T H A M E S V A L L E Y ARCHAEOLOGICAL · The site is located on the western side of Fleet, to the...

T H A M E S V A L L E Y

S E R V I C E S

ARCHAEOLOGICAL

Land at Netherhouse Copse, Hitches Lane, Fleet, Hampshire

Geophysical Survey (Magnetic)

by Kyle Beaverstock

Site Code: NCF18/109

(SU 7958 5329)

Land at Netherhouse Copse, Hitches Lane, Fleet, Hampshire

Geophysical Survey (Magnetic) Report

For Berkeley Homes Ltd.

by�Kyle�Beaverstock

Thames�Valley�Archaeological�Services�Ltd

Site Code NCF 18/109

September 2018

iThames Valley Archaeological Services Ltd, 47–49 De Beauvoir Road, Reading RG1 5NR

Tel. (0118) 926 0552; Fax (0118) 926 0553; email [email protected]; website: www.tvas.co.uk

Summary

Site name: Land at Netherhouse Copse, Hitches Lane, Fleet, Hampshire

Grid reference: SU 7958 5329

Site activity: Magnetometer survey

Date and duration of project: 12th - 20th of September 2018

Project coordinator: Tim Dawson

Site supervisor: Kyle Beaverstock

Site code: NCF18/109

Area of site: c. 21ha

Summary of results: The geophysical survey was successfully completed across the entire study area. It recorded a range of magnetic anomalies, several of which may indicate the presence of buried archaeological features. These include probable field boundaries and a possible structure.

Location of archive: The archive is presently held at Thames Valley Archaeological Services, Reading in accordance with TVAS digital archiving policies.

This report may be copied for bona fide research or planning purposes without the explicit permission of the copyright holder. All TVAS unpublished fieldwork reports are available on our website: www.tvas.co.uk/reports/reports.asp.

Report edited/checked by: Steve Ford� 9.10.18 Tim Dawson� 9.10.18

1

Land at Netherhouse Copse, Hitches Lane, Fleet, Hampshire A Geophysical Survey (Magnetic)

by Kyle Beaverstock

Report 18/109

Introduction

This report documents the results of a geophysical survey (magnetic) carried out at Hitches Lane, Fleet,

Hampshire (SU 7958 5329) (Fig. 1). The work was commissioned by Anna Harper on behalf of Berkely Homes

(southern) Limited, Berkeley House, Bay Tree Avenue, Leatherhead, Surrey KT22 7UE.

Planning permission (16/01651/OUT) has been gained from Hart District Council to create new housing

and a country park on land north of Netherhouse Copse, Hitches Lane, Fleet, Hampshire (Fig. 1). The consent

includes a condition (17) relating to archaeology.

This is in accordance with the Department for Communities and Local Government’s National Planning

Policy Framework (NPPF 2012) and the District’s policies on archaeology. The field investigation was carried

out to a specification approved by Mr Neil Adam, Senior Archaeologist for Hampshire County Council. The

fieldwork was undertaken by Kyle Beaverstock, Ashley Kruger, David Sanchez, Daniel Haddad and Daniel Neal

and the site code is NCF18/109.

The archive is presently held at Thames Valley Archaeological Services, Reading in accordance with

TVAS digital archiving policies.

Location, topography and geology

The site is located on the western side of Fleet, to the north of Crookham Village and to the east of Dogmersfield

(Fig. 2). The site comprises of three irregularly shaped fields, one large field to the north and two smaller fields

to the south. Whilst the land is relatively flat in the two southern fields the northern field contains a low hill

which rises from 69m above Ordinance datum (aOD) to 79m aOD in the centre of the field. The land has been

used for arable farming but is currently under pasture. The underlying geology is stated as being Bracklesham

Beds (BGS 1981). Conditions during the survey were overcast but dry for the northern field and clear and dry for

the southern areas (Pl. 1-4).

2

Site history and archaeological background

The archaeological potential of the site has been highlighted in a desk-based assessment (James 2016). A modest

range of sites and finds are recorded for the area but recent fieldwork to the north-west has revealed Middle

Bronze Age occupation and a ceremonial monument along with a Roman settlement (Pine 2016).

Methodology

Sample interval

Data collection involved the traversing of the survey area along straight and parallel lines using two cart-

mounted Bartington Grad601-2 fluxgate gradiometers. Even coverage was achieved with the use of regularly

spaced markers at the ends of traverses and the real-time positional trace plot. Readings were taken at 0.25m

intervals along traverses 1m apart, providing an appropriate methodology balancing cost and time with

resolution. Traverses were walked at an alternating east to west zig-zag orientation across the northern survey

area and north-west to south-east in the eastern field. No significant obstructions were encountered within the

propsed area other than a small ridge of overgrowth in the centre of the large northern field and some further

overgrowth between the two southern fields.

The Grad 601-2 has a typical depth of penetration of 0.5m to 1.0m. This would be increased if strongly

magnetic objects have been buried in the site. Under normal operating conditions it can be expected to identify

buried features >0.5m in diameter. Features which can be detected include disturbed soil, such as the fill of a

ditch, structures that have been heated to high temperatures (magnetic thermoremnance) and objects made from

ferro-magnetic materials. The strength of the magnetic field is measured in nano Tesla (nT), equivalent to 10-9

Tesla, the SI unit of magnetic flux density.

Equipment

The purpose of the survey was to identify geophysical anomalies that may be archaeological in origin in order to

inform a targeted archaeological investigation of the site prior to development. The survey and report generally

follow the recommendations and standards set out by both English Heritage (2008) and the Chartered Institute

for Archaeologists (2002, 2011, 2014).

Magnetometry was chosen as a survey method as it offers the most rapid ground coverage and responds to

a wide range of anomalies caused by past human activity. These properties make it ideal for the fast yet detailed

surveying of an area.

3

The detailed magnetometry survey was carried out using two dual sensor Bartington Instruments Grad 601-

2 fluxgate gradiometers mounted upon a Bartington non-magnetic cart. A two-wheeled lightweight structure

pushed by hand, the cart consisted a bank of four vertically-mounted Bartington Grad601-2 magnetic sensor

tubes at 1m apart and a Trimble Geo 7x centimetre edition GPS. Readings were collected by two Bartington

Grad601-2 loggers and collated using MLgrad601 software on a Linx 12x64 tablet running Windows 10

mounted at the rear of the cart. This enables readings to be taken of both the general background magnetic field

and any localised anomalies with the difference being plotted as either positive or negative buried features. All

sensors are calibrated to cancel out the local magnetic field and react only to anomalies above or below this base

line. On this basis, strong magnetic anomalies such as burnt features (kilns and hearths) will give a high response

as will buried ferrous objects. More subtle anomalies such as pits and ditches can be seen from their infilling

soils containing higher proportions of humic material, rich in ferrous oxides, compared to the undisturbed

subsoil. This will stand out in relation to the background magnetic readings and appear in plan following the

course of a linear feature or within a discrete area.

The Trimble Geo7x centimetre edition GPS system with centimetre real-time accuracy was used to tie the

cart traverses into the Ordnance Survey national grid. This unit offers both real-time correction and post-survey

processing; enabling a high level of accuracy to be obtained both in the field and in the final post-processed data.

Data gathered in the field was processed using the TerraSurveyor software package. This allows the survey

data to be collated and manipulated to enhance the visibility of anomalies, particularly those likely to be of

archaeological origin. The table below lists the processes applied to this survey, full survey and data information

is recorded in Appendix 1.

Process EffectClip from -1.8 to 2.2 nT Enhance the contrast of the image to improve the

appearance of possible archaeological anomalies.

De-stripe: median traverse Removes the striping effect caused by differences in sensor calibration, enhancing the visibility of potential archaeological anomalies.

De-spike: threshold 1, diameter 3 Compresses outlying magnetic points caused by interference of metal objects within the survey area.

De-stagger: 50cm, Shift Positions Cancels out effects of site’s topography on irregularities in the traverse speed.

The raw data plot is presented as a greyscale plot shown in relation to the site (Figs. 2, 5, 8, 11) with the

processed data then presented as a second figure (Figs. 3, 6, 9 12), followed by a third plan to present the

abstraction and interpretation of the magnetic anomalies (Figs. 4, 7, 10, 13). Anomalies are shown as colour-

coded lines, points and polygons.

4

The greyscale plot of the processed data is exported from TerraSurveyor in a georeferenced portable

network graphics (.PNG) format, a raster image format chosen for its lossless data compression and support for

transparent pixels, enabling it to easily be overlaid onto an existing site plan. The data plot is combined with grid

and site plans in QGIS 2.18.15 and exported again in .PNG format in order to present them in figure templates in

Adobe InDesign CS5.5, creating .INDD file formats. Once the figures are finalised they are exported in .PDF

format for inclusion within the finished report.

Results

The geophysical survey of the site identified several magnetic anomalies across the area, some of which may

represent buried archaeological features. These linear positive anomalies are all located within the larger field

which comprises the majority of the site (Figs. 6 and 9) and most likely represent buried cut features such as

ditches of unknown date. The two most extensive of these anomalies run from near the north-western corner of

the site with one heading roughly southwards for 165m [Fig. 7: 1] and the second heading in a more easterly

direction for a distance of 270m [2]. At the southern end of [1] a further strong positive anomaly [3] curves to

the south-east for a distance of 125m while, near the junction with [1], a pair of weaker linear positive anomalies

run perpendicularly eastwards [4]. To the north-east of these is another weak curvilinear positive anomaly [5] on

an approximately east-west orientation with a set of stronger anomalies [6] running almost parallel to one

another in a northerly direction towards [2]. To the north of linear anomaly [2] are several shorter lengths of

weak positive anomalies. Two of these [7 and 8] are orientated approximately perpendicular to [2], the third

forms a right-angle [9] with the two edges measuring c.7m in length and meeting in an east-pointing angle, while

the fourth consists of a curvilinear [10] which almost forms the northern half of a circle with a diameter of

c.20m. Between [7] and [8] is a set of stronger positive anomalies which appear to for a pair of conjoined

rectangles on a north-west – south-east orientation [11]. The final anomalies of possible archaeological origin are

located at the eastern end of [2] where a pair of parallel weak positive anomalies [Fig. 10: 12] extends south-

west from the end of the stronger anomaly. The majority of these anomalies most likely represent buried field

boundary ditches of unknown date but the pair of rectangular features at [11] may be the remains of a structure.

The only magnetic anomalies of note identified in the southern areas of the site are two patches of

magnetic debris located towards the eastern boundary [Fig. 13: 13 and 14]. These strong dipolar

positive/negative readings are most likely the result of buried ferrous or magnetically enhanced material such as

building rubble.

5

Strong magnetic readings were recorded around much of the site’s perimeter due to the presence of

ferrous objects in the hedgerows. Similarly, buried ferrous objects, which could include for example fragments

of modern farm equipment, can be seen in the large number of magnetic spikes recorded across the entire survey

area.

Conclusion

The geophysical survey was successfully completed across the entire study area. It recorded a range of magnetic

anomalies, several of which may indicate the presence of buried archaeological features. These are exclusively

found within the northern field of the site and primarily represent cut features such as ditches and gullies, which

were probably field boundaries of unknown date. Of particular note are the rectangular anomalies towards the

northern edge of the site which may indicate the presence of buried structural remains of potential archaeological

interest. The strong magnetic disturbance around the site perimeter and the areas of magnetic debris in the

southern site areas may mask weaker magnetic anomalies of archaeological origin.

References BGS, 1981, British Geological Survey, 1:50,000, Sheet 284, Solid and Drift Edition, Keyworth CIfA, 2002, The Use of Geophysical Techniques in Archaeological Evaluation, IFA Paper No. 6, Reading CIfA, 2011, Standard and Guidance: for archaeological geophysical survey, Reading CIfA, 2014, Standard and Guidance: for archaeological geophysical survey, Reading English Heritage, 2008, Geophysical Survey in Archaeological Field Evaluation, English Heritage, Portsmouth

(2nd edn) James, R, 2016 ‘Land north of Netherhouse Copse, Hitches Lane, Fleet, Hampshire, Archaeological desk-based

assessment’, Archaeology South East, report 5320, Portslade NPPF, 2012, National Planning Policy Framework, Dept Communities and Local Government, London Pine, J, 2016, A Middle Bronze Age Pit Circle and Field System, and Roman Settlement at Hitches Lane, Fleet,

Hampshire, TVAS Occas Pap 12, Reading

6

Appendix 1. Survey and data information

Programme:Name: TerraSurveyorVersion: 3.0.34.4

12/9/18Raw dataNorthwest corner: 479350.322733201, 153481.095326009 mSoutheast corner: 479485.522733201, 153116.835326009 mDirection of 1st Traverse: 90 degCollection Method: ParallelSensors: 2 @ 1.00 m spacing.Dummy Value: 32702

Source GPS Points: 92239

DimensionsComposite Size (readings): 1040 x 2802Survey Size (meters): 135 m x 364 mGrid Size: 135 m x 364 mX Interval: 0.13 mY Interval: 0.13 m

StatsMax: 99.22Min: -103.93Std Dev: 4.64Mean: -0.49Median: -0.19Composite Area: 4.9248 haSurveyed Area: 2.964 ha

Processed dataStatsMax: 2.41Min: -2.00Std Dev: 0.49Mean: -0.01Median: 0.01

GPS based Processes: 6 1 Base Layer. 2 Unit Conversion Layer (Lat/Long to UTM). 3 DeStripe Median Traverse: 4 Despike Threshold: 1 Window dia: 3 5 DeStagger by: 50.00cm, Shift Positions 6 Clip from -1.80 to 2.20

13/9/18Raw dataSurvey corner coordinates (X/Y):Northwest corner: 479429.94728532, 153492.781620688 mSoutheast corner: 479534.72728532, 153112.661620688 mDirection of 1st Traverse: 90 degCollection Method: ParallelSensors: 1Dummy Value: 32702



StatsMax: 100.49Min: -109.71Std Dev: 4.43Mean: 0.84Median: 0.92Composite Area: 3.9829 ha

Surveyed Area: 1.8886 ha



14/9/18Raw dataNorthwest corner: 479476.406660346, 153514.259246781 mSoutheast corner: 479601.856660346, 153112.559246781 mDirection of 1st Traverse: 90 degCollection Method: ParallelSensors: 1Dummy Value: 32702



StatsMax: 94.10Min: -109.14Std Dev: 6.46Mean: 0.44Median: 0.82Composite Area: 5.0393 haSurveyed Area: 2.9025 ha



17/9/18Raw dataSurvey corner coordinates (X/Y):Northwest corner: 479703.145081502, 152934.588957486 mSoutheast corner: 479798.435081502, 152882.588957486 mDirection of 1st Traverse: 90 degCollection Method: ParallelSensors: 2 @ 1.00 m spacing.Dummy Value: 32702


7

DimensionsComposite Size (readings): 733 x 400Survey Size (meters): 95.3 m x 52 mGrid Size: 95.3 m x 52 mX Interval: 0.13 mY Interval: 0.13 m







StatsMax: 107.34Min: -109.75Std Dev: 8.49Mean: 0.62Median: 1.11Composite Area: 9.1772 haSurveyed Area: 5.4103 ha Processed dataStatsMax: 2.41Min: -2.00Std Dev: 0.60Mean: -0.03Median: 0.02











StatsMax: 107.23Min: -109.74Std Dev: 8.26Mean: -0.19Median: 0.56Composite Area: 3.9159 haSurveyed Area: 1.8017 ha

8



SU 79000 80000

Land at Netherhouse Copse, Hitches Lane,Fleet, Hampshire, 2018

Geophysical Survey (Magnetic)Figure 1. Location of site within Fleet and Hampshire.

NCF 18/109

53000

54000

55000

Reproduced under licence from Ordnance Survey Explorer Digital mapping at 1:12500Crown Copyright reserved

SITE

SITE

Basingstoke

Andover

SOUTHAMPTON

New Forest

PORTSMOUTHGosport

Farnborough

Ringwood

Winchester

+100

-100

Figure 2. Plot of raw gradiometer data.

0m 250m

SU 79500

53000

53500

N Land at Netherhouse Copse, Hitches Lane,Fleet, Hampshire, 2018


NCF 18/109

nT

+2.2

-1.8

Figure 3. Plot of minimally processed gradiometer data.

0m 250m

SU 79500

53000

53500

N Land at Netherhouse Copse, Hitches Lane,Fleet, Hampshire, 2018


NCF 18/109

nT

Figure 4. Interpretation plot.

N

0m 250m

SU 79500

53000

53500

NCF 18/109Land at Netherhouse Copse, Hitches Lane,

Fleet, Hampshire, 2018Geophysical Survey (Magnetic)

LegendPositive anomaly - possible cut feature (archaeology)

Ferrous spike - probable ferrous objectMagnetic disturbance caused by nearby metal objects/services

Weak positive anomaly - possible cut feature

Scattered ferromagnetic debris

+100

-100

Figure 5. Plot of raw gradiometer data. Detail: NW.

0m 100m

SU 79400 79500 79600

53200

53300

53400

53500

N

NCF 18/109

nT



+2.2

-1.8

Figure 6. Plot of minimally processed gradiometer data. Detail: NW.

0m 100m

SU 79400 79500 79600

53200

53300

53400

53500

N

NCF 18/109

nT



Figure 7. Interpretation plot. Detail: NW.

0m 100m

N

SU 79400 79500 79600

53200

53300

53400

53500



1

3

4

2

11 8

910

7

6

5





+100

-100

Figure 8. Plot of raw gradiometer data. Detail: NE.

0m 100m

SU 79500 79600 79700

53200

53300

53400

53500

N

NCF 18/109

nT



+2.2

-1.8

Figure 9. Plot of minimally processed gradiometer data. Detail: NE.

0m 100m

N

NCF 18/109

nT



SU 79500 79600 79700

53200

53300

53400

53500

Figure 10. Interpretation plot. Detail: NE.

0m 100m

N



SU 79500 79600 79700

53200

53300

53400

4

2

10

6

5

12





+100

-100

Figure 11. Plot of raw gradiometer data. Detail: S.

0m 100m

SU 79400 79500 79600

52900

53000

53100

53200

N

NCF 18/109

nT



79700

53300

+2.2

-1.8

Figure 12. Plot of minimally processed gradiometer data. Detail: S.

0m 100m

SU 79400 79500 79600

52900

53000

53100

53200

N

NCF 18/109

nT



79700

53300

Figure 13. Interpretation plot. Detail: S.

N



SU 79400 79500 79600

52900

53000

53100

53200

79700

0m 100m

13

14





Plate 1. The northern field, looking north-east from the summit.

Plate 2. The northern field, looking north up the southern slope of the hill.


Geophysical Survey (Magnetic)Plates 1 to 4.

NCF 18/109

Plate 3. The south-eastern field, looking south-east. Plate 4. The south-western field, looking north.

TIME CHART

Calendar Years

Modern AD 1901

Victorian AD 1837

Post Medieval AD 1500

Medieval AD 1066

Saxon AD 410

Roman AD 43 AD 0 BCIron Age 750 BC

Bronze Age: Late 1300 BC

Bronze Age: Middle 1700 BC

Bronze Age: Early 2100 BC

Neolithic: Late 3300 BC

Neolithic: Early 4300 BC

Mesolithic: Late 6000 BC

Mesolithic: Early 10000 BC

Palaeolithic: Upper 30000 BC

Palaeolithic: Middle 70000 BC

Palaeolithic: Lower 2,000,000 BC

Thames Valley Archaeological Services Ltd,47-49 De Beauvoir Road,

Reading RG1 5NR

Tel: 0118 9260552Email: [email protected]: www.tvas.co.uk

Offices in:Brighton, Taunton, Stoke-on-Trent and Ennis (Ireland)

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