Practical Work in Geography (Map, Graph and Data Interpretation)
This domain tests map reading, scale and direction, representation of relief, graph construction and interpretation of statistical maps.
Core rules and concepts
- Scale: statement (1 cm = 5 km), representative fraction (1:500,000) and graphical bar. Convert an RF to a statement by dividing the denominator by 100,000 to get kilometres per centimetre. Large-scale maps (1:50,000) show detail; small-scale maps (1:1,000,000) show broad patterns.
- Direction: true north from grid lines, magnetic north from a compass; magnetic declination is the angle between them. Bearings are measured clockwise from north.
- Relief: contour interval is the vertical gap between successive contours. Closely spaced contours mean a steep slope; a V pointing upstream marks a valley; concentric closed contours mark a hill or a depression, depending on hachures or spot heights.
- Graphs: line for trends over time, bar for comparison, pie for parts of a whole, scatter for correlation.
- Statistical maps: dot for distribution, choropleth for averages and densities, isopleth for continuous surfaces such as rainfall, flow lines for movement.
Worked example
A toposheet has RF 1:50,000. A straight road measures 7.2 cm on the map. Ground distance = 7.2 × 50,000 = 360,000 cm = 3.6 km. The conversion step (100,000 cm = 1 km) is where most errors occur.
Traps that cost marks
Shading a choropleth map with absolute totals rather than rates; reading contour interval as the height of the highest point; ignoring declination when converting magnetic to true bearings; mixing centimetres and kilometres; choosing a pie chart for data that change over time.