The stage on which the history of County Durham has been enacted forms a compact area ofjust over 1,000 square miles of north-eastern England. The rivers Tyne, with its tributary the Derwent, and Tees tidily delimit the area to the north and south, respectively. Westwards the county has its beginnings in the high Pennines in the backbone of England, at a unique anchor point which it shares with four other historic counties. It is from here, at Burnhope Seat some 2,450 ft. above sea level, that the county’s own river, the Wear, begins its initially purposeful eastward journey to the sea. In mid-course, however, it changes character and meanders northwards, incorporating, as if in homage, a loop around the promontory of the cathedral city after which the county is named; it then surprisingly shuns an obvious confluence with the Tyne by turning east again to carve with difficulty its own mouth at Sunderland. An explanation for the behaviour of the Wear is embedded in the story of the physical evolution of the area. As a prologue to the history of the county, a brief outline of this physical background will enhance an appreciation of subsequent human response, for the former has set a variety of problems and questions, at the same time offering clues and opportunities for understanding the relationship between mankind and the environment.
The entire solid geology of the county is given a gentle eastwards dip by the anticlinal folding of the Pennines. The strata thus become progressively younger towards the coast, from Carboniferous, through Permian to Triassic in the south-east. The western half of the county comprises the Pennine Uplands, a dissected plateau-like block of Carboniferous Limestone forming the highest moorlands, with broad ridges and fell tops continued eastwards by sandstone bands of Millstone Grit. A change in the bedrock to Lower Coal Measures below approximately the 1,000-ft. contour makes little initial difference to relief and appearance (blanket peat and heather) . In the intervening dales igneous intrusions have affected the valleys of the upper Wear and Tees, most spectacularly in the waterfalls of Cauldron Snout and High Force where quartz-dolerite, part of the Whin Sill, occurs. The same series of intrusions is responsible for the deposits of vein minerals – lead, zinc, fluorite, barite and witherite.
The progressive eastward decline in altitude of the Coal Measures has been accentuated by the Wear in its central section, here flowing northwards at right angles to the original tilt of the land. Consequently, a Wear Lowlands region may be recognised, delimited roughly by the Marsden Rock 400-ft. contour to the west but strongly to the east by the sharp rise of the Magnesian Limestone escarpment. The Lowlands have a rolling topography, a feature largely attributable to the variable distribution of glacial drift. Beneath the drift lies a considerable thickness of the so-called ‘exposed’ coalfield, a succession of sandstone, shale and clay bands, together with some ironstone, in addition to some twenty coal seams.
The prominent escarpment of Permian Magnesian Limestone, rising to 700 ft. in the south-west but lower to the north, is breached at only two points – by the river Wear to the north and by the Ferry Hill Gap in the south. The same escarpment, of course, marks the line at which the coalfield becomes ‘concealed’ beneath the Permian series. From the relatively level scarp top the gentle dip-slope of the Magnesian Limestone forms the East Durham Plateau which ends at the sea in a pronounced 50-100-ft. cliffline. North of Sunderland the cliff has been moulded into spectacular stacks, most notably at Marsden Rock. Here and there the coastline is cut by deeply-incised ravines or denes; the mouth of the Wear is cut into the plateau in similar manner.
The Triassic deposits which underlie the extreme south-east of the county are everywhere masked by a thick deposit of glacial drift. Even so, much of the Tees Lowlands is less than 100 ft. above sea level and has areas of poor natural drainage in a gently rolling landscape. The Skerne is the most notable of the left-bank tributaries of the Tees.
The foundation of solid geology, which itself has been subject to folding and faulting and cycles of erosion on a geological time scale – the oldest rocks were laid down some 250,000,000 years ago – was given much of its surface detail only during the last 30,000 years as a result of the most recent ice age. The advance and retreat, or build-up and stagnation, of over 1,000-ft. thickness of ice that covered the county brought a wide range of erosion and depositional effects. At one time a Scandinavian ice sheet mingled with that of advances originating in the Southern Uplands and Cheviots and in the Lake District. Upland features were sharpened, channels were cut by meltwater and a new topography was given to most of the area below 600 ft. with glacial or fluvio-glacial deposits of clays, sands and gravels. In the middle Wear Lowlands the superficial drift deposits may exceed 200 ft. in thickness. Notable deposits are the well-sorted sands and gravels which originated in a lake trapped between the Pennine foothills and Permian escarpment to west and east and by the retreating ice to the north. The prominent Ferryhill Gap (265 ft. above sea level) represents a spectacular meltwater channel which allowed the trapped waters to drain southwards. To the north the ice-blockage contributed to the Wear being diverted in the vicinity of the present Chester-le-Street eastwards across the Permian escarpment. Its broad, truncated former valley, which continues to the Tyne, is today occupied by the Team, a stream hardly worthy to be called river. For the length of its present northward course the cross-profile of the middle Wear exhibits an alternating Succession of wide, open valley and narrow gorge. The former result from the reworking of the superficial deposits and exhuming of former drift-filled channels; gorges occur where the downcutting, initiated on the same drift, encountered and cut into the buried solid geology. The incised meander loop around Durham City is the best-known example of a relatively widespread landscape feature.
The climatic amelioration, which led to the progressive retreat and disappearance of the ice sheet, allowed vegetation to colonise the surface of the newly-emergent and freshly-fashioned landscape. At first, from about 10-12,000 years ago, a covering of grasses and herbaceous plants spread north and west, to be followed by a succession of forest species – pine and birch, then hazel, elm and oak, with alder by 3,000 B.C. The same approximate date marks the first arrival of man as a significant environmental agent, although for perhaps the two preceding millennia a few small and scattered communities had hunted over parts of the area. A hunting and gathering economy only had a negligible effect on the environment, but the Neolithic era marked the beginnings of forest clearing and cultivation, thus initiating the sequence of landscape change which inexorably was to gain momentum over the centuries as the interplay of migrants and indigenous peoples affected settlement and colonisation, exploitation and development. The history of the county has thus been played out on a stage increasingly shaped by man himself. It is the aim of the succeeding chapters to highlight the significant strands that have gone into the weaving of the present tapestry.