By the start of the Neolithic period, the major post-glacial rise in global sea levels, and the fluctuations in relative sea levels cause by eustatic uplift, had both slowed down. Britain had been cut off from Continental Europe by the inundation of the Channel, which constrained the arrival of new types of plants, insects and animals. But there were still some areas on the north-west coast and in its river estuaries where local adjustments continued to occur. This was particularly true of the complex drainage area around Morecambe Bay, where relative sea level was still rising at a rate of about 0.50 metres per 500 years between c 4100 – 3900 cal BC i.e. during the Late Mesolithic to early Neolithic transition period (Lloyd et al 2012).
The end of the Early Neolithic period, the Late Bronze Age and Early Iron Age, as well as the Late Medieval period, are all associated with relatively rapid changes towards more unstable weather conditions in Britain and Europe, with colder winters and wetter summers (Bevan et al 2017). These climatic changes are thought to have affected the viability of agriculture and land-use, particularly in upland or poorly drained areas. In turn, this may have led, indirectly, to changes in settlement patterns and activity foci.
Whilst large-scale and regional changes in climate remain of direct interest to studies of populations, settlement patterns and economic regimes, most site-specific palaeoenvironmental studies focus on the effects of people in their local landscapes, and on disentangling these from ecological developments.
Grosvenor’s (2014) PhD thesis investigated upland and lowland sites in Cumbria (C) and focused on evidence for changes in climate, vegetation and land-use during the Mesolithic-Neolithic transition. Climatic changes and effects were relatively minor. Whilst there was evidence for more intensive clearance during the Neolithic than during the Mesolithic, there was evidence for a delay of about 200 years in the upland landscapes when compared to the lowlands.
Importantly, the scale of impact on vegetation in the upland landscape was far more extensive than the archaeological evidence had suggested. Furthermore, the upland landscape appeared to recover relatively quickly after clearance events, whilst in the lowland environment, the newly open vegetation remained far more dominant.
Appley’s (2013) PhD thesis investigated the prehistoric environment of the Furness peninsula (C), providing important environmental background to prehistoric activity and changes in relative sea levels. The Furness peninsula and Walney Island (C ) were repeatedly visited or settled in the Late Mesolithic and Early Neolithic periods, and some of the activities included trade in stone axes and the use of Lake District volcanic tuff as a raw material.
Appley obtained evidence for two marine transgressions during the Late Mesolithic period in the valley of the Sarah Beck, close to Holbeck Park Avenue (C), providing a landscape characterised by intertidal mudflats, saltmarsh and tidal creeks. As sea levels dropped in the later Neolithic, carrs and peatlands formed, and two burnt mounds sitting directly on the marine sediments (adjacent to a palaeochannel that cut through them) demonstrate that the sea had largely retreated from the valley by the Early Bronze Age. His work illustrates the key links between archaeological sites in their contemporaneous landscape settings and studies of changes in relative sea levels.
At Drigg (C), the current coastline is eroding away another burnt mound associated with a (previously inland) palaeochannel. Woody peat (possibly indicating a submerged forest like that found in the current intertidal area) lies immediately beneath a burnt mound. Radiocarbon dating shows that the peat started to form in the Late Neolithic period 3810-3650 cal BC (Quartermaine and Cook 2010).
At Ince Marshes (Ch), the upper peat deposit in this estuarine location began to form during the Early Neolithic period (radiocarbon dated to about 4900 – 4600 cal BC) and shows a change from wooded conditions to wetter, more open habitats including phragmites (reeds), sphagnum moss and heathland (RSK 2016).
The presence of peaks of charcoal- mostly in the upper peat but also in the lower (Mesolithic) peat – suggest human activity as the burnt wood includes sap-rich species such as willow/poplar which do not catch fire easily.
Grosvenor et al’s (2017) study of pollen data from Urswick Tarn (C) in the lowland Furness peninsula and Blea Tarn (C) in the upland central massif integrated a range of pollen data from southern Cumbria to consider the dating and causes of the Elm Decline- often used as a marker of increased human impact and the start of Neolithic activities, although its causes are complex and controversial. Both sites show that the pre-disturbance landscape consisted largely of mixed woodland including hazel, birch, oak and alder, with a period of vegetation stability between about 7100 and 6800 cal BP (Late Mesolithic ~ 5000 cal BC).
Like some other sites, both show two phases of elm decline and vegetation disturbance, although each site has slightly different dates for each phase. The dates are quite early for the elm decline in the British Isles, and the authors find little evidence for a major role for climate change. Instead, they conclude that human clearance of trees (possibly targeting trees weakened by disease) was the main driver of the vegetation changes, and they emphasise the significant impact of human activities on the landscapes of southern Cumbria.
Current investigations of environmental samples from Lunt Meadows (M) by a team from Exeter University have found cereal-type pollen in deposits dated to the Late Mesolithic (5th millennium BC) (Jones et al n.d). New work by Albert & Innes (in press) has clarified identification criteria to help distinguish between pollen grains of a domestic cereal (barley, Hordeum) and those of sweet grasses (Glyceria). This work is based on their studies of cereal-type pollen found in an area with several concentrations of Late Mesolithic rod microliths at Dog Hill, Calderdale (WY), just to the ENE of Rochdale (GM) in the southern Pennines.
At Stainton West, near Carlisle (C), pollen data suggest that agriculture was introduced in the Early Neolithic period between 3800 cal BC and 3700 cal BC, but this does not appear to coincide with any major shift in cultural affinity of the people using the site (Brown et al in prep).
At Arclid South quarry (Ch), pollen evidence from peat deposits in a lowland mire indicates that from the Middle to Late Neolithic periods the local vegetation was woodland dominated by oak and hazel with alder/birch carr. These are the four most frequently occurring taxa in the charcoal assemblages from the nearby burnt mound located at the edge of the mire basin; suggesting that little had changed by the Middle Bronze Age when the burnt mound was in use (Jones et al 2017).
The palaeocological sequence from Hatchmere (Ch) covers the period from the end of the Mesolithic (~6000 cal BP) up to around AD 1800. Woodland taxa – particularly oak, alder and hazel – are dominant through the Neolithic until the Late Bronze Age, again emphasising a long history of woodland habitats. But at Hatchmere there is also some evidence of woodland clearance & cereal pollen from the Early Bronze Age onwards (Chiverrell et al 2016).
The increases in phosphorus levels indicative of increased human or animal activity occur in steps that coincide with the Neolithic, Bronze Age, and Medieval periods, and occur again in the first half of the 20th century, consistent with anthropogenic causes or influences (Boyle et al 2015). This is an important new methodology for tracing the impact of people on their environments.
The palaeoecological sequence from the nearby Peckforton Mere (Ch) covers the period from the end of the Mesolithic (~6000 cal BP) to the beginning of the Medieval Period (around AD 1066) (Chiverrell et al 2016). The Peckforton diagram shows a more consistently wooded landscape than that from Hatchmere, with arboreal species, particularly alder, dominant throughout the record. In common with the Hatchmere record, the Peckforton results show two phases of clearance (each followed by some woodland regeneration), occurring first in the Early Bronze Age (~4000-3600 cal BP) and then again in the Iron Age (~2600-2000 cal BP).
Studies of material at Beckburn windfarm (C) add considerably to our knowledge and understanding of vegetational change, and the impact of people on the environment of Solway Moss during the Bronze Age. The data show that, during the Early Bronze Age there was little disturbance of a generally wooded environment, but during the Middle Bronze Age there is evidence for greater anthropogenic impacts, including limited tree clearance, slight increases in open-ground indicators (grasses, ribwort plantain) and the incidence of cereal-type pollen. This renewed clearance may correlate with the movement of arable farmers across Solway Moss, but during the Late Bronze Age to Iron Age there is evidence for forest regeneration, accompanied by a slight reduction in grass pollen (Rutherford 2018 & in prep).
Deer Dyke Moss, Cumbria, is one of a complex of lowland raised mires on the eastern fringe of the Leven estuary. Pollen evidence shows extensive forest cover on both the drier hills surrounding the site and in the Leven estuary wetlands, from the base of the core (c 1200BC) until c 700BC, with a minor peak in agricultural indicators from c. 970BC onwards. Although this dates to the Late Bronze Age, the implication is that this environment had remained wooded for most of the early-mid Holocene (Coombes et al 2009).
Quartermaine & Leech (2012, 6-10) provide a useful overview of vegetation and climate change in the Lake District during the Holocene.
The Upland Peats Study for North-West England looked at four landscape areas: the South West Fells of Cumbria (C), the Langdale Fells in the central Lake District National Park (C), the Forest of Bowland (L), and Anglezarke Moor (L) on the uplands bordering Greater Manchester (Huckerby et al 2010).
The results revealed a varied and complex picture across each of the four areas, exemplified by the following examples from Cumbria. The onset of peat formation appears to have been associated with clearance evidence around the South West Fells and Langdale Fells. At Barnscar and The Knott some clearance cairns may be Neolithic. Around Cockley Moss and Hesk Fell, however, peat formation commenced later in the Bronze Age. At Mart Crag Moor axe factory sites, Great Langdale, pollen analysis indicates that at the time of the axe production Martcrag Moor was an open grass and heather dominated landscape with some hazel and alder scrub. It suggests that the land was in use as pasture (Huckerby et al 2010).
In the southern Pennines, quite close to Anglezarke Moor at Hyndburn windfarm (L), an unusually long and complete peat core was recovered from the blanket mire on Oswaldtwistle Moor. More than three metres of peat contained abundant and well-preserved pollen dating from the Early Neolithic through to the late Medieval/post-Medieval period (Raynor and Rutherford 2013).
Pollen from the earliest peat indicates woodland dominated by alder, with birch and oak. Elm pollen is scarce, suggesting either that an elm decline had already happened, or that elm trees were not suited to the altitude of 245-370 m.a.s.l. The top of the basal pollen zone is dated to 3970-3790 cal BC, during the earlier part of the Early Neolithic. During the Late Neolithic at 2910-2690 BC, there is a sudden rise in percentages of grass pollen and micro-charcoal, although trees are still dominant in the pollen record and this is a short-lived event. Lithics of Neolithic types were recovered from archaeological investigations at the windfarm site, indicating human activities in the area during this period.
In the subsequent period, dating to the Early Bronze Age c 2040-1880 cal BC, the vegetation shifts from predominantly woodland towards a mixture of woodland and moorland pollen. The main feature is the rise of pollen of Calluna (heather) and the spread of Sphagnum moss spores on the uplands (Raynor and Rutherford 2013).
The chief factor controlling vegetation change on Oswaldtwistle Moor (L) from the Early Neolithic to the Middle Bronze Age seems to have been one of increasing waterlogging and podsolisation from the Bronze Age onwards, as a result of environmental disturbance or deterioration (caused by people or climate or both) favouring the spread of heather and moss on the moor. Evidence for deliberate burning activities by people: for example, to clear areas for animal grazing, enhanced the spread of heather moorland but this did not occur until the Middle to Late Bronze Age dated 1270-1040 cal BC. Cereal pollen does not appear until the Early Medieval period c. cal AD 890-1040 (Raynor and Rutherford 2013).