DERWENT, the name of several English rivers (Celtic Dwr gent, clear water). (I ) The Yorkshire Derwent drains North Yorkshire moors, rising in their eastern part. A southern head stream, however, rises in the Yorkshire wolds near Filey, about a mile from the North Sea, but it flows inland owing to a coast morainic deposit. The early course of the Derwent lies through the flat open vale of Pickering between the Yorkshire moors and the Yorkshire wolds, the upper part of which is known as the Carrs, when the river follows an artificial drainage cut. It receives many tributaries from the moors, then breaches the low hills below Malton, and reaches the central plain of Yorkshire. Its direction, hitherto westerly, now becomes southerly, roughly parallel to the Ouse, which it joins near Barmby-on-the-Marsh, af ter a course, of about 7o m. As a tributary of the Ouse it is included in the Humber basin. It is tidal up to Sutton-upon-Derwent, 15 m. from the junction with the Ouse, and is locked up to Malton, but the navigation is little used. A canal leads east from the tidal water to the market town of Pocklington.
(2) The Derbyshire Derwent rises in Bleaklow hill north of the Peak and traverses a narrow dale, which, with the tributaries, the Noe, watering Hope valley, and the Wye, is famous for its beauty (see DERBYSHIRE). The Derwent flows south past Chats worth, Matlock and Belper and then, passing Derby, debouches upon a low plain, and turns south-eastward, to join the Trent, af ter flowing 6o m., near Sawley. It falls in all some 1,7oo ft. (from Matlock 200 ft.), and no part is navigable, save certain reaches at Matlock and elsewhere for pleasure boats.
(3) The Cumberland Derwent rises below Great End in the Lake District, draining Spinkling and Sty Head tarns, and flows through Borrowdale, receiving a tributary from Lang Strath. It then drains the lakes of Derwentwater and Bassenthwaite, after which its course, hitherto northerly becomes westerly past Cock ermouth to the Irish Sea at Workington. The length is about 34 m., and the fall about 2,000 ft. (from Derwentwater 244 f t.) ; the waters are beautifully clear, and the river is not navigable. At a former period Derwentwater and Bassenthwaite formed one lake, but they have been separated by lacustrine deltas at the mouths of the river Greta, which now joins the Derwent immediately below Derwentwater, and the Newlands Beck, which enters Bas senthwaite.
(4) A river Derwent rises in the Pennines near the borders of Northumberland and Durham, and forming a large part of the boundary between these counties, takes a north-easterly course of 3o m. to the Tyne, which it joins 3 m. above Newcastle.