Cross Section and Sketch Maps
Senior 6 · Geography
Cross Section and Sketch Maps
Lesson 3 of 4
22 min
A visitor to the school on Hill Y wants to know how to walk there from the village on Hill X. Map 1 holds the answer, but it is buried under thirteen contours, grid lines and symbols that the visitor does not need. A sketch map keeps only the features that serve a purpose and leaves the rest out. In an examination you will be asked to draw one of two kinds: a sketch map of a map extract (or part of it) showing named features, or a sketch map from memory of a country or region, such as Rwanda or East Africa.
Definition
Sketch map: a simplified map drawn by hand to show selected features in their correct relative positions, shapes and sizes, without the full detail or exact survey accuracy of the original. It still needs a frame, a title, a key and a north arrow, and should state its approximate scale.
Example: a sketch of Map 1 showing only the river, the swamp, the road and the village.
Definition
Generalisation: simplifying features when a map is redrawn with less detail: smoothing small bends in a river, joining scattered houses into one settlement symbol, and showing an area such as a forest by its outline alone.
| Element | What to do |
|---|---|
| Frame | Draw a neat rectangle with the same shape (proportions) as the area it shows. |
| Title | Say what the map shows: "Sketch map of the area of Map 1 showing drainage and communications". |
| Content | Show only the features asked for, each in its correct position relative to the others. |
| Symbols | Use simple conventional symbols: blue lines for rivers, outlines for areas, a single symbol for a village. Every symbol goes in the key. |
| Labels | Print names neatly, horizontally where possible; river names may follow the river. |
| North and scale | Add a north arrow and state the scale, e.g. "half the size of the original, about 1:100 000". |
| Neatness | Use a sharp pencil; don't crowd the map; don't shade large areas so heavily that labels disappear. |
Figure 6: a sketch map of the area of Map 1. The 1,600 m contours stand in for the whole relief, 8 houses have become one village symbol, and the forest and swamp are shown by an outline with a few symbols inside.
Worked example 1: carrying River Z across the grid
Problem. You are drawing the sketch map at half the size of Map 1, so each grid square is 1 cm instead of 2 cm. Where do you mark River Z?
Solution. Read the river's crossing points on Map 1:
| Where the river crosses | Position on Map 1 | Distance from the west edge of the sketch |
|---|---|---|
| North edge (northing 25) | about easting 14.1 | |
| Northing 22.5 (at the bridge) | easting 14.0 | 4.0 cm |
| South edge (northing 20) | about easting 14.05 | about 4.0 cm |
Mark the three points and join them with a smooth line that bends slightly west of the 14 easting between the bridge and the south edge, as the river does on the map. The river runs almost due south, close to the 14 easting, through the whole map.
Worked example 2: choosing what to show
Problem. Draw a sketch map of Map 1 to show "relief and communications". Which features go in, and how are they drawn?
Solution. Relief: Hill X and Hill Y, shown by their 1,600 m contours as shaded areas and named, and the valley of River Z, which may be shown by the river itself. Communications: the murram road, the bridge and the footpath. Leave out the forest, the swamp, the houses and the school; they were not asked for, and including them wastes time and clutters the map. Every symbol used (land over 1,600 m, road, bridge, footpath, river) goes in the key.
Questions such as "Draw a sketch map of Rwanda and on it mark Lake Kivu, the Akagera River and three towns" test whether you know where things are. A reliable method is to use latitude and longitude as your grid.
Figure 7: a sketch map of Rwanda. Note how the border runs through the middle of Lake Kivu, follows the Rusizi River in the south-west and the Akagera River in the east.
Warning
Common mistakes
Tip
Exam technique. Draw the frame and the light grid first, and use about a third of a page. Put the key in a box beside the map, not squeezed inside the frame. Label rivers in italics or along their course, and write settlement names horizontally.
David Kelly: "Drawing a sketch Map for Leaving Certificate Geography". A sketch map drawn from an Ordnance Survey map extract for the Irish Leaving Certificate examination. As you watch, compare each step with the grid-square method above.
Practice
Summary
Sources and credits
Map 1, Figure 6, the worked examples and the exercises were written and drawn by Ganzaa.
Video: "Drawing a sketch Map for Leaving Certificate Geography", David Kelly, embedded from YouTube.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
