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Environmental Statement

Volume 6 – Onshore

PINS Document Reference: 7.6.6.6

APFP Regulation 5(2)(a)

January 2015

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SMart Wind Limited

Hornsea Offshore Wind Farm

Project Two – Environmental Statement

Volume 6 - Onshore

Annex 6.6.6 – Intertidal Walkover Survey Report

SMart Wind Limited

11th Floor

140 London Wall

London

EC2Y 5DN

Tel 0207 7765500

Email info@smartwind.co.uk

Copyright © 2015.

All pre-existing rights reserved.

Liability

This report has been prepared by RPS Group Plc (RPS), with all reasonable skill, care and diligence within the terms of their contracts with SMart Wind Ltd or their subcontractor to RPS placed under RPS’ contract with SMart Wind Ltd as the case may be.

Document release and authorisation record

PINS document reference 7.6.6.6

Report number UK06-050700-REP-0054

Date January 2015

Company name SMart Wind Limited

mailto:info@smartwind.co.uk

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Table of Contents

1 Summary ............................................................................................................................. 1 2 Introduction .......................................................................................................................... 2 3 Location and description ...................................................................................................... 3 4 Geology and topography ...................................................................................................... 5 5 Planning background ........................................................................................................... 6

5.1 Introduction ........................................................................................................... 6 5.2 Archaeological and historical background ............................................................. 6

6 Methodology ........................................................................................................................ 8 7 Results ................................................................................................................................. 9 8 Discussion and conclusion ................................................................................................. 16 9 Project archive ................................................................................................................... 17 10 Acknowledgements ............................................................................................................ 18 References ............................................................................................................................... 19 Table of Appendices Appendix A of Annex 6.6.6: Geoarchaeological Assessment ................................................... 20 Appendix B of Annex 6.6.6: Gazetteer of archaeological sites ................................................. 22

Table of Figures

Figure 1: Location plan of the survey area at scale 1:50,000. ...............................................1 Figure 2: Map from client showing location survey. ...............................................................4 Figure 3: Plan of the proposed cable route intertidal zone at scale 1:25,000, showing sites

of potential archaeological significance. .................................................................6 Figure 4: Extract from an Admiralty chart (scale not known) showing the intertidal zone in

the area of Tetney Haven and Horseshoe Point. ...................................................7 Figure 5: Extract from the 1856 1" to the mile Ordnance Survey map (not to scale),

reproduced from RPS, 2011. .................................................................................7 Figure 6: Intertidal survey find locations. ............................................................................. 15

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Table of Colour Plates

Plate 1: General view of the survey area, looking north-east towards the estuary. ............ 3 Plate 2: Metal wire mass A001, looking north; the barbed-wire separator lies to the north-

east. ...................................................................................................................... 9 Plate 3: Metal wire mass A002, looking west; A001 is in the background. ......................... 9 Plate 4: Exposed sandy silt unit on foreshore, looking west. .............................................. 9 Plate 5: Possible Second World War target mound B001 looking north. ............................ 9 Plate 6: Possible Second World War target mound B002 looking south. ......................... 10 Plate 7: General shot of timber vessel fragment C001, looking north. ............................. 10 Plate 8: Detail shot of keel C001, looking west; rib and planking are visible below water. 10 Plate 9: General shot of timber vessel fragment C002, looking south-east. ..................... 10 Plate 10: Timber post C003, largely submerged, looking north-north-west. ....................... 11 Plate 11: General shot of metal post group C004, looking north-north-east. ...................... 11 Plate 12: Timber post D001, looking north-west. ................................................................ 11 Plate 13: General view along row, looking north-west. ....................................................... 11 Plate 14: Timber post E001, looking north-west. ................................................................ 12 Plate 15: General view along row, looking north-west. ....................................................... 12 Plate 16: Submerged cable seen in channel between posts E001 and E002, looking

north-east. ........................................................................................................... 12 Plate 17: General view across silt deposit E008, looking south-east. ................................ 12 Plate 18: General view along the row of concrete set posts E009-E011, looking west; E009

is in foreground. .................................................................................................. 13 Plate 19: Metal box F002, looking west. ............................................................................. 13 Plate 20: Concrete-set timber post F003, looking north-west. ............................................ 13 Plate 21: Concrete-set timber posts F004 and F005, looking north-north-east. ................. 13 Plate 22: Concrete-set timber post F006 with F007 in background, looking north-east. .... 14 Plate 23: Discontinuous grey sandy silt with humidified organics, exposed on upper

foreshore ............................................................................................................. 21 Plate 24: Close up of the above unit. Pen for scale. ........................................................... 21 Plate 25: Band of grey silt with rootlets and black humidified organics. ............................. 21 Plate 26: Line of stakes along upper foreshore. ................................................................. 21

Table of Tables

Table 1: Gazetteer of sites identified in and around the intertidal zone by the Desk-Based Assessment. ............................................................................................................. 22

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1 SUMMARY

1.1.1 The proposed onshore infrastructure (both the indicative onshore cable route and the HVDC converter/HVAC substation site at North Killingholme) for Hornsea Offshore Wind Farm Project Two is immediately adjacent to that of Project One. The synergies were identified at an early stage and all environmental surveys to inform the baseline were designed to inform the EIA for both Project One and Project Two. The remainder of this intertidal walkover survey report, from this point onwards, is thus unchanged from the corresponding Project One report.

1.1.2 An archaeological evaluation comprising a walkover survey was undertaken in the intertidal zone adjoining Horseshoe Point, near North Cotes in East Lindsey, Lincolnshire. The survey area covered an area 500 m to either side of the route of the proposed Hornsea Offshore Wind Farm Project One onshore cable.

1.1.3 The purpose of this survey was to inform the planning process associated with the construction of an overland cable route from a proposed offshore wind farm at Hornsea, East Yorkshire to a new HVDC converter/HVAC substation adjoining the existing power station at North Killingholme, North Lincolnshire.

1.1.4 The survey of the intertidal zone (with an archaeological evaluation carried out on the proposed corridor of the overland cable route) forms the final part in a staged programme of archaeological assessment agreed with Lincolnshire County Council Historic Environment Services and the Unitary Authorities of North and North East Lincolnshire.

1.1.5 Only post-medieval and modern structures and artefacts were observed during the survey. These fell for the most part into two groups; post alignments that appeared to represent navigational aids, and military structures from the inter-war period or the Second World War. Fragments of either one or two undatable timber vessels were also recorded.

OS mapping © Crown copyright. All rights reserved. PCAS licence no. 100049278.

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2 INTRODUCTION

2.1.1 Pre-Construct Archaeological Services Ltd (PCAS) was commissioned by RPS Planning and Development (RPS), on behalf of SMart Wind Ltd, to carry out an archaeological evaluation in the form of a walkover survey of the intertidal zone, extending from Horseshoe Point, near North Cotes, East Lindsey, Lincolnshire.

2.1.2 The proposed Hornsea Offshore Wind Farm will be located off the east coast of Yorkshire and requires a landfall point to connect an onshore cable to the National Grid. SMart Wind Ltd has secured a 1 GW connection at North Killingholme (TA 152 189). The proposed scheme has a designated landfall at Horseshoe Point, and RPS requested that an intertidal survey be undertaken at this location.

2.1.3 This archaeological evaluation, combined with a more extensive scheme carried out on the proposed corridor of the overland cable route, forms the final part in a staged programme of archaeological assessment agreed with Lincolnshire County Council Historic Environment Services. This report details the results of the walkover survey of an area 1 km in width and extending 2.5 km north-east across the intertidal zone.

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3 LOCATION AND DESCRIPTION

3.1.1 The proposed cable route is up to 40 km long, and runs from the landfall site at Horseshoe Point in North Cotes parish in the district of East Lindsey (NGR TA 380 021) to a proposed new HVDC converter/HVAC substation , adjoining an extant power station, in North Killingholme parish in the county of North Lincolnshire (TA 152 189).

3.1.2 The intertidal zone lies between the low tide mark and the sea defences at the north-eastern edge of North Coates Airfield. The proposed offshore cable route corridor runs largely north-north-eastward from the sea defences, turning east-north-east at the low tide mark. Part of its eastern side is roughly bordered by the lower reaches of a sinuous tidal creek. A large portion of the offshore route corridor falls within the Donna Nook RSPB nature reserve.

3.1.3 Chiefly, the survey zone consisted of the offshore cable route consultation corridor (marked in blue on fig. 2). A portion of the near shore option 500 m buffer (marked with a red dot-dash line on fig. 2) that lay outside the consultation corridor on the south-west side of the tidal creek was also surveyed, but due to safety considerations, the creek was not crossed.

Plate 1: General view of the survey area, looking north-east towards the estuary.

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Figure 2: Map from client showing location survey.

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4 GEOLOGY AND TOPOGRAPHY

4.1.1 To the east of Tetney, the surface drift geology consists chiefly of marine and estuarine alluvium deposits laid down above glacial till, although a large band running parallel to the coast displays an overlying landscape of partially levelled saltern mounds; the solid geology changes from Burnham Chalk to Flamborough Chalk in the immediate vicinity of the coast (BGS, 1990 and 1991). A geoarchaeological survey noted that the area of the proposed offshore cable route consists of foreshore, including salt-marsh to the south and low energy beach deposits to the north (Gearey, 2012).

4.1.2 The proposed onshore cable route falls entirely within the Lincolnshire Marshes. The south-eastern portion, from the landfall near Horseshoe Point as far as Tetney, runs across the Outmarsh. The landscape here is flat and low-lying, at a typical elevation of 3 m above Ordnance Datum (aOD), open, and dissected by numerous drains, some forming substantial landscape features, which lie within the tidal reach (Cater and Johnson, 2012). The topography of the intertidal area is not stable, as can clearly be seen by comparing modern Ordnance Surveys with recent satellite or aerial photographs. Early 19th century maps show a channel running from ‘North Cotes Haven’ (now the airfield) directly out to sea. The proposed cable route runs across the line of this channel as well as a former inner lagoon close to the modern shore: there is no trace of either of these historic features today. Similarly, defensive trenches dug in the foreshore during the Second World War have completely disappeared (RPS, 2011).

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5 PLANNING BACKGROUND

5.1 Introduction

5.1.1 The Overarching National Policy Statement for Energy EN-1 (designated July 2011), which sets out national policy against which proposals for major energy schemes will be assessed and determined, requires applicants to describe the significance of heritage assets affected by a proposed development and the contribution of their setting to that significance (EN-1, 5.8.8). This evaluation forms the final part of a staged programme of archaeological assessment, which will inform an application for consent.

5.2 Archaeological and historical background

5.2.1 A comprehensive archaeological desk-based assessment, with accompanying aerial photographic assessment, has been prepared (RPS, 2011 and APS, 2011).

5.2.2 The geoarchaeological report (appended in full as Appendix A) noted that material is accumulating, rather than eroding, along this stretch of the Lincolnshire coastline, limiting the potential for geoarchaeological recording. However, two areas where underlying deposits were slightly exposed in plan were observed below the dune system which defines the landward edge of the foreshore: these deposits were identified as former intertidal salt marsh environments, and assessed as being later rather than earlier Holocene. The later Holocene sequence in the Lincolnshire Marsh (see Van de Noort et al. 2001) consists of an 'upper peat' dating from c. 1700 calibrated BC and representing a phase of marine regression, sealed by marine silts. Recent research has suggested that this upper unit comprises two layers: the lower horizon dated to the Iron Age, and the upper to the late- or post-Roman period. Sedimentation of this uppermost horizon may have continued up until the construction of sea defences in the Middle Ages.

5.2.3 During the post-medieval period, as earlier, the gradual eastward creep of the coastline, accelerated by salt production and consolidated by the construction of sea defences, meant that havens grew further from their parent settlements. A short stretch of the sea defences in the Horseshoe Point area (marked NC4 on fig. 3) can be dated to the 17th century, although the majority of the 1638 sea bank is now a considerable distance inland (the Desk Based Assessment notes that the place-name ‘Horseshoe Point’ is derived from the horseshoe-shaped salient formed by the sea defences at North Cotes). The creation of the sea bank, with the extensive alterations to the drainage patterns of the area caused by reclamation and enclosure in the later 18th century, blocked the former North Cotes Haven, and the new Tetney Haven was created to the west of Horseshoe Point (RPS, 2011).

The labelled sites are listed in detail in Appendix B. The plan is derived from the desk-based assessment for this project (RPS, 2011).

Figure 3: Plan of the proposed cable route intertidal zone at scale 1:25,000, showing sites of potential archaeological significance.

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5.2.4 An Admiralty chart of 1852 shows the positions of two wrecks near the outfall of Tetney Haven (fig. 4). The sites of these wrecks, both of wooden vessels (marked NC5 and NC6 on fig. 3), have been identified by the desk-based assessment (Annex 6,5,1), although it is not certain whether or not any remains of these vessels survive.

5.2.5 The proposed cable route across the intertidal zone is shown in dark blue, the end of the land cable route in dashed light blue, and the 500m buffer of the near shore option in dashed purple (extract provided by the client).

5.2.6 The 1856 1" to the mile Ordnance Survey map (fig. 5) shows an ‘occasional water’ (NC 8) – a linear lagoon running parallel and close to the modern shore – that was presumably the main anchorage for shipping in the post-medieval period (RPS, 2011). The north-west end of this feature can also be seen on fig 4. The cable route crosses

the former alignment of this lagoon in the intertidal zone, a short distance from the modern sea defences.

5.2.7 A secondary phase of enclosure at North Cotes in 1858 included the reclamation of a substantial area of salt-marsh to the north-west of Horseshoe Point. This area was used as an army camp at the beginning of the First World War, but was taken over during the war by the Royal Flying Corps. The airfield reopened in 1927 as a pilot training centre, using the nearby ranges of Donna Nook and Theddlethorpe, and was returned to active service in the Second World War. Aerial photographs from this period show extensive infrastructure that has subsequently been removed. This includes a network of secondary runways and dispersal bays for attack aircraft, as well as many temporary buildings, including some standing on or close to the proposed cable route. RAF North Coates remained in military service until 1990 (RPS, 2011).

NW end of the ‘occasional

water’

N

Figure 4: Extract from an Admiralty chart (scale not known) showing the intertidal zone in the area of Tetney Haven and Horseshoe Point.

Figure 5: Extract from the 1856 1" to the mile Ordnance Survey map (not to scale), reproduced from RPS, 2011.

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6 METHODOLOGY

6.1.1 A team of three PCAS staff undertook the walkover survey, accompanied at all times on the survey by Graham Merrikin, a retired coast guard volunteer and local resident who provided onsite experience in safely crossing the intertidal zone. A further PCAS staff member remained in visual contact (via binoculars) with the team and half hourly contact was maintained between the team leader and the shore.

6.1.2 The fieldwork was carried out on 04 and 05 September 2012, dates selected to provide optimum low tides for the survey. Field staff walked parallel transects separated by 100 m, guided by handheld GPS, and began at 8.00 am from Horseshoe Point following the retreating tide to the limits of the survey, then returned ahead of the tide along the next sequence of transects. A geoarchaeologist joined the team on 04 September 2012 to provide advice on potential exposed organic remains (such as buried trees) and carried out a visual assessment of the intertidal zone (Appendix A).

6.1.3 The location of archaeological features was recorded (by marking them as unique waypoints) with handheld GPS units accurate to +/- 3m (Garmin eTrex H); the waypoint codes generated were used to identify features.

6.1.4 Archaeological features were primarily recorded through digital photography, while field sketches and other pertinent information were recorded on pro-forma record sheets. Colour slide and monochrome photography supplemented the digital archive.

6.1.5 Weather conditions were largely fine, but with occasional cloud and a light shower during the afternoon of 04 September 2012.

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7 RESULTS

A001 and A002 (NGR A001: TA 37722 02897; A002: TA 37721 02899)

7.1.1 Two separate concentrations of rusted metal wire, 5 m apart, partially obscured by sand and covered with seaweed. Thickness of wire: c.5-8 mm. The presence of a looped bar (recognisable as a barbed-wire separator) suggests that this represented the remains of Second World War coastal defences.

A003 (NGR A003: TA 37712 02798)

7.1.2 Location of exposed sandy silt deposit with inclusions of organic material exposed on foreshore (photo representing approx. 10% of the material) – area photographed and located on request of the geoarchaeologist. (See Appendix A – Plate 1 and Plate 2).

B001 (NGR B001: TA 37713 03043)

7.1.3 Grass-covered mound, 2m x 2.5 m in size, significantly higher than surrounding sand. Possible target mound from Second World War ranges.

Plate 2: Metal wire mass A001, looking north; the barbed-wire separator lies to the north-east.

Plate 3: Metal wire mass A002, looking west; A001 is in the background.

Plate 4: Exposed sandy silt unit on foreshore, looking west.

Plate 5: Possible Second World War target mound B001 looking north.

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B002 (NGR B002: TA 37694 03136)

7.1.4 Significant mound, partially covered by grass, 6-8 m in diameter, again significantly higher than surrounding sand. Possible Target mound from Second World War ranges.

C001 )NGR C001: TA 37778 03357)

7.1.5 Fragment of a timber vessel, partially obscured by sand. These remains covered an area approximately 5 m x 4 m and comprised a c.2 m section of the keel of a vessel with one rib and associated planking. Timbers appeared to be secured with iron rivets.

C002 (NGR C002: TA 37819 03447)

7.1.6 Fragment of a timber vessel, 4 m x 0.35 m in size, largely obscured by sand. Composed of several timber elements secured with iron rivets. Possibly part of the same vessel as C001.

Plate 6: Possible Second World War target mound B002 looking south.

Plate 7: General shot of timber vessel fragment C001, looking north.

Plate 8: Detail shot of keel C001, looking west; rib and planking are visible below water.

Plate 9: General shot of timber vessel fragment C002, looking south-east.

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C003 (NGR C003: TA 38339 03984)

7.1.7 Vertical half-round timber post, 0.15 m x 0.1 m, barely breaking surface of shallow depression in which it was located. Later identified as one of a more significant group (See D001-7)

C004 (NGR: (centre) C004: TA 37674 02944)

7.1.8 Five metal posts approximately 100 mm in diameter defining a rough semicircle with straight side aligned north-west – south-east, approximately 6 m long. Possible Second World War defensive structure.

D001-007 (NGR D001: TA 38545 03774 - D007: TA 38301 04023)

7.1.9 Line of seven timber posts, 0.15 m in diameter and protruding above surface by up to 0.2m (D003 was submerged). Overall length of line – 345 m; oriented north-west – south-east. Posts were not spaced evenly, as some may have been lost/obscured, but enough survived to suggest an original spacing of 40 m.

NGR: D001: TA 38545 03774 D002: TA 38514 03804 D003: TA 38485 03834 D004: TA 38457 03863 D005: TA 38401 03922 D006: TA 38339 03984 D007: TA 38301 04023

Plate 10: Timber post C003, largely submerged, looking north-north-west.

Plate 11: General shot of metal post group C004, looking north-north-east.

Plate 12: Timber post D001, looking north-west.

Plate 13: General view along row, looking north-west.

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E001-007 (NGR E001: TA 38351 03367- D007: TA 38539 03576)

7.1.10 Line of seven timber posts, 0.15 – 0.2 m in diameter, protruding above surface by up to 0.3 m. Overall length of line – 280 m, oriented north-east/south-west; posts were spaced evenly (c.45 m apart), but E002 and E006 were offset by 2-3 m to the north-east of the line.

A deeper channel between E001 and E002 revealed a submerged cable on the line of the posts.

E008 (NGR: (centre) E008: TA 38634 3260)

7.1.11 Deposit of clayey silt adjacent to cocklebed (on west side) and carved away by channel to north-east. c. 9 m x 25 m in size, this may represent silts seasonally deposited within the channel, presently being eroded by channel movement.

NGR: E001: TA 38351 03367 E002: TA 38381 03402 E003: TA 38415 03439 E004: TA 38446 03472

Plate 14: Timber post E001, looking north-west.

Plate 15: General view along row, looking north-west.

Plate 16: Submerged cable seen in channel between posts E001 and E002, looking north-east.

Plate 17: General view across silt deposit E008, looking south-east.

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E009-011 (NGR E009: TA 38612 03036 - E011: TA 38519 03026)

7.1.12 Line of three timber posts set in 60 cm diameter concrete bases. Overall length of line – 95 m, oriented approximately east-west. Concrete settings projected 0.5 - 0.75 m from sand (within shallow pools). Probably anchor points for channel markers.

F002 (NGR F002: TA 38347 03115)

7.1.13 Outline of a metal box almost entirely buried in sand. 0.8 m x 0.7 m in size, aligned north-south.

F003-005 (NGR F003: TA 38411 03262 - F005: TA 38432 03301)

7.1.14 Three roundwood timber posts (0.15 m in diameter) in circular concrete settings 0.55 m in diameter. Although they formed a north-north-east/south-south-west oriented line, F003 was separated from the others by 30 m; F004 and F005 were less than 4 m apart. F005 had an iron loop, suggesting that they may have been used as moorings.

NGR: E009: TA 38612 03036 E010: TA 38560 03029 E011: TA 38519 03026

NGR: F003: TA 38411 03262 F004: TA 38432 03299 F005: TA 38432 03301

Plate 18: General view along the row of concrete set posts E009-E011, looking west; E009 is in foreground.

Plate 19: Metal box F002, looking west.

Plate 20: Concrete-set timber post F003, looking north-west.

Plate 21: Concrete-set timber posts F004 and F005, looking north-north-east.

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F006-007 (NGR F006: TA 38638 02928, F007: TA 38684 02945)

7.1.15 Two timber posts (0.2 m in diameter) in circular concrete settings (0.5 m in diameter) approximately 50 m apart, and aligned east north-east-west-south-west. Some evidence that the concrete was cast in a metal container, perhaps an oil drum.

Plate 22: Concrete-set timber post F006 with F007 in background, looking north-east.

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Figure 6: Intertidal survey find locations.

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8 DISCUSSION AND CONCLUSION

8.1.1 All the artefacts and structures encountered appeared to be of post-medieval or modern date. No pottery or other finds of post-medieval or earlier date were retrieved, and modern artefacts such as bottles, which were excluded from the survey, were observed to be sparse. The paucity of small artefacts indicates that the intertidal reach is being regularly scoured by marine currents.

8.1.2 Fragments of timber vessels were recorded in two locations, although it is possible that both fragments derived from the same wreck. The boat or boats did not appear to have been large, and were provisionally identified as fishing boats; nothing about their construction indicated a date. The wrecks noted on the 19th century Admiralty chart were not seen; the presence of a sand bar at the outer reach of the survey may have obscured them.

8.1.3 The majority of structures recorded were post alignments: concrete settings confirmed their modern date in many cases, while one post alignment appeared to be associated with a submerged cable. These seem most likely to be channel markers for navigation, possibly originally intended to anchor floating markers such as buoys. The row of posts associated with the cable, E001-E007, marked an alignment parallel to, but not on the line of, the main runway at RAF North Coates, and may have been intended for aerial rather than marine navigation.

8.1.4 The other structural remains recorded during the survey could all be interpreted as military in origin, consisting of Second World War defences and markers for bombing practice from the inter-war period or later.

8.1.5 The geoarchaeological survey recommends that any further archaeological work at Horseshoe Point should include a programme of borehole survey or test pit excavation to establish in more detail the character of these deposits. Depending on the results of such work, then palaeoenvironmental assessment, possibly supported by radiocarbon dating, may be necessary. It should also be noted that if there are any extensive in situ earlier Holocene deposits at the study site, then there is a possibility that these may have archaeological as well as palaeoenvironmental potential (Appendix A).

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9 PROJECT ARCHIVE

9.1.1 The site recording, currently in the custody of PCAS, will be deposited in entirety, with a printed and bound copy of this report, at North Lincolnshire Museum within six months of the completion of the report. It may be consulted there by citing the North Lincolnshire Museum accession code NCAC.

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10 ACKNOWLEDGEMENTS

10.1.1 Pre-Construct Archaeological Services would like to thank RPS Planning and Development for this commission and for the background information provided by them. Particular thanks are also due to Graham Merrikin for his advice and assistance during the project.

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REFERENCES

Air Photo Services (APS), 2011, Hornsea Project 1, Onshore Cable Route, North Cotes (c. TA380025) to North Killingholme (TA152188), Lincolnshire: Aerial Photographic Assessment. Unpublished client report on behalf of RPS Group. British Geological Survey (BGS), 1991, Patrington: England and Wales Sheet 81, Solid and Drift Edition, 1:50,000 Series. BGS, Keyworth. British Geological Survey (BGS), 1990, Grimsby: England and Wales Sheet 90, including sheet 91, Saltfleet; Solid and Drift Edition, 1:50,000 Series. BGS, Keyworth. Cater, D. and Johnson, M., 2012, Hornsea Wind Farm: Option 3 (Southern Route) Onshore Cable Route: Archaeological Fieldwalking Survey. Unpublished client report for Pre-Construct Archaeological Services. Ordnance Survey, Grimsby, Louth and Market Rasen: Landranger Series Sheet 113, scale 1:50 000. The Ordnance Survey, Southampton. RPS Planning & Development, 2011, Hornsea Offshore Wind Farm Onshore Cable Route and Substation: Historic Environment Desk-Based Assessment. Unpublished report. Van de Noort, R., and Ellis, S., (eds.), 2001, Wetland Heritage of the Lincolnshire Marsh: an archaeological survey. Humber Wetlands Project, University of Hull.

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APPENDIX A OF ANNEX 6.5.6: GEOARCHAEOLOGICAL ASSESSMENT

by Dr. Benjamin Gearey

Introduction

This report summarises the results of a geoarchaeological survey at Horseshoe Point, Lincolnshire. The survey consisted of a rapid walkover to assess the general potential of the area and to identify any exposed deposits of geoarchaeological or palaeoenvironmental potential. No intrusive work (i.e. coring or test pit excavation) was carried out as part of this investigation. The study area consists of foreshore including salt-marsh to the south and low energy beach deposits to the north.

Results

The overall depositional environment at the study site is one of aggradation with little evidence of erosion or exposures in section, limiting the potential for geoarchaeological recording. However, two areas where underlying deposits were slightly exposed in plan were identified below the dune system which defines the land-ward edge of the foreshore.

The first area (Plate 23) consisted of a grey, sandy silt unit, with inclusions of humified organic material, woody fragments and rootlets (Plate 24). This deposit appears to be relatively thin (0.05 m maximum, although greater depths below the current beach surface are possible) and discontinuous along some 15-20 m approximately north-south parallel to the dune line.

The second area was located slightly further down the foreshore, around 20 m below the dune line. At this location, several discontinuous bands (maximum 0.15-0.20 m wide) of grey-black silts with rootlets and humic material (Plate 25) were exposed at the beach surface. These exposures appear to be associated with a line of wooden stakes which protrude from the foreshore close by (Plate 26). The condition of these stakes does not indicate these are of great antiquity (see below).

It is not clear to what depth these deposits extend below and under the current beach. In the case of the first area, it appears that the silts form a relatively thin veneer above coarse sands (Plate 24). Limited cleaning around the exposures in area two demonstrated that the bands of silts seem to represent the upper exposures of more extensive units. However, the extent and depth of the sediments could only be established by intrusive work such as excavation or boreholes.

Discussion and Conclusions

It seems likely that the silts identified in both areas represent former intertidal salt-marsh environments. It is not possible to suggest an approximate age but it can be hypothesised that these are likely to be later rather than earlier Holocene. The later Holocene sequence in the Lincolnshire Marsh (see Van de Noort et al. 2001) consists of an 'upper peat' dating from ca.

1700 Cal. BC and representing a phase of marine regression. Minerogenic sediment depositions (or ‘tidal silts’) overlie this peat. Recent research has suggested that this upper unit comprises two layers; both representing extensive estuarine conditions. The lower horizon in this uppermost unit is dated to the Iron Age, and the upper unit to the late- or post-Roman period. Sedimentation of this uppermost horizon may have continued up until the construction of sea defences in the Middle Ages. The stakes (Plate 26) may be related in some way to such later sea defences in this area of the foreshore. It is possible that the silty sediments observed at both locations relate to this later phase of landscape development. However, this must be regarded as a tentative working hypothesis. The palaeoenvironmental potential of these deposits is also unclear on the basis of the current information and depends to a large extent upon the depth and character of the sediment sequences below the contemporary beach.

It is recommended that any further archaeological work at Horseshoe Point includes a programme of borehole survey or test pit excavation to establish in more detail the character of these deposits. Depending on the results of such work, then palaeoenvironmental assessment, possibly supported by radiocarbon dating, may be necessary. It should also be noted that if there are any extensive in situ earlier Holocene deposits at the study site, then there is a possibility that these may have archaeological as well as palaeoenvironmental potential.

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Plate 23: Discontinuous grey sandy silt with humidified organics, exposed on upper

foreshore

Plate 24: Close up of the above unit. Pen for scale.

Plate 25: Band of grey silt with rootlets and black humidified organics.

Plate 26: Line of stakes along upper foreshore.

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APPENDIX B OF ANNEX 6.5.6: GAZETTEER OF ARCHAEOLOGICAL SITES

Gazetteer of sites identified in and around the intertidal zone by the Desk-Based Assessment. The sites are located by reference number on Figure 3. Table 1: Gazetteer of sites identified in and around the intertidal zone by the Desk

Based Assessment.

Ref. no. Description

Te28 Possible remains of wrecked vessel close to Mean Low Water in the intertidal zone identified on aerial photographs.

Te29 At least four partially submerged posts close to Mean Low Water visible on 1946 aerial photograph.

NC1 Saltern site at North Cotes. Report of grey pottery found at the bottom of saltern at North Coates. May be associated with salt working.

NC2 RAF North Coates: used throughout the Second World War by squadrons of Coastal Command, closed in 1948, later used as a maintenance unit, then by a helicopter squadron and later as a missile site.

NC3 1859 sea defence as shown on North Cotes Enclosure Map.

NC4 Course of 1638 sea bank.

NC5 Possible remains of a wooden wreck.

NC6 Wooden wreck visible in 1946; 200 m long.

NC7 Mounds used as targets in Second World War practice range - possible related to shoreline causeway.

NC8 Linear lagoon believed to have been the main anchorage for shipping in the post-medieval period.

NC9 Bomb craters on foreshore beside North Coates Airfield.

NC10 Second World War pillbox or infantry post.

NC11 Associated with NC10.

NC12 Former course of Old Fleet Drain/Tetney Haven as shown on 1828 admiralty map.

NC13 20th century steel vessel visible on 1947 aerial photograph.

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1 Summary2 Introduction3 Location and description4 Geology and topography5 Planning background5.1 Introduction5.2 Archaeological and historical background

6 Methodology7 ResultsA001 and A002 (NGR A001: TA 37722 02897; A002: TA 37721 02899)A003 (NGR A003: TA 37712 02798)B001 (NGR B001: TA 37713 03043)B002 (NGR B002: TA 37694 03136)C001 )NGR C001: TA 37778 03357)C002 (NGR C002: TA 37819 03447)C003 (NGR C003: TA 38339 03984)C004 (NGR: (centre) C004: TA 37674 02944)D001-007 (NGR D001: TA 38545 03774 - D007: TA 38301 04023)E001-007 (NGR E001: TA 38351 03367- D007: TA 38539 03576)E008 (NGR: (centre) E008: TA 38634 3260)E009-011 (NGR E009: TA 38612 03036 - E011: TA 38519 03026)F002 (NGR F002: TA 38347 03115)F003-005 (NGR F003: TA 38411 03262 - F005: TA 38432 03301)F006-007 (NGR F006: TA 38638 02928, F007: TA 38684 02945)

8 Discussion and conclusion9 Project archive10 AcknowledgementsReferencesAppendix A of Annex 6.5.6: Geoarchaeological AssessmentIntroductionResultsDiscussion and Conclusions

Appendix B of Annex 6.5.6: Gazetteer of archaeological sites