Soil Survey of Scotland, 1950s-1980s
Background to the One-Inch (1:63,360) map series
by Dr Allan Lilly, Principal Soil Scientist, The James Hutton Institute
The Soil Survey of Scotland began mapping in 1938 and by 1947 was given the responsibility of the systematic mapping of Scotland’s soil resource by the Department of Agriculture and Fisheries for Scotland. The initial surveys were in connection with afforestation but at the onset of the Second World War, the focus switched to agricultural land and increasing food production. The Survey effectively came to an end in 1986 and by this time it had produced a range of soil maps at scales from 1:10,000 up to 1:250,000. The main output was a series of 34 maps at 1 inch to the mile (1:63,360) based on the Ordnance Survey one-inch map series, and seven sheets at 1:250,000 that covered the entire country. Approximately 95 per cent of the cultivated land in Scotland was therefore mapped at a scale of 1: 63,360 (with some at 1:50,000 scale) and all of the country at a reconnaissance scale of 1:250,000. During this period, The ‘Survey’ was based in Aberdeen and was a department within the Macaulay Institute for Soil Research but it had a number of outlying regional offices that changed as the surveyors moved to map new areas.
Surveying and field mapping
The actual survey was done by a technique known as ‘free survey’ where the surveyor dug small inspection pits to confirm or refute his (they were all male) ideas on how the soils were changing in the landscape. The location of these inspection pits were marked on 1:25,000 scale topographic maps such as the ‘War Time’ GSGS (Geographical Section, General Staff) sheets, Ordnance Survey 1:25,000 maps and, latterly, black and white aerial photographs. The location of the inspection pits and any line work delineating areas of similar soils were meticulously recorded in the field and later made more permanent by using fine-nibbed ink pens to record abbreviated, shorthand descriptions of the soils on to the field sheets or photograph. The GSGS sheets had a different grid system (Cassini projection system) to the 1:25,000 (Transverse Mercator) and 1:63,360 scale maps which made transferring the line work difficult.
During the winter months, these boundaries between the different soils were ‘fixed’ with the help of a stereoscope and aerial photographs allowing the user to see the terrain in three dimensions. These lines were transferred to a ‘field sheet’, which also contained information on the inspection pits, and to ‘clean copy’ 1:25,000 Ordnance Survey maps using a sketchmaster, an instrument that allows two separate map or photograph images to be superimposed through a single eye-piece, and then passed on to the cartographic for photographic reduction, scribing and preparation of the 1:63,360 scale map sheets. Scribing involved using a fine-pointed stylus to scrape away a film from a plastic sheet to produce a negative image of the polygons. This was then turned into a positive version and adhesive map unit symbols were added manually. Paper copies were made and hand-coloured to check that all polygons were closed.
Scotland’s published One-Inch (1:63,360) soil maps
One of the main outputs of the Soil Survey of Scotland was a series of coloured maps at a scale of 1:63,360. Although many of these map sheets were based on the Ordnance Survey Seventh Series topographic base maps, some of the early published soil maps were based on earlier topographic maps in this series. These earlier maps do not align with the current Ordnance Survey National Grid but are slightly offset. Some 1:50,000 maps were produced, such as those for Orkney and Ardnamurchan.
The 1:63,360 maps aimed (within the scale of the mapping) to show soil polygons that comprised only one soil type. This led to outputs with varying degrees of accuracy depending on the complexity of the soil pattern. Where the soils differed markedly over a short distance such that individual soil types could not be mapped, soil complexes were delineated, often based on a distinct landform unit with a distinct suite of soils.
The coloured maps had a common colour-coding system for the different soil types throughout:
- brown earths (browns)
- podzols (pinks, oranges or reds)
- mineral gleys (blues)
- peaty gleys (greens)
- immature, shallow and mountain soils (greys)
- alluvial soils (yellows)
(Read further information on these categories)
More information on Scotland’s soils can be found at: