12 Ordnance Survey Maps 98 41 Sub-zones R and S 40 Lake R 98 40 39 Golden S 01 38 39 40 99 2 00 01 02 03 41 EXAM TIP
If there are two or more sub- zone letters on the map, then the boundary separating the two letters is the vertical or horizontal line that runs from 00 to 00. Draw a line from 00 to 00 to highlight the difference in sub-zones for grid referencing.
38 98 99 2 00 EASTINGS Six-figure grid reference
A six-figure grid reference is used to give a more exact location (Fig. 12.4). They are calculated in the following way.
1. Record the sub-zone letter and the four-figure grid reference, as shown previously.
2. Using a ruler, divide the horizontal line at the bottom of the grid square and the vertical line to the left of the grid square into 10 equal parts. On a 1:50,000 scale map, each space will be 2 mm.
3. Using a ruler and pencil, link the feature being recorded down to the horizontal line at the bottom of the grid square and left to the vertical line to the left of the grid square.
4. The third digit of the easting is the number of tenth parts across the horizontal line the feature is located.
5. The third digit of the northing is the number of tenth parts up the vertical line the feature is located.
77 17 78 79 80 81 82 83 17
SKILLS ACTIVITY
16 6 16
What is the six-figure grid reference for the nature reserve?
15 7 15 01 02 03 38
Fig.12.3 Sub-zones, eastings and northings; four-figure grid references: Golden S 01 38 and lake R 98 40.
14
14 13 77 78 79 80 EASTINGS 173 81 82 83 13
Fig.12.4 Six-figure grid references: Train station N 797 156.
