New Late Holocene Palaeoenvironmental Records from Loonan and Blythemo, Mainland, Orkney

New Late Holocene palaeoenvironmental records from Loonan and Blythemo, Mainland, Orkney

A thesis submitted to the University of Manchester for the degree of Master of Philosophy in the Faculty of Humanities

August 2016

Geneviève Marie Potts

School of Environment, Education and Development

LIST OF CONTENTS

List Of Figures 5

List Of Tables 6

Abstract 7

Declaration 8

Acknowledgements 9

Chapter 1 – Introduction

1.1 Background 10

1.2 Importance Of This Research 11

Chapter 2 – Regional Context

2.1 Introduction 12

2.2 Physical Description of Orkney 12

2.3 Orkney Climate 13

2.4 Solid Geology 16

2.5 Quaternary Glaciations 19

2.6 Superficial deposits 22

2.7 Holocene Sea Level change 23

2.8 Modern vegetation and land use 24

2.9 Archaeological background of Orkney 26

2.10 Previous paleoecological research on Orkney 32

2.10.1 Woodland development on Orkney 32

2.10.2 Removal of the woodland 35

2.10.3 The development of the heathland communities 36

2.10.4 The impact of Iron age and later societies 36

2.10.5 Shetland 37

2.10.6 North West Scotland 38

2.11 Importance of the research and research aims 39

2.12 Site identification 40

2.12.1 Site 1: Loonan 43

2.12.2 Site 2: Blythemo 46

2.13 Conclusions 48

Chapter 3 – Methods

3.1 Introduction 50

3.2 Rationale 50

3.3 Modern climatic data 52

3.4 Field methods 53

3.5 Sampling and storage 55

3.6 Background of methods 56

3.6.1 Peat 56

3.7 Laboratory methods 58

3.7.1 Humification 58

3.7.2 Pollen analysis 61

3.7.3 Charcoal 65

3.7.4 Geochemistry 66

3.7.5 Dating methods 68

3.8 Conclusion 70

Chapter 4 – Results

4.1 Introduction 71

4.2 Peat stratigraphy 71

4.2.1 Loonan 71

4.2.2 Blythemo 72

4.3 Age depth curves and dates 72

4.4 Loonan pollen and geochemistry 80

4.5 Blythemo pollen and geochemistry 86

Chapter 5 –Discussion

5.1 Introduction 92

5.2 Interpretation of pollen and charcoal 92

5.2.1 Loonan 92

5.2.2 Blythemo 95

5.3 Interpretation of geochemistry 98

5.4 Overall interpretation 101

5.4.1 Loonan interpretation 102

5.4.2 Blythemo interpretation 103

5.5 Summary of influences to climate change 103

Chapter 6 – Conclusion

6.1 Overview 105

References 108

Word Count: 21,213

LIST OF FIGURES

Figure 2.1 The position of Orkney and the arrangement of the archipelago 13

Figure 2.2 Ocean circulation map 15

Figure 2.3 Wind speed map around Scotland 16

Figure 2.4 Solid and drift map 18

Figure 2.5 Geology of Orkney 19

Figure 2.6 Glacial Evidence on Orkney 20

Figure 2.7 Superficial deposits 22

Figure 2.8 Holocene isobase models for Orkney 24

Figure 2.9 Neolithic timeline 28

Figure 2.10 Vegetation succession described by Bunting (1996) 34

Figure 2.11 General location map. 41

Figure 2.12 Locality of Loonan and Blythemo, North Mainland 43

Figure 2.13 Sitemap Loonan 44

Figure 2.14 View North across the site. Area where core was collected 44

Figure 2.15 Typical vegetation at Loonan with dip wells 45

Figure 2.16 Site map of Blythemo 46

Figure 2.17 View North East across the site. Area where core was collected 47

Figure 2.18 Typical vegetation at Blythemo 48

Figure 3.1 Climate Summary from 1995-2015 53

Figure 3.2 Diagram of energy flow in a mire ecosystem 56

Figure 4.1 Loonan age depth curve 73

Figure 4.2 Blythemo age depth curve 74

Figure 4.3 Loonan pollen profile 76

Figure 5.2 Loonan geochemistry 77

Figure 5.3 Blythemo pollen profile 78

Figure 5.4 Blythemo geochemistry 79

LIST OF TABLES

Table 3.1 Elements determined by ICP-OES 66

Table 4.1 Loonan Stratigraphy 71

Table 4.2 Blythemo Stratigraphy 71

Table 4.3 Calibrated age Loonan 73

Table 4.4 Zone boundary age Loonan 73

Table 4.5 Calibrated age Blythemo 74

Table 4.6 Zone boundary age Blythemo 75

ABSTRACT

The University of Manchester, Geneviève Marie Potts, M.phil

New Late Holocene palaeoenvironmental records from Loonan and Blythemo, Mainland, Orkney.

August, 2016

The Orkney Islands have been the subject of many archaeological studies but few studies have attempted to reconstruct the past environment of the Islands. Following palaeoenvironmental reconstructions previously undertaken on parts of the Orkney Mainland (Moar, 1969; Bunting, 1994, 1996). The aim of this project is to reconstruct past environment using multiproxy techniques, a study area in the critical region is required, and a technique of reconstruction known to produce replicable and accurate palaeoclimatic data.

The peat cores collected from two sites on North mainland Orkney were prepared for pollen analysis, and also peat humification to add finer resolution to the results obtained. Peat geochemistry will also be used as a potential palaeoclimatic indicator (Biester, et al. 2003). Cores will be dated using radiocarbon dating.

The profile from Loonan was dated from c. 2692 BP and Blythemo c.3689 BP, from this age depth models and pollen assemblages were found to show the a multiproxy analysis of these sample sets from Orkney. Some similarities were found between Bunting (1994) in relation to Bronze age and Iron age influences. More extensive work with better preservation of pollen would aid a conclusion to accurate palaeoclimate records on these site on Orkney.

DECLARATION

No portion of the work referred to in the thesis has been submitted in support of an application for another degree or qualification of this or any other university or other institute of learning.

COPYRIGHT STATEMENT i. The author of this thesis (including any appendices and/or schedules to this thesis) owns certain copyright or related rights in it (the “Copyright”) and s/he has given The University of Manchester certain rights to use such Copyright, including for administrative purposes. ii. Copies of this thesis, either in full or in extracts and whether in hard or electronic copy, may be made only in accordance with the Copyright, Designs and Patents Act

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This page must form part of any such copies made. iii. The ownership of certain Copyright, patents, designs, trade marks and other intellectual property (the “Intellectual Property”) and any reproductions of copyright works in the thesis, for example graphs and tables (“Reproductions”), which may be described in this thesis, may not be owned by the author and may be owned by third parties. Such Intellectual Property and Reproductions cannot and must not be made available for use without the prior written permission of the owner(s) of the relevant Intellectual Property and/or Reproductions.

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ACKNOWLEDGEMENTS

I would firstly like to thank the SEED for a grant in my second year and NERC for awarding funding for the radiocarbon dates both were essential to helping me finance the fieldwork and analysis.

Secondly, many thanks to Jeff Blackford and Pete Ryan for their guidance, humour and understanding and help with fieldwork visits. Also thanks to the invaluable laboratory staff John and JY for assistance during preps. Rosie Wilkinson also provided support and encouragement during this work, so thank you also.

Finally, many thanks to my husband Lee and also my best friend Lisa for supporting me throughout. And I couldn’t have funded it without Nantwich Swimming Pool being flexible with my working hours allowing me to work around the research, which was greatly appreciated.

Chapter 1 - Introduction

1.1 General overview

Environments change for a variety of reasons, for example external forces, such as climate change or cosmic bombardment and internal forces, such as human activities, edaphic change, geomorphic change, and tectonic activity. This thesis is concerned with environmental change on Orkney; in particular the significance of climatic change and the impact of past human populations on the Orcadian environment. The response of human populations to the changing environment is also considered.

‘Palaeoecology is the investigation of individuals, populations, and communities of ancient organisms and their interactions with and dynamic responses to changing environments’ (Gastaldo et al., 1996, pp.10). Palaeoecology uses proxy measures of past ecosystem processes. As such it does not directly measure past ecosystem change but the indirect effect of these changes on the organisms and inorganic components of that system. There are therefore an additional assortment of difficulties in interpreting the palaeoecological data in terms of past ecosystems.

However, palaeoecology remains one of the most reliable methods to do this.

Increasingly in palaeoecological studies, a multi-proxy approach is adopted. When a number of methods are used in isolation and then combined to show a multi-proxy set of results, more secure palaeoenvironmental interpretations are possible. When reconstructing changes in the environment via proxy records, the degree to which the response and adaptation is caused by variations in one or more of the forces of environmental change outlined above is a subjective assessment (Mortitz and

Agudo, 2013). There is a growing recognition of the importance to replicate and produce high quality environmental reconstructions to add to an ever greater spatial database, adding weight and links between studies (Payne et. al, 2016). A demand for higher resolution studies to accurately pinpoint significant climatic changes or archaeological events is also a common trend (Seddon et. al., 2014).

1.2 Importance of this research

Orkney provides an opportunity to investigate environmental change within a geographically defined area with a rich archaeological record. Its location in the

North Atlantic makes it susceptible to change in one of the key drivers of climatic change in north-west Europe through the Holocene. In spite of these obvious advantages, there are relatively few, securely dated, published palaeoecological records from Orkney. The addition of two records from north-west Mainland provides additional, high quality reconstructions in this understudied area.

Chapter 2 – Regional Context

2.1 Introduction

This chapter describes Orkney, its climate, geology, and current vegetation and land use. It goes on to outline the archaeological record and then discuss the palaeoecological record of Orkney.

2.2 Physical description of Orkney

Orkney is situated at 58° 43 - 59° 23’ N; 2° 22 - 3° 04’ W (Whittingham et al., 2015) and consists of more than seventy islands and skerries. Situated off the northeastern coast of Scotland, it is separated from the mainland by the turbulent Pentland Firth, where the North Atlantic Ocean converges with the North Sea (see Figure 2.1).

To the left: Scotland and the relative position of Orkney

Above: the main islands of Orkney

Figure 2.1 The position of Orkney and the arrangement of the archipelago. Map data from Edina 16/09/13

2.3 Climate on Orkney

Orkney has a cool, hyperoceanic climate (Berry, 2000). It is typified by strong winds, with a narrow annual temperature range, with seasonal averages varying from 3°C in winter to 12°C in summer (Bunting, 1994). It lies at approximately the same latitude as St. Petersburg and Leningrad in Russia, Anchorage in Alaska, and the southern tip of Greenland. Considering its northerly latitude, the Orkney climate is considerably

13 milder with a narrower temperature range. This ‘cool and equable’ climate (Bunting,

1996) is a consequence of the Atlantic Gulf stream.

The Gulf Stream brings warmer ocean currents via the North Atlantic Drift (Figure

2.2). The Gulf Stream is the ocean circulation pattern that moves warm water from the east coast of North America in a northeasterly direction extending into the North

Atlantic drift that extends to Norway. In the 1960s, the North Atlantic Drift was thought to be the main influence on the more temperate European climate (Ross,

1966). However this idea of the ocean circulation pattern being the main control for this milder maritime climate (Willis, 1995), has been challenged as a simplified view

(Seager et al., 2002) and it is now thought that the ‘atmospheric circulation system interacting with the oceanic mixed layer’ (Seager et al., 2002) that causes the greatest difference. This means that thermal convection not only moves poleward causing milder European winters, but also thermal storage and release of land masses coupled with stationary heat waves restricted by land topography, also plays an interactive part in heat transport (Seager et al., 2002). The Gulf Stream minimises extremes of temperature. Frosts are infrequent, but the cool summers limit the growning season to five to six months, compared to seven to eight months in lowland England (Berry, 2000).

Figure 2.2 Ocean circulation map. (Britannica Encyclopedia, 2015)

The constant westerly winds, which average gale force three (Orkneyjar, 2013), are an indicator of the exposed environment that is characteristic on Orkney. Figure 2.3 shows that wind speeds are high compared to other areas of Scotland, although generally there is some shelter from mainland Scotland which contributes to a reduction in the temperature range. Precipitation is approximately 1600mm per year recorded on western mainland (Met Office, 2013), and is distributed fairly evenly

15 throughout the year, however as with most of the United Kingdom, autumn and winter are more affected by the Atlantic depressions (Met Office, 2013).

Figure 2.3 Wind speed map around Scotland (Scottish Government Website, 2015)

2.4 Solid Geology

The solid geology of Orkney is relatively simple. Mainland and the northern isles are underlain by base rich flagstones and sandstones of Late Devonian Middle Old Red

Sandstone age, dated to around 385 to 400 million years old. Differential weathering of thin harder and softer beds within these Devonian Old Red Sandstones has led to the development of small escapments and weakly defined terrace features in west

Mainland, Rousay and Westwray, where low lying hills reach 170-270m altitude.

There are also some metamorphic gneisses and igneous granites deposited on top of this particularly on Western Mainland. Further east on Eday, Sanday and South

Ronaldsay thicker sandstone beds have resulted in more pronounced ridges and escarpments. Western Hoy is geologically quite distinct, underlain by the massive

Hoy sandstones of Devonian Upper Old Red Sandstone age, dated to around 375 to

390 million years old. These hard rocks underlie Cuilags (433m) and Ward Hill (479m) the highest points of relief on Orkney. With the exception of western Hoy, the topography of Orkney is subdued, with much land being below 70m altitude

(Keatinge and Dickson, 1979). In addition to topography, bedrock contributes to soil formation and pH and, therefore, is a factor on the vegetation colonisation. Generally the Old Red Sandstones weather to relatively light and fertile soils (Bunting 1996).

There are some volcanic rocks on Hoy and this bedrock proliferates more fertile soil and subsequently allows more diverse vegetation to establish (Wickham-Jones,

1998). Figure 2.4 shows the abundance peat (golden brown) till (blue) and upper stromness flagstone (dark brown).

Figure 2.4 Solid and drift geology Map, Natural Environmental Research Council,

1999. (Four-point star- Loonan, five-point star- Blythemo)

Figure 2.5 Geology of Orkney (Brown, 1996: p2) (Four-point star- Loonan, five-point star- Blythemo)

2.5 Quaternary Glaciations

Throughout the Quaternary, glacial cycles have actively deposited and eroded the land. There is evidence of glacial scouring on Orkney and other depositional landforms, and these indicate a northwesterly or north-northwesterly movement of ice (Peach and Horne, 1880). Peach and Horne (1880) also described evidence of striations on rocks and roche moutonnées as well as boulder clay (see Figure 2.5).

Figure 2.6 Glacial Evidence on Orkney (Hall,1996 p9) (Four-point star- Loonan, five- point star- Blythemo)

Little evidence for pre-Late Devensian glaciation exists on Orkney as this would have been removed by subsequent glaciations (Wickham-Jones, 1998; de la Vega-Leinert,

2007). It is postulated that the late Devensian glaciation covered Orkney in ice and

20 reached its maximum extent around 24 ka years ago (Hall et al., 1996). Deglaciation began around 15 ka years ago with Orkney largely ice free by 13 ka years ago. Small- scale cirque glaciation occurred during the Loch Lomond stadial around 12 ka years ago and is evident in the hills of north-western Hoy (Brown, 2000). With the exception of these Loch Lomond stadial corries and moraines of north-west Hoy, the

Quaternary glaciations have acted to further smooth the topography of Orkney.

Through elevation and aspect, topography has a strong influence on vegetation distribution, as this influences the moisture content and sunlight that will create localised conditions for vegetation establishment. Understanding the environmental conditions for the plant communities is important when interpreting the palynology results of this study.

2.6 Superficial deposits

Figure 2.7 Superficial deposits on Orkney from BGS survey data (Farrell, 2009).

Superficial deposits cover approximately 85% of the land surface of Orkney (Figure

2.7). The late Devensian ice deposited glacial till across much of Orkney and this forms the parent material of many Orcadian soils. In isolated parts of western

Mainland, as well as over quite large areas of the northern isles Sanday, Westray,

Eday and North Ronaldsay, there are deposits of blown sand. Extensive peat deposits have also formed and cover much of western Mainland, eastern Hoy and central

Rousay. Orcadian soil formation has been strongly influenced by these superficial

22 deposits (in particular the boulder clay), as well as the hyperoceanic climate, topography and human activity (Davidson and Jones, 1985).

2.7 Holocene Sea Level Change

The Quaternary glaciations have also had a profound influence on relative sea level around the Orkney islands. The elevation of the land was depressed under the weight of the ice, the sea level also lowered, as the water was drawn to the increasing mass of ice to form glaciers. Figure 2.8 shows the changes in isobases, showing the impact of the build up and subsequent melting of the ice sheets on the relative sea level height. This resulted in the Islands being around 30 metres below their current level relative to the sea c. 15 ka years BP (Wickham-Jones, 1998). Since the isostatic changes in land level and relative sea level changes, the coastline has been affected to different degrees. This has produced relict erosional features along the cliffs at varying levels (Renfrew, 1985). However, in contrast to much of the

Scottish coast, Orkney has relatively few raised shoreline features. It is thought that apart from minor stillstands, relative sea level has continuously risen from -4m OD, 8 ka years ago to the present day (de la Vega Leinert et al. 2000; de la Vega Leinert et al., 2007).

Figure 2.8 From De la Vega Leinert (2007) p757. Holocene isobase models for Orkney, (a) Lambeck (1995) for 7000 14C BP, (b) Lambeck (1993) for 6000 14C BP (c) and Smith et al. (2006) for the Holocene Storegga Slide tsunami Shoreline of ca. 7100 14C yr BP, (d) the Main Postglacial Shoreline, of ca. 5700–6900 14C yr BP and (e) the Blairdrummond Shoreline, of ca. 4000–5000 14C yr.

2.8 Modern vegetation and land use

Trees and shrubs are virtually absent from Orkney except where recently planted

(Jones, 1979) and these are severely stunted and misshapen (Bailey, 1971).

Herbaceous communities dominate the contemporary natural flora. Keatinge and

Dickson (1979) describe three characteristic lowland vegetation types: machair, fen and the dales. Machair vegetation forms on the coastal blown sand deposits and is characteristically a short pasture with Festuca rubra (creeping fescue) and Agrostis tenuis (common bent-grass) with some perennial herbs including Plantago maritima

(sea plantain). The fens are dominated by wetland herbaceous plants, including

Filipendula ulmaria (meadowsweet), Juncus spp. (rushes) and Carex spp. (sedges) with some Caltha palustris (marsh marigold). The dales, which are well established

24 on Mainland, are tall herb and fern communities, with Luzula sylvatica (greater woodrush), Deschampsia caespitosa (tufted hair-grass), Juncus effusus (soft rush), the tall herbs Filipendula, Geum rivale (water avens), Cirsium palustre (water thistle) and the ferns Athyrium felix-femina (lady fern) and Dryopteris dilatata (broad buckler fern).

At higher altitudes particularly in north western Mainland and eastern Hoy, peat has formed, providing habitats for heathland communities. These are dominated by

Calluna vulgaris (ling) with Empetrum nigrum (crowberry) Erica cinerea (bell heather) and Juncus squarrosus (heath rush). Eriophorum vaginatum (cotton grass) is also frequent on the blanket bogs (Keatinge and Dickson, 1979).

The only native woodland on Orkney, is at Berriedale on Hoy. It is Britain’s most northerly naturally occuring woodland (Chapman and Crawford 1981). In a deep, sheltered south-east facing gully the woodland consists of Sorbus aucuparia (rowan),

Betula pubescens (downy birch), Populus tremulus (aspen), Salix cinerea (common sallow) and some Corylus avellana (hazel). The ground flora is similar to the tall herb communities of the dales, rich in ferns and tall herb species, as well as Luzula sylvatica (greater woodrush) and Vaccinium myrtillus (bilberry) (Keatinge and

Dickson, 1979).

Productive agricultural land accounts for just over 50% of the land surface area of

Orkney (Bailey, 1971). Most of this is used for livestock farming with grasses and other fodder crops grown to feed beef and dairy cattle and sheep. Most of the grasses are cut to make silage, rather than hay, as this is better suited to the unpredictable climate of Orkney (Bailey, 1971). Barley, oats and some root crops are

25 also grown, most arable crops however are unsuited to the climate of Orkney. Even outside the areas of intensive agriculutral activity, most of the landscape has been influenced by human activity (Bunting, 1994). Many of the peat deposits have been cut for domestic fuel and to convert the peatlands to improved pasture (Crawford,

2000).

2.9 Archaeological background of Orkney

The archaeological record of Orkney is remarkably complete, and indicates continuous occupation since the Mesolithic. All periods from the Mesolithic to the present day are represented (Bunting, 1994). Orkney represents one of the most intensively studied archaeological landscapes in the world, although the focus has been on the highly visible megalithic monuments and features of the Neolithic and

Iron Age periods (Farrell et al., 2014).

Mesolithic (c. 11000 to c. 6000 cal BP)

A small number of stone tools, flints and charred hazelnut shells have been found on

Mainland from contexts dating back to 9000 cal BP (Wickham-Jones and Downes,

2007). These indicate the presence of Mesolithic people on the islands. The population of the time were likely to have been nomadic hunter-gathers (Noble,

2006). The temporary nature of any shelters, which would have been made of organic materials, serve to give the Mesolithic a low archaeological visibility. The classic Mesolithic coastal shell middens of the Western Isles and the west coast of

Scotland are absent (Farrell et al., 2014), and it is possible that these have been lost to subsequent relative sea level rise. The palaeoecological record does indicate a

Mesolithic presence and an impact on the Orcadian environment, which was similar in nature and scale to other areas of the British Isles (Simmons, 1975). At Keith’s

Bank on Hoy, a woodland disturbance associated with fire and an increase in animal grazing was used to imply Mesolithic activity (Blackford et al., 1996). At Quoyloo

Meadow on west Mainland, a woodland disturbance associated with fire was also thought to represent the impacts of Mesolithic groups, dated to 7400 cal BP

(Bunting, 1996).

Neolithic (c. 6000 to c. 4000 cal BP)

By contrast there is very clear evidence of the presence of Neolithic people on

Orkney. The Orcadian Neolithic is represented by impressive stone monuments, including Ring of Brodgar, burial chambers such as at Maeshowe, and settlements such as Knap of Howar, Papa Westray and Skara Brae. Neolithic groups on Orkney practised mixed arable and pastoral farming and arrived some time around 6000 years cal BP (Ritchie, 1995). Key Neolithic locations such as Knap of Howar, Papa

Westray, and Skara Brae became populated, leaving evidence of permanent settlements just after 6000 cal BP, with radiocarbon dates at Papa Westray suggesting occupation from around 5600 until 5100 years cal BP (Ritchie, 1995).

Figure 2.9 Neolithic Timeline, Tait, 2006: P 73.

The Neolithic timeline (figure 2.9) shows the progression of some key archaeological construction for the time period. The Knap of Howar, Papa Westray, is one of the oldest stone buildings in Britain, the farmstead has evidence of arable and pastoral farming; fishing and hunting would also contributed to the diet of the farmers at this time. Evidence of a previous settlement at this site is also apparent from refuse.

Spatial links to the coast is evident in 65% of cairns and settlements on Orkney, in comparison to Northern Scotland, where the majority are linked to landforms like hills (Phillips, 2004).

Skara Brae was another important example of Neolithic settlement, as well as the main dwelling a wealth of artefacts including pottery, tools and jewellery were found suggesting a village of between 50-100 people. Again Skara Brae has a close relationship to the coast, so much so parts of this settlement have already been eroded by coastal processes.

Maeshowe, a stone chamber originally contained within a ring of standing stones, is a preserved as an excellent example of a stone chamber. The Norse raided this stone chamber and looting its treasure, leaving only graffiti as a record of it. The exact use is hard to establish, but its orientation is aligned to the solstices, suggesting a more ceremonial or ritual use.

Many examples of standing stones remain across Britain, however the standing stones of Stenness and the Ring of Brodgar are excellent examples of a persevered ceremonial sites all built within the Neolithic. All these structures and artefacts show how advanced the society was at this time, being capable of organising labour and generating production surpluses. The means they had to change the environment will certainly shape the findings on Orkney.

Bronze Age (c. 4000 to c. 2800 cal BP)

By comparison to the preceding Neolithic, the Bronze Age archaeological record on

Orkney is much less clear. There are numerous burnt mounds which are usually thought to be Bronze Age domestic features, although their age and function is uncertain (Barber, 1990). Bronze Age metalwork is also limited on Orkney, with fewer than 20 artefact finds, some of which have been recovered from bogs, which may have ritual significance (Farrell et al., 2014). The burnt mounds are evenly distributed across Mainland and most of the other islands (Anthony, 2003). This suggests a more dispersed pattern of settlement and a shift away from the centralised organisation implicated by the monumental structures of the Neolithic.

Evidence of trade from these sites is scant, and it is possible that the Orcadian Bronze

Age was represented by small self-sufficient communities (Øvrevik, 1985). The

29 transition from the Neolithic to Bronze Age on Orkney is often seen as a cultural, and possibly also a population decline (Hedges, 1975). The causes of this decline may be environmental, but which are likely to also include cultural and social change (Farrell et al., 2014). Changes in farming practices at this time could be due to climatic change that influenced temperature, length of growing season and soil moisture/waterlogging. Soil degradation may be another environmental change that explains the Bronze Age ‘decline’. The climate of north west Scotland was wetter and cooler 3400 to 3100 cal BP (Anderson, 1998; Charman et al. 2006), with increased storminess on Orkney recorded by dune instability at Mill Bay on Stronsay (Tisdall et al. 2003).

Iron Age (c.2800 cal BP to c. 1350 cal BP)

The Iron Age of Orkney is represented by the characteristic roundhouses and brochs.

There are over 100 of these stone towers distributed evenly across Mainland and the other islands (Davidson et al., 1976). It seems likely that population increased in the

Iron Age (Bunting, 1994) and there was an intensification in agricultural activity

(Keatinge and Dickson, 1979). Barley was the main cereal crop, and there seems to have been an increase in arable cultivation with time coinciding with the introduction of new crops including oats and flax (Keatinge and Dickson, 1979). Animal manure was used as fertiliser in the Iron Age, which implies stalling of animals and an intensification of animal husbandry (Farrell, 2009).

The roundhouses and brochs likely served to illustrate the power and influence of the

Iron Age elite. The increase in population and agricultural intensification, allied to a deteriorating climate at the beginning of the Iron Age (van Geel et al., 1996;

Mauquoy et al.,2004), might have resulted in greater competition for land and a more aggressive society. It is possible that some of the roundhouses and brochs had a defensive function (Ritchie, 1995).

Metalworking is known from three sites on Orkney. At Howe in west Mainland (Ballin

Smith, 1994), Minehowe in east Mainland (Card and Downes, 2003), and at Knowe of

Skea on Westray (Moore and Wilson, 2005). It is possible that further Iron Age metalworking sites might be found in the future (Farrell, 2009).

The Picts (c.1350 to c. 1150 cal BP), Norse (c. 1150 to 480 cal BP) and Later societies

Orkney was part of, or at least aligned to, the Pictish kingdom from around 600 AD

(1350 cal BP). It terms of agriculture and economy it appears to have been a continuation of the preceding Iron Age. There is evidence of population decline with settlement and farmstead abandonment during latter half of Pictish rule. There is an historically recorded plague episode in Scotland between 664 and 668 AD, with Irish dendrochronological records indicated a marked climatic deterioration 648 – 720 AD

(Baillie, 1998), which provides the backdrop to this decline.

The Norse settled on Orkney around 800 AD (1150 cal BP). This settlement was based on a mixed arable and pastoral farming economy. Barley, oats and flax were the key arable crops, with cattle, sheep and pigs the dominant domestic animals (Bond,

2007). This mode of agriculture fits with the Norse settlement of other North Atlantic islands. The Norse earldom of Orkney was established by 900 AD (1050 cal BP) and the last Norse earl died in 1231 AD (719 cal BP). Scottish influence grew with Orkney ruled by a succession of Scottish earls, although it officially continued to be part of

31 the Norse kingdom until 1468 AD (482 cal BP) when it was impignorated to the

Scottish crown (Bunting, 1994).

2.10 Previous palaeoecological research on Orkney

There have been very few palaeoecological studies on Orkney (Farrell et al., 2014) and very few with secure chronologies. Many Orcadian sediments incorporate a

‘hard water’ effect (Keatinge and Dickson, 1979), whilst attempts to date sequences using biostratigraphy are problematic in areas where there are few trees and a limited range of arboreal taxa (Farrell et al., 2014).

2.10.1 Woodland development on Orkney

The vegetation in the area has undergone successional changes due to a combination of both local and global factors. The temperature range, wind speed and salinity all have an influence on the type of vegetation that has developed on Orkney.

Anthropogenic influences have also impacted on the landscape of Orkney. The precise form and nature of the early to mid-Holocene woodland on Orkney remains unclear (Farrell et al., 2014). Today, there are a few pockets of planted woods on some of the Mainland estates, but these are artificially cultivated. The largest natural, although not substantial woodland, is Berriedale on Hoy (Bunting, 1994).

This woodland is found sheltered in a deep south-east facing gulley. Investigating tree regeneration at Berriedale, Chapman and Crawford (1981) suggest that if

32 human-induced pressures such as grazing were removed, the woodland would be able to expand into less sheltered parts of the islands.

Macrofossil remains of Betula, Corylus and Pinus have been recovered at Bay of Skaill

(Traill, 1868), however based on pollen analyses at the Loons and Yesnaby on western Mainland, Moar (1969) describes the mid-Holocene woodland in west

Mainland as at best a ‘scrubland’ of birch and hazel. Moar (1969) sees Orkney as having an impoverished arboreal flora and argues that, with the exception of birch, the native of status of trees on Orkney is doubtful. Keatinge and Dickson (1979) arrive at a similar conclusion from a palynological study at Glims Moss, on western

Mainland, although they recognise Salix (willow) shrubs may have been present in wetter areas. For both these studies it is argued that the occasional grains of Pinus,

Ulmus, Quercus and Alnus most likely derive from long-distance transport from mainland Scotland. Tree macrofossil remains and archaeological timbers and charcoal from a variety of tree species could represent driftwood or the import of trade goods. Taxus baccata (yew) charcoal has been recovered from the Neolithic chambered tomb at Quanterness (Renfrew, 1985), whilst Laryx (larch) and Picea

(spruce) charcoal have been recovered from archaeological contexts at Howe,

Stromness, neither have been native to the British Isles since the last glacial maximum (Keatinge and Dickson, 1979).

However, more recent analyses have argued for a denser and more diverse woodland cover, at least in the mid-Holocene. At both Crudale Meadow and Quoyloo

Meadow, Bunting (1994) records shrub and arboreal pollen in excess of 80% of the

33 pollen sum. From 9000 cal BP, a dense Betula-Corylus woodland with some Salix and

Alnus developed. Similar Betula-Corylus woodland with Salix and Alnus developed at

Scapa Bay (de la Vega Leinert et al., 2007) and at Bay of Skaill, but this latter woodland also included some Quercus (de la Vega Leinert et al., 2000). When the woodland at Quoyloo Meadow (Bunting, 1994) (figure2.10) was disturbed at around

7400 cal BP, the secondary woodland that recovered included Quercus and Pinus.

Bunting (1994) argued that Quercus and Pinus may have been present in the more sheltered eastern Mainland, whilst pollen analysis, at Liddle Bog, South Ronaldsay, supports the theory of a greater diversity of arboreal taxa in eastern Orkney (Bartlett,

1983). Indeed, the remains of a Buzzard (Buteo buteo), which inhabits wooded areas, has also been found on Mainland, Orkney (Wickham-Jones, 1998).

Figure 2.10 Vegetation succession at Crudale Meadow and Quoyloo Meadow described by Bunting (1994).

2.10.2 Removal of the woodland

The woodland began to be cleared at around 6000 cal BP, coinciding with the arrival of Neolithic farmers on Orkney (Moar, 1969; Keatinge and Dickson, 1979; Bunting,

1994). The Neolithic culture brought new agricultural methods and pressures on the landscape which influenced the vegetation on Orkney in much the same way as in other parts of the British Isles. Wickham-Jones (1998) identified the strong influence of farming and settlement building on the landscape. Woodland would have been cleared to create fields and pastures, with timbers used for fuel and building materials, including building some of the iconic Neolithic megalithic monuments

(Wickham-Jones, 1998). A significant rise in Plantago lanceolata around 5200 cal years BP and a gradual decline until around 4600 cal years BP in shown at Bay of

Skaill (de la Vega-Leinert et al., 2000), with similar assemblages reflecting the impact of pastoral farming, recorded at Crudale Meadow and Quoyloo Meadow (Bunting,

1994) (Fig. 2.10)

Renfrew (1985) suggests that much of the woodland was cleared by 5000 cal BP following the arrival of Neolithic people. However, Bennett (1990) and Keatinge and

Dickson (1979) argued that climatic change rather than anthropogenic impact was responsible for this decline in arboreal pollen at 5000 years cal BP. The arrival of the

Neolithic people was coincidental. Closer inspection of the scarce number of pollen records through this time period, indicate that woodland decline was asynchronous and spanned probably 2000 years. Early woodland declines are seen at Keith’s Peat

Bank on Hoy at 7300 cal BP (Blackford et al. 1996) and Loch of Torness also on Hoy at

6800 cal BP (Bunting, 1996). Later woodland declines are recorded at Loch of Skaill

35 and at Glims Moss, both at c. 5400 cal BP (Keatinge and Dickson, 1979). Given the extended period of woodland removal, local conditions such as exposure, drainage, edaphic change and anthropogenic impact are more likely to explain woodland removal than climatic change. At some locations for example Scapa Bay (de la Vega

Leinert et al., 2007) anthropogenic impact is implicated as woodland removal occurs alongside indicators of pastoral land. The drawn out period of woodland decline at

Crudale Meadow (Bunting, 1994) perhaps implicates autogenic processes.

2.10.3 The development of heathland communities

By the Bronze Age, 4000 cal BP, Orkney was largely treeless. Blanket peat and heathlands had started to develop c. 7600 cal BP at Loch of Torness on Hoy and at

6500 cal BP at Loch of Knitchen, Rousay (Bunting, 1996). Dates from basal peats in west Mainland are much later, with peat and heathland development between 3700 cal BP and 3050 cal BP (Keatinge and Dickson, 1979). Heathland had become an important element of the landscape around Hobbister, Mainland by 3350 cal BP

(Farrell et al., 2014). These sequences record intense pastoral activity in the Bronze

Age, with fire used to maintain heathland grazing resource, although there are suggestions of a decline in more marginal areas towards the end of the Bronze Age

(Farrell, et al., 2014).

2.10.4 The impact of Iron Age and later societies

Heathland continued to expand in the early Iron Age, notably at Scapa Bay at 2600 cal BP (de la Vega Leinert et al., 2007). It is possible that some heathland expansion was related to the well recognised shift to wetter climatic conditions at 2800 cal BP

(van Geel et al., 1996; Mauqouy et al., 2004), but the asynchronous nature of heathland spread across Orkney indicates climate change was only one of a number of factors that would also include pedological change and anthropogenic impact

(Farrell, et al., 2014). Intensive agricultural activity in the Iron Age is indicated by increases in Plantago lanceolata and Artemisia-type pollen at 1850 cal BP at Glims

Moss, west Mainland (Keatinge and Dickson, 1979) and Loch of Knitchen, Rousay

(Bunting, 1996). There are very few securely dated palynological assemblages from the post Iron Age period. It is assumed that there were few significant changes, with a continuation of the largely treeless open landscape (Farrell, 2009).

2.10.5 Shetland

Although, Orkney is located geographically closer to mainland Scotland than to

Shetland, there are similarities between the Northern Isles. Due to the impact of the global circulatory systems and also to climatic influences from weather systems moving from Scandinavia on to the archipelago.

Long-term impacts on Orkney and Shetland from natural and anthropogenic influences have affected them both. The topography on Shetland is more pronounced, and its mainland more than 180 metres higher in elevation. Peat is much more extensive than on Orkney, possibly due to the level of exposure or through the excessive stresses caused by the poor management of farming practices

(Wickham-Jones, 1998).

Woodland cover developed earlier on Shetland than Orkney, reaching its full extent by 9650 cal BP at Dallican Water (Bennett et al., 1992). Bennett et al. (1992) argue that Quercus was locally common by 9200 cal BP, although that would be an early date for Quercus colonisation in the south of Scotland (Tipping, 1994). Ulmus and

Fraxinus may even have been present by 7500 cal BP (Bennett et al. 1992) and it is thought that the earlier establishment and wider diversity of arboreal species is due to the greater shelter available in eastern Shetland. As on Orkney, woodland removal started with the onset of the Neolithic, associated with clearance for agriculture and settlement (Bennett et al., 1992). However, the major landscape change occurs on

Shetland at around 3000 cal BP (Jóhansen, 1985), in the late Bronze Age/early Iron

Age, which is later than on Orkney. An intensification of agriculture by these later settlers appears to have been responsible for the removal of the woodland cover by

3600 cal BP at Dallican Water (Bennett et al., 1992); 3150 cal BP at Clickimin

(Edwards et al., 2005); and by 2830 cal BP at Gunnister (Bennett et al., 1993).

2.10.6 North West Scotland

The Orkney Islands are closer to Scotland than any other land mass. Research on the vegetation history has shown similarities to those on Orkney (Blundell and Barber,

2005), despite different anthropogenic pressures upon the land. Geologically

Caithness and Orkney are similar, underlain by Old Red Sandstone that weather to similar gently undulating hills and subdued topography (Farrell, 2009). A comparable

Betula-Corylus woodland appears to have become established (Tipping, 1994). As on

Orkney, woodland decline is contemporary with the arrival of Neolithic archaeological groups beginning at around 6000 cal BP (Charman, 1994), although as on Orkney, woodland removal was likely a combination of factors including autogenic change and climate change, as well as anthropogenic impact. In contrast to Orkney, local pine woodlands became established at Loch Farlary at 5200 cal BP (Tipping,

2008) and around Cross

Lochs at 4800 cal BP (Charman, 1994). The pine woodland then declined at 4400 cal

BP coincident with an increase in bog surface wetness (Charman, 1994). Tipping et al.

(2008) ascribe the reduction in pine woodland at Loch Farlary at 4000 cal BP to grazing pressure rather than climate change. Following this, Caithness was almost completely treeless, and blanket mires became much more extensive. There are indications of an increase in the intensity of anthropogenic land use at 2650 cal BP at

Loch of Winless (Peglar, 1979) although the chronology is not certain due to the presence of calcareous sediments in this part of the core.

2.11 Importance of the research and research aims

Orkney is an understudied area palaeoecologically. There are few securely dated palaeoecological sequences and as a result the form and status of former woodland cover is uncertain. The timing and cause of heathland expansion is unclear and the role and significance of climatic, autogenic and anthropogenic change on the

Orcadian landscape is uncertain. Orkney has a rich archaeological record. With the focus on the iconic Neolithic and Iron Age structures, Orkney represents one of the most intensively studied archaeological landscapes in the world (Farrell et al., 2014).

However, there have been relatively few studies to have explored the environmental context of this archaeological record. The post Iron Age record is particularly poor, with only two records securely dated beyond the Iron Age at Crudale Meadow

(Bunting, 1996), and at Hobbister (Farrell et al., 2014). The addition of two records from north-west Mainland in the current study provides additional, high quality reconstructions in this understudied area.

The main aim of the research is to reconstruct environmental change through the late Holocene. A key aim will be to investigate the importance of climatic change and the impact of past human populations on the changing Orcadian environment.

2.12 Site Identification

Figure 2.11 General location map. Top left: Scotland and Orkney. Top right: Orkney

Islands. Bottom: North Mainland Orkney (Digimap: Edina 2015)

A solid and drift geology map and Ordinance Survey map was used initially to locate potential research sites. The characteristics needed to conduct a study were a peat based site with adequate depth to show late Holocene changes. They were chosen for the individual characteristics such as relief and catchment. These sites aimed to be different locations from other published studies, to show new findings and also having the ability for a comparison to similar sites. The general study area is presented in figure 2.11. Many peat sites have been disturbed for peat cuttings both

41 past and current, which poses a major issue for studies of this nature. The sites were visually inspected for signs of obvious anthropogenic disturbances; extensively disturbed areas are unlikely to give a continuous record and the most recent sediments are likely to have been removed and, were therefore avoided.

The balance for quality detailed chronology and number of sites to add depth to the generalisations has to be made. The compromise was made to add detail to aid robust statistical analysis, so this limits the site number. The most detailed record achievable would be one site in absolute detail. Of course, this poses many site- specific assumptions and hinders the general picture that one would assume. Many sites would enable a more certain regional overview, limiting particular site assumptions but with limited time and assets, it would lead to a diminished quality in the chronology and, therefore, less meaningful results.

The aim was a detailed chronology, so therefore two sites where chosen, this seeks to reduce the assumptions from local conditions but maximise the detail, which is more important when assuming relict conditions. The proximity to the ocean will, of course, have a bearing on the temperatures and conditions and, therefore, the

Mainland Island was the greatest in size and both sites are fairly central to the Island, as it will be slightly less tempered by the surrounding oceans and slightly more sheltered from the wind. The two sites that were chosen were in the same locality,

Loonan is in a lower level lake catchment and Blythemo is from a hilltop catchment on the other side of a hill to Loonan. Approximately one kilometre separates Loonan to Blythemo in a south-west direction (figure 2.12). Having the two sites from the

42 same catchment does also have limitations, if results show similarities, it may be purely be a coincidence and conclusions must be cautiously applied. Considering the limitations of different ways of gathering information, it was decided to proceed in choosing two sites in a same catchment with various topological differences and have more detail than possible in more sites.

Figure 2.12 Locality of Loonan and Blythemo, North Mainland (Digimap: Edina, 2015).

2.12.1 Site 1: Loonan

HY 32269 BNG 26280, 57m el ±19’

Figure 2.13 Sitemap Loonan (Star) (Digimap: Edina, 2015)

Figure 2.14 photos Left: View North across the site. Right: Area where core was collected

The area named Loonan is part of a wider section of peat that extends over the north-eastern side of Orkney Mainland (Figure 2.13 and 2.14). It is part of Birsay

Moors, which is situated in an area of 2000 hectares of moorland containing both wet and dry heath. It is a lowland area in the catchment of Loch of Swannay. It is currently typically vegetated by sedges like Eriophorum angustifolium and Carex and heaths like Calluna vulgaris (figure 2.15).

Figure 2.15 Typical vegetation at Loonan with dip wells

It is managed by the RSPB to protect the peat and the habitat it forms for birds like the arctic skuas (Stercorarius parasiticus), hen harrier (Circus cyaneus) and merlins

(Falco columbarius). Parts of the reserve are restricted extensively at nesting times for some of these birds. There is access on the south side limited to peat-cutters tracks. The area immediately surrounding Loonan is used for pastoral agriculture.

The actual site is dissected by a series of furrows and ridges, a remnant from past peat cutting activity. However, all areas have significant vegetation suggesting that there have not been recent activities. Peat profiles were taken from the longest available face on this site available from previous peat cuttings.

2.12.2 Site 2: Blythemo

HY 34985 BNG 24673, 161m el ±21’

Figure 2.16 Site map of Blythemo (Diamond)

Figure 2.17 Left: View North East across the site. Right: Area where core was collected

The second site on mainland is located on the same nature reserve as Loonan on the opposite side of Mid-hill (the hill in the centre of the reserve 193m elevation). This is approximately 3 Km South West of the Loonan site. There are wind turbines situated along the ridge separating the sites. Blythemo is shown in figure 2.16 and 2.17.

On this side of the hill, the peat has been extensively cut and used as grazing pastures on the other. Cutting tracks are extensive to the west the site and evidence of recent cutting is apparent. This site, managed by the RSPB is used to maintain a range of habitats. Calluna vulgaris is more predominant on the site with some

Sphagnum papillosum (figure 2.18). The site survey results show a more diverse range of species at Loonan compared with Blythemo. While there are similarities between the two sites, with Calluna being present for all but one sample point.

Narthecium is more abundant at the Blythemo site, and Carex is only found at

Loonan, as is Vaccinium

Figure 2.18 Typical vegetation at Blythemo

2.13 Conclusions

The North Atlantic drift has a particular impact upon the islands and, therefore, the

Orkneys have been chosen as a study site because of their location, although many places are sensitive to changes in temperature and moisture balance. The island location also gives it a unique and more controlled set of variables to decipher and eliminate factors in the changes because of the immediacy to other landmasses. The proximity to the Scottish mainland and Shetland is also an advantage as some work on climatic reconstruction has been carried out there, allowing a comparison to

Bennett et al. (1994) on Shetland.

Orkney has an interesting history and provides a study area that could provide relevant evidence both locally and regionally. More importantly Orkney’s location, central to climatic changes that take place and the North Atlantic region, usually the first to show effects of changes coming from the Atlantic Ocean and therefore is an excellent indicator of future changes.

Chapter 3 - Methods

3.1 Introduction

This chapter outlines the methods employed to find the location for this study and also the approaches and the rationale for the field work, laboratory procedures as well as the dating and statistical methods used.

3.2 Rationale

The research question aims to establish and quantify any significant climatic fluctuations. The key to this is an analysis of modern climatic data by obtaining accurate, measurable results. Actual instrumental climatic records show only a relatively brief interlude of the history of climate change which is why the investigation into recovering past changes are critical. The process of uncovering undocumented conditions is important to extend the written records. This allows detailed analysis of current trends, but also potential predictions of future changes and patterns, which are still widely unknown and rely on modelling (IPCC, 2007).

Numerous palaeoecological methods can be drawn upon to deduce past climatic conditions from proxy indicators; the direct or inferred indicators used may be physical, chemical or biological. As proxy indicators are inferred, the methods for

50 uncovering the indicators and relating them to true climatic conditions all have limitations. The methods available have a varying degree of confidence and relevance; however, with further research techniques are constantly improving, producing more precise and accurate results. For example, a finer resolution of a more recent study has shown the response of a change in conditions to be quicker than once was thought (Amesbury et al., 2012).

Jones et al. (2009) argue that research should aim to show annualised patterns of seasonality and to help identify patterns in temperature and climate (locally and regionally) and also longer term climatic cycles can be up to around 100,000 years long, for example, the Milankovitch cycle. The methods that can be used to deduce the different time scales and subsequently apply theories and understanding to which is key to accurate, reliable results.

Research using proxy records over the last century has been widely used and has shown much success. Flora and fauna tolerate specific environmental conditions, some broad spectrum (tolerant of a wide variety of circumstances) and some narrow spectrum (specific set of variables can be tolerated). Some species with a narrow tolerance to a pH for example, are a good indicator of discovering past hydrogen ion levels in a sample. When these organisms are found, the related ideal conditions are inferred with the assumption there tolerance is the same in modern samples. A pioneer in quaternary reconstruction by proxy records was von Post

(1916) who established that pollen was an important indicator and relict pollen grains were found preserved in many sediments. Following this, a development of many other indicators for climatic changes have been discovered including Testate

51 amoebae, Diatoms and Coleoptera, which have all been popular choices in modern climate reconstructions.

A multi-proxy approach aims to reconstruct a climate using an amalgamation of indicators, this can exploit the advantages and sensitivity of each of the ‘palaeo’ techniques. In theory, a combination of these methods would give the most accurate results and the highest level of confidence (Charman, 1994). However, replicable results with complete confidence are almost impossible; indicating that methods can be improved and modified, but are still the most popular means of investigation (Daley and Barber, 2012,; Barber, 2012; Reynolds et al., 2013).

3.3 Modern climatic data

Importantly current conditions should be available for comparison in the discussion section and will be briefly summarised (figure 3.1). As both sites are situated in proximity to each other although they are in different catchments, the overall input from the weather system will be assumed to be the same. The data presented here is averaged over 20 years and across the entire archipelago. It shows a small temperature range with constant rain and wind patterns over the year. There is only a modest change in dry days from the driest month that is in May to the wettest month in November by 16%. However, there is 174% increase precipitation measured between these times.

Figure 3.1 Climate Summary from 1995-2015 (my weather2, 2015)

3.4 Field methods

Comparison between single sites is very limiting, identifying and isolating individual dynamics of the area is difficult, as shown by Charman et al. (2006). Researchers

53 need to explore climatic and other related data sets to find out what influences proxy indicators, this is difficult when accounting for every individual limiting factor for each study (Jones et al., 2009). Samples must be obtained from areas with minimal anthropogenic disturbances from settlements, farming and peat cutting. All sites will have some level of disruption, but selecting a site that has the longest continual record is important. Also, it is important not to contaminate samples and label all collection, according to a systematic approach.

The wider location that was chosen by observing the solid and drift geology map data and was further considered on arrival. The aim of the initial visit was to locate a continuous assessable core that would allow the late Holocene climate changes to be determined. On the first visit to Orkney (2008) a monolith was taken from

Loonan, the location was chosen because of the locality and accessibility and the exposed face allowed more material to be collected than other coring methods. The longest profile was taken to provide to give the largest time interval. It was also taken from an area that was relatively undisturbed that would produce more accurate results.

Firstly, the largest face was identified with a tape measure. The exact location was recorded using a GPS; the area was marked out using a tape measure and a spade.

The top layer was scraped away using a trowel, to provide a clean surface. The blocks were then cut using a spade, starting at the top each section was carefully

54 extracted and labelled into manageable sections. Clear labelling, especially in relation to the top and bottom, was recorded and rechecked. Each section was wrapped in cling film and bagged to preserve the moisture and condition of the peat. The samples were carried in plastic boxes to help maintain the layers.

A second visit (2009) was needed to obtain a second core for comparison. After assessing other sites on Hoy and Rousay, it was decided to return to the Blythemo site on mainland to obtain more extensive samples. A peat profile was taken from the largest available face to allow enough material for laboratory analysis. It was sampled in the same way that the monolith from Loonan was taken. Along with this pH and conductivity were re-measured by the same method and more extensive vegetational surveys obtained at both Loonan and Blythemo. A transect running across the site was surveyed with a corer to find the maximum depth of the peat.

The core with the greatest depth was retrieved for analysis. This was done using a

Russian corer.

3.5 Sample Preservation and Storage

Core peats samples were inserted into half pipe tubing and wrapped in cling film.

Block peat samples were extracted straight into cling film and sealed inside plastic bags. All samples we clearly labelled and records and photos kept. The samples were carefully transported back to a dark, cold room where the reduced

55 temperature (2-4⁰C) hinders microbiological growth. The laboratory methods will be described in the proceeding sections.

3.6 Background of Methods

3.6.1 Peat

Figure 3.2 Diagram of energy flow in a mire ecosystem (R = respiration) (Moore,

1987, p.8)

“Peat is sedentarily accumulated material consisting of at least 30% (dry mass) of dead organic material” (Peat Society, 2015) and has varying degrees of decomposed organic matter making up its composition. The formation of peat (figure 3.2) can be

56 described at plant litter being “attacked by detritivorous animals or ... decomposed by the microbial components of the ecosystem” (Moore, 1987, p.8), where vascular plants and Sphagnum have the main contributing effect (Belyea and Clymo, 2001).

The top layer is where aerobic activity occurs (acrotelm) and the bottom layer beneath the water-table is anaerobic (catotelm) and is dependent on the vegetation and the water input (Breemen, 1995). Sphagnum maintains anaerobic conditions by harbouring water within its physical structure and by drawing in nutrients and water by its root system inhibiting other species of non-vascular plants, which cannot tolerate the fluctuating water levels and nutrient poor peat.

The increase in Sphagnum is directly related to the rise in peat formation increasing the net energy store within the mire where layers of decaying organic matter build from the bottom up. Sphagnum can occur on both hummocks and hollows, but on hummocks it is more efficient in leaching water into its root system (Belyea and

Clymo, 2001).

The lack of free oxygen inhibits microorganisms breaking down all of the plant material, which happens in other habitats (Yeloff and Mauquoy, 2006). Plant competition can affect the dominance, for example, the amount of sunlight influences Sphagnum types, whereas temperature is a more dominant control on vascular plants as is root depth (Buttler et al., 2015). Cooler temperatures can inhibit the rate of decomposition of material situated within it and wetter environments encourage faster growth of peat, however these layers are less humified due to a short time period in aerobic conditions in the acrotelm. An

57 ombrotrophic ‘raised bog’ will only have a precipitation for its moisture budget input, having a high acidic content (low pH) is therefore generally colonised by

Sphagnum and heaths like Calluna vulgaris, where minerotrophic peatlands

(blanket peat) will have a slightly higher pH and a greater mineral content as water inputs have passed through bedrock adding minerals, vegetation is typically sedges like Eriophorum and Carex. The study by Aaby (1976) used ombrotrophic mires to show climatic change, as it is a direct indicator of water table levels from precipitation alone and is by far a better representation of water inputs into a system. The peat itself and the macro- and microfossils within the peat can be studied in isolation or in relation to each other and also the mineral composition can indicate climatic conditions.

3.7 Laboratory Methods

3.7.1 Humification

The composition of peat can be studied to suggest the climate dynamics of the period when it was formed. When these layers build, they form a sequence of layers which can reflect the changes in decomposition. This layer of decomposition is indicative of the conditions affecting the area. The degree of decomposition can be measured in the laboratory. A general assumption with peat stratigraphy is that the darker the band, the more humified it is. Studies including Langdon et al. (2003) and

Yeloff and Mauquoy (2006) have shown how humification can contribute to a multiproxy study as an indicator of bog surface wetness (BSW). However, it can have a major role in interpreting climatic fluctuations through BSW but has been suggested that summer temperatures are a more efficient factor (Charman, 2007).

The wetness of an ombrotrophic bog is an excellent record of the conditions at a particular point, to represent a local area or a series of analyses must be completed for a regional area. During decomposition humic substances are produced, the colour of the water measured via a colorimeter (from the peat has been used to deduce how humified a sample is, which can be quantified using light transmission).

The darker the colour, the more humified it is. The humic substances need to be identified and quantified, as they alter transportation mechanisms of both organic and inorganic substances which potentially could falsify the results (Gaffney et al.,

1996). The degree of humification of samples of peat shows the decomposition rate at the time it was formed, linked with the surface wetness BSW of the substrate

(Blackford and Chambers, 1993). A variation in vegetation species forming the organic matter of the peat can also cause a difference in humification readings and ideally the species would be solely representative through all the samples to avoid this dissimilarity in results (Hughes et al., 2012).

A relative measurement can quantify the humified samples; Samples were taken in approximate 1cm3 blocks that were then left to dry overnight at 105⁰C in an oven. It is also noted that some changes in conditions are not found in the results obtained from the peat, as the degree of humification can change slower that the external influences affecting it. Although humification is a useful proxy record it may not be

59 the most sensitive, showing a more holistic view of reconstructing climate unless accumulation and sampling rates are both comprehensive, so sampling was done at

1cm intervals (Amesbury et al., 2012).

Each sample was dried in an oven at 40°C then ground into a powder to give an exact weight of 0.1g (±0.0001g). The use of 8% sodium hydroxide was then used break down the peat. Blackford and Chambers (1993) suggest that the extraction method using sodium hydroxide is the most exact. 50ml was added into a beaker with each sample. Each sample was brought to the boil then simmered for 60 minutes to aid the release of humic acids and then cooled. All samples were topped up with distilled water to 100ml and filtered through a funnel and Whatman

Qualitative 1 paper. The filtered mixture was then diluted to 50% with more distilled water making the sample up to 50ml.

A colorimeter was used with the finished filtered sample to give a percentage light transmission reading. The reading, when calibrated to the organic content of the sample, is more accurate, this method was refined in (Blackford and Chambers,

1993). A wavelength 540nm is commonly used to show the sensitivity was also utilized in this study (Blackford and Chambers, 1993); however, it is also suggested that 550nm is adequate (Mauquoy et al., 2002). This method is dependent on the state of the decomposition and an appropriate wavelength used consistently throughout. Each sample was compared to distilled water, with that value to be taken as 100% and each sample was re-measured three times to give an average reading. When conducting the humification analysis, the timing between the different elements of the procedure does not appear to be significantly important,

60 as long as it is consistent for each sample, the different rates of evaporation of sodium hydroxide also seems to have a negligible impact on the results, (Blackford and Chambers, 1993) so this was done consistently for all samples.

3.7.2 Pollen Analysis

Pollen analysis can be used to show both short-term and long-term vegetational changes (Ritchie, 1995), although there are limitations to the method. As outlined in

Birks and Birks (2000) pollen analysis assumes that there is a direct relationship between the pollen deposited in the sediment and the vegetation that produced it.

However, the pollen-vegetation relationship is complicated with varying production, dispersal and preservation factors for each species. The issue of dispersal factors is the same for each species as it is preserved in the same way with negligible movement once deposited. There are generalisations and errors will be produced with this assumption. However, it has been one of the most popular methods for the last half a century (Birks, 1965; Simmons and Innes, 1988; Innes and Simmons,

2000; Farrell et al., 2014), because it gives a broad description of vegetative changes, while most indicators show only the changes at an exact point, although in more sheltered areas the pollen may include a more local signal, this should be considered during the interpretation of the results.

Palynology is a common method for reconstruction; however, in an environment with few types of trees and other kinds of vegetation, the development of

61 succession markers may not be thoroughly represented due to pollen dispersal methods. Different plants produce varying quantities of pollen, sizes and also they can be distributed by various methods and preservation can also vary. For example

“Populus, Taxus and Juniperus are easily destroyed” (Goodwin, 1934). This needs to be considered when comparing directly one type to another. There needs to be consideration given to the representation of Orkney as a whole and the radius of the catchment of the pollen rain associated with the types of vegetation and environment that the samples have been taken from.

Vegetational changes are slow in response to altering in comparison to other proxy records, due to the reliance on a transport method to germinate in other places, can be is up to 2000 years difference (Bennett, 1990). Figueiral et al. (1999) showed that the dispersal pattern for pollen could be far greater than the actual plant macrofossil material, which will be noted when looking at actual remains and pollen, however it can be misleading when directly comparing studies, especially when the samples are more representative of long-distance pollen fall out or if the samples are contaminated (Bennett, 1990). When the pollen is deposited there is a possibility of down-washing and up-washing to a small degree (Clymo and Mackay,

1987), however, this will be on a scale smaller than the sampling resolution so will not be an issue for this study. More importantly for the Blythemo site, in particular, the possibility of over-representation of plants that are carried by the movement of streams, are taxa such as Alnus, if they are found in increased abundance it may indicate a period of flooding (Birks and Birks, 2000)

The laboratory analysis starts by removing the surface layer of peat with a blade to clean the surface of any loose debris. Then a 1cm3 sample was taken as described in

Faegri and Iversen (1989), done by volume displacement with de-ionised water in a

10ml cylinder, then 5ml of 10% hydrochloric acid (HCl) was also added to remove calcium carbonate in the samples. Lycopodium spores were added and the reaction was left to settle. The exotic marker spores added to the known volume are used in a known concentration to work out the total pollen concentration (Benninghoff,

1962). To remove the humic acids 20ml of 10% potassium hydroxide (KOH) was added and put in a water bath with a glass stirring rod in each sample for 30 minutes. Then they were decanted into a centrifuge tube, balanced with de-ionised water and centrifuged for 3 minutes at 4500rpm and decant the supernatant disposing of the waste as per the laboratory procedures. The next stage was for the removal of the fibrous plant debris. Samples were agitated with distilled water in a vortex mixer and carefully wash through a 125µm sieve in a funnel into a new centrifuge tube and then put in the vortex mixer again to break larger debris up.

Balancing with deionised water centrifuge for 3 minutes at 4500rpm and decanting, this was repeated until the supernatant runs clear. The next stage was to remove the cellulose by acetolysis. In a water bath, the pellet was suspended in 5ml glacial acetic acid to dehydrate the sample and then it was centrifuged for 2 minutes. In clean, dry glassware and wearing appropriate personal protective equipment, the acetolysis mixture was made (from 1 part concentrated sulphuric to 9 parts anhydride). 5ml of this mixture was added to the sample and it was placed in the water bath for 2 minutes before centrifuged and decanted. Glacial acetic acid was then added by the same method to remove the acetolysis mixture. Then KOH was

63 added and removed, also in the same process to neutralise the acid. De-ionised water removed any remaining alkali. 5ml of ethanol was added centrifuged and decanted from the sample ready for tert-butyl alcohol which was gently warmed in the water bath to form a liquid (solid at room temperature), 1ml was added and the sample was then centrifuged, this dehydrates the sample ready for preparation for the microscope slides. Silicone oil was added to help mobilise and preserve the pollen grains on the slide; samples were left 24 hours to let any remaining tert-butyl alcohol to evaporate through a cotton wool plug before preparing slides. On glass microscope slides, one drop of the sample from a pipette was covered with a coverslip and sealed with clear nail varnish.

The standard method found in Moore et al. (1991) is the usual method adopted to prepare samples for identification as with this study. Catalogues and keys in

Erdtman (1969); Faegri and Faegri (1989) and Moore et al. (1991) was used to identify the pollen types, and assumptions on identifying pollen grains will be consistent when using a standard reference guide. To ensure a diverse representative range of taxa is recorded 300 grains excluding aquatics and spores was recorded for each depth (Birks and Birks, 2000). The exotic marker grains were counted to provide a concentration level.

Tilia software was used to show pollen diagrams with zones of distinct change. This was then grouped into total land pollen (TLP), trees and shrubs, heaths, herbs, aquatics and also spores. The CONISS statistical function was run to identify areas of similar quantifiable zones to aid analysis. To further aid analysis Canoco software

64 was used as statistical methods to plot proposed taxa against to axis to indicate wet and dry indices.

3.7.3 Charcoal

Charcoal is formed at 280⁰C - 500⁰C making it robust and, therefore, preserved during the pollen preparation methods. During pollen counts, charcoal was quantified by measuring the size against the guide on the viewfinder on the microscope, where 50µm is a count of 1. It is suggested that this magnitude or greater is more indicative of local fire events (McDonald et al., 1991). Relationships related to the discovery of charcoal cannot be attributed to a single parameter, such as precipitation or temperature alone as the dispersal mechanisms making it in isolation a weak climate reconstruction tool (Kloster et al., 2015). The size of charcoal fragments is also a factor in whether it is a localised event, smaller fragments of charcoal are distributed over a larger area, due to the lighter nature it can be carried further by aeolian mechanisms, with larger fragment being under- represented due to the sieving process during pollen preparations (Clark, 1988).

During the identification of charcoal it is assumed that intensity and frequency of fire events cannot be separated (Clark, 1988) making any assumptions difficult without relating it to a known occurrence. Therefore, charcoal is used with caution to provide some correlation to other proxies.

3.7.4 Geochemistry

Many elements can be used as an indicator of climate change. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to analyse samples to show if any trace metals and elements are present in samples. The elements are then related to other by proxies to show if there are any significant changes in the environment.

ICP-OES is a popular method, as it is a non-intrusive rapid resource. It is also ocst effective method of measuring large quantities of elements. This method produces more simultaneous ‘excited’ ions compared to furnace methods giving a greater range of trace elements (Oblesik, 1991). The argon plasma used in this method is also so inert, that it has less chemical interaction with the substrate also lending it to the having the ability to give a larger spectrum of trace elements in the results, these are shown in the table 3.1(Hou and Jones, 2000)

Table 3.1 Elements the can be determined by ICP-OES (Hou and Jones, 2000: p14)

Titanium and silicon (Hӧlzer, 1998), which can be an indicator of erosion, linked with pollen marker species can show land use changes will also correspond with the chemical responses if present. Plantago lanceolata is one indicator of farming

66 practices that would be linked with the levels of titanium and silicon and if present in results it will add to the analysis. Mercury can also be used as a marker for changes in the environment. With low concentration rates of more stable mercury found in periods of warmer environmental conditions and less stable mercury accumulated at a higher rate during periods of colder times (Martinez-Cortizas et al., 1999). This is useful as an environmental indicator as prolonged temperature changes will impact on the environment and, therefore, the vegetation. Sphagnum, for example, can also retain more mercury than other species, so the spores present at a particular depth should also be examined (Roos-Barraclough et al.,

2002).

Problems with using mercury as an indicator is that the accumulation rates between sites and for different locations within the same site can show significantly variable results (Rydberg, et al., 2010) and between levels found in each individual plant, due to differing levels of sequestration (Roos-Barraclough et al., 2002)

ICP-OES analysis using a CEM Mars Xpress microwave digestion and Perkin Elmer

2100DV spectrometer was carried out. Samples were taken at 1cm intervals and dried overnight at 105⁰C. Then sieved through a 2mm sieve to remove any coarse vegetation remains. 0.2000 g of the sample was of the sediment was added to a microwave vessel with 10ml of nitric acid, this sample was bunged and placed in the digestor with the programme set. After the digestion, the sample was left to cool and then filtered into a 25ml volumetric flask through GFC filter paper. The sample was made up to 25ml on a volumetric flask with deionised water. 5ml of the filtrate

67 was then made up to 20ml on another volumetric flask, and then 14ml was transferred to a centrifuge tube.

In the ICP-OES, the machine is turned on, screw the argon regulator to a pressure of

7bar, the nitrogen to 3bar with the extraction on. Lighting the plasma was done on

Winlab32 software clicking the plasma icon and switch icon. The peristaltic pump tubing should be located and locked once pump starts running to prohibit the nebuliser chamber from flooding. The plasma should ignite within 1 minute and left for 15 to stabilise. After calibrating the samples on the software calculating the concentration is done by:

Value from ICP x 25 x 4 / original weight of oven dried sample

3.7.5 Dating Method

There are many other proxy methods that can be used to determine past conditions. So far pollen reconstructions have been mentioned to provide a history of the changes in vegetation, humification indicates how well the peat is broken down which is potentially indicative of the climate. To add to this, and to allow completion of other climatic records, accurate dating is required. All these proxy methods are closely linked with water level and need to be dated with good chronological control to allow comparison between sites.

Radiocarbon dating is one way of finding the age range of a sample and is the most commonly used. This provides a date in the form of a year accompanied by a range this method is reliable, although costly, the observer can choose the samples to date and but it can be time-consuming. It will be used in this research to add significance and reliability to results (Birks and Birks, 2000) Radiocarbon analysis has developed from traditional methods of counting only decaying 14C to AMS

(Acceleration Mass Spectrometry) to recording all atoms in the sample which is indicative of smaller sample sizes. Therefore, modern AMS sample size need to preferable produce 3-5mg of carbon to provide accurate results.

For this study 10 AMS dates were used for two cores to provide the chronological control. The dates were chosen from shifts of wet and dry indicators on the humification results. Samples Radiocarbon were prepared by taking 1cm sub- samples and sent to the NERC facilities with the appropriate site and sample descriptions in clean glass vials and sealed in plastic bags. At the NERC Radiocarbon

Facility NRCF010001 the samples were processed by:

‘Samples were digested in 1M HCl (80⁰C, 8 hours), washed free from mineral acid with deionised water then digested in 0.5M KOH (80⁰C, 2 hours). The digestion was repeated using deionised water until no further humics were extracted. The residue was rinsed free of alkali, digested in 1M HCl (80⁰C, 2 hours) then rinsed free of acid, dried and homogenised. The total carbon in a known weight of the pre-treated sample was recovered as CO2 following combustion in an elemental analyser

(Costech Instruments). The gas was converted to graphite by Fe/Zn reduction’

(NERC analytical report).

3.8 Conclusion

More significant movement is anthropogenic disturbance driven by peat cutting for fuel. This is an issue in Orkney with its limited access to other types of fuel i.e. wood as there is little tree development on Orkney. All proxies have errors. However, the multi-proxy approaches are the most reliable when supporting evidence for reconstructions of past climates. From this humification, geochemistry and pollen will be the predominant source of data in this research and dated by radiocarbon.

Chapter 4 – Results

4.1 Introduction

This chapter will describe the pollen, humification and geochemistry across the

Loonan and Blythemo. The analysis of this proxies will continue in chapter 5. Some of the data is shown against each other to enable a comparison and interrelations between sites and proxies. The Palynology is described in zones outlined by CONISS program then each phase is discussed in terms species populations, geochemistry and humification changes, the dates are from radiocarbon dating.

4.2 Peat Stratigraphy

4.2.1 Loonan

The core collected at Loonan was 227cm long, showed in figure 2.14. 0cm-69cm had roots and slightly decomposed vegetation within it. It was stripy in appearance at 69cm-150cm showing different layers of humified peat. The Cyperaceae peat

150cm-190cm was more humified in appearance. The base went down to clay.

0cm-69cm Sphagnum peat, vegetation/roots 0cm- 20cm

69cm-150cm Cyperaceae peat/Sphagnum peat

150cm-190cm Cyperaceae peat

190cm-227cm Well humified monocot. peat

Table 4.1 Loonan Stratigraphy

4.2.2 Blythemo

This core (figure 2.17) at the top had roots apparent in the structure for 15cm, the banding of the peat was not as apparent as Loonan and again went down to clay.

0cm-64cm Sphagnum peat, vegetation/roots 0cm- 15cm

64cm-95cm Cyperaceae peat/Sphagnum peat

95cm-120cm Cyperaceae peat

120cm-152cm Decomposed monocot. peat

Table 4.2 Blythemo Stratigraphy

4.3 Age depth curves and dates

Figure 4.1 Loonan Age depth curve

Depth Pos Neg Depth Error Cal BP Upper Lower Error Error

135 5 113 269 13 156 100

265 5 162 284 0 122 162

695 5 1478 1560 1403 82 75

1225 5 2230 2334 2153 104 77

1875 5 2317 2356 2159 39 158

2255 5 2796 2857 2750 61 46

Table 4.3 Calibrated age Loonan

Upper Zone Boundary C. Age Depth Model Yr BP

LOO-1 2419

LOO-2 1917

LOO-3 966

LOO-4 196

LOO-5 -1141

Table 4.4 Loonan zone boundary ages

-500 0 500 1000 1500 2000 0 y = 0.0004x2 + 2.2177x - 51.88 500 R² = 0.9996

1000

1500

2000

2500

3000

3500

4000

4500

Figure 4.2 Blythemo age depth curve

Depth Pos Neg Depth Error Cal BP Upper Lower Erro error

0 -59

625 5 1546 1685 1415 139 131

955 5 2434 2696 2345 262 89

1425 5 4030 4146 3911 116 119

Table 4.5 Calibrated age Blythemo

Upper Zone Boundary C. Age Depth Model Yr BP

BLY-1 3921

BLY-2 3249

BLY-3 3027

BLY-4 2064

BLY-5 1289

BLY-6 514

Table 4.6 Blythemo zone boundary ages

The radiocarbon dates were calibrated using the CALIB radiocarbon calibration programme (version 7.1html). The age-depth model is based on the median probability dates reported by CALIB. The y-axis error bars represent the 2 sigma

(94.5% probability) calibrated age range for each date. The x-axis error bars represent the sample depth of the radiocarbon sample.

ZONE LOO-6 LOO-5

LOO-4

LOO-3

LOO-2

LOO-1

Figure 4.3 Loonan pollen profile

ZONE TreesHeaths & ShrubsHerbs Humification Al Ca Cd Co Cr Cu Fe Mg Mn Ni Sn Pb Ti Zn 0 Stratigraphy LOO-6 97 ± 35 10 LOO-5 20 153 ± 37 30 LOO-4 40 50 60 1598 ± 37 70 LOO-3 80 90 100 110 2231 ± 35 120

Depth (cm) Depth 130 140 LOO-2 150 160 170 180 2290 ± 37 190 200 LOO-1 210 220 2692 ± 37 230 20 40 60 80 100 20 40 60 1000 2000 5 10 15 10 10 10 10 2 4 6 8 10 2000 4000 100 200 10 10 20 40 60 80 100 200 300 20 40 60 % T x 1000 x 1000

Sphagnum peat Cyperaceae peat Well humified monocot. peat

Figure 4.4 Loonan Geochemistry

Trees & Shrubs Heaths Herbs Aquatics Spores

ZONE BetulaAbiesAlnusCorylusIlex Empetrum Calluna VacciniumPoaceae type Cyperaceae PolygonumPotentilla typeViscumPlantagoPlantago lancelataPlantago mediaSolidago majorNarthecium vigaurea type MyriophyllumHydrophylumLycopodiellaPteropsida inundataPolypodium (mono) indetPteridiumSphagnum Charcoal Trees & ShrubsHeaths Herbs Humification 0 Stratigraphy 10 BLY-7 20 30 40 BLY-6 50 1644 ± 37 60 70 BLY-5 80 90 Depth 2402(cm) ± 37 BLY-4 100 110 BLY-3 120 130 BLY-2 3689 ± 37 140 150 BLY-1 160 20 40 60 20 40 60 80 100 20 40 20 40 60 20 20 20 40 20 20 20 40 60 20 40 20 40 60 80 100 20 40 60

Sphagnum peat Cy peraceae peat Decomposed monocot. peat

Figure 4.5 Blythemo Pollen profile

ZONE

BLY-7

BLY-6

BLY-5

BLY-4

BLY-3

BLY-2

BLY-1

Figure 4.6 Blythemo geochemistry

4.4 Loonan pollen and geochemistry descriptions (figure 4.3, 4.4)

Zone LO-1 172-230cm (225.5cm -2692± 37 B.P) (187.5cm -2290± 37 B.P)

The first zone is dominated by herbs with between 50.5% and 70.7% of TLP (Total land pollen); this is heavily compromised of Poaceae and Cyperaceae that appear to have an inverted relationship. Ranunculus acris a meadow buttercup has a low, consistent c. 1-2% of TLP most of the zone, typical of disturbed pastures or grazing, as is Plantago lanceolata that shows a similar low-level occurrence. Potentilla is shown at 9.6% at 225cm and steadily decreases to 0.7% at 204cm where it then disappears. Calluna dominates the heaths (29.0% - 55.1%). and has a comparatively consistent level across the zone. Vaccinium type and Empetrum are also present at the lower part of the zone. There is the greatest abundance of species of trees and shrubs were shown at this level, but all are at very low levels (<1%). Pinus and Alnus show similar trends to each other, both found in the lower part of the zone with one reoccurrence around 200cm. Corylus and Ilex were identified in single instances; Abies was identified in the upper part of the zone. Myriophyllum, an aquatic type, thrives in small pools of freshwater and shows a decreasing trend in this zone. Polypodium and Pteridium spores also are present in the lower part and disappear indications of cool, wet conditions. Sphagnum is also abundant and disappears, but returns at 200cm peaking at 7.6%. Charcoal in this zone is moderate with consistent abundance up until the 180cm, where no further evidence was found in this zone.

The geochemistry for the lower two zones (LO-1 and LO-2) fluctuates greatly.

Manganese and calcium show similar peaks and troughs, the abundance of iron also has some similarity. Lead is a consistent element; the source is potentially atmospheric pollution. Zinc and titanium both show simultaneous peaks 180cm, although zinc also shows a peak 65% greater at 188cm, which is not reflected in a rise of titanium records.

Overall this phase is dominated by Calluna, Cyperaceae and Poaceae, suggesting disturbed environments. The presence of tree pollen like Pinus can be over represented in counts and although present in this phase this is not necessary indicative of trees in the immediate area. However, this zone does have the most diverse species range of trees and shrubs indicating pockets of scrub are evident despite changes in vegetation. Humification is moderate throughout indicating relative accumulation rates of the peat. The low levels of spores are indicative of moderately dry or temperate conditions. However, Cyperaceae levels are consistently high which thrive either alongside scrubland or wetlands so some wetter areas must have prevailed. The geochemistry suggests a more changeable picture with more flashy peaks in aluminium, iron, calcium which indicates variable conditions of rainfall as these elements can be leached if rainfall is high.

Zone LO-2 106 - 172cm (122.5cm – 2231 ± 35 B.P)

This zone has some similarities to zone LO-1, but the ratio between herbs and heaths has greater fluctuation, being dominated by Calluna and Poaceae. However,

Cyperaceae is significantly lower and a distinct rise in Narthecium is shown in significant abundance throughout the zone and has a relationship with the calcium- poor soil. Although Sphagnum is absent at some depths, however, it shows an overall decreasing trend, which is largely inversely correlated to humification.

Polypodium is the only spore to be identified at multiple depths, but numbers are low so no conclusive evidence can be drawn from this. Plantago lanceolata continues at low concentrations, although absent 136cm-152cm and has one spike in the upper part of the zone where Narthecium is absent. Charcoal is intermittent through this zone and is high at the times when the heaths are prominent. There are three peaks in heaths making up 50% of the TLP, and two for heaths. Trees and shrubs were very sporadic, with Betula, Abies, Ulmus and Corylus making up less than 1% of TLP.

The geochemistry is interesting, with similar large fluctuations in calcium, manganese, aluminium and iron until 134cm there after all levels dramatically reduce to the top of the zone. Conversely, levels of lead which was consistent through zone LO-1 and most of this zone suddenly starts to rise at 110cm,

Sphagnum also shows a similar peak. The levels of magnesium begin to increase after 134cm which can enhance the alkalinity of the substrate, however there is no increase in alkaline plant abundance, so the decrease in other hydrogen giving elements may leave the peat pH steady.

In summary, during this phase a significant event occurs at around 134cm when some trace element levels fall and Narthecium peaks. This zone has the smallest abundance of trees and shrubs throughout the entire sample for this site. The peak in iron (6000 ppm) just before at 146cm could suggest the beginning of a change, which is the largest spike in iron geochemistry for this site.

Zone LO-3 43 - 106cm (68.5cm - 1598 ± 37 B.P)

This zone is predominantly occupied by heaths in a bi-modal distribution lending itself to the abundance of Calluna and the overall percentage of herbs is reduced leading on from zone LO-2. Trees and shrub values although low, making it the highest percentage during this zone, consisting of Corylus, Abies and Ulmus. This is the only record of Ulmus in this monolith. Empetrum also shows two peaks coinciding with the presence of Calluna. Erica tetralix is also found at the same time, inferring there were some patches of wetter heath. Poaceae follows the two peaks in heath; Potentilla levels are found to be raised at 80cm peak, that favours dry conditions. Narthecium is largely absent from this zone. Cyperaceae was found at lower levels than in other zone, which prefers wetter heath. At the bottom of the zone, Chenpodiaceae is present which is abundant in salty, alkaline or disturbed ground. Charcoal mirrors one of the bimodal peaks again, suggesting burning events with heath generally recovering from fire quicker than other vegetation types. Humification steadily rises during zone LO-3, the availability of humic acid

attributes improving warmer conditions. Solidago virgaurea a forest or meadow herb and Ranunculus acris that prefers moist meadow environments are also found in this zone in limited numbers.

The abundance of trace elements found at this stage are remarkably different to the previous stage. Magnesium is high until 56cm where it starts to dip. Nickel is a useful environmental indicator is completely absent from this stage. Copper is attributed to soil with high organic matter and is seen as a slightly higher level in this zone as humification increases. Manganese had an average of 4.47 ppm compared to levels of over 100 ppm in zone LO-2. Lead has started at the bottom of the zone with a peak and continues to a second peak and with a much higher background level, similar to the percentage of heaths in TLP.

Overall indicators suggest that conditions supported more dry heath plants than wet and there are marked increases in magnesium at this time. Heaths and charcoal are dominate towards the top of the zone and very few aquatic and spores.

Zone LO-4 19-43cm (26.5cm -153 ± 37 B.P)

This zone is dominated by herbs similar to zone LO-2, with moderate-low

Cyperaceae counts, fluctuating Poaceae and a significant rise in Narthecium. Also, some evidence of Potentilla, Ranunculus acris, Succisa and Plantago lanceolata indicates grazing and farming land uses. There are few trees and shrubs, only a few occurrences of Betula, Corylus and Ilex. Calluna shows a slight reduction followed

by an increasing trend. Empetrum is only shown at 42cm and Vaccinium is also only present at one depth also. One of the raised levels of Calluna at 36cm is at the same depth as one of the few charcoal evidence found.

The geochemistry shows a sharp rise in levels of aluminium, calcium, manganese, iron and lead and also chromium and copper to a lesser extent. Zinc and titanium maintain low-level fluctuations. The humification at this time increases and then follows a decreasing trend suggesting a more rapid accumulation of peat.

Zone LO-5 4-19cm (13.5cm - 97 ± 37 B.P)

This zone is more balanced in herbs and heath; this is made up of Narthecium,

Calluna and Poaceae. Erica tetralix uppers at the top part of the zone making its greatest dominance through the entire core. Plantago lanceolata also increases in the upper part, as does the rise in charcoal. There are few spores and aquatics here.

However, Sphagnum is the exception to this with consistent levels approximately at

10% of TLP. There are few trees and shrubs again, Betula is found at the middle part of the zone and Pinus, Alnus and Ilex in the upper zone.

The trace elements for aluminium, calcium, iron and zinc show a slight decrease in levels until 8cm were this decline is accelerated. Nickel spikes to 5ppm just ahead of this decrease of the other elements. Lead levels remain constant and Titanium increases in two spikes. Humification remains low and steady.

Zone LO-6 (0-4cm)

This zone is dominated by herbs, with a slight decreasing trend. Heaths are the other significant element in this zone, nearly solely consisting of Calluna. There is a small presence of Alnus, Betula and Pinus, although this is at very low level.

Poaceae has its most significant contribution for the herbs, with also some evidence of Potentilla a hardy herb and Narthecium. Cyperaceae types (sedges) marsh-loving varieties are present in a small amount but aquatic spores are absent. Spore concentration is low with low levels of Pteropsida, Polypodium and Pteridium, and significant Sphagnum levels throughout.

The geochemistry for this shows a large decrease in aluminium, calcium, iron and magnesium. Marginal decreases in chromium, copper, manganese and titanium, with increased levels of zinc and lead. Overall, this stage is typical of disturbed vegetation or grazing, with only one spike of charcoal the evidence of localised burning is low, while the humification transmission is steadily rising indicating more humic slightly drier or warmer conditions. The presence of Plantago lanceolata at the start of the zone and the decrease in titanium.

4.5 Blythemo pollen and geochemistry descriptions (figure 4.5 and 4.6)

Zone BLY-1- 144cm - 152cm

This zone is extremely dominated by Calluna, with only occasional Poaceae and

Potentilla, Polygonum and Cyperaceae found. Polypodium and Pteridium are also sporadic with some increasing low levels of Sphagnum. Alnus is the only arboreal pollen type found and is only found at the beginning of the zone when humification is decreasing. After this initial decline, a sharp increase was seen in humification.

Calcium, copper, manganese and zinc show a decreasing trend in this zone, in contrast to lead and titanium levels which rapidly increase to levels of 60 ppm.

Aluminium, iron and magnesium also increase. Chromium was found to be low throughout as was cadmium and cobalt. Levels of tin are low throughout the entire monolith. However, a small-scale rise at the beginning of the zone is seen.

Zone BLY-2 124cm - 144cm (142.5cm - 3689 ± 37 B.P)

This zone is described as a balance between Calluna and Cyperaceae. At the lower end of the zone Calluna is low, it peaks to levels as high as 90% and decreases thereafter, Cyperaceae is inversely correlated. Poaceae is present at the start of the zone, with one reoccurrence. Calluna peaks with the rise of charcoal. Narthecium is evident at the top of this zone. Alnus is found at 140cm only, which is the only arboreal pollen discovery in this zone.

Humification decreases in a linear fashion, as does lead. The heaths group, as a percentage of TLP initially increases and then decreases thereafter. Aluminium and titanium also follows this pattern, whereas calcium and magnesium show an inverse relationship to this. The amount of iron and zinc and copper and Nickel to a smaller degree all decrease during this time.

Zone BLY-3 116cm - 124cm

This zone sees an overall increase in herbs, due to Narthecium increasing and

Poaceae also being present. Calluna is abundant reaching 70% of TLP in the centre of the zone. Alnus and Corylus are present at 120cm at the beginning of the zone.

Spores consist of a Sphagnum and Lycopodiella inundata, two moisture loving mosses. Charcoal appears after 100cm in line with the proliferation of Calluna.

The geochemistry shows increases from 31.4 ppm to 275.4 ppm for aluminium, calcium also shows a similar increase. Copper and iron show a bimodal distribution, whereas lead plateaus around 10 ppm. Titanium increases exponentially during this zone. Overall there is reduced levels of peaks in the geochemistry, but there was some stability in this zone with few peaks and gradual increases in levels.

Zone BLY-4 84cm - 116cm (95.5cm - 2402 ± 37 B.P)

The overall trend is similar to zone BLY-3, with an rise in heaths, the difference is the emergence of arboreal pollen towards the top of the zone. Narthecium flourishes in wet boggy conditions and this is abundant around 90cm, this is straddled by the profusion of Cyperaceae, which also thrives in boggy conditions,

Sphagnum also increases. Both Empetrum and Calluna that prefer drier conditions decrease in this zone and wetland herbs at the upper section on this zone increase.

Alnus and Betula are both present at this upper section of the zone coinciding with

Poaceae abundance.

The geochemistry shows titanium and copper mirrors this switch from wet to dry plants. Prior to this occurrence magnesium spikes by 1000 ppm. Post the proposed wet and dry shift zinc also spikes. The humification shows an average decrease, with a rebound at around 90cm.

Zone BLY-5 56cm - 84cm (62.5cm - 1644 ± 37 B.P)

Calluna again dominates the heaths, with strong evidence of its expansion throughout this zone; charcoal also is abundant in this zone. Sphagnum shows an inverse relationship to the presence of charcoal. Poaceae and Cyperaceae levels are relativity stable throughout this zone. Empetrum is also present at three different depths spanning the zone. Tree and shrub pollen from is present at the upper and lower sections of the zone consisting of Betula and Alnus. Potentilla and Plantago major, a species that is an indicator of disturbed land is present during this zone.

Humification only shows a small range of values in this zone. The most distinct feature shown in the results from the geochemistry is a fluctuation of iron to 3620.8 ppm and magnesium to levels of 2548.2 ppm. Lead, calcium, manganese and

Aluminium also suggest a change at 76cm. Levels of copper in contrast does not show any significant change.

Zone BLY-6 19cm – 56cm

As with the previous zone, Calluna is the most prolific of pollen types, giving the heaths a larger proportion of TLP, with some more sporadic evidence of Empetrum throughout the zone. Levels of Poaceae are higher and more consistent than in other zones. Cyperaceae is also consistent but much less significant than Poaceae.

Some accounts of Viscum a hemiparasitic plant, that grows in branches, however, no accounts of shrubs were recorded at this depth, but Corylus is found in the sample both above and below this depth. Alnus and Ilex pollen is also found in this zone and low levels of arboreal pollen are found more consistently than any zone represented at this site. Sphagnum and Polypodium both have some success in being established. Charcoal is evident in the upper section of the zone.

After the significant peak of levels of iron in zone BLY-5, levels of the trace metal fluctuates greatly. Similar flashy results are also shown in aluminium, lead, titanium and zinc. Calcium was shown to a plateau, apart from one peak of 4899.6 ppm at

38cm. Humification stays consistent. Two small occurrences of tin at the upper and lower ends of the zone are also shown. Chromium is at low levels throughout with a small peak also at 38cm.

Zone BLY-7 19cm – 0cm

Calluna is shown at similar levels to zone BLY-5, however, Cyperaceae was almost absent with only two individual depths recording this evidence and both were at levels of 1% TLP. Poaceae is shown to the upper section of the zone and other herbs are sporadic through this zone. Charcoal is present at low levels despite high levels of Calluna. Polypodium and Pteropsida are shown in inversely to each other regardless of being abundant in similar conditions. Trees and shrubs are the most abundant in this zone compared to all other zones. Corylus is found at numerous levels, as is Abies and Alnus, Betula is also represented at 15cm to a level of 1.6%

TLP.

A small rise in lead and a large rise in aluminium levels are present at 10cm. Iron, calcium and magnesium both show dual peaks of abundance. Humification remains at a similar level to zones BLY-3 through to this zone. Other results from the geochemistry remain at low concentrations.

Chapter – 5 Discussion

5.1 Introduction

The aim of the research was to accurately describe the new late Holocene on

Orkney, using recognised palaeoecological techniques. As outlined this will aim to provide a catalogue of palaeoenvironmental change with an underpinning of archaeological references.

5.2 Interpreting pollen and charcoal

As previously discussed there are important considerations in relaying the pollen number counts, including how abundant the pollen rain is for a single species, how far the pollen grain can travel related to size and assumptions associated with inferring conditions from a vegetation assemblage to climatic parameters, mainly water-table level. Then associating two different sites needs caution as pollen will naturally disperse and accumulate differently in dissimilar environments. The following interpretations are based on figures in results section.

5.2.1 Loonan interpretation

Zone LO-1

This has a high number of herbs, with disturbance indicators such as Plantago lanceolata. Dry heaths prevail with evidences of charcoal, which heaths can recover from quicker than other vegetation. Pinus, Abies and Alnus suggest that tree populations are existing, although this does not mean that the pollen is from

Orkney but it does suggest that land use has not removed all wooded areas. c. 2692

BP dates the 225cm layer and c. 2290 BP wetter conditions were becoming drier and recovering from woodland decline (Bunting, 1994).

Zone LO-2

In the upper part of the zone Betula proceeds Ulmus which is in line with woodland succession, suggesting the drier conditions at this time are favouring pioneering species to propagate. The lower levels of the zone show Cyperaceae at low levels and absence of wet heath types i.e. Erica tetralix which also suggests that conditions are drier for this phase. Narthecium the wet loving species is consistently present, with Sphagnum moss also showing abundance during this zone

Zone LO-3

Overall this zone appears to increase in wet tolerant Cyperaceae towards the top of the zone. However, Poaceae is shown to be present in two sections of zone LO-3, which is evidence of the land being cleared and also Chenpodiaceae and Rumex are present both ruderals colonising open space. More significant amounts of charcoal are present with higher levels of Calluna at the top of the zone indicating burning and recover of the recovery of heaths. With a rise in arboreal pollen a more succession of species is suggested, until the end when charcoal is found.

Zone LO-4

After the high levels of charcoal in the upper part of zone LO-3, Calluna levels steadily increase in this zone showing the resilience to fire events. Cyperaceae reduces through the zone, but levels of Narthecium levels are strong indicating wetter conditions, Sphagnum levels are also raised.

Zone LO-5

This zone shows a large amount of wet indicators in decline and Calluna levels increasing inferring a change in conditions from wet to dry. Erica tetralix is in its most abundant during this zone thriving in the higher water table levels.

Zone LO-6

The re-emergence of Betula and Pinus shows more stable conditions, although this is assumed to be from windblown pollen from neighbouring mainland countries.

Arable indicators from disturbed ground are also found into the more modern assemblages.

5.2.2 Blythemo

Zone BLY-1

Dry heath dominates the assemblage, spores are seen to reduce and the aquatics are completely absent indicating drier conditions. Alnus pollen is the only representation of arboreal pollen, but no pastoral indicators are present and were few open land use indicators (i.e. Poaceae).

Zone BLY- 2

A wet-shift is generally observed with Sphagnum and Cyperaceae dominance. Also supported by the increase in Narthecium at the end of the zone. Plantago

lanceolata emerges at the upper section of BLY-2 and more Poaceae, so this could indicate potential land use changes towards small scale farming practices.

Zone BLY-3

A sharp increase in Narthecium and lower Calluna abundance could indicate more of wetter period than BLY-2.

Zone BLY-4

With Betula and Alnus present and increased Empetrum generally indicate prevailing drier ground conditions. Although, Narthecium and Cyperaceae are also present which prefer higher water table levels.

Zone BLY-5

This zone shows more synchronicity between the inverse relationship between wet and dry plants, with a clear peak of Calluna and charcoal coinciding with a dip in

Sphagnum spores. Cyperaceae is consistent throughout this zone with some sporadic evidence of moisture loving plants, overall giving wet-dry-wet shifts.

Zone BLY-6

This zone shows similarities to the previous phase, but with a raised levels of open land indicators and aquatics and spores. Corylus is indicated to show more land succession, possibly a climate anomaly giving rise to less arable farming practices.

Zone BLY-7

This zone shows the most abundant arboreal pollen indicators, which could follow the rise in Corylus from zone BLY-6 and lead to less disturbed land use. Calluna is dominant through all of the top zone.

The assemblage consists of more diverse species on the Loonan site, particular the number and species range of aquatics is particularly low on Blythemo. This was also true of the surface samples. Both site have low percentages of arboreal pollen, due to the fact only small numbers of arboreal vegetation types are found on Orkney, and most found in this research will be from mainland Scotland. This will have

similar conditions (Tipping et al., 2008) and give a regional signal of climatic conditions. Local conditions are more important from herbaceous and heath vegetation types as they are more dependent on site conditions. Blythemo has the a higher percentage of TLP for trees and shrubs compared to Blythemo, which may be due to it more exposed position for trapping pollen rain.

5.3 Interpreting geochemistry

Zone LO-1

There are flashy peaks in the trace elements indicating sharp inputs possibly caused by leaching from rainfall in the peat and also local pollution.

Zone LO-2

At 146cm iron levels spike and the change in levels for most other metals at 134cm suggests a significant change in conditions and encourages plant growth.

Zone LO-3

This level shows increased levels of magnesium throughout this zone, which could be down to drier conditions when levels of magnesium can be mobilised easier

(Freeman et al., 1993)

Zone LO-4

This zone has a distinct increase in metals, particularly those that are a by-product of fossil fuel combustion. This could suggest that this zone is around the time of the industrial revolution, dated at c. 153 BP, which would be correspondent to an increase in pollution.

Zone LO-5

Levels of all elements seem to show a marked decrease, dated around c. 97 BP, this could be the start of the decline in heavy industry.

Zone LO-6

The levels are generally increasing up to the present day, with other sources of pollution possibly contributing to this.

BLY-1

Levels of lead aluminium, iron and magnesium and titanium levels increase, which could be a product of erosion.

BLY- 2

Iron and titanium levels increase and then decrease suggesting that as with the previous zone erosion cold be a factor.

BLY-3

The exponential increase again in titanium could show more increased erosion by for example raised runoff rates.

BLY-4

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Again titanium and copper mirrors the switch from wet to dry vegetation dominance, possibly due to erosion rates.

BLY-5

Large lead, magnesium and iron fluctuations, however titanium and copper are at lower levels, so with reduced erosion elements mobilising from drier peat is possible.

BLY-6

The spikes seen in most elements suggests changeable conditions throughout this zone. Possibly the influx of more pollution post industrial revolution.

BLY-7

This zone is more stable than and may suggest less extreme events to modern times

5.4 Overall interpretation

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The subsections 5.4.1 and 5.4.2 summarise the overall changes in the data.

5.4.1 Loonan interpretation

Loonan shows an initial presence of woodland in LO-1, declining in LO-2 this fits in with Iron Age environmental changes. Mainly a population increase during this time and wider use of agricultural crops and would fit in with this decline in woodland and change in land use as found in Keatinge and Dickson, 1979. Bunting (1994) found the between the two study sites, Crudale meadow and Quoyloo moss on mainland Orkney at this time land use was more subjective to human influences.

Loonan shows more comparisons to Quoyloo meadow even being spatially further from Loonan’s site, supporting that a more dominant and ‘aggressive’ society groups leads to a variety of changes in individual pockets throughout the landscape, both show a decline and woodland recovery before becoming more dominant with herbs and heath. The changes in the environment is hard to distinguish as consequence of anthropogenic developments or wider climatic changes, the geochemistry is suggestive of wetter periods for example (LO-1 and LO-2) showing flashier peaks in calcium and aluminium, followed by more stable conditions with short periods of exceptions in subsequent zones. The humification curves also show greatest change in LO-1 and LO-2 supporting more changeable conditions during the Iron age.

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5.4.2 Blythermo interpretation

The record from Blythermo is approximately another 1ka years on Loonan’s profile, recording further into the Bronze age. Again comparisons can be made to Buntings

(2004) study, with herbs dominating the last 3-4ka years with small influences from arboreal pollen, suggesting pockets of small scale woodland fluctuating influenced by the overall exposure of Orkney. Calluna is a also present throughout the profile for both sites, indication areas of waterlogged bogs. Titanium an erosion indicator

(Hӧlzer, 1998) show strong similarities to heath colonisation in Zone BLY-02 and

BLY-03 advocating a dryer more stable period allowing vegetational succession before woodland decline and possibly wetter conditions in line with Anderson’s

(1998) study and increased storminess (Tinsley et al. 1974). Peaks in charcoal and

Calluna appear to be correlated, although surprisingly absent in others, the link between the two is made by authors such as Blackford et al. (1996) associate burning events and management of the heath for farming practices, shown throughout the times we would assume larger settlements and less nomadic communities.

5.5 Summary of influences to climate changes

Moar (1969) found on Orkney that Plantago lanceolata was the beginning of the

Neolithic era, but this predates both cores taken for this study. This taxa was

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present at Loonan in LOO-1 and LOO-2, but was absent in layers at Blythemo up to zone BLY-6, dated at a much later time, possibly suggesting more agricultural practice surrounding this lower level site. Evidence from the Bay of Skaill surrounding Skara Brae archaeological site, show a raise in sea level at approximately 2900 years BP (Renfrew, 1985). Evidence from Loonan and Blythemo would also suggest wetter conditions at this time or just after, although there are no major river systems as a major geomorphic catalyst. At Loonan the possibility of infilling of the Loch of Swannay to heathland would be suggested by the high level of wet heath taxa present at the base of Loonan’s core. Following this, the arable and disturbance indicators e.g. Potentilla rise in LOO-3 and BLY-5, found in Peglar’s

(1979) study at 2500 B.P. Renfrew (1985) also infers this would by mirrored by an decline of Corylus, this is something that this study cannot concur, due the overall low levels of tree pollen throughout the cores sampled. Looking at the broader outlook the overall change considering the small land mass and such a high level of documented cultural changes through the environmental and landscape remains quite unchanged (Keatinge and Dixon, 1979)

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Chapter 6 – Conclusion

6.1 Overview

It is difficult to distinguish climate change from palaeo-records, as all possible causes to any change must be considered. Overall, the climatic inputs will have the largest influence on the environment, but anthropogenic land use changes can also have a staggering consequence. Unpicking the web of interlinked natural and man- made consequences on a location such as Orkney with extensive known archaeological history is certainly a benefit. From such evidence it is known that key locations (e.g. Knap of Howar, Skara Brae) were settled in the Neolithic times,

Bronze age climate deterioration made it difficult to live and farm, followed by colder and wetter Iron age conditions and Roman and Norse influences changing settle types and agriculture.

Loonan’s results showed a finer resolution of climatic changes over the 2692 ±37 yrs compared to Blythemo, showing generally more gradual changes in the proxy indicators measured. Although the results from Loonan showed a general dry-wet- dry shift, indicated by the presences of arboreal and Calluna taxa and peaks of humification rates, this is similar to results found by Bunting (2004) and land use changes tie in with Iron ages occupation and the proliferation of agricultural techniques and practices. The population of areas around Knap of Howar prior to the Bronze and Iron ages also provide artefacts and evidence of land uses at this

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time, there was major impact on human activity after the woodland decline

(Bunting, 2004). Bunting (2004) also suggest that the is a lack of evidence from both the North and the east which this study situated in the north also adds knowledge to.

Blythemo’s core was more compact, but provided records beyond 3689 ± 37 yrs to explore. There were differences in vegetation despite the locality of the sites to each other. This site presented a greater heath and arboreal representation possibly due to a more prominent physical point, however the overall pollen flora was less than Loonan’s.

Both sites have provided information back to the Bronze age or Iron age, further exploration of the site could provide more detailed chronologies and more detailed analysis, especially Blythemo could have dissected into grater resolutions to give more influential evidence. Further analysis from fresh samples and may provide material that has a high preservation level of pollen giving more confident results.

Other sites include Rousay offers an extensive area of peat, however due to the abundance of the substrate on a relatively small island much of it has been cut. This makes the areas difficult to access. There is potential to obtain cores of up to three metres from a site at (HY40662, BNG 29899), although exposed peat faces are not obtainable from this area. The signs of peat cutting are not recent and the vegetation is fairly well established over the undulating surface, although cutting

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has been prolific. The Island of Hoy also offers possibilities for obtaining a core as the development of peat in the area is substantial. Hoy is higher elevated compared with the other islands of Orkney. Hoy again because of its abundance of peat has been extensively cut and is now managed. In the area surrounding the Glens of

Kinnaird on Hoy, Berriedale wood, the most northerly area of woodland exists. On exploring the area a potential peat face was found, however during the excavation on the surface much of the layers were distorted in such away cutting of mass movement processes must have been responsible and layers of silt have been washed in among the peat. As the access to and from the Island is restricted this site had to be abandoned, with a further investigation possibly required. This would then require a longer trip. Both Rousay and Hoy offer opportunities for further study. However, they have not been used in this research due to the prolific peat cutting in the area and time restrictions on sampling and these smaller islands may show more climatic events as previously discussed.

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