal angle measured clockwise from a north baseline. the azimuth is the most common military method to express direction.
How do we obtain a back azimuth?
Add 180 degrees ( if azimuth is 180 or less)SUBTRACT 180 degrees ( if azimuth is 180 or more)
What is a magnetic azimuth?
it is determined by using magnetic instruments such as lensatic and M2 compasses.
What is a grid azimuth?
A protractor is used to measure the angle between grid north and the drawn line. This measure azimuth is the grid azimuth.
What are the four different protactors.
1) Full Circle
2) Half Circle
What does the declination diagram display?
The angular relationship represented by prongs between magnetic, grid, and true north.
What is the grid magnetic angle?
The GM angle value is the angular size that exists between Grid and Magnetic north.
What is the grid convergence?
An ark indicated by a dashed line connecting the prongs for true north and grid north. The value of the angle for the center of the sheet is given to the nearest full minute with it's equivalent to the nearest mil.
What is the conversion between magnetic and grid north?
There is an angular difference between grid and magnetic. Since location of mag north doesn't correspond exactly with the grid north lines, a conversion from magnetic to grid or vice versa is needed.
What is the intersection?
The location of an unknown point by successively occupying at least two ( preferably three) known positions on the ground and then map sighting on the unknown location.
What are the two methods for intersection?
1) the map and compass method
2) the straight edge method
When is the straight edge method used?
When a compass is not available.
What is resection?
The method of locating one's position on a map by determining the grid azimuth to at least two well defined locations that can be pinpointed on a map.
When using resection, what method can give you greater accuracy?
To use THREE or MORE well defined locations.
What is modified resection?
The method of locating one's position on the map when the person is located on a linear feature on the ground such as a road, canal, or stream.
What are the ways to determine your location on a map?
What is the most common and simplest instrument for measuring direction?
The Lensatic Compass
When is the compass to cheek technique normally used?