PS Map Projections & Cartography Flashcards

What is the angular difference between grid north and true (geodetic) north called?

Answer: Meridian convergence (mapping angle)

Meridian convergence (also called the mapping angle or gamma) is the angular difference between true north and grid north at a given point.

Which contour line is drawn heavier (darker) to aid map reading and appears at every fifth contour interval?

Answer: Index contour

Index contours are drawn in a heavier line weight at every fifth contour interval and are typically labeled with their elevation.

What symbol on a topographic map indicates a closed depression (a low point surrounded by higher terrain)?

Answer: Hachured contour lines

Depression contours are drawn with hachure marks (short tick marks) pointing inward toward the low point to distinguish them from normal contours.

What is the Universal Transverse Mercator (UTM) system's standard zone width in degrees of longitude?

Answer: 6 degrees

The UTM system divides the world into 60 zones, each spanning 6 degrees of longitude, from 80°S to 84°N latitude.

What is the false easting assigned to the central meridian in each UTM zone to avoid negative easting values?

Answer: 500,000 meters

UTM assigns a false easting of 500,000 m to the central meridian of each zone so that all points within the zone have positive easting values.

What is the map scale classification for a map with a representative fraction of 1:1,200?

Answer: Large scale

Maps with representative fractions of 1:600 to 1:12,000 are considered large-scale maps, with 1:1,200 being among the most detailed used in surveying.