Cartographic and OS map skills (OCR J383 Paper 3)
Paper 3 of OCR J383 tests geographical skills across all three papers, but the dedicated skills paper includes OS map, graphical and numerical questions. Map skills are often underrevised — they offer relatively easy marks if you know the conventions.
OS map conventions
Scale
| Scale | What 1 cm represents | Use |
|---|---|---|
| 1:50,000 (Landranger) | 500 m | General overview; transport; large features |
| 1:25,000 (Explorer) | 250 m | Detail; fieldwork; footpaths |
Calculating distance: measure in cm on map, multiply by the scale denominator, convert units. Example: 4 cm on a 1:25,000 map = 4 × 25,000 cm = 100,000 cm = 1,000 m = 1 km.
Grid references
- 4-figure (grid square): 2 eastings + 2 northings. Identifies a 1 km² square.
- 6-figure (point): 3 eastings + 3 northings. Identifies a 100 m² point.
Remember: "Along the corridor, then up the stairs." Eastings (horizontal/across) FIRST; Northings (vertical/up) SECOND.
For 6-figure: estimate tenths within the square. Grid line 45 with the feature ⅗ of the way across = 453. Grid line 72 with feature ¾ up = 727. Reference: 453 727.
Contour lines
- Contour lines join points of equal height above sea level.
- On 1:25,000 OS maps, contour interval = 10 metres.
- Close contour lines = steep slope.
- Wide apart contour lines = gentle slope.
- Concentric circles (contours getting smaller) = a hill.
- V-shaped contours pointing uphill = a valley (the V points toward higher ground).
Common OS map symbols
- Blue line = river; Blue dots = marsh.
- Red/A road = classified road; B road = B road.
- Church with tower = +; without tower = †; without spire = ‡.
- Triangulation pillar (trig point) = △ with a dot.
- PH = public house; PC = phone; PO = post office; MS = milestone.
Identifying geographical features from contours
- Spur: ridge extending from a hill; contours bulge downhill (V-shape pointing downhill).
- Valley/valley bottom: V-shaped contours pointing uphill.
- Cliff: contours very close together on a coastal or valley edge.
- Plateau: wide area of equally-spaced/no contours at high altitude.
- Col/saddle: low point between two hills; hourglass shape on the map.
Compass directions and bearings
- 8-point compass: N, NE, E, SE, S, SW, W, NW.
- 3-figure bearing: measured clockwise from north (000° to 360°). North = 000°; East = 090°; South = 180°; West = 270°.
Common OCR exam mistakes
- Reversing grid references — eastings first (left to right), northings second (bottom to top).
- Forgetting that V-shaped contours in a valley point uphill (toward higher ground).
- Not converting units when calculating distances — always check whether your answer should be in km, m or cm.
- Misreading compass bearings — use a protractor if provided; remember to measure clockwise from north.
AI-generated · claude-opus-4-7 · v3-ocr-geography