Landscape change

An active landscape and what change means

Without getting too theoretical, and keeping this short introduction practical and succinct, the landscape concept under scrutiny is an arena in which activities have been and continue to be inscribed onto its surface. Thus, any activity in the past added time-depth to the landscape. The effect of these activities and time-depth is reflected in the changes to the material arrangement of the landscape, the results of which set in motion the possibility of other potential episodes of change.

However, landscape change is a relative dimension to another understanding of landscape that is related to its resilience. Resilience is essentially the continuity of features that have had a structural presence in the landscape over the long-term. In fact, it is difficult to discuss change without referring to the parts which are resilient. In this respect, change is only "one-side of a coin'. However, change is the conventional identifier that archaeologists have used to understand the past; whether this is identifying indexes of change in ceramic styles, or in the use of materials and forms of buildings, or for this discussion, in the arrangement of sites, settlements and land-uses within discrete spaces in the landscape. This falls under the rubric of landscape archaeology.

Measuring change and resilience in landscape

Principally landscape archaeology uses techniques that identify and measure the relationship between past change and the parts that were more resilient i.e. that have continued to have a structural role in shaping the landscape. Landscape archaeology's most useful technique of identifying/measuring the relationship between change and resilience has been to recognise the different episodes of activities in the long-term i.e. those activities that have been made visible because they have left materials behind, either below ground or on the surface of the landscape.

Conventionally archaeology examines these processes from two scales: the human or site-scale (perhaps related to field archaeology, geophysics, and landscape survey on-the-ground); and the regional or landscape-scale (viewed using aerial photographs, lidar, or satellite imagery). However, both of these scales (and their techniques) are contributing to the understanding of landscape's history, and our understanding of the relation between change and resilience in the long-term.

For example, at the site-scale geophysics can be used to reveal the degree of complexity within a site, showing a compressed temporal view of all its events or periods of spatially inter-related features. This is also similar to oblique photography which captures images of sites that are positioned in their wider (landscape) contexts and which contain varying complexities depending on the conditions under which the photography was captured.

The archaeological skill involved in disentangling both of these scaled-views reveals the degree of complexity that is shown below and on the surface of the landscape, Furthermore, this is also a reflection of the processes of change and resilience in the human inhabitation of the landscape. As a consequence such an understanding establishes the basis for landscape archaeology's interpretation, while establishing spatial planning's monitoring of landscape change

Monitoring landscape

At the other end of the scale - from the regional or landscape scale - the degree of change and resilience can be compared between images of a settlement that has been captured at different times. For example either seen on vertical aerial photographs or satellite and other remote sensing imagery such as radar or lidar, as well as the emerging information derived from hyperspectral analysis. Comparisons between imagery from different times amplifies the processes of landscape change and resilience that have taken place between the different times when the imagery was captured. And furthermore, comparisons between these various sets of imagery show processes that may be acerbated. This is because in our contemporary setting there is an immense speed of change derived from mechanised forces associated with new building, land-use or infrastructures - this has been called space-time compression.

However the same imagery that is used to measure more recent change can also be used to identify similar feats of change and resilience that have occurred in the past, that operated over a much longer period of development. However, no matter from what time and how long the inscription work took place, like the geophysics image, other imagery such as aerial photographs, lidar and satellite imagery will usually contain traces of much earlier activities that show up as crop marks, soil marks, shadows from earthworks, or other anomalies.

A cultural landscape, or a landscape of culture: the relation between Nature and Culture

As archaeologists we usually consider "Cultural' change as the only part of our remit of examining landscapes. But the kind of imagery that aerial archaeology and remote sensing uses also lends itself well towards the study of change and resilience in "Nature'. In fact, like the processes of change and resilience that I have discussed above, Cultural change cannot be studied without Natural change because to do so something of the importance that each contributes to the others understanding can be lost.

Thus, in mapping a boundary seen on an aerial photograph or from lidar it is important to consider the Natural landscape in helping to understand the boundary. This occurs, for example, in at least two ways: the effect that the cultural feature is having on the hydrology and vegetation of the natural environment; creating wetland areas up against the upslope side. And secondly, perhaps more important for this discussion, in adding to the interpretation of boundary and why it was constructed in the first place; say in joining two natural features such as a lake and a valley river, and how it has continued to shape the history of the landscape by becoming a administrative boundary between two districts.

Landscape and archaeology

In this way, the study of change and resilience from the perspectives of landscape and archaeology combine as a topic that studies the cultural relationship with the natural environment. This can be considered in terms of a functional, economic, or political perspective, as well as from a social or symbolic view. In this respect, landscape processes of change and resilience are important to identify because they are representative of a much wider complexity that is associated with inhabitating the landscape. In conventional terms the complexity is usually referred to as a palimpsest. And in the same way as attempting to disentangle earlier traces of writing from contemporary ones on a velum, or in examining an oblique photograph to tease out the archaeological site, the landscape can be "read'.

In order to "read' the landscape different image sources are used. Sources other than archaeology can be used to do this, such as historical documents. Sources like these when linked to other sources can be used to identify past activities, say, that refer to the establishment of settlement, or point towards legislations that have documented changes in land-use, say, in relation to improvement and drainage (at least in the historic period). However, these other sources are greatly enhanced by linking them to spatial representations, and in their analysis through tools such as GIS. Thus, GIS and other mappings, allow the event of an activity, like a change in settlement, or the development of a land drainage system, to be related to the material evidence on the ground. Thus, imagery and historical documents when combined with spatial representation become a powerful tool by which to establish the link between the documentation of human work in the long-term and the actualisation of it in the landscape.