The Flag Fen Auger Survey Project

Posted on: 21/10/2025

Volunteers celebrate after completing one of the final auger points. Image: David Matzliach

Between the 15th of September and the 3rd of October 2025 volunteers and archaeologists from the Cambridge Archaeological Unit and the McDonald Institute for Archaeological Research carried out an auger survey at Flag Fen. Investigating over 200 points in the surrounding area, the project explored the setting of the Bronze Age monument to better understand this fascinating prehistoric site.

What is an auger survey?

Images: Flag Fen volunteer, Emma Bothamley

An auger survey is an archaeological method that is designed to examine the different layers, known as deposits, present below the ground. An auger, a tool similar to a corkscrew that captures an amount of soil/sediment as it is turned into the ground, is used to examine how the layers change beneath our feet.

The depth of each auger turn is carefully monitored, and the recovered sediment is laid out in sequence to create a soil profile. This profile shows how the layers of soil change from the present ground surface under our feet down to the “natural”, the layer below which no human activity is present.

Identifying each layer is key, using the characteristics of the soil to work out where different sediments begin and end. Changes in the compaction of the soil (is it compact, soft, loose?), its colour, its composition (is it silty, sandy or clayey?), and the presence or lack of other elements like stones, charcoal or fragments of waterlogged wood are all used to separate the deposits. This information is recorded for each auger point and added to the depth measurements of each layer, building a valuable dataset of the landscape over time.

Understanding Flag Fen’s Landscape

Images: Flag Fen volunteer, Emma Bothamley

Flag Fen is a fascinating prehistoric monument, a timber causeway stretching over a kilometre across a basin between areas of high ground at Fengate and Northey. Alongside the archaeology of the monument itself, it is essential to build up a detailed understanding of the surrounding landscape. Investigating wider questions can provide archaeologists with fresh insights and ideas about how a site might have developed over time and how it was used. For example, how deep is the basin in which Flag Fen’s timber causeway was built? How wet was the landscape when the monument was being used?

In the Fens, an environment where thick layers of peat can make “reading” the buried landscape and archaeology difficult, an auger survey is an ideal, simple technique to build a picture. The value of the survey lies in augering across a wide area, comparing each point’s information and building up a detailed knowledge of the underlying changes. At Flag Fen 202 points, spaced at 50m intervals, were augered along the length of the monument and extended into the surrounding area.

The next steps for the project are the creation of a computer deposit model by Dr Phil Stastney from the McDonald Institute for Archaeological Research’s Fenscapes project. Using the information recorded from the auger survey and combining it with other data sources the model will help to build a more complete overview of Flag Fen and its environment. The model’s insights into the landscape’s topography and how the site’s deposits vary will be an important element in informing any future work at Flag Fen.