Durobrivae - Geophysical Surveys

Pilot Survey - 2017

A pilot survey in 2017 marked the start of the NVAT's long-term programme of investigation at Durobrivae.

 

The objective was to evaluate the effectiveness of a range of geophysical survey techniques in relation to the site. The work was undertaken by volunteers from the Community Archaeology Geophysics Group (CAGG) and FRAG under the direction of Kris Lockyear of UCL.

 

Two areas of the town were targeted using earth resistivity, magnetometry, and ground penetrating radar. The mag survey gave good definition or roads and buildings and allowed coverage of a large area. The other techniques proved useful in understanding specific features.

North-west section of site using magnetometry, GRR and resistivity (left to right)

A Roman-Celtic temple was revealed in the north-west segment close to an area where aerial images have suggested civic buildings. Use of GPR enable the temple layout to be explored at different depths.

Temple: GPR time-slices 8 & 9

A - building to the north of the temple where it appears the walls have been robbed but some of the floors left intact

B - large building to the east of the temple

C - wall along the west side of the temenos of the temple

D - long wall running across the site with perhaps an entrance-like feature in it at the western end

The other area of focus was the circular mound in the south-east quadrant. The surveys revealed empty space in the middle, with a polygonal linear feature around it (showing as a magnetic positive and therefore either a cut feature, or a brick-built wall). To the east / south-east of the tumulus is a largely open area, somewhat fan shaped in appearance. To the south is a rectangular building with an east-west alignment.

Rectangular building south of mound as shown by earth resistance survey

Full Magnetometry Survey - 2018

This 2018 Durobrivae geophysical survey was commissioned by the Nene Valley Archaeological Trust and conducted by Archaeological Services Durham University.

 

The magnetometer survey encompassed 23 hectares within the walled area of the town. The survey has revealed a plan of the town, which developed along both sides of Ermine Street, a major Roman road. The layout of the town does not conform to any regular grid pattern of streets, but has various roads on different alignments.

 

Substantial lengths of the town wall have been detected, especially around the southern parts of the town, where possible wall towers or bastions have also been identified as well as two large external ditches. The survey has confirmed that the wall is staggered at at least two of the main gates, the south-east (London) and south-west (Irchester) gates.

South gate and double ditches

Many buildings have been detected, often represented by stone wall footings though others are interpreted from probable robber trenches or construction slots. The buildings are concentrated along the roads, typically with a short gable end at the street frontage, though many other buildings are also present, set further back, away from the roads. Two particularly large buildings or complexes have been detected, both on the west side of Ermine Street. The southern of these comprises a very large courtyard building, set a short distance back from the road within a largewalled enclosure, with smaller, ancilliary buildings (possibly stables and/or baths) and almost certainly a temple at the south-western corner of the enclosure. This complex may have been a mansio, though the large complex just to the north could equally have served such a function. Unusually for a Roman ‘small town’, both buildings appear to have had official or public functions.

Durobrivae - Large buildings and possible temple south-west of Ermine Street

The majority of buildings measure between 12-18m in length and 7-9m in width, though both larger and smaller buildings are also present. The buildings which share a street frontage are densely packed and there is magnetic evidence to suggest that a substantial fire spread through many of the buildings towards the northern corner of the walled town, along both sides of Ermine Street; the fire appears to have extended for about 130m along the road.

Many smaller isolated anomalies probably reflect waste pits, wells, ovens and hearths. Larger irregular shaped pits were almost certainly for sand and gravel extraction.

Pre-Roman features detected within the survey might include a few circular and arcuate ditches, which could possibly be associated with Bronze Age barrows. The age and nature of the low mound and its associated ditches in the south-east quarter of the site remain uncertain. Whilst the area within the inner ditch circuit appears to be undisturbed, there may have been some encroachment of settlement across the outer ditch circuits. This feature may be part of the prehistoric landscape of the Nene Valley.

Durobrivae - Circular mound and ditches

Another feature which probably pre-dates the Roman settlement is a ditch aligned north-east/south-west, which appears to underlie the whole of the walled town area. This could perhaps be the remains of a landscape-scale boundary ditch, such as those recorded at Ferry Meadows to the east.

Durobrivae and Surrounding Area

The Nene Valley Archaeological Trust also facilitated a geophysical survey of the neighbouring Normangate Field between Durobrivae and Castor to the north of the River Nene. This emphasises the intensity of urban activity outside of the walled town.

This is incorporated into the following composite map which also includes information derived from aerial photographs.

Composite derived from 2018 magnetometry surveys, aerial photographs and LIDAR

Ermine Street runs north-west to south-east. Normangate Field to north of River Nene.

Water Newton Fort on higher ground. Durobrivae to the south-east.

R Gibson (after S Malone)

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