Archaeological Surveying and Mapping

Recording and Depicting the Landscape

Philip Howard

• Publisher: Routledge
• Year: 2006
• Print ISBN: 9780415306638
• eBook ISBN: 9781134400850
• Topic: Social Sciences
• Subtopic: Archaeology
• Index: Social Sciences

A comprehensive and practical guide to surveying for archaeologists, with clear instructions in archaeological mapping, recording field work and detailed case studies from the UK, Europe and the US.

Philip Howard provides a user's guide to methods and instruments of surveying to enable archaeologists to represent their own fieldwork confidently and independently. Archaeological Surveying is an invaluable resource which:

• provides beginner's instructions to software used in computerised surveying, including IntelliCAD 2000, Terrain Tools, Christine GIS and Global Mapper
• introduces the archaeologist to a range of surveying instruments such as GPS, electronic distance measures, theodolites and magnetic compasses
• includes low-cost software.

This textbook is an essential read for any field archaeologists who are in need of an introduction to surveying, or simply wish to update their techniques.

Chapter 1
The science and profession of surveying

The science of surveying, and the status of the surveyor, have been differently perceivedat different times. In the ancient world (Lewis, 2001) the aspects of surveying, engineering, astronomy and astrology were closely linked, and the practitioners of these sciences were of high status – some achieved a renown which has come down to the present day, such as Hero of Alexandria and Archimedes. Closer to our own time, when surveying as we know it was beginning to take shape, a good grasp of surveying was seen as essential to the gentleman, landowner and soldier. Peacham (1634, p.77) offered this summary of the uses of geometry:

But in briefe the use you shall have of Geometry, will be in survaying your lands, affoording your opinion in building anew, or translating; making your milles aswell for grinding of corne as throwing foorth water from your lower grounds, bringing water farre off for sundry uses; Seeing the measure of Timber, stone and the like (wherein Gentlemen many times are egregiously abused and cheated by such as they trust) . . . you cannot without Geometry fortifie your selfe, take the advantage of hill or levell, . . . order your Battallia . . . [or] plant your Ordnance.

In the famous work Pantometria, often quoted, though mistakenly I think, as the origin of the word ‘theodolite’, Digges (1571) had already said

. . . neither is there any liberall or free minde . . . that will not take great delight and pleasure to see how by Arte a man may measure the distances of places remote and farre a sunder, approaching nighe none of them, and that as well, yea and farre more exactly than if with Corde or pole he should paynfully passe them over.

His work has many illustrations of surveying practices which are designed to facilitate the conduct of war (in assessing the height of fortifications, for example), and these have as marginal items cannon breathing rather languid-looking plumes of smoke, and men setting out lines and angles using halberds as markers. In recent years (Ronan, 1991) it has even been suggested that Leonard Digges and his son Thomas may have invented a reflecting telescope a century before Isaac Newton, but that this invention was kept secret by the government because of its potential value in identifyingenemy ships at sea. (This suggestion was thought sufficiently interesting to appear in the Daily Telegraph on 31 October 1991, and even made its way into Hansard, the daily record of the UK Parliament, though for the purpose of making a political pointrather than as a matter of scientific importance.) Many surveying instruments (as well as other kinds) which survive from this period (see, for example the Online Register of Scientific Instruments, http://www.isin.org or the Museum of the History of Science, Oxford, http://www.mhs.ox.ac.uk) seem from their rich decoration to have been display items for the wealthy who wished to be associated with this branch of science.

As surveying became a more common activity, first for the landowner and later for the state, the task of carrying out the work no doubt fell more often on humbler folk (as it probably always did), and as the carrying-out of a survey was often regarded as the precursor to something worse the status and favour of these workers suffered accordingly. Partridge and Beale (1984), Barrère and Leland (1889), and Grose (1785, quoting ‘Ray 1678’) all give a slang name for the surveyor’s chain as ‘the devil’s guts’, ‘So called by farmers, who do not like that their land should be measured by their landlords’ (Grose, op. cit.) Usill (1900) indicates that the surveyor is often regarded as a trespasser, and this is made even more starkly evident in a leading article in The Times (Wednesday 5 September 1855), discussing the early railway surveyors:

. . . what of those young gentlemen who were transformed for the nonce into civil engineers, in full employment at five guineas a day, and travelling expenses paid? Lads who scarcely knew the difference between a theodolite and a gridiron were disseminated through the country, to the sore discomfiture of the country gentlemen, in whose nostrils they stank even as poachers.

So, contempt from farmer and squire was the lot of the surveyor, though Debenham (1955, preface to the first edition of 1936) notes that for the public the profession has an air of mystery: ‘. . . involving, it is thought, the use of strange and expensive instruments, acquaintance with the higher mathematics, and a high degree of perfection with the pen’. Some at least of his predecessors seem to have been of the same opinion; quoting Usill again:

. . . it may be proper to mention the previous knowledge which a surveyor ought to possess, and to notice the instruments which he is to employ in his operations. As a surveyor has perpetual occasion for calculation, it is necessary that he be familiar with the first four rules of Arithmetic, and the rule of Proportion, both in Whole Numbers and in Fractions, especially Decimals, with the nature of Logarithmsand the use of Logarithmic Tables, and with at least Algebraic Notation. As it is his business to investigate and measure lines and angles, and to describe them on paper, he should be well acquainted with the elements of Geometry and Trigonometry, and with the application of these principles to the mensuration of Heights, Distances, and Surfaces. In particular, he should be familiar with the best practical methods of solving the ordinary geometric problems, and should be expert in drawing lines and describing figures. He should be acquainted with the principles and practice of Levelling; he should know something of the principles and practice of Optics and Magnetism, and he should possess at least a smattering of the arts of drawing and Painting.

Debenham goes on to say, however, that ‘awe is partly due to the fact that the surveyor is hardly ever seen’, and that if one should be sighted ‘the disappointment in what he is doing will generally be intense, since he has . . . practically none of the paraphernalia which is normally associated with the occult art of topographic surveying’. Greed (1991), while making valid points about the difficulties faced by women seeking to make their way in a predominantly male profession, displays some prejudices of her own in making a distinction between the ‘professional’ work of the surveyor (quantity surveying, estate management issues, etc.) and the merely ‘technical’ business of making the accurate measurements on which the rest of the work is based. At one point she even refers to ‘obscure technical trivia . . . which only technicians are meant to know in order to do their job’ [my italics].

So from being fêted elite members of society, practitioners of surveying have descendedthrough the social ranks of the gentry to the hated status of interlopers, perhaps rising a little to stabilise as at least the possessors of some knowledge, if only of an obscure nature, and which no one else would want.

My own experience of being identified as a surveyor has been variable. I have been assumed by members of the public, who didn’t know that I was an archaeologist, to be doing work in advance of something they regarded as undesirable: a new road, new houses, and so on. Among other archaeologists I have occasionally encountered the feeling that what I was doing was rather a waste of time; once I was told that ‘a theodolite is more trouble than it’s worth’. This isn’t just my experience, either. Alcock (1980) offers the opinion that ‘the making of plans to an appropriate level of accuracy is the central discipline of field archaeology. But it is a discipline which is often sadly neglected by practising field workers.’ Hogg (1980) is even more clear on the subject:

Field Archaeology and Excavation are the foundations upon which the whole structure of archaeological knowledge is built, and of the various techniques which make up these methods of investigation surveying is probably the most important. The need for accurate plans is surely self-evident . . . Nevertheless, of these techniques surveying is also the most neglected. There is an illusion that it is difficult, and as a result works which are otherwise excellent describe idiosyncratic methods which are both unduly laborious and potentially inaccurate.

This last sentence is the most telling. There is a widespread impression that surveying is difficult, and often quite sensible people cause themselves more trouble by trying to avoid it. The caution is perhaps understandable. Standard textbooks on surveying still include many pages of geometrical formulae and explanations which can appear confusing. Some time ago I came across a very short work which emphasises this point: ‘Fundamental trigonometry and geometry for topographic science: a summary of trigonometricformulae and proofs’ (Gordon, 1993). The title of this (very useful) work encapsulates the difficulties faced by many people when coming to grips with the more sophisticated aspects of surveying; almost every word is calculated to strike fear into the heart – ‘fundamental’, ‘trigonometry’, ‘formulae and proofs’. I am one of the very many for whom school experience of mathematics beyond simple arithmetic involved bewilderment, boredom, and occasional humiliation. It was only when archaeology led me into regions where the application of this kind of science was necessary that it really started to make sense, and I was fortunate to have good teachers when I needed them. I hope in turn to encourage some others.

A lot of things have changed since I started surveying; the advent of powerful and affordable computers ought to have made a difference, but there remain problems. One is the old danger of ‘a little learning’. Bettess (1992) makes the point that the use of electronic technology enables those with limited mathematical knowledge to extend the range of their surveying, while Bowden (1999) cautions against assuming that the ability to push buttons makes a surveyor. It should be possible to avoid the worst of this difficulty, but a greater one is that of getting access to the necessary software. The standard packages for surveying, CAD (computer-aided drafting) and GIS (geographic information systems) are all priced well into four figures, and their purchase causes problems even for some small companies, let alone individuals or groups such as local archaeological societies. I hope to be able to show in the succeeding pages that there are indeed suitable kinds of software available at low prices and in some cases even free, which enable those who are interested to extend their surveying ability to a remarkable extent.

Of course, not everyone agrees that the use of electronic methods of data collection and representation are necessarily a good thing. Two recent publications (Bowden 1999, English Heritage, 2002) have emphasised the continuing use of simple traditionaltechniques of surveying, and in particular the plane table (described in more detail later), a device which allows drawings to be created in the field. I wouldn’t personally reject the use of any technique, provided that it is applied properly and the producers of a survey make it quite clear exactly what they have done, but Bowden (op. cit., p.60) presents a series of arguments for traditional methods of surveying and drawing actually being superior to electronic ones. The points he makes are these:

• An experienced team can work ‘at least as fast’ with traditional methods as with electronic ones.
  This is arguably true.
• ‘The end product is superior’ because the traditional techniques ‘entail a close observation of the ground’, and ‘allow the fieldworker to treat . . . features as complete entities rather than as series of lines to be chased . . . [it] forces the archaeologist to look at them properly in a way which electronic survey does not’.
  I don’t accept that this is really true. Certainly I have come across examples of poor surveys carried out with electronic instruments, but they were done by people who weren’t good surveyors. You can be a bad surveyor with traditional techniques as well, and a good one with electronic ones.
• Drawing in the field instantly identifies errors.
  There is something to be said for this, but this benefit is now available from a variety of electronic devices which have graphical screens to display the survey data as they are collected. Producing the drawing in the field has a down side as well. While the photographs in Bowden’s book (and the English Heritage pamphlet) show plane table surveys taking place in good weather, Wright (1982) makes very clear his own experience of plane-tabling in less favourable conditions, whether too wet, too cold, too hot, too windy or otherwise disagreeable (as when beset by insects).
• Electronic systems are prone to breakdown.
  Again, I don’t really accept this. We all remember the occasions when any device breaks down, rather than all the other times when it doesn’t, but my own experience of electronic surveying equipment is that it isn’t particularly liable to fail (though proper care and maintenance is called for).
• Disadvantages of digital drawings are that ‘they are usually aesthetically challenged’, and that ‘digital media are not archivally stable’.
  The first depends; electronic drawings can look good, but they need skill and care, as do manual ones. Electronic methods don’t do away with the need for skill, but how many people have the time or native ability to learn to draw hachures (for example) so that they look good? There are few more ugly additions to a survey drawing than badly drawn hachures, repeated many, many times. Hachures producedby computers may be more mechanical-looking, but I would rather see that than bad manual ones. We may be talking about the difference between an ideal and something fully acceptable that most people can achieve.
  The second point is true: digital media aren’t ‘archivally stable’. We are moving into an era in which many kinds of material which were formerly stored in the form of paper are being replaced by digital archives. My own experience of universitylibraries is that electronic versions of texts, particularly current issues of periodicals, are becoming more and more common; this isn’t without its own problems, but the ever-increasing demands for physical space can’t be met. Stability in this world means something different, not the longevity of a particular piece of paper or plastic film, but the management of live data sets. (Condron et al., 1999; see also the Archaeology Data Service web site, http://ads.ahds.ac.uk/.)

Traditional methods of surveying will continue to be of use for a long time, particularlyin fields like archaeology where a lot of work is carried out with low levels of funding, but this doesn’t mean that traditional methods of drawing have to be used as well. Not only are computer methods more easily capable than the average person of producing acceptable results, but you don’t also need the space for a drawing office in a house which already has a computer. Perhaps I should give my own list of reasons for ‘going digital’ (not necessarily in order of importance):

• It’s easy to copy results; one hard copy has almost no intrinsic value, unlike manually produced drawings which may have taken hours or days to generate. Files containing maps and other drawings can be duplicated and disseminated freely.
• Many different representations of a set of data can be made from one file – multiple scales and combinations of map features are possible. It gives a better result to create a new drawing at a different scale rather than to enlarge or reduce hard copy (for example, you can reduce the scale of drawn features while keeping the text the same size). There is, of course, always a maximum scale at which data can be plotted, but that’s true of traditional methods as well.
• Drawing quality doesn’t depend on individual skill.
• Much more accurate plotting is possible, and this can exploit the accuracy of field instruments. (There is little point using a theodolite to measure angles to twenty seconds of arc and then plotting them with a protractor which can’t define an angle smaller than half a degree.)
• The digital drawing can itself be used as a dynamic environment in which to carry out further work. When some features have been surveyed, perhaps using sophisticated instruments, they can become the ‘control’ for other detail features, e.g. by making 90° offsets from a wall. This can be done manually, but it’s much easier and more accurate in an electronic drawing.
• Through organisations like the Archaeology Data Service, large complex data sets can be stored safely and accessed easily by a dispersed community of users.
• Surveys can be georeferenced (given co-ordinates in a real-world system) and combined with other data – from an archaeological point of view one of the most important ‘other’ data types is the oblique aerial photograph, which can be rectifiedand incorporated into digital vector maps in a way which isn’t possible using manual methods. You can then pinpoint features on the photograph, obtain their grid co-ordinates, and use a satellite navigation unit (GPS) to find them on the ground for further investigation, perhaps by fieldwalking or geophysics.
• If traditional techniques have been used in the field, spreadsheet programs make it easy to perform repetitive calculations (with much lower probability of making mistakes), and results can be copied and pasted directly into electronic drawings, automatically creating features.

A note on software packages

At various points in this book examples will be given of the use of particular software packages. None of these is being endorsed as superior to any other, but they represent those which the author has found satisfactory for the specific purpose and which are available at very modest cost or free. Other software may exist which is as good or better, though often at a much higher cost.

Two packages need to be mentioned specifically. One is the CAD software IntelliCAD (http://cadopia.com). This is the only serious rival I have been able to find to the ‘industry standard’ AutoCAD. IntelliCAD is available in several versions, some of which cost several hundred dollars (US), although still much cheaper than AutoCAD. In keeping with the philosophy of this book, I have used a version from 2001 (which was still available in 2004 from the Product Archive on the web site) which cost approximately $200. In some respects this version is limited, especially in the absence of solid modelling, but it is still a very comprehensive package and will perform very well in surveying applications.

The other is a spreadsheet package. I have tried in many places to show how a spreadsheet can be used to take a lot of the labour (not to say pain) out of the calculations which ought to make a surveyor’s life easier. Most PC computers are bought with a set of software including ‘office’ applications, one of which will be a spreadsheet. I have looked at a number of these, and while all can be used for surveying purposes, not all of them ...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• List of illustrations
• Chapter 1: The science and profession of surveying
• Chapter 2: The aims of an archaeological survey
• Chapter 3: Basic methods of surveying
• Chapter 4: Control surveying
• Chapter 5: Application of surveying instruments
• Chapter 6: Surveying on a global scale
• Chapter 7: Using cad software
• Chapter 8: Gis in archaeological mapping
• Chapter 9: The shape of the ground
• Chapter 10: Sources of digital map data
• Chapter 11: The butter market, barnard castle, county durham
• Chapter 12: The boeotia field survey project
• Chapter 13: A survey of an earthwork feature on cockfield fell, county durham
• Chapter 14: Durham city
• Chapter 15: Terrain model of lomello
• Chapter 16: Sandoval county, new mexico
• Bibliography