Matt Edgeworth

Diachronous beginnings of the Anthropocene: The lower bounding surface of anthropogenic deposits

Across a large proportion of Earth’s ice-free land surfaces, a solid-phase stratigraphic boundary marks the division between humanly modified ground and natural geological deposits. At its clearest, the division takes the form of an abrupt surface at the base of deposits variously called ‘artificial ground’, ‘anthropogenic ground’ or ‘archaeological stratigraphy’ – which together comprise a distinctive part of the geosphere called the ‘archaeosphere’. In other cases the bounding surface is more diffuse, gradational or mixed, due to action of non-human agencies and anthropedogenic forcings. It is alternately conformable and unconformable. Layers above typically contain artificial features, structures, artifacts and other material traces of human activity, in contrast to their relative absence in layers below. A fundamental characteristic of the boundary is that it is diachronous, still being formed and renewed today. In examining the boundary, this paper asks – does it reflect the diachronous onset and development of the Anthropocene itself?

Stratigraphic and Earth System approaches to defining the Anthropocene

Stratigraphy provides insights into the evolution and dynamics of the Earth System over its long history. With recent developments in Earth System science, changes in Earth System dynamics can now be observed directly and projected into the near future. An integration of the two approaches provides powerful insights into the nature and significance of contemporary changes to Earth. From both perspectives, the Earth has been pushed out of the Holocene Epoch by human activities, with the mid-20th century a strong candidate for the start date of the Anthropocene, the proposed new epoch in Earth history. Here we explore two contrasting scenarios for the future of the Anthropocene, recognizing that the Earth System has already undergone a substantial transition away from the Holocene state. A rapid shift of societies toward the UN Sustainable Development Goals could stabilize the Earth System in a state with more intense interglacial conditions than in the late Quaternary climate regime and with little further biospheric change. In contrast, a continuation of the present Anthropocene trajectory of growing human pressures will likely lead to biotic impoverishment and a much warmer climate with a significant loss of polar ice.

Colonization of the Americas, ‘Little Ice Age’ climate, and bomb-produced carbon: Their role in defining the Anthropocene

A recently published analysis by Lewis and Maslin (Lewis SL and Maslin MA (2015) Defining the Anthropocene. Nature 519: 171–180) has identified two new potential horizons for the Holocene−Anthropocene boundary: 1610 (associated with European colonization of the Americas), or 1964 (the peak of the excess radiocarbon signal arising from atom bomb tests). We discuss both of these novel suggestions, and consider that there is insufficient stratigraphic basis for the former, whereas placing the latter at the peak of the signal rather than at its inception does not follow normal stratigraphical practice. Wherever the boundary is eventually placed, it should be optimized to reflect stratigraphical evidence with the least possible ambiguity.

Follow the Cut, Follow the Rhythm, Follow the Material

Archaeologists do not have to look to external theory to kick-start the interpretation of material remains. Greater confidence can be placed in the meanings which emerge from our most basic encounters with archaeological evidence, which impart a direction and trajectory to research from the very outset – realigning applied ideas and giving impetus to new intellectual currents. Such emergent meanings already have intrinsic movement and vibrancy, deriving from a strong grounding in an unfolding material world opened up through excavation and direct contact with things. This paper explores the ways in which archaeologists follow the rhythms and flows of cuts, artefacts and other material entities.

The relationship between archaeological stratigraphy and artificial ground and its significance in the Anthropocene

Abstract This paper investigates the relationship between archaeological stratigraphy (in archaeology) and artificial ground (in geology) and considers their wider application to the investigation and characterization of the Anthropocene. Evidence from two archaeological case studies is used to illuminate key points. The first case study examines stratigraphic sequences from beneath the city of Leicester, UK; the second looks at stratified deposits within the prehistoric settlement mound of Abu Hureyra, Syria. Earthworks, riverworks and cultivation soils are also considered. Archaeological and geological perspectives are combined to develop a unified view of anthropogenic deposits that cover large parts of the surface of the Earth.

Scale and diversity of the physical technosphere: A geological perspective

We assess the scale and extent of the physical technosphere, defined here as the summed material output of the contemporary human enterprise. It includes active urban, agricultural and marine components, used to sustain energy and material flow for current human life, and a growing residue layer, currently only in small part recycled back into the active component. Preliminary estimates suggest a technosphere mass of approximately 30 trillion tonnes (Tt), which helps support a human biomass that, despite recent growth, is ~5 orders of magnitude smaller. The physical technosphere includes a large, rapidly growing diversity of complex objects that are potential trace fossils or ‘technofossils’. If assessed on palaeontological criteria, technofossil diversity already exceeds known estimates of biological diversity as measured by richness, far exceeds recognized fossil diversity, and may exceed total biological diversity through Earth’s history. The rapid transformation of much of Earth’s surface mass into the technosphere and its myriad components underscores the novelty of the current planetary transformation.

Micropalaeontology reveals the source of building materials for a defensive earthwork (English Civil War?) at Wallingford Castle, Oxfordshire

Microfossils recovered from sediment used to construct a putative English Civil War defensive bastion at Wallingford Castle, south Oxfordshire, provide a biostratigraphical age of Cretaceous (earliest Cenomanian) basal M. mantelli Biozone. The rock used in the buttress – which may have housed a gun emplacement – can thus be tracked to the Glauconitic Marl Member, base of the West Melbury Marly Chalk Formation. A supply of this rock is available on the castle site or to the east of the River Thames near Crowmarsh Gifford. Microfossils provide a unique means to provenance construction materials used at the Wallingford site. While serendipity may have been the chief cause for use of the Glauconitic Marl, when compacted, it forms a strong, almost ‘road base’-like foundation that was clearly of use for constructing defensive works. Indeed, use of the Glauconitic Marl was widespread in the area for agricultural purposes and its properties may have been well-known locally.

Grounded objects. Archaeology and speculative realism

The philosophical movement known as speculative realism (SR) has much in common with archaeology. As well as a shared concern with objects and with time, both have orientations towards an external reality that exists (or existed) outside the domain of human knowledge. This paper explores overlaps and commonalities in these two very different types of investigation. Proceeding from an archaeological perspective, it critically assesses the relevance of some of the key ideas of SR for archaeology, while also looking at ways in which these can be challenged, honed, adapted and transformed through encounters with archaeological objects. It asks the question, what can archaeology usefully contribute to the SR project?

Excavation as a ground of archaeological knowledge

In answering the question ‘why excavate?’, much of the discussion in this stimulating session was pitched at the level of managerial considerations (in commercial archaeology) or the pros and cons of excavation for the discipline as a whole (in academic archaeology), with some attention paid to issues of publication. While acknowledging the great importance of that debate, and the many interesting points put forward, I would like to suggest that excavation also has significance for archaeologists on a much deeper, existential, level.

Humanly Modified Ground

Humanly modified ground covers a large proportion of the ice-free terrestrial surface of the Earth. It consists of settlement debris, dumped waste, landfill, reclaimed land, cut features, earthworks, cultivation soils, and other kinds of ground significantly modified by humans. Considered as a single entity, it is expanding at accelerating rates as human population increases and is still in the process of formation and transformation. Technically part of the geosphere, it has aspects that are unprecedented in earlier geologic strata. It contains an abundance of artifacts and novel materials, as well as bones of humans and domesticated animals.