Chronicle Heritage now offers geoarchaeology services, thanks, in part, to the addition of an expert in the field.
Lisa Snape, Associate Archaeologist, joined Chronicle Heritage Arabia in May 2024. She has a Master of Science in Geoarchaeology from the University of Reading and a Doctor of Philosophy (Ph.D.) in Archaeology from Durham University, both in the United Kingdom. Snape has worked on a number of Chronicle Heritage sites in Saudi Arabia, most notably a site in the northwest corner of the country where she used portable optically stimulated luminescence (OSL) analysis and dating.
OSL, which goes well beyond carbon dating, is a “method to directly date sediments and soils by looking at the last time minerals were exposed to sunlight prior to burial,” said Snape. “We can use different luminescence signals and experimental techniques to go as far back as approximately 700,000 years ago,” according to a relatively recent study of early-to-middle Pleistocene wind-blown sediments from the Eastern Mediterranean (Faershtein and others 2020).
The sampling will provide a local paleoclimatic record of northwest Saudi Arabia, according to Mary Davis, Senior Archaeologist that worked with Snape at the site. “The results of this preliminary characterization will be with us very soon.”
Why is Geoarchaeology Important?
As the saying goes, the past informs the present. In the case of geoarchaeology, practitioners use what they learn about human interactions with past environments to inform present interactions with the environment and landscape.
The discipline is especially relevant in areas affected by climate change, according to Snape.
“We can use the past to inform the present concerning the environment, looking at how to sustainably use the landscape, and how we can use low-impact approaches to things like farming and irrigation,” she said.
Snape said there are a handful of environmental issues she tracks when working in Saudi Arabia, including:
- Flooding
- Erosion
- Desertification
“It’s important to know about climatic events and how they may impact the preservation and visibility of an archaeological site,” said Snape.
OSL in Practice
Snape has been using OSL since she was a Ph.D. candidate at Durham University. She said the technique can be used in various settings, but that it is “especially effective in arid environments where you have a lot of sunlight and you have a wind-blown component to the sediments, which makes the sediment much more ideal for luminescence dating.”
“In arid climates, you’re going to get more phytoliths, whereas they’re less likely to survive in, say, a wetland in the UK, where you’re more likely to find pollen, which preserves well in acidic peatland contexts,” said Snape.
Phytoliths are microscopic siliceous particles formed by a plant that are highly resistant to decomposition, according to Merriam-Webster.
On the Chronicle Heritage project site in northwest Saudi Arabia, working with other experts in the field, Snape and colleagues were able to identify protected areas where they could target Paleolithic artifact layers with a buried land surface below, which offered unique opportunities to test the OSL technique with the aim of developing a chronostratigraphy for these sites.
“We wanted to understand whether these artifacts were in situ or whether they were redeposited from other sites,” she said. “We spent a lot of time collecting the artifacts and studying them. And then, below these, taking samples at night under red light conditions, and taking blocks to then date these buried land surfaces potentially back as early as the lower Paleolithic period. We are also interested in how people lived in the landscape and utilized natural resources.”
Bringing Geoarchaeology to the UK, Europe & the US
As a Ph.D. candidate, Snape used OSL and applied geoarchaeology to irrigation and agricultural features in Spain, the Caucasus, and Oman. Now, she wants to bring the service to not just those countries, but the rest of Europe, the United Kingdom, and the United States through Chronicle Heritage.
“I’m interested in how these techniques can be used across Europe and beyond,” she said.
Her past geoarchaeology work also includes “looking at ancient agricultural systems, such as the Stonehenge landscape,” as well as “a European research project on agricultural terraces in Belgium, Italy, France and the UK.”
Snape said that, essentially, any archaeological site calls for a geoarchaeological assessment.
“I think it’s really important to have a geoarchaeological assessment of the landscape before any archaeological work is undertaken to determine how much archaeology you’re going to find, to what scale it’s going to be at, and what preservation potential there is for the sites and landscapes. It’s an important stage of any development project to have that initial geoarchaeological assessment of the site and know how it relates to the landscape and the environment.”