Anglo-Saxon Cross

The Destruction of the Archaeological Record




Introduction

It has long been recognised that the archaeological remians are steadily being destroyed by a number of mechanisms. These mechanisms include both human intereference through urban development, road bulding, farming as well as natural forces such as wind and water erosion. The major problem is that it has been impossible to know the actual effect of these processes. In the mid 1990s, English Heritage attempted to find out through the implementation of the Monuments at Risk Survey (MARS). The key realisation was that the Royal Air Forces aerial photographic survey of England in the 1940s offered a start date and record from which it would be possible to measure the degree of destruction of a sample of the ancient monuments in England. MARS, therefore, developed two basic means for calculating the loss of (horizontal) area covered by a monument and the loss in vertical height of a monument.

The survey has shown that in the last 50 years at least a major archaeological monument has been destroyed every day, whilst a quarter have suffered some form of destruction in their aerial extent. The major factors affecting destruction are identified as development, agriculture and natural erosion.

The Monuments at Risk Survey

The Monuments at Risk Survey was started in 1995 and run by Professor Timothy Darvill of (Bournemouth University). It cost approximately £350,000 per annum for three years. It was published in 1998 (Darvill, T.C. and Fulton, A. 1998).

MARS was a nationwide survey of the survival and decay of England's archaeological heritage over the last 50 years. It has long been recognised as a crucial step in developing approaches to management of the archaeological resource. It was believed thhat quantified results from MARS would provide the profession and wider public with baseline information about the state of the resource and the effect of impacts, such as land use, on it.

Although surveys on the impact of land uses such as agriculture are well documented, they only present a localised, often judgmental view of destructive practices. For the first time, MARS provided a national picture, based on a representative sample, here 5% and in an objective manner. This information is to be used to target strategic and lower level resources and will be a tremendously valuable tool in supporting archaeological elements of land management.

Project Aims

From the Project's original website. There are three main aims to the Project:

The first aim is to provide a systematic quantification of England's archaeological resource in terms of:

The second aim is to investigate the archaeological implications of monument decay for different classes of monument, in terms of the information preserved at different states of survival

The third aim is to prepare appropriate publications and presentation material to convey the project results to a variety of audiences

The Question of Survival and Decay

MARS arose out of a need to understand and quantify the processes affecting the state of England's archaeological monuments.

There will be three main strands to the study. First is the quantification of the state of the resource in c.1995 through a national programme of field checking. Second, is the quantification of the changing state of the resource since 1940 through the examination and analysis of available aerial photographs. Third, is the researching of a series of case studies relating to defined classes of monument and tracts of distinctive countryside.

Overall, MARS will examine over 25 variables relating to the archaeological resource. Some of these will be considered and described in future issues of the Chronicle, here attention is directed to the approach that has been developed to cope with the two most difficult variables: survival and decay.

Survival is taken as a point-in-time measure of the prevailing state or condition of a monument relative to some former state; a reflection of the cumulative effects of all the natural and man-induced processes that have come to bear on the monument. Ideally, survival should be measured with reference to the original state of the monument, but in practical terms it is almost impossible to determine the original state of all but a few particularly well-recorded and in general fairly recent monuments. Accordingly, it is necessary to estimate or project the original or greatest recorded extant. Rather easier is the measurement of the area of the monument and the height / thickness of deposits that remain. These measurements can be made for any point in time if the information is available or can be seen.

From these measurements it is possible to quantify survival in two ways; horizontal (area) survival and vertical survival.

Area Loss (horizontal survival) is quantified as the percentage area loss (PAL) calculated as:

A1 - A2

Percentage Area Loss = ------- X 100

A1

where:

A1 = Projected original extent

A2 = Area extent at the time of the survey

Vertical Survival is quantified as the percentage height loss (PHL) calculated as:

H1 - H2

Percentage Height Loss = ------- X 100

H1

where:

H1 = Projected average original height / depth / thickness dimension

H2 = Estimated average height / depth / thickness dimension at the time of the survey

Alongside these measurements it is proposed to use a more general appraisal of gross survival. This can be estimated as the percentage of the volume of monument lost between the projected original extent and the point in time for which the gross survival estimate is being made. This is known as the percentage volume survival (PVS). Gauging the PVS means taking account of the full intricacies of the shape and form of the monument under scrutiny, but because of these great intricacies there is no easy formula which models or describes such changes. However, the human mind is quite good at making general estimates of such changes, at least in terms of broad categories. Thus visual observations at the time of field checking, and visual analysis of aerial photographs and other sources for earlier data collection windows will give a reasonable general impression.

Decay is a through-time measure of changes to the survival of a monument and elements of it. The archaeological record is a product of human activities. Inevitably, individual parts of the record for example earthworks, timber buildings, bone needles or ironwork - begin to decay from the moment of deposition. The rate at which decay occurs depends upon a range of factors. If decay is regarded as a continuous process then it can be measured in terms of the degree of change between one point in time and another. The time period over which the decay process is measured is suggested here as 10 years, this being a realistic interval during which even fairly slight changes in survival can be observed. Viewed graphically, decay is measured in terms of the declination of that part of a decay curve which lies within the purview of the time unit under scrutiny.

Decay is thus measured from decade to decade, using the following simple formula in which the decade decay factor (DDF) is determined by comparing the percentage volume survival of a monument at the beginnning of (any) decade (PVS1) to the percentage volume survival of the same monument at the end of that same decade (PVS2).

DDF = PVS1 - PVS2

Main Results

  1. There are 937,000+ monuments listed on Sites and Monuments Records in the UK. Of this number, 300,000 are archaeological sites.
  2. Since 1945, 48% of land with archaeological monuments has revealed some evidence for destruction of the archaeological remains. Among these monuments, 9% of land reveals a pattern of total destruction, and 39% of land reveals a pattern of piecemeal destruction.
  3. The key causes of destruction are identified as cultivation, natural processes, development and urbanisation, mineral extraction, and road-building.
  4. Since 1945 there has been a fall in the percentage of monuments with good areal survival by 20%.
  5. 25% of monuments on publicly accessible land.
  6. 18% of monuments covered by some form of legislation, 6% are Scheduled. Scheduled sites have survived nearly twice as well as non-scheduled ones.
  7. Many sites have suffered a change of land-use since 1945.
  8. 2% of monuments are at high risk (esp. field systems and standing buildings).
  9. There are 4520 monuments that will require special attention in next 3-5 years.
  10. Since 1945, 23,500 monuments have been completely destroyed.
  11. There has been a decline in the proportion of monuments with good areal survival from 95% in 1945 to 76% in 1995.

Library Resources

Darvill, T.C. and Wainwright, G. 1994. The Monuments at Risk Survey: an Introduction. Antiquity 68: 820-24.
Darvill, T.C. and Wainwright, G. 1995. The Monuments at Risk Survey: an Introduction. Conservation and Management of Archaeological Sites, 1: 59-62.
Darvill, T.C. and Fulton, A. 1998. The Monuments at Risk Survey 1995: main report. Bournmouth University / English Heritage
Darvill, T.C. and Fulton, A. 1998. The Monuments at Risk Survey 1995: summary report. Bournmouth University / English Heritage


Link to the ALGY 399 Sydney Jones Library Reading List.

Internet Resources

English Heritage maintains a webpage devoted to the findings of the Monuments at Risk Survey. It sets out the basics of the programme, and their response to its findings. Some old MARS web pages from the original project team are still available.



Top of Page