The past ten years have seen a number of palaeoenvironmental surveys undertaken in the region. This work has contributed significantly to our understanding of prehistoric coastal, lowland and upland environments, and has been complemented and supported by some offshore work on now-drowned landscapes dating to the immediate and early post-glacial periods.
Offshore, the West Coast Palaeolandscapes project (Fitch and Gaffney, 2012) used existing 2-D and 3-D remote sensing data (obtained by commercial offshore development projects) to model the submerged landscapes in Liverpool Bay. They successfully mapped high ground and freshwater drainage systems that could have provided foci for late glacial and early Holocene human occupation and activities. They also noted that the failure of some companies to record full georeferencing metadata for their surveys meant that some data could not be re-used.
On land, the BRITICE-CHRONO five year NERC (Natural Environment Research Council)-funded project into the decay of the last ice sheet over Britain and Ireland has sampled extensively in north west England, mainly inland but also at coastal locations in Cumbria and Merseyside http://www.britice-chrono.group.shef.ac.uk/ . Chiverrell et al (2013) used Bayesian modelling to investigate the chronology of how the last British-Irish ice sheet decayed or re-advanced over an 8000 year period, whilst Clark et al (2018) provide an up to date map of known glacial movements that is relevant to the geological origins of lithic raw materials in glacial deposits (particularly useful for studies of prehistoric stone resource procurement). The map is free to download and is supported by a geodatabase and comprehensive bibliography.
Lang et al (2010) used the remains of chironomids (non-biting midges) and other proxy data from sediment cores to investigate changes in climate in North West England during the late glacial period. Ambient temperatures changed very rapidly (in both directions) during the last stages of the last glacial period, affecting the nature of the environment and its attractiveness to people living here during the Upper Palaeolithic period.
Smith et al’s (2012) study of sea level changes found that there was a rapid and major rise in relative sea level in northern Britain and Ireland, coinciding with the change from Early to late Mesolithic c 7000 – 6800 cal BC, which must have affected the nature and locations of places previously occupied or used for various activities.
In the intertidal zone and coastal strip, the second stage of the North West Rapid Coastal Zone Assessment (NWRCZA) examined eight coastal inter-tidal peat sites located between the Dee and the Solway (see Eadie et al 2012, Chapter 6). The sites at Cleveleys (L), Walney Island (C), Annas Mouth (C), Eskmeals (C), Drigg (C), St Bees (C) and Beckfoot (C) were sampled for radiocarbon dating and pollen assessment. The project has produced a significant body of new data indicating that the start of coastal peat formation took place much earlier than had previously been thought.
At Cleveleys, located just south of Fleetwood (L), a radiocarbon date from peat in a palaeochannel of c13110–12150 cal BC indicates the onset of peat growth during the late glacial Windermere Interstadial. The project has added considerably to our understanding of the complexity of post-glacial sea-levels. The data from Cleveleys, for example, demonstrated that the sea inundated the land there by 7040–6650 cal BC.
At all eight sampled sites peat growth continued through the Mesolithic, with some peat deposits spanning the Mesolithic/ Neolithic transition. The project has shown through successful dating and preliminary assessment of evidence how coastal peat deposits of the north-west coastline represent a significant resource for investigating late glacial and early post-glacial environments (Eadie et al 2012, Chapter 6).
The Annas Mouth, Bootle (C) survey work has added to the growing number of locations around the British coastline where surviving submerged remains of early postglacial forests are recognised, and contributes to the national database of intertidal and coastal peats (Historic England, n.d.).
North West England also retains proxy evidence for major early post-glacial climate change at upland sites inland. Vincent et al (2010) extended their earlier work on loessic sediments in the Yorkshire Dales to the limestone area of North West England. They found further evidence for major increases in slope instability and soil erosion relating to a brief, but severe, downturn in climate at approximately 8,200 years ago at sites in Cumbria and north Lancashire, including Warton Crag (L) and Whitbarrow (C). They estimated that during this period (within the Early Mesolithic) there was a reduction in mean annual air temperature at these upland locations of ~2.6 – 4.6 degrees Celcius. They infer that this led to greater snow accumulation in winter, that the snowpack persisted for longer periods, and that there was an increase in frequency and magnitude of frost-related processes and meltwater flooding. They note that other sites (at lower altitudes) show a contemporaneous shift to wetter conditions.
At Sizergh Castle (C), a programme of community archaeological work directed by Oxford Archaeology North and commissioned by Levens Local History Group and the National Trust combined palaeoenvironmental investigation of a kettle hole with survey and excavation of an associated burnt mound.
The deep, basal deposits of blue-grey silty clay and shelly marls in the kettle hole could not be dated by radiocarbon assay due to the lack of suitable organic material. The sparse pollen indicated an open environment with areas of open water, and pioneering species of grasses, herbs and trees. The plentiful microcharcoal may indicate cold, dry conditions prone to natural fires. Very similar evidence has been found at other Cumbrian sites and probably relates to the last cold event (the Loch Lomond Stadial) of the Late Glacial period. This fits with an Early Mesolithic radiocarbon date of 8290-8230 cal BC for the base of the overlying peat. The Early Mesolithic peat contains pollen dominated by shrubby deciduous woodland with some open water, but no indicators of disturbance (Druce and Rutherford 2014).
An important, long, pollen core from a windfarm site at Beck Burn on the Solway Moss has provided continual proxy evidence of changes in climate, vegetation and landuse from the early post-glacial to the post-medieval periods (Rutherford , 2018, and in prep). In the early period, the landscape contained typical post-glacial small bodies of open water, that gradually became infilled with peat as the sea level rose and the warm dry climate encouraged vegetation growth. This eventually led to peat deposits in the basins and closed, mixed, woodland on the higher drier land.
For the coastal lowlands of the SW Lancashire plain, the final volume of the North West Wetlands survey has been published (Middleton et al, 2013). Although the fieldwork for this project was completed in 1996, it still provides a useful baseline of environmental studies and archaeological discoveries.
A few inland lowland wetlands in Cheshire have received detailed analyses, some due to commercial developments and some as an extension to the Cheshire Hillforts Landscape Partnership Project funded by the Heritage Lottery Fund.
Studies of cores from Ince Marshes in the Mersey estuary (RSK Environment Ltd, 2016) are important for their detailed pollen & macrobotanical investigations of two strata of peat, whose formation was linked to changes in relative sea level. The first is early post-glacial: peat formation started about 10,000 – 9,500 cal BC and continued throughout the Mesolithic period to about 7500 – 7300 cal BC. The deposits provide good evidence for warming climatic conditions. The combination of pollen and plant macrofossils from the same sampling points provides complementary details facilitating interpretations of climate and vegetation changes, and the macrobotanical items provided suitable radiocarbon samples.
A new type of scientific analysis was applied to sediments at Hatchmere (Boyle et al 2015) where the authors studied the impact of people on landuse through comparisons of phosphorus levels. The phosphorus evidence corresponds well with the botanical evidence from Hatchmere, with stable levels indicating little anthropogenic alteration of the landscape up to c 6000 years ago ie the end of the Late Mesolithic.
New investigations and synthetic work on past environments have also been undertaken in targeted upland areas in Cumbria, Lancashire and Greater Manchester. The two volumes of the Upland Peats survey (Huckerby et al 2010a & 2010b) are important for creating baseline data.
The analyses demonstrate that the onset of peat formation varied considerably through time, responding to local conditions as well as to large-scale climate changes. It also notes that some locations indicate modifications to local vegetation (from the Mesolithic onwards), that may relate to human activity, but where activity or occupation sites have not yet been discovered.
The project led to important conclusions regarding the management of upland peats, which are being targeted increasingly by windfarm developments and by projects and programmes designed to reduce flooding and to reduce carbon release through peat erosion.
It is clear that each site is likely to have undergone a unique sequence of events requiring individual investigation. Whilst data from nearby sites can contribute to wider, landscape-scale studies, they should not be used as substitute data.
An overview by Innes and Tomlinson (2008) of palaeoenvironmental work in Merseyside provided a comprehensive bibliography of specialist work undertaken in the region during the previous twenty-five years, focusing on Merseyside and Lancashire, but also taking some adjacent sites into consideration. They reviewed the late glacial and early post-glacial periods (times of rapidly changing relative sea levels), the development of various types of sediments, woodland history and the local impact of later prehistoric and Romano-British agriculture and other forms of landuse.