Map Reading and Navigation Flashcards

What is a 'saddle' in topographic map reading?

Answer: A low point between two higher elevations

A saddle is a low area connecting two higher points, shown on a topographic map as an hourglass-shaped arrangement of contour lines.

On a nautical chart, a number printed in the water area typically indicates what?

Answer: The water depth at that location

Numbers printed in water areas on nautical charts represent the depth of the water at that point, usually in feet or fathoms.

What is 'dead reckoning' in navigation?

Answer: Estimating current position using a known past position, speed, and direction

Dead reckoning is the process of calculating one's current position based on a previously known position, then accounting for speed, heading, and elapsed time.

Which of the following best describes the 'relief' shown on a topographic map?

Answer: The three-dimensional shape and elevation of the land surface

Relief on a topographic map refers to the representation of the three-dimensional shape of the terrain, primarily shown through contour lines.

A map's 'projection' refers to which of the following?

Answer: The mathematical method used to represent the curved Earth on a flat surface

Map projection is the mathematical transformation used to represent the spherical Earth on a flat, two-dimensional map, which always introduces some distortion.

In the U.S. Public Land Survey System (PLSS), what is a 'township'?

Answer: A 6-mile-square unit of land

In the PLSS, a township is a 6-mile by 6-mile square of land containing 36 one-mile-square sections, used to systematically divide most of the United States.

What does an 'index contour' line look like on a topographic map compared to regular contour lines?

Answer: It is a heavier, darker line labeled with its elevation

Index contours are thicker, darker lines drawn at every fifth contour interval and are labeled with their elevation to make it easier to read the map.