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Guidance Sheet No.15: USING DRAWING CONVENTIONS

What are drawing conventions?

Drawing conventions are the symbols used to depict natural and man-made features in a simple but

understandable format. Most of these the standardised symbols were originally designed by the Ordnance Survey

in the 19th century for use in the first comprehensive British mapping programme, in order to produce maps that

were consistent across the country. The conventions are now widely used by professional archaeologists in their

field sketches and measured site plans of all scales. For the CSI: Rombalds Moor project, you will need to use

drawing conventions in your Location Sketch (B4) and in your Panel Plan (B8). These are outlined separately

below.

Drawing conventions and the Location Sketch

You will be probably be working at a range of scales for your Location Sketch. The symbolic ‘language’ of drawing

conventions varies slightly with the scale at which the features are depicted so that at large scales (such as 1:100

or 1:200), features are shown in greater detail than at smaller scales (such as1:500, 1:1,000 or 1:10,000 for

example). OS Landranger maps are commonly at smaller scales of 1:50,000, 1:25,000 or 1:10,000. At these

scales, archaeological features such as built structures and earthworks are shown with minimal detail – built

structures are only shown in outline for example. At larger scales – that could be anything above 1:1,000 – more

detail can be shown, with wall thicknesses and complex earthworks depicted accurately. The diagram below shows

the main drawing conventions at scales of 1:1,000-1:100 for a variety of natural and artificial features.

Figure 1. Drawing conentions used by archaelogists and cartographers at scales of 1:100-1:1,000

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Using hachures

One of the more useful drawing conventions for prehistoric landscapes is called the ‘hachure’ and you may find it

useful for your Location Sketch. Banks, ditches, and slopes (scarps), for example, are all depicted using hachures.

However, hachures can also be the quite problematic. If drawn badly, they can be more confusing than useful and

can over-dominate your drawing. Here are a few straightforward guidelines to help you:

1. Hachures are straight lines, thicker at one end than the other, like a tadpole or extended isosceles triangle. The

thick end marks the highest part of the feature, at the point where it starts to slope away (the ‘break of slope’). The

line of the hachure represents the length and direction of the slope, with the end of the line showing the bottom of

the slope.

2. The thick end of the hachure should be gently rounded, rather than angular, and should never be too thick.

3. To make hachures work, it is crucial to draw each one perpendicular to the break of slope (ie where the incline of

a feature changes), so that they follow its direction at all times. Look especially at how hachures are used in Figure

3 to depict rounded earthworks and depressions. The edge of a very clear break of slope is marked in a different

way to a less well-defined change in slope. It is not always easy to identify where the break of slope lies, especially

where the slope has a shallow gradient, or is located on sloping ground. In such cases, it is best to keep the length

of the hachures relatively short so that they depict the shape of the structure more realistically.

4. If there are natural slopes across your site, you will need to use drawing conventions to differentiate between

‘natural’ hachures and the hachures recording archaeological features, as shown in Figure 2.

5. Don’t draw in more hachures than needed – this will just make your drawing confusing and cluttered.

6. Only include hachures if you are confident in using them!

Showing the location of rock art panels

On your Location Sketch, you will need to also show the position of the panel you are recording. This should be

depicted as an X with a small circle around it. If there are other carved panels in the area covered by your sketch,

you should show each of these as a small X, with its panel name and number written clearly next to it. If you use

the same Location Sketch each panel in a closely clustered group, make sure you encircle the X for the panel to

which the rest of the recording form refers.

Figure 2. Hachures used for field recording of features at different scales

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Figure 3. Hachures used for depicting earthworks in a completed site plan. Note the difference between how hachures are represented in the field drawing (ie very roughly) and the finished plan Drawing conventions and the Panel Plan The carved panels will be recorded at a much larger scale than you use in the Location Sketch – generally between 1:5 and 1:25. There are no standard conventions for depicting different types of carvings, or topographic features on rock surfaces. As we will be basing our recording on the panel drawings made by the Ilkley Archaeology Group, we will be following their drawing conventions. Please use labels to clearly indicate any additions you make to the IAG drawings, and to differentiate between natural fissure and carved grooves where this is not disputed.

Figure 4. IAG Drawing Conventions

Showing other features You should indicate any other features of interest by encircling the area affected and using clear labels. Features marked in this way may include:

a) areas badly affected by moss or lichen cover

b) areas of pooling water

c) badly eroded areas

d) scratched or chipped areas

e) modern graffiti

f) natural hollows or channels