Map Reading and Land Navigation Flashcards
What is longitude?
Longitude lines run north to south (top to bottom) and are at right angles to latitude lines. They are also called meridians.
What map scale are soldiers most likely to encounter?
1:75,000 (1 inch = 75,000 meters)
Where are the instructions for reading the map to be found?
The map reading instructions can be found in the marginal information and may include items such as scales, the sheet name and number, a declination diagram, an elevation guide, and more.
What does red on a map mean?
Red indicates cultural features such as populated areas, main roads, and boundaries on old maps.
What is latitude?
Latitude lines run east to west (left to right) and are at right angles to longitude lines. They indicate the distance of a point north or south of the equator.
What does green on a map mean?
Green indicates vegetation with military significance such as woods, orchards, and vineyards.
How is a ridge designated on a map?
A ridge is a series of connected hills, with multiple smaller circles in a line surrounded by contour lines.
What is resection?
Resection is the process of locating one’s position on a map by determining the grid azimuth to at least two (preferably three) well-defined locations that can be pinpointed on the map.
What are the three parts of a lensatic compass?
- The cover: protects the floating dial and has a sighting wire and two luminous sighting dots
- The base: contains the floating dial, two scales, a glass top with fixed black index lines, a bezel ring, and a thumb loop
- The lens: used to read the dial and includes the rear sight slot
What are the two methods for holding/using a compass?
- The center hold technique: Hold the cover and base parallel to the ground with the lens angled towards the user; the non-dominant thumb sits below the bezel ring
- The compass-to-check technique: Hold the base parallel to the ground, with the lens and cover angled to use both and see the dial; the compass is held against the cheek in line with the nose
What does blue on a map mean?
Blue indicates water features such as lakes, swamps, rivers, and drainage.
What is declination?
Declination is the angular difference between any two norths and is also known as the grid-magnetic (G-M) angle value. A soldier is typically interested in declination of grid and magnetic norths.
What is intersection?
Intersection is a the process of locating 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 does black on a map mean?
Black indicates manmade features such as buildings and roads.
What does red-brown on a map mean?
Red-brown indicates cultural features, all relief features, and elevation such as contour lines on red-light readable maps.
What is an azimuth?
An azimuth is a horizontal angle measured clockwise from a north base line.
How is a draw designated on a map?
A draw is a part of the mountain that draws up and into the mountain, with the contour lines sharply drawn in between contour lines indicating peaks.
What is a back azimuth?
A back azimuth is an about face from the azimuth. To calculate the back azimuth:
If the azimuth is less than 180, add 180.
If the azimuth is greater than 180, subtract 180.
If the azimuth is 180, the back azimuth is 0.
What is a map?
A map is a graphic representation of a portion of the earth’s surface drawn to scale, as seen from above.
How is a depression designated on a map?
A depression is a complete circle contour line with no further contour lines within it, but with interior tick marks to indicate a steep decline.
What are the three types of north?
- True north: a line from any point on the earth’s surface to the North Pole; indicated by a vertical line with a star on top
- Magnetic north: the direction to the North Magnetic Pole, as indicated by the north-seeking needle of a magnetic instrument; indicated by a diagonal line with N on top
- Grid north: the North established by using the vertical lines on the map; indicated by a vertical line with GN on either side of the line at the top
What is a magnetic azimuth?
A magnetic azimuth is an azimuth determined by using a magnetic instrument such as lensatic and MZ compasses.
What is a grid azimuth?
A grid azimuth is the measured azimuth as drawn on a map connecting two points on the map with a straight line.
How is a spur designated on a map?
A spur is a part of the mountain that sticks down and out of the mountain, with the contour lines sharply drawn away from contour lines indicating peaks.
