Geophysical
survey training – results from the surveys
During
a week in April 2017 geophysical surveys were carried out on two
sites in the Cannock Chase area with the project volunteers. The main
purpose was to provide training in the use of geophysical
survey methods
to enable the volunteers to conduct their own research on new sites
in the future.
The volunteers were trained to use two different geophysical methods, earth resistance (above left) and magnetometer survey (above right) © Historic England/Cara Pearce.
The
first site was a group of possible burnt mounds, expected to be of
Bronze Age date, previously identified from lidar data in the eastern
part of Cannock Chase. Earth resistance survey was targeted over the
three most prominent mounds and the results suggested the centre of
the mounds contain stony material strongly contrasting with the
surrounding damper soils deposited by the near-by river. Magnetometer
survey was also carried out over the site but only the mound to the
south (MST999), produced high readings expected from a burnt feature.
The results indicate that there are differences in the composition of
the three mounds that suggests they may vary in character and origin,
or perhaps some have been more heavily disturbed since they were
constructed.
[Left]
digital terrain model from the airborne lidar, showing the location
of the three mounds investigated on land at Sheepwash Farm and the
main geophysical survey area outlined in yellow. The jagged line
running up the image to the left of the mounds is the watercourse of
the Rising Brook. Chase Through Time 2016 lidar. Source:
Staffordshire CC/Fugro Geospatial BV 2016 © Historic England.
[Right]
A gentle swelling in the ground (about 0.5m high) shows the position
of mound A (Staffordshire HER MST999), viewed from the north-east ©
Historic England.
Greyscale
images of the geophysical survey results from both sides of the
Rising Brook superimposed on the Ordnance Survey background mapping
and satellite imagery from Google Earth ©
Crown copyright and database right 2017, OS 100024900. Satellite
imagery © 2017 Getmapping plc (from Google Earth).
Later
in the week a second survey was undertaken inside the Iron Age
hillfort at Castle Ring, although here the magnetometer produced weak
readings that were not very helpful. The earth resistance survey was
of more value, and mapped a known medieval building in the north-west
of the hillfort and evidence for associated activity in its
surrounds. A second possible building shown in the earth resistance
data may be either a new part of the medieval complex, or perhaps a
later structure related to the use of the site during the Second
World War.
Aerial
photograph of Castle Ring, taken from the north-west, with the
extensive bracken vegetation cover clearly visible. The medieval
building platform is visible in the foreground of the image with the
village of Cannock Wood in the background (NMR_20829/52, © Historic
England Archive).
A useful and interesting set of results was obtained from the data collected by the volunteers at both of the sites, and also gives us a good idea of what geophysical survey methods are best suited for future investigation in the Cannock Chase area.
Castle
Ring, Cannock Wood: Earth resistance results in relation to the 1987
RCHME plan of the
hillfort
earthworks and features with topographical expression in the interior
©
RCHME/Crown
copyright.
Reproduced from RCHME
1987 Castle Ring Hillfort, archaeological survey report: NMR no.
SK 01 SW 1.
Unpublished internal report prepared by Marcus Jecock, Historic
England Archive
reference
no. 909039.
Visitor
access issues affecting the sites:
Please
note that the burnt mounds described in this post are on private land
and are not normally accessible to the public without first seeking
permission from the landowner. Castle Ring hillfort is a publicly
accessible open space managed by Cannock Chase District Council.
More
information
Hodder,
M A and Welch, C, 1987 Burnt Mounds in the South Staffordshire Area,
Staffordshire Archaeological
Studies, 4, 15-24
English
Heritage 2008 Geophysical
Survey in Archaeological Field Evaluation,
2nd ed., Swindon: English Heritage.
We
want your feedback!
If
you have an interest in the study and investigation of the sites in
the Cannock Chase area described here and can help by adding further
supporting information then please leave a comment in the box below.
Andy
Payne,
Geophysics
Team, Historic England
Find
out more about Historic England’s involvement in the Chase Through
Time project, here:
https://historicengland.org.uk/research/research-results/recent-research-results/west-midlands/cannock-chase/
Detailed
Historic England research reports on the two geophysical surveys
carried out for the Chase Through Time project can be accessed online
at:
