(The geology and soils of the Country Park)
The west Leeds area, like much of Leeds, is dominated by Coal Measures ( Leeds forms the northern limit of the Yorkshire Coalfield), and Millstone Grits of the Upper Carboniferous period.
Characterised by alternating strata of sandstones, shales and mudstones and coal seams, which were laid down between 323 and 313 million years ago, these sedimentary rocks are the result of alternate river and marine deposits of sands, silt and mud and organic matter deposited, buried and compressed to eventually form stone.
The Millstone Grits were laid down between 323–313 million years ago, when much of northern England was covered by a huge river delta. Rivers deposited alternate layers of sand, mud and silt into channels, outwash falls and swamps in the delta, which were compressed by subsequent layers, gradually forming rock.
The resulting sandstones are generally medium to coarse in texture, and often contain pebbles of quartz, so are highly valued for their durability as a building stone. These sandstones were extensively quarried in the Hawksworth, Calverley and Bramley areas, the latter being noted for its Bramley Fall Rough Rock. Kirkstall Abbey, Leeds Town Hall and the Corn Exchange are all constructed from Millstone Grit quarried from the west Leeds area.
The sandstones and coal seams associated with Coal Measures were laid down some 310 million years ago, when Britain sat over the equator and a vast tropical forest had grown over the Millstone Grit deposits of the ancient river delta.
The sandstones associated with the Coal Measures have a fine texture, as represented by the Elland Flags series. Rich in mica, these split easily along regular bedding plains and provide Yorkshire Flagstones, as well as the brick sized building stone characteristic of Bradford. Coal Measure sandstones could also be intricately carved, as can be seen on the exterior of Leeds Kirkgate Market.
The coal seams of the Lower Coal Measures, found in the west Leeds area, were limited and shallow, as compared to those of the Middle Measures in south Leeds. Nevertheless, the remains of bell pits, such as those at Hunger Hills in Horsforth, offer evidence that coal was mined in this part of Leeds.
The shales and mudstones associated with the Coal Measures provided material for making the bricks that largely replaced building stone. Terracotta and ceramic industries also flourished using the same local resource.
Following the end of the last Ice Age, some 10 000 years ago, the retreating ice sheets and glaciers dropped the loads that they had been carrying. This material which consisted largely of rock debris ranging in size from huge boulders, or erratics, to very finely ground rock, or till, blanketed the solid rock with varying thickness of material. As the ice sheets decayed the resulting deluge of meltwater swept along sands, gravels and muds. Where the flow slowed or was impeded to form temporary lakes, this material was deposited to form thick beds of silts, sands and gravels, as can be found along the course of the River Aire.
The National Soil Resources Institute has devised a national soil classification system, based on 27 soil types.
The West Leeds Country Park area supports three of these soil types.
The course of the River Aire has had a hugely significant impact on the soils adjacent to its course, and these are classified as loamy and clayey floodplain soils, with naturally high groundwater. They are representative of high water tables, and have a tendency towards supporting wet flood meadow with carr woodlands. They represent 2.6% of soils in England.
To the south of Pudsey, and in the Calverley / Farsley area, the soils are freely draining, slightly acidic loamy, which tend to underlie neutral and acid pasture and deciduous woodland. They represent 15.5% of soils in England.
The rest and majority of the area is represented by slowly permeable seasonally wet acid loamy and clayey soils. These support seasonally wet pasture and woodland, indicate an impeded drainage. They represent 7% of soils in England.
West Leeds Country Park and Green Gateways
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