Geology/archaeology in action: a personal perspective

This article uses Bruno Latour’s concept of Science in Action to consider the relationship between archaeology and geology. It is argued that neither the New Archaeology nor Postprocessual Archaeology provides a strong foundation for dialogue between archaeology and geology. Significant differences in temporal scale and structure pose a significant hurdle to integration of geology and archaeology. However, the practice of both disciplines is characterized by an internal tension between the use of imagination and intuition versus a reliance on data. This dynamic provides the basis for cooperation between geology and archaeology, but it must be realized that collaboration requires that geologists be seen as equal partners in inquiry rather than as specialists in service of an archaeological research agenda.

In his influential book Science in Action, Bruno Latour (1987) illustrated his view of the two sides of science through a series of simple cartoons of a Janus-faced image. In Latour’s view, science is at once a process where all is in play—science in the making—and at the same time a set of established facts. Latour’s Janus figure is an effective visual metaphor and one that is used in this paper to develop a perspective on the common ground shared by geology and archaeology (Fig. 1).

It is first worthwhile to consider the internal dynamics of archaeology, which are often represented as a dichotomy between New Archaeology and Postprocessual Archaeology (see for example Chazan 2013). These are not the Janus faces of archaeology, two voices that speak from one body, but rather something of a two-headed monster where each face projects forward simultaneously, in seeming combat for our attention. Although the New Archaeology/Post-Postprocessual dichotomy remains of pedagogical value, the reality of archaeological practice has long left this dynamic behind. In particular, neither Postprocessual nor the New Archaeology provides a strong basis for geoarchaeology. Postprocessual archaeology, at least in its rhetoric, often opposes scientific method, although the call for a contextual understanding of archaeological deposits provides an excellent basis for attention to site formation processes. Unfortunately, in the postprocessual literature, ‘contextual’ is often exclusively linked to aspects of human subjectivity relegating other aspects of context to secondary status. The result is to undervalue methods that do not inform us about subjective experience and in some cases to shoehorn geoarchaeology into filling this role.

It might be assumed that New Archaeology, which drew on a rhetoric valorizing science, would offer a strong prospect for a unified geoarchaeology. However, I find that a number of aspects of the New Archaeology have actually had a negative effect on the development of a serious working relationship between geology and archaeology. The New Archaeology emphasized archaeology as a social science (Binford 1962). Rather than valuing scientific practice, the New Archaeology placed an emphasis on the rhetoric of positivism, a rhetoric that today feels dated in almost all aspects of natural science research and never really applied to geology. The goal set by the New Archaeology for the geologist is to provide data needed to further the archaeological agenda. Ironically, the New Archaeologists who rebelled against being dismissed, in a tellingly sexist phrase, as the ‘handmaidens of history’, did not hesitate to relegate geologists to the scullery.

At a deeper level, the New Archaeology developed in part as a reaction against what Walter Taylor described as ‘the archaeologist as technician’ (Taylor 1967). To a degree, the New Archaeology deemphasized the development of analytical skills in favour of couching research programs within the framework of hypothesis testing. There were areas such as faunal analysis and palaeoethnobotany where the New Archaeology encouraged the development of analytical skill, but there are strong reasons to largely attribute these developments to the effects of Economic Archaeology as developed by Grahame Clark rather than the American New Archaeology (see discussion in Trigger 1989: 244–286).

Differences Between Geology and Archaeology

Both archaeologists and geologists are interested in processes that took place in the past. However, there are significant differences in the temporal dimension of these disciplines. The most essential is that archaeologists are interested in the human past with a time depth of 2.5 million years while geologists look at a timescale that reaches back over 2 billion years. Even when geologists are looking at Quaternary processes, which overlap chronologically with archaeology, or events taking place over very short time intervals, they are conscious of longer-term processes of landscape formation. Beyond this essential difference in time scale, the fact that archaeologists’ subject matter is the human past introduces a narrative structure that is largely absent from geology. Archaeologists are, after all, talking about people much like themselves whereas geologists are engaged with physical processes, which are governed by natural laws that are predictable to a certain degree. The contrast in narrative strategies is evident in the differences between the disciplines in practices related to periodization. The recent decision of the International Union of Geological Sciences (IUGS) to move the boundary between the Pliocene and Pleistocene provides an archaeologically relevant illustration of how geologists approach periodization (Gibbard et al. 2010). One issue was the determination of the position of the Quaternary within a hierarchical chronological system. But the key question was where to situate the Pliocene-Pleistocene (epochs) Boundary which in accepted systematics is also the boundary between the Quaternary and Neogene periods. The accepted boundary had been the base of the claystone conformably overlying the sapropelic marker bed ‘e’ in the Vrica section in Calabria, southern Italy, dated to 1.8 mya. The problem with this marker was the widespread consensus that 1.8 mya does not mark the inception of global cooling. The IUGS decided, following by a vote of members, to set the Pliocene-Pleistocene boundary to the top of the sapropelic Nicola bed in the Monte San Nicola section dated to 2.58 mya. This age is a fixed point in time that correlates to a long-term planetary process of global cooling linked to the closure of the Panama isthmus. It is important to emphasize that the goal in fixing the chronological marker was not based on a determination of a ‘moment’ when the earth’s climate changed. Rather, it is a fixed and identifiable point within a gradual process. There is no moment when the earth’s climate changed so that the boundary point is to some extent arbitrary within a range.

It is worth noting that geological systematics does generally recognize human activity as a relevant factor. However, the IUGS committee grudgingly allows for the recognition of the Holocene as an epoch ‘distinct from the Pleistocene, in recognition of the fundamental impact of humans on an otherwise unremarkable interglacial’ (Gibbard et al. 2010: 101). More recently, geologists have taken up the proposal of the Anthropocene as an epoch in which humanity has become a planetary force.

In contrast, the conceptual basis of archaeological chronologies is rarely the subject of explicit debate. For the Palaeolithic, chronologies combine an absolute age range with characterization of lithic industries. The characterization of lithic industries can combine notions of progress in the degree of sophistication alongside stylistic markers used as signifiers of a continuous population (Chazan 1995). The process involved in defining the chronology is rarely made explicit (although see Dusseldorf et al. 2013 for a recent exception). To my knowledge, there has never been an effort to base archaeological chronologies on fixed arbitrary points in time that are linked to global processes, although archaeologists increasingly use oxygen isotope stages as a temporal scaffolding. The distinctiveness of archaeological chronology is the insistence on creating entities—whether industries or cultures—that are then situated in time. These entities are not considered as simply convenient or recognized as arbitrary markers as is the case with geological time divisions. These archaeological entities are essential tools for incorporating prehistory into the kinds of narrative structures found in the writing of later stages of history—creating a unified narrative of human life on earth. For geologists, there is no such imperative as their history is not of humanity but rather of physical processes in the history of planetary systems.