Durham E-Theses Pollen analysis and vegetional history of the `akeld' basin Borek, M. J. E. How to cite: Borek, M. J. E. (1975) Pollen analysis and vegetional history of the `akeld' basin, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/9173/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk -POLLEN ANALYSIS AND VEGETATIONAL HISTORY OF THE 'AKELD' BASIN M. J. E. Borek, University of Durham. August, 1975. Dissertation Submitted as part Requirement for the Master of Science Degree in Ecology CONTENTS page ABSTRACT 1 INTRODUCTION 2 CHAPTER 1. 5 AREA AND SITE DESCRIPTION 1.1 Location and Topography. 5 1.2 Structure and Lithology. 8 1.3 Evolution of Relief and Glaciation. 11 1.4 Archaeology and History. 13 1.5 Site Description. 18 CHAPTER 2. 23 STRATIGRAPHY 2.1 Introduction 23 2.2 The South 49° East Transect. 23 2.3 The South-West and North-East Transects 26 2.4 Conclusion. 30 CHAPTER 3. 33 THE POLLEN DIAGRAM 3.1 Preliminary Work. 33 3.2 Collection of Samples. 33 3.3 Preparation of Slides. 34 3.4 Pollen Analysis. 36 3.5 Zonation of Pollen Diagram and Interpretation. 40 ACKNOWLEDGMENTS 57 BIBLIOGRAPHY 58 APPENDIX 1 59 STRATIGRAPHY DATA. APPENDIX 2 72 POLLEN ANALYSIS DATA. FIGURES FIG. 1 Map of north-east England. FIG. 2 Photograph of the Akeld basin. FIG. 3 Photograph of the Cheviot Massif. FIG. 4 Geology map of north-east England. FIG. 4a Geology maps of the site. FIG. 5 Map of Bronze and Stone Age Settlements. FIG. 6 Six inch map of the site. FIG. 7 Photograph of the south-east transect. FIG. 8 Stratigraphy of the south-east transect. FIG. 9 Photograph of site looking east. FIG. 10 Photograph of the site looking south. FIG. 11 Stratigraphyof the north-east and south west transects. FIG. 12 Pollen diagram - Trees and Shrubs. FIG. 13 Pollen diagram - Herbs and Spores. -1- ABSTRACT A pollen diagram has been constructed for the Akeld Steads region of the Glen Valley in Northumberland. This diagram provides an interesting variation in the vegetational history of the area. Evidence suggests that although the late post glacial vegetation was similar to that of the rest of the region, Quercus appeared before Ulmus in this area. This feature is contrary to the usual pattern suggested, however, it is seen on other northern diagrams but has not been commented upon by their authors. The persistence of pine in the area until the late Boreal period may be associated with the Cheviot Hills which overlook the basin. The lack of deposit during the late Boreal and early Atlantic periods may be attributed to local hydrological conditions prevailing at that time. There is some evidence for the presence of Man in the area from the Boreal period onwards. This evidence comes from the pollen diagram and stratigraphy of the site and is further substantiated by the archaeological discoveries made in the area. -2- INTRODUCTION It is recognised and acknowledged in the field of Quaternary Ecology that vegetational change follows and reflects climatic change. Vegetational change is necessarily slow due to the time required for migration and the establish• ment of the various species in the newly formed habitats. The evidence for this vegetational history comes from two forms of fossil remains. These are, firstly the macroscopic fragments of fruits, seeds and wood and secondly the microscopic pollen grains. The latter have the highest resistance of all plant parts to bacterial and fungal decay , although they may be less resistant to oxidation. This resistance is due to the sporopollenins in the exines of the pollen grains. These fossil remains occur in peat deposits and in fresh water and marine sediments and much of the evidence of plant distribution during the post glacial period comes from pollen preserved in peat bogs which began forming during this time. The pollen is extracted from various levels of the deposit, the individual pollen grains identified and the number of grains of each species or taxa counted. These numbers are then presented in a form of a pollen diagram. The numbers plotted on the diagram may be either Absolute, that is the actual number of pollen grains counted for each species or taxum, or they may be Percentages, that is the number of grains counted for each species or taxum calculated -3- as a percentage of total tree pollen. Therefore, both absolute pollen counts and percentages have been used to describe vegetational changes. Although Hesselman maintained that the former may record changes in species abundance more truthfully, von Post pointed out that these might be mis• leading due to insufficient knowledge of sedimentation rates. However, Davis (1967) has shown that although absolute counts record changes more faithfully than percentage diagrams, the changes thus demonstrated are almost identical to those appearing in percentage diagrams for the period of forest vegetation at least. When interpreting pollen diagrams it is important to realise that pollen falling onto a peat bog may have come from a close local source or from a regional one. The latter being particularly represented by anemophilous plants whose pollen may disperse into the air currents above the tree canopy. Another problem arises from the differential production of pollen and schemes have been devised to correct this factor. The most recent scheme produced by Anderson (1973) for north-west Europe forest vegetation proposes that the tree pollen grains counted should be multiplied as follows:- Pinus, Betula, Quercus, Alnus x \ Carpinus, x 1/3 Ulmus, Picea, x g Fagus, Abies x 1 Filia, Fraxinus, x 2 Pollen production may also depend on climate, soil conditions and vegetation form. Corylus, for instance, seems -4- to be a low pollen producer in dense forest, where it is seen in the role of an understorey shrub but a great pollen producer in the open. Bearing these problems in mind and making allowances for them the vegetational history of an area can be described with some degree of confidence. This project, as originally envisaged was an investigation of the vegetational history of a small region of Northumberland. A potentially interesting site had been noted by Dr. J. Turner, Department of Botany, University of Durham, as containing a peat deposit of some depth. If old enough this deposit could reveal interesting information as to early post-glacial history of the area and if much younger in age, of the changes in the forest vegetation broughout about by prehistoric and historic man. It was known from work by local archaeologists that the area was occupied during Neolithic and Saxon times. -5- CHAPTER 1 AREA AND SITE DESCRIPTION 1.1 Location and Topography The site of study (Akeld Steads O.S. Nu 966305) is part of a large basin of some 16 square miles which is bounded on the south and west by the north eastern foothills of the Cheviot Massif and on the north and east by the Ford and Doddingtonhills (Fig. 1 and 2). For the purpose of this study the basin will be referred to as the "AKELD BASIN". The hills of the Cheviot Massif occupy some 250 square miles and rise to 900 feet in places. They represent the north-eastern extremity of a prominant range of uplands known as the Cheviot Hills. The latter are aligned predominantly from south west to north east and rise to 1800 feet. As such they form an important watershed dividing streams draining south east and east into the North Sea and those flowing northwards into the river Tweed. Although the Cheviot Massif is part of the Cheviot Hills it differs structurally from the rest of them giving rise to distinctive topography. Its hills are predominantly gentle sloping with broad areas of plateau between the deep valleys. However steep sided valleys do occur in the northern and eastern peripheries including Akeld Hill and Harehope Hill which form the southern boundary of the basin. (Fig.3). Outcrops of bedrock are rare occurring chiefly as tors and crags. The Massif is drained by a fairly dense network of streams some of which, like the Coquet, become principal streams, FIGURE 1 CO V ) i CO r CD II —» I 0 T P 7. \ r \ 01 ,4' J o 7- v. T a A * / • 3 X 0) 0) C NN / An > A 6*° ^ N \ O'J V \ ft 1 SA % * A O 1 if V. \ \ -7- FIGURE 2 1 ESCARPMENTS STONES HAMBLETON HILL F = AKELD STEADS FARM W = WOOD AND FEN/CARR A = SITE OF STUDY Ar = ARABLE FIELDS Photograph of the Akeld basin taken from the top of Hambleton Hill (OS.967284) -8- others such as the Wooler Water and the river Glen, arise in various places on the Massif and becomes tributaries to the larger rivers. To the north-east of the hills is the broad lowland of the Merse and curving round the eastern perimeter of these hills are a series of low lying basins.