GlosArch has an active fieldwork programme. We perform geophysical surveys of sites of potential archaeological intertest using resistivity and magnetometry to look beneath the ground and we undertake archaeological excavations at sites brought to our attention by members. No prior experience is required to take part in either of these activities and training and equipment are available to borrow. We also study sites and landscapes using publicly available resources, including historic maps, aerial photographs and LIDAR.
For details of forthcoming activities please see the Home page.
Geophysical Surveys
Resistivity surveying measures changes in the ground resistance to a current passed between a pair of reference electrodes and a pair of sensing electrodes, caused by archaeological features beneath the ground. Solid objects, such as buried foundations or paths, result in higher resistance, whilst cut features such as ditches result in lower resistance. Readings are taken at regular intervals over a series of 20mx20m grids and the values are used to create a two-dimensional image of what is under the ground using computer software. GlosArch owns a TR/CIA resistivity meter.
Recent surveys have been undertaken a on Cleeve Hill at the site of the grandstand of the first racecourse, at the hillfort and The Ring on Cleeve Common, and ahead of excavations at Brookthorpe and Minsterworth. Further work is planned on Cleeve Hill.
Magnetometry, as the name suggests, uses tiny variations in the earth’s magnetic field to identify archaeological features beneath the ground. Disturbance of the ground, for example by a filled-in ditch, changes the orientation of magnetic particles in the ground relative to the earth’s natural field and can be detected by the magnetometer. As with resistivity surveying, readings are taken at regular intervals over a series of 20x20m grid squares and the measurements are converted to an image of the site using computer software. GlosArch recently purchased a Frobisher DFG-1 magnetic gradiometer.
Recent surveys have taken place at Brookthorpe and at the Cleeve Common hillfort. Future work is planned at some other potentially interesting sites on Cleeve Hill as well as extending the survey at Brookthorpe and surveying some features at Castlemeads on Alney Island opposite Gloucester prison.
Cleeve Hill – Cheltenham’s first racecourse.
Following our successful identification last year of the second grandstand of the original Cheltenham racecourse, which was active from 1819 until the 1840’s, we have recently undertaken a magnetometry survey to try to locate the first grandstand, that was burnt down, probably as a result of arson, in 1829. No clear evidence of this wooden structure has been detected to date. The work generated quite a lot of media interest with an interview on BBC Points West and a report in The Racing Post.
The possibility of a small excavation, some time next year, is being considered.
Forthcoming Geophysical Surveys
Castlemeads, Gloucester
The committee has agreed to undertake a magnetometry survey of earthworks identified by LIDAR at Castlemeads on Alney Island opposite Gloucester prison. Resisitivity confirmed the presence of archaeology (Glevensis 52) and magnetometry will be undertaken as an adjunct to this survey, to try to gain more information on this important site. The dates for the survey are Friday 27th and Saturday 28th October, with contingency days of Sunday 29th/Monday 30th. I estimate the survey should take 2 days as we will be surveying around 20 grids.
If you would like to take part please email: fieldwork@glosarch.org.uk Please note no previous fieldwork experience is required to take part.
Excavation
GlosArch and its predecessor GADARG (Gloucester and District Archaeological Research Group) has a long history of archaeological excavations. Before the advent of the commercial archaeology units, our members were involved in excavations during the redevelopment of Gloucester in the 1970s and 80s and during the building of the M5 motorway.
Following careful planning a number of trenches are sited over likely archaeological features, often identified by geophysical surveying. Once the turf and topsoil has been removed the excavators carefully remove soil a layer at a time to reveal the hidden features, which may be foundations, pits, ditches and other features. Artefacts recovered from the soil layers are recorded along with the layer in which they were found. These can be studied further at a later date and may be sent for expert analysis. They can help us determine how old the site is. The features identified are recorded by photography and drawing to help us to understand what was going on at the site and the sequence of events.
Current Excavations
Brookthorpe
In 2021 and 2022, GlosArch volunteers, led by Neil Cathie excavated several trenches in two fields adjacent to the M5. The aim of the project is to locate the final remains relating to a Roman villa that was largely destroyed when the M5 was built in 1969.
The trenches revealed substantial amounts of Roman building materials including roof tile, painted plaster and an impressive 9kg of tesserae (mosaic tiles) of six different sorts. Further excavation is planned for Sunday 12th, Monday 13th, Friday 17th and Saturday 18th November.
The interim report on the work can be found here
Severn Bank, Minsterworth
A discussion between one of our members and the landowner of this house, which borders the River Severn, led to this project to try to locate the remains of a farmhouse that is seen on a map of the village from 1757. Following resistivity and ground penetrating radar surveys in 2019, it was decided to undertake excavation to try to locate the building and understand some of the features seen on the geophysics.
Once again, Neil Cathie led the dig which placed several trenches over features seen on the geophysics. Although no building was identified, some building materials were found along with an array of pottery, nails, bone and iron ore nodules. There also appeared to be a trackway corresponding to a linear feature on the geophysics.
Subsequently LIDAR has been obtained that shows the traces of ancient hedge lines, which will enabled us to target the building more accurately.
We returned to the site in early August and identified further pottery, building materials and occasional interesting small finds which may help us to date the site. we also identified the remains of a stone wall in the expected place, and orientation, rather deeper than anticipated. The dig also saw the first outing for new tent, bought with a grant from BGAS, for which we are most grateful.
Time caught up with us again, so we are considering returning to the site next year.
Miserden
Neil Cathie led a preliminary excavation on a site near Miserden at the request of the landowner. The initial results are promising, with a well-constructed wall, abundant building materials together with a range of pottery and other artefacts. The intention is to return to undertake a small further excavation in the near future.
LIDAR
LIDAR (Light Detection and Ranging) is a way of imaging the ground using a Laser carried by an aeroplane. The Laser beam is bounced off the ground and recorded by the plane, giving accurate measurement of the height of points on the ground. When these points are put together they can create an image of thew ground surface. Since the Laser penetrates vegetation the image is not restricted by trees or shrubs covering the ground. The method has been used to locate lost cities in the jungles of central America for example.
In 2009, GlosArch (GADARG) undertook a project to assess various features of possible archaeology that had been identified along the Cotswold edge by LIDAR. Of the eight sites assessed, six showed evidence of significant archaeology, whilst at two the investigations were unable to confirm anything of significance. The results of this work have been published as “Seeing through the trees” which can be viewed here
More recently, we have employed LIDAR to investigate the hillfort on Cleeve Hill, Glos., (Glevensis 55), a site on the top of Churchdown Hill (Glevensis 54), our excavation sites at Brookthorpe and Minsterworth (see Excavations) and to locate the grandstand of the first Cheltenham racecourse on Cleeve Common. If you are interested in accessing LIDAR data for somewhere you wish to study, please let us know and we will be able to help.
Fieldwalking
This is a powerful archaeological procedure to systematically sample the upper surface of cultivated or disturbed ground, in an effort to locate or map the distribution and extent of archaeological sites. The basic assumption is made that the topsoil contains distinctive traces of archaeological activity deposited onto or into the topsoil from above, for example waste from an episode of flint knapping by someone sitting on the ground and also material from features underneath the topsoil that are exposed to the effects of cultivation or ground works and therefore mechanically brought into the ploughsoil. Cultivation will have mixed all these different sources of material together, and a proportion of what is in the soil will be visible on the surface.
Conventionally, fieldwalking in grids or along lines called transects has formed the backbone of archaeological survey fieldwork, at least where visibility is fairly good. A single researcher or team will walk slowly through the target area looking for artefacts or other archaeological indicators on the surface, often recording aspects of the environment at the time. The method works best on either ploughed ground or surfaces with little vegetation. On ploughed surfaces, as the soil is turned regularly artefacts will move to the top. Erosion and soil loss on uncultivated and lightly vegetated soil (e.g., in semi-arid environments) may also cause artefacts to ‘rise’ to the surface.