Why were we digging here?

An archaeological excavation presents a rare opportunity to explore and investigate the remains of past communities. More often than not, due to the location and size of archaeological excavations these ‘windows into the past’ are a frustratingly restricted view of a much bigger and still hidden picture. However, some archaeological excavations offer an opportunity to a far broader perspective. Located in Hertfordshire, a few miles west of Bishop Stortford, the A120 Little Hadham Bypass and Flood Alleviation scheme is such a project. Its scope, covering a large swathe of the countryside, is allowing us the chance to examine not just a small, single location but to study, at a ‘landscape scale’, the way in which people from thousands of years ago settled within and utilised their environment.

archaeological excavation at A120
The archaeological excavations during the Summer of 2019

The following pages explain how the archaeological excavations came about; the important discoveries that were made on site; and how the on-going research is teasing out more nuanced stories regarding the people that lived and worked in this part of Hertfordshire, around 2000 years ago. In regard to this last point, the work is by no means complete; we will be updating these pages with further details in the forthcoming months. Further details on the wider project and progress associated with the construction work can be found at www.hertfordshire.gov.uk/a120bypass.

The investigations into the potential for surviving buried archaeological remains began in earnest in 2016. As with all projects of this nature, the research begins with an exploration of the local record offices and archives for evidence of former archaeological discoveries and finds in the area. Historic maps and air photographs are also used to help understanding how the landscape has changed over time and how this might affect the survival of any buried remains. Air photographs are a particularly useful tool to aid in the identification of buried archaeological remains. Due to differences in the way moisture is held in the soil, buried archaeological remains can often produce soilmarks or cropmarks (caused by differential growth) that can be seen on air photos.

view of evaluation trench
A trial trench with evidence of buried archaeological remains

However, this ‘desk-based’ research can only tell us so much. Therefore, a geophysical survey was undertaken to cover all of the land that could be affected by the construction of the new bypass and the flood alleviation scheme. A variety of different geophysical survey techniques can be deployed to prospect for buried archaeological remains; in this instance, a magnetometry survey was employed. Without needing to break the surface of the ground, this type of survey allows for the detection of buried archaeological remains producing different magnetic fields (‘anomalies’) compared to the surrounding undisturbed geology. The output of this survey is a plan of the area revealing different shades and patterns of grey (known as the ‘grey-scale’ plan). Completely invisible from the surface, some of these patterns take the form of shapes indicative of buried remains such as the foundations for walls, in-filled ditches or pits.

Geophysical survey results. Courtesy of GSB Prospection Ltd
Geophysical survey results. Courtesy of GSB Prospection Ltd

This desk-based research and geophysical survey pointed towards the possibility that buried archaeological remains survived within the area of construction. However, more conclusive evidence was required. Therefore, as is common practice, a programme of archaeological trial trenching was undertaken to test whether these cropmarks and geophysical anomalies were in fact buried archaeological remains. Spoiler alert(!), these trial trenches, measuring just 50m long and 2m wide, confirmed that there were remains of a former prehistoric and Roman period settlement surviving buried beneath the agricultural fields. This information allowed for the development of a strategy to undertake further, detailed archaeological excavations in advance of construction.