The Perth and Kinross area includes two of Scotland’s major geological features: the Grampian Highlands and the East Central Lowlands of the Midland Valley. The Highland Boundary Fault divides these into the area’s Highland and Lowland zones, with differences reflected in topography, vegetation and land use. Both are characterised by a diverse mix of rural and urban land use, which varies considerably from rich lowland arable farming to extensive upland forestry, and from the main population centre of Perth to small, remote communities, such as Kinloch Rannoch. More detailed information can be found in the Perth and Kinross State of the Environment Report (Perth & Kinross Council 2007) and for past land use through the Historic Land Use Assessment Map.
The topography of the region is largely the product of glacial processes acting upon varying underlying geology. To the south of the Highland Boundary Fault, broad, flat, fertile straths correspond with the areas of soft sandstone eroded during glaciation. The fertile soils that now cover these areas are the result of glacial drift deposits and eroded material carried down by rivers from the Highland glens. The post-glacial raised beaches of the Carse of Gowrie contain some of Scotland’s richest farmland; however prior to drainage for the agricultural improvement, it was wetland formed on uplifted marine clay. The flooded Lowland Basin of Loch Leven was formed where the retreating ice sheets of the last Ice Age scoured a hollow in the softer sandstone between the harder Lomond Hills, Cleish Hills and Ochils. The land surrounding the loch is flat with extensive areas of marsh and wetland and an area of valley peat at Portmoak at the foot of the Lomond Hills.
North of the Highland Boundary Fault, generally harder stone, metamorphosed from sedimentary rocks, have resulted in higher elevations, despite being subject to similar glacial processes. Much of this area is covered in either moorland or blanket bog and less fertile soils. However, where upland glens have been created or enlarged by glaciation, more fertile soils occur on drift deposits which support agriculture. Around Atholl, the landscape changes from the open moorland to a large valley landform with glacially steepened sides enclosing the predominantly flat, open floodplain of the River Garry. Here, the less resistant calcareous limestone has led to distinctly different soils and vegetation, notably forests of large trees and fertile farmland around the Blair Castle Estate. At the western end of Loch Rannoch is an area of blanket mire on a large open flat plateau which forms Rannoch Moor, one of the best examples of a blanket peat bog in Scotland. It preserves the stumps of many deciduous trees gradually consumed as the bog developed under the cool post-glacial conditions that have prevailed since the last Ice Age. The rivers and lochs have also played a key role in influencing human settlement. Foremost of these, draining much of the uplands with a catchment area of around 5,000 square kilometres, is the River Tay, Scotland’s longest river and the largest in Britain in terms of freshwater discharge. It is fed by over 70 freshwater lochs and seven other significant rivers including the Earn, Almond, Tummel, Garry and Isla. The area’s major lochs (Rannoch, Tummel, Earn and Lyon) are predominantly oriented east–west, with the Ericht and Tay oriented south-west to north-east.
Scotland’s landscape character has been mapped through regional Landscape Character Assessments (LCAs), covering local authority areas. Commissioned by Scottish Natural Heritage (SNH – now NatureScot), these underpin our understanding of the landscape and are used for natural heritage and planning policy making, and development planning. They provide baseline information for Landscape and Visual Impact Assessment (LVIA) for developments such as wind farms, housing and infrastructure, afforestation and mineral extraction. Landscape Character Types (LCTs) are homogenous types of landscape defined as ‘areas of consistent and recognisable landscape character’. In Perth and Kinross these range from the rugged massif of the Highland Summits and Summits and Plateaux of the Cairngorms and Tayside, to the lowland hills, river corridors and basins with straths and valleys in between. They are shown in Figure 1 along with the names of the main rivers, lochs, hill-ranges, straths and glens, as referenced throughout the period chapters. Further information about LCAs and a digital map of Scotland can be found at nature.scot.
The most significant geographical division in the area is between the Highland and Lowland zones, and this is considered as an overriding research theme in each chapter. Use of these terms is not intended to automatically imply cultural division in the past, nor is it used as a shorthand for monument survival, resulting in variation in subsequent land use, as proposed by Stevenson (1975). Rather it is simply a recognition that the geology, topography and soils of these areas must have resulted in similar variation in agricultural practices as exist today. The extent to which these variations in prehistory resulted in cultural differences, as witnessed in the post-medieval period (PKARF Post Medieval section), is one aspect of research that the framework as a whole should explore, and for which the area is well placed to address.