School of History, Classics and Archaeology

Alicia Hart Sawyer

Alicia Hart Sawyer

An Integrated Microstratigraphic Approach to Prehistoric Fuel Use in the Archaeological Record: Developing the Potential of Ash through Integrating Microfossil Analysis and Geochemistry in Viking Age Iceland

Year started


Project outline

Ash – the inorganic residue that remains after the combustion of the resource – represents a ubiquitous component of archaeological sites and can be targeted as an indicator of controlled use of fire for a range of activities: food preparation, heat, crop processing and goods production (metals and pottery). Ash residues also provide information on the type of fuel resource utilized for these activities and is therefore closely linked to understanding human-environment interactions. Despite its prevalence and importance in identifying and understanding these past behaviours, research on ash residues has primarily focused on fuel derived from wood, leaving non-woody resources – and the behaviours linked to these resources – largely ignored. Non-wood fuels are difficult to identify using traditional archaeological methods. In regions where wood was a limited commodity or not available, peoples naturally turn to other fuels as their primary resource. Identifying these types of ash deposits is key if we are to understand the full range of socio-cultural activities at local scales.

This research will fill this gap in our understanding by developing a multi-scalar geoarchaeological approach for the identification of non-woody ash and other fuel resources. The proposed approach will combine traditional macroscopic geoarchaeological principles including stratigraphy, sedimentology, and pedology, with microscopic approaches including thin-section micromorphology, bulk geochemical analyses through the application of Fourier Transform Infrared Spectrometry (FTIR) and portable X-ray fluorescence spectrometry (pXRF), and microfossil identification through the application of Scanning Electron Microscopy (SEM). For the sake of archaeological comparison, this research will be supplemented with controlled experiments of burned fuels in order to create a database of references for burned signatures. By developing a method to identify unique properties and characteristics of non-woody fuel residue using set burn conditions the results serve as identifications of specific fuel resources but will also allow for comparability between fuel types. While this research focuses on fuel use in Viking Age Iceland, the goal is that the method and ash database developed through this research will be applicable to archaeological contexts in other regions and time periods.

Funding awards

Research Excellence Academy Studentship 2017-2020
Marjorie A. O’Connell Smith Scholar, Boston University 2014-2016

Academic qualifications

BA Anthropology, University of California, Los Angeles (Summa Cum Laude) 2008
MA Geoarchaeology, Boston University 2016. Thesis: Site Formation Processes at Three Viking Age Farm Middens in Skagafjörður, Iceland

Publications And Conference Presentations

2015 Holcomb, J. A. and A. Sawyer. Quantifying Context: Integrating pXRF Chemostratigraphy and Thin-Section Micromorphology at Skagafjörður Northern, Iceland. Paper presented at the Geological Society of America annual meeting: Baltimore, MD.
2015 Sawyer, A. Modeling Past Landscapes Using Tephra Chronostratigraphic Horizons: a Method Combining GIS and Micromorphology. Presentation given at the Northeast Environmental Archaeology Network annual meeting: Boston, MA.
2015 Sawyer, A. and J. A. Holcomb. Interpretation of Midden Formation Processes at Three Farms in Skagafjörður, Northern Iceland using Thin Section Micromorphology and pXRF Chemostratigraphy. Poster presented at the Society for American Archaeology annual meeting: San Francisco, CA.