In creating the maps for a world atlas, decisions have to be made on which areas of the world to show at which levels of detail. The key factor in this decision-making process is map scale – the relationship between distances or areas on the map and the equivalent distances or areas on the ground.
The scale factor
Scale determines the level of detail that can be shown. Larger scales allow more local detail to be included, but as scale decreases more cartographic and editorial decisions have to be made on which elements to omit, and which to simplify or generalise so that they are legible and understandable at the smaller scale. In a world atlas, 1:1,000,000 would be considered to be large scale – 1 cm on the map equating to 1,000,000 cm (10 km) on the ground – whilst regional and continental maps would be shown at smaller scales, for example 1:30,000,000.
Large scale 1:1,000,000 1cm=10km Times Comprehensive 12th edition
Medium scale 1:5,000,000 1cm=50km Times Comprehensive 12th edition
Small scale 1:28,000,000 1cm=280km Times Universal Atlas
Choice of scale directly relates to the size of the map and therefore to the overall size, or format, of the atlas itself. The page size can be a very limiting factor in choosing the scales at which particular areas can sensibly be mapped. It would take a very thick ‘pocket-sized’ atlas to map even the whole of Europe at 1:1,000,000.
Choosing which scales to use
The question therefore arises of which areas of the world to show at which map scales. Or, to put it another way, which areas should we show in more detail than others? Which regions are more important in the users’ eyes, which ones warrant more detail, which ones just make nice looking maps? Is the Middle East more important than Japan? What proportion of the atlas should be devoted to Europe, and how much to less familiar regions? One radical approach taken by some atlas publishers – or perhaps just a cunning way of avoiding hard decisions! – is to show the whole world at the same scale. Whilst allowing direct comparisons of distances and areas across the globe, this method takes no account of the variations in population density, communications networks, complexity of settlement pattern, etc. So vast empty areas of northern Siberia are mapped at the same scale as the New York area, with the resultant massive compromises on the level of detail which can be included in the latter. In preference to this approach, we aim to find the best relationship between scale, the amount of information on the ground which we think should be shown, and the perceived relative importance of a region. There is no magic formula to this and correspondents are often keen to influence our decisions.
One regular contributor of editorial ideas (which we always welcome) suggested four criteria to work by: the ‘marketability’ of an atlas in a certain area – which areas are important to who we think will be the main buyers; the ‘news value’ – are there particular regions currently in the news and of topical interest; ‘Points of interest’ (a tourist aspect – which places can be expected to be shown); and ‘population density’ – implying larger scales for more densely populated regions. Each of these has value, but not all are practical – the news agenda, for example, changes far more frequently than the content of printed atlases can.
Obviously not everyone will be happy with the final set of maps and their scales – users commonly judge the overall value of an atlas by how well it deals with their home area. ‘Why do you practise this “discrimination”?’ I was asked, in relation to our map of the Balkan region at the scale of 1:2.5M. Much of the rest of Europe was mapped in more detail at the larger scale of 1:1M. Accusations of a particular ‘cultural perception’ and ‘lack of interest on your side’ were made. It would be a sad day indeed when ‘lack of interest’ on an editor’s part determined which areas would be mapped, or resulted in some areas being left out altogether!
Feedback leads to a new 'spread'
When the first digitally produced Millennium Edition of the Times Comprehensive Atlas of the World was published in 1999, it was the first time we had completely reviewed the coverage and scale of its maps since its first edition in 1967 (they had all been constantly revised since then, I hasten to add). A long-standing map of Alaska was dropped in favour of increased coverage of central Asia and other regions judged to be of greater interest. Numerous complaints were received – why was this unique part of the USA mapped at a much smaller scale than the contiguous states? As a result, we created a brand new map of Alaska for the 12th Edition in 2007 at the expense of a map of central Chile and Argentina – we await a deluge of letters from Buenos Aires, Santiago and everywhere in between with trepidation…
The new Alaska 'spread' is also included in the forthcoming Times Concise Atlas 11th edition (published Sep 09) shown above, click to enlarge.
Mick Ashworth
Ashworth Maps and Interpretation Ltd
Consultant Editor to The Times Atlas of the World