Tuesday 26 October 2010

Bradford Beck – A rejuvenated stream


by William Varley, geographer, Addingham

Gathering its tributaries on the uplands to the west of the city centre Bradford Beck initially flows to the east before taking an abrupt turn and flowing in a north-north-westerly direction towards Shipley and the Aire Valley.

Flowing north from the city centre the Beck occupies a valley that has only in part been formed by the actions of the stream itself. Glacial action in the Pleistocene ice age also helped to form this valley. During the Pleistocene ice spread down from the north covering the whole area and a large glacier occupied the Aire Valley. Water became bound up as land ice and sea levels fell. This lowering of the base level gave renewed energy to ice and water and the Aire Valley was over-deepened by the moving glacier. The valley was eroded to a much lower level than the current valley floor. A tongue of ice also pushed up the Bradford Beck valley eroding the valley as it went.

As the ice retreated glacial till (boulder clay) was left behind. The flat land on which the city centre is built, the floor of the valley to the north and the Aire Valley are underlain by this material. As ice melted the stream was ‘rejuvenated’. Its capacity to erode renewed by the lowering of base level, it cut down through the earlier glacial deposits deepening its valley. The Aire Valley was occupied by lakes of glacial meltwater held back by a series of terminal moraines, for example at Tong Park, Hirst Wood and Marley. Huge thicknesses of sands and gravels were deposited in these lakes. At Bingley there are 130 feet of sands, gravels and glacial till filling the present valley.

Although Bradford Beck was never large enough or reliable enough to sustain large-scale water-powered industrial development, it did provide the water supply for the Bradford Canal. The canal served as a link from the city to the Leeds Liverpool Canal. It is interesting to note that the development of the Leeds Liverpool Canal was led by Bradford merchants. A Bradford entrepreneur John Stanhope paid for the first survey in 1766. The initial propose of the canal was to bring limestone from the Craven district which could be burned with local coal to make quicklime. The quicklime made the mortar used to build the growing city.

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