Map Reading
What this domain tests
Map reading tests scale, direction, grid references, bearings, symbols, contours and the interpretation of topographical sheets. Expect numerical scale conversions and relief descriptions.
Core rules
- Scale forms: statement (1 cm = 1 km), representative fraction (1:50,000) and linear scale. RF is unitless; the same RF means the same proportional reduction.
- Large scale shows small areas in detail (1:10,000); small scale shows large areas (1:1,000,000).
- Grid references give eastings before northings. Bearings are measured clockwise from north; a back bearing differs by 180°.
- Contours join equal elevations. Closely spaced contours mean steep slopes; widely spaced mean gentle slopes. V-shaped contours point upstream; spurs point downstream. Contour interval is the vertical difference between successive contours.
Worked example
On a 1:50,000 sheet, a straight road measures 6.4 cm. Ground distance = 6.4 × 50,000 cm = 320,000 cm = 3,200 m = 3.2 km. Reasoning: multiply the map length by the denominator, then convert centimetres to metres by dividing by 100 and to kilometres by dividing by 1,000.
Traps
Writing an RF with units (1:50,000 km is wrong); measuring along a winding road with a straight edge; reading grid references northings first; treating contour V's as downstream; forgetting magnetic declination when converting grid bearing to magnetic bearing.