Edinburgh - Geography

Geography

Bounded by the Firth of Forth to the north and the Pentland Hills, which skirt the periphery of the city to the south, Edinburgh lies in the eastern portion of the Central Lowlands of Scotland. The city sprawls over a landscape which is the product of early volcanic activity and later periods of intensive glaciation. Igneous activity between 350 and 400 million years ago, coupled with faulting led to the dispersion of tough basalt volcanic plugs, which predominate over much of the area. One such example is Castle Rock which forced the advancing icepack to divide, sheltering the softer rock and forming a mile-long tail of material to the east, creating a distinctive crag and tail formation. Glacial erosion on the northern side of the crag gouged a large valley resulting in the now drained Nor Loch. This structure, along with a ravine to the south, formed an ideal natural fortress which Edinburgh Castle was built upon. Similarly, Arthur's Seat is the remains of a volcano system dating from the Carboniferous period, which was eroded by a glacier moving from west to east during the ice age. Erosive action such as plucking and abrasion exposed the rocky crags to the west before leaving a tail of deposited glacial material swept to the east. This process formed the distinctive Salisbury Crags, which formed a series of teschenite cliffs between Arthur's Seat and the city centre. The residential areas of Marchmont and Bruntsfield are built along a series of drumlin ridges south of the city centre, which were deposited as the glacier receded.

Other viewpoints in the city such as Calton Hill and Corstorphine Hill are similar products of glacial erosion. The Braid Hills and Blackford Hill are a series of small summits to the south west of the city commanding expansive views over the urban area of Edinburgh and northwards to the Forth.

Edinburgh is drained by the Water of Leith, which finds its source at the Colzium Springs in the Pentland Hills and runs for 29 kilometres (18 mi) through the south and west of the city, emptying into the Firth of Forth at Leith. The nearest the river gets to the city centre is at Dean Village on the edge of the New Town, where a deep gorge is spanned by the Dean Bridge, designed by Thomas Telford and built in 1832 for the road to Queensferry. The Water of Leith Walkway is a mixed use trail that follows the river for 19.6 kilometres (12.2 mi) from Balerno to Leith.

Designated in 1957, Edinburgh is ringed by a green belt stretching from Dalmeny in the west to Prestongrange in the east. With an average width of 3.2 kilometres (2 mi) the principal objective of the green belt was to contain the outward expansion of Edinburgh and to prevent the agglomeration of urban areas. Expansion within the green belt is strictly controlled but developments such as Edinburgh Airport and the Royal Highland Showground at Ingliston lie within the zone. Similarly, urban villages such as Juniper Green and Balerno sit on green belt land. One feature of the green belt in Edinburgh is the inclusion of parcels of land within the city which are designated as green belt even though they do not adjoin the main peripheral ring. Examples of these independent wedges of green belt include Holyrood Park and Corstorphine Hill.