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A Landscape Strategy for Lancashire - Landscape Character Assessment

2. The Evolution of Lancashire



In the Lancashire study area, it is the irregular juxtaposition of contrasting rocks that forms the basic structure of the landscape. But geology is not the only factor to have shaped the landscape; the intricate interplay of geology, geomorphology, pedology, biogeography and human activity have all had a significant influence. Figure 4 shows the range of historic landscape types found in Lancashire; it identifies broad but distinctive patterns of fields, settlements and land cover which have developed through a long history of human habitation and exploitation. The spatial distribution of resources, such as water power, coal, metals, building stone and timber, the development role of technology and the distribution of agriculture are all key influences on the most recent and visible layer of the landscape ([1]) .

2.1 Physical Influences

2.1.1 Geology and Topography

The underlying geology of Lancashire (Figure 5) is comparatively simple and is formed from four major rock types from three main geological periods. Rocks of the Upper Carboniferous include the Millstone Grit and Coal Measures. The Lower Carboniferous rocks include the limestones of Silverdale and the Ribble Valley which run through Clitheroe into Yorkshire. Permian and Triassic rocks include the sandstones and mudstones which make up the west of the county. The underlying geology, combined with climate and topography, has had a profound influence over the industrial development of Lancashire. Geology is reflected most noticeably in the distribution and variety of building materials used across the county.

These geological strata are covered by layers of glacial and fluvio-glacial sediments which date from the end of the Pleistocene Ice Age. These form a skin of superficial deposits, or drift, which in places are so thick as to eradicate all visual clues as to the nature of the underlying solid geology. This drift is modelled and shaped by fluvial, marine, aeolian and frost processes which combine to create distinctive features and landscapes.

The county can be divided into three broad topographic zones - the lowlands, the uplands and the river valleys (Figure 6). The lowlands are generally formed of Permian and Triassic rocks which are overlain by thick deposits of glacial drift, blown sand, peat, alluvium and silt. These are soft, gently rolling landscapes interspersed with eskers (gravel ridges) and low hillocks (drumlins). Occasionally higher and more irregular relief, such as the ridges around Chorley and Leyland, indicates that the underlying rocks have emerged from beneath the drift. Most of the uplands are formed from Carboniferous rocks which rise high above the plain; they are characterised by features such as boulder erratics. The gritstone plateaux are surrounded by steep glacier smoothed slopes. In the Silverdale area limestone has created a characteristic landscape of crags and valleys and other limestone features.

2.1.2 Natural Features

English Natures Natural Areas, reflect the distribution of wildlife habitats and natural features throughout the countryside as determined by their underlying geology, past land use patterns and the cultural history of individual areas (see Figure 2). They provide a framework for planning and implementation of nature conservation objectives and Biodiversity Action Plan (BAP) targets. Some Natural Areas are conterminous with the Countryside Agencys Countryside Character Areas (CCAs), whilst others encompass two or more Countryside Character Areas.

Box 2.1 Natural Areas in Lancashire - Key Characteristic Habitats 

([2])

Natural Areas

Key Characteristic Habitats

Cumbria Fells & Dales

(only Morecambe Bay Limestones CCA in Lancashire)

* extensive limestone pavements, rock ledges and crevice vegetation

* limestone coastal cliffs overlooking extensive saltmarshes

* mixed ash woodland, juniper scrub and yew woodland

* lowland calcareous grassland, and herb rich neutral pastures

* calcareous lakes and reedbeds (Leighton Moss is the largest
reedbed in  NW England)

* remnant lowland raised bogs

Lancashire Plain & Valleys

* arable field margins, ditches and boundary hedgerows

* lowland wet grasslands, including coastal and floodplain grazing
marshes

* isolated fragments of species-rich neutral grasslands,

* fragments of lowland raised bogs

* small pockets of lowland heathland and acid grassland

* large numbers of small field ponds throughout the coastal plain

Forest of Bowland

* extensive areas of blanket bog on fells

* extensive areas of wet and dry upland heathland

* purple moorgrass and rush pastures on upland fringes

* upland oak and mixed ash woodlands in cloughs and valleys

* fast flowing streams and rivers

* fragments of herb-rich neutral hay meadows in valleys

* small areas of upland calcareous grassland on limestone outcrops  

Southern Pennines

* extensive areas of blanket bog on moorland tops

* impoverished areas of wet and dry upland heathland

* large areas of upland acid grassland * frequent springs and flushes

* fast flowing streams and rivers, and reservoirs

* some upland hay meadows in valleys

* grasslands upland oak and mixed ash woodlands in valleys

Urban Mersey Basin

* lowland oak and mixed ash woodland

* arable field margins and boundary hedgerows

* small pockets of herb-rich neutral grassland

* fragmented areas of lowland raised bogs

* large numbers of small field ponds

Yorkshire Dales
(only Leck Fell in Lancashire)

 

* limestone pavements, rock ledges, crevice and gorge vegetation

* upland calcareous grassland on limestone outcrops

* upland mixed ash woodlands in cloughs and valleys

* large areas of wet and dry upland heathland

* frequent springs and flushes

* fragmented areas of basin and valley mires

Liverpool Bay

* large expanses of saltmarsh within the Ribble Estuary (some
of the most extensive in the country)

* extensive areas of inter-tidal sand and mudflat

* fragmented areas of sand dune along the Fylde coast

Morecambe Bay

* large expanses of ungrazed saltmarsh on the Wyre estuary

* extensive areas of inter-tidal sand and mudflat (second largest
in the UK)

* intertidal and subtidal boulders and cobble skears with associated
mussel beds

* vegetated shingle

* occasional brackish pools on the landward side of sea walls

Figure 7 provides a broad indication of the principal habitats found in Lancashire. Habitats such as moorland, scrub, woodland, pasture, arable fields and marsh are derived from the complex interplay of geology, soil and landform, but the influence of man in clearing and settling the land is a key determinant of land cover and, ultimately, habitat value.

([1]) Whittow, John, Geology and Scenery in Britain, Chapman & Hall, 1992

([2]) English Nature, Natural Areas in the North West Region, English Nature, 1999

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