'Through the visible one orientates oneself' (Berger 2005, 50)
An aptitude for the visual has long been important in finding ways to observe and record the world: James Hutton's watercolours of geological strata; archaeological drawings of sites and finds (Nurse et al. 2007); Darwin's annotated sketches of creatures and birds (Donald and Munro 2009). It is not just the resultant artwork that is important here. It is also the close attention and observation it requires, which involves thinking through ideas, and reflecting upon the wider interpretive outlook (Bender et al. 2007; Ferraby 2015b). The importance of this is highlighted when we consider how working with images has shaped the discipline of archaeology: influential thinkers within archaeology have come from a visual background - Philip Rahtz a keen photographer, Mortimer Wheeler an art student – people whose way of seeing has been drawn into the discipline more widely (Bradley 2009, 227). Working visually is a process of actively observing and absorbing the archaeological landscape; it is a process of connecting place and mind.
The use of technologies to create these visual interpretations of the world around us has also shaped the ways in which we think about ourselves within it. Engaging with instruments and machines has created another level of dialogue; one that offers another medium of aesthetic communication (DeSilvey and Yusoff 2007). The constantly evolving possibilities of technologies create a hunger to discover what is not immediately visible:
'As instruments such as lens, telescopes, microscopes, eyeglasses, spyglasses and magic lanterns altered perspectives and revealed newfound wonderment in the world, the desire to see through and beyond that which was optically available to the human eye drove the conditions of engagement and underpinned the Enlightenment pursuit of knowledge (which still has a distinct legacy today).' (DeSilvey and Yusoff 2007, 576)
Through the machines we employ, we are able to stretch our imaginations into new worlds, to ask new questions and find new solutions to old problems. For archaeologists, the past – and our knowledge of it – is wrapped up in the development of modern technologies. The different ways that we employ and visualise data provide new lenses through which to look at the world. In turn, the process of reading these images, of understanding the meanings they potentially carry, changes the way we observe. Experience with geophysical imagery can build an imagination that can travel under the surface, connecting the visible and invisible. It is an ongoing balance between the search for a 'ground-truth' and the process of imagining, coming up with ideas and testing them. Geophysics then, and the images it produces, creates its own way of understanding of the world.
What is particularly magical about geophysics is its ability to give us contact with the underworld; the sub-surface stories that lie waiting to be discovered. This requires a particular kind of imagination. Harry Hess, in his discovery of plate tectonics, expressed the same need for the imagination in understanding processes of the Earth that are not directly visible. He felt that the theory of plate tectonics was so abstract it required a certain way of thinking to be able to accept it. He therefore asked people to:
'suspend their disbelief long enough for his observations about seafloor spreading …. He needed his audience, in the absence of much hard data, to speculate imaginatively, as if reading poetry' (McKay 2013, 46, my emphasis).
The images produced through geophysical survey give richness to our archaeological imagination, allowing us to think not just about landscapes, but also through and under them. Geophysics does not offer a whole picture, rather it reveals to us elements that form the base matter of landscape: soils, stones, moisture, chemicals, magnetics and voids. The fact that this can be achieved on a landscape scale, rather than in isolation, gives us a snapshot of our land and sea that shows strands of history connecting over time and space. In this sense, geophysics has many parallels with photography. Both techniques are processes that capture time in particular ways, but which also invite us to think about the very concept of temporality and our place in it. In Camera Lucida, Roland Barthes describes how:
'For me the noise of Time is not sad: I love bells, clocks, watches – and I recall that at first photographic implements were related to techniques of cabinetmaking and the machinery of precision: cameras, in short, were clocks for seeing' (Barthes 1981, 15).
Photography offers an interesting way of thinking about time: what is captured, what is lost, the visibility of motion and static, what that moment communicates, comparisons over time. And the photograph itself becomes layered with time and meaning:
'Photography cannot help but represent the world archaeologically, since it cannot help but record its objects and landscapes in a temporal context, the traces of the past scattered across their surfaces' (Hauser 2007, 59).
Images of geophysical data are, like photographs, the capture of experience (Sontag 1973). Although the geophysicist decides where to survey, the technology captures a sweep of whatever is there regardless of the surveyor's own preoccupations with a particular period or activity. The data is a collection of the particular earthy matter: the foundation of our interpretations. The raw image therefore shows the temporality of the landscape according to what data has been captured, allowing the archaeological imagination stratigraphic freedom. It also presents a lens of landscape change: the layers of different activity caught in one image showing the flux of landscapes and the time scales across which these occur. The geophysical image itself, then, becomes another layer of cultural mediation created in the landscape.
Imagery produced by geophysical data also collects its own history, stories and sense of time. As the quality of data collection changes, we are beginning to see a history of geophysics in the images we are able to produce. But as well as the overall history, each image also holds with it the people who collected the data, the weather and conditions on site, stories of the season, the hands and mind that sat and processed the data and created the final images. Geophysics may be a hard science, but it does not differ in its inevitable saturation of people and stories. The art of geophysics, then, is also the art of time and of place.
The images can give rise to unanticipated understandings of landscapes. The collections of data exposed have the potential to echo the rhythm of ongoing events and processes within the landscape. The landscape is 'time materializing' (Bender 2002, 103), always in formation (DeSilvey 2012; Edmonds 2004; Ferraby 2015a; Harvey 2010; Ingold 1993; 2000; Massey 2006; Tilley 1994). An awareness of these temporalities of landscape and the multiple narratives flexing through them allows greater consideration of the complexities we can extract from them, the stories we can tell. But this relies upon certain ways of seeing. Geophysics offers us a set of imagery in which we can see the ebb and flow of activity in varied, animate forms. These have changed the way in which we as archaeologists see the landscape. The scales over which we can observe archaeological features and relationships have extended further into the micro- and macro-scopic. As such, geophysical data have given archaeologists the opportunity to contrast 'the temporalities of the taskspace and the temporalities of tectonics' (Massey 2006, 33). The extension of temporal and spatial understanding provided by geophysical imagery has extended our archaeological imagination, giving us a much greater sense of our relationship with the land, both today and in the past.
Scale within geophysical imagery also offers another way of seeing, in a way that is more related to abstraction and imagination. When these images are dislocated from spatial data or a map, the image can begin to take on its own sense of scale. In the detailed abstractions of monochromatic magnetometry or a fine-grained Ground Penetrating Radar slice, new landscapes can emerge: tiny yet huge worlds that challenge any sense of scale. A whole topographic existence can be caught in miniature. In this way, 'landscape is not just a matter of looking out and over, but it is also a matter of looking in, peering at small things, observing the minute details that make up the world around us in all its complexity' (Ferraby 2015b, 43).
Although found in the world of academic reports, articles and books, geophysical imagery, like other art forms, can communicate beyond words. In the formal procedures of report writing it can be difficult to find ways of describing geophysical features. We have developed a geophysical vocabulary positive – negative – anomaly – rectilinear – curvilinear – reflection – gain – trend and turn of phrase 'a positive, rectilinear feature runs from the south-west of the site', 'the anomalies are focused in one of the enclosures', 'the reflection may be a product of the nearby church wall'. It is, however, very difficult to capture in words the often rich and complex relationships of the data cells; the subtleties and uncertainties of the possible features that come in and out of focus. The image remains at the heart of the work, to be returned to again and again, its meaning shifting as our eye learns to recognise different features or patterns.
These concepts of scale, lenses, rhythms, stories, changes, histories and possibilities throw light on many different nuances and imaginaries of geophysics. On the one hand it is a form of remote sensing: a way of studying the surface and sub-surface of the Earth using signals (light, magnetics, heat, resistance), keeping us distant and removed from the ground. But what we see when we look through another lens is an artform that can bring us closer to the materiality and memories of the past, to the details and nuances of the land and sea that allow us to see ourselves. The images produced from geophysical data are not without feeling. They are not stark data. Rather they bring us closer to the world; they are a tool that we can use to frame ourselves. The collection of data allows us an opportunity to be in a landscape or seascape for a time, our concentration attentive to the character of that place. The processing of data is a poetry of algorithms designed to draw out past features of human life from the knitted histories of the geological. And interpretation of data is a way of thinking through and drawing out these features, making sense of them and trying to find the best way of representing that understanding to others.
To perceive the details and depths of geophysical imaginary takes attention, curiosity, practice and knowledge. It shows that there is neither a 'science' nor 'art' of geophysics, rather a way of being able to speculate imaginatively about the abstract marks and tones that the data create. In this way, working with geophysical imagery is very similar to painting or drawing: the landscape is an imaginative artform. Blake describes how 'To Me This World is all One continued Vision of Fancy or Imagination' (Blake in Keynes 1980, 9). Despite the seemingly objective face of data, working on and with the imagery of geophysics is subjective and personal.
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