TEES  , a

river of England, rising on the eastward slope of Cross Fell in the Pennine Chain, and traversing a valley about 85 m. in length to the North Sea . In the earliest part of its course it forms the boundary between the counties of Westmorland and Durham . The head of the valley, of which the upper portion is known as Teesdale, is not without desolate grandeur, the hills, exceeding 2500 ft. in height at some points, consisting of bleak moorland . A succession of falls or rapids, where the river traverses a hard series of black basaltic rocks, is known as Caldron Snout; and from a point immediately below this to its mouth the Tees forms the boundary between Durham and Yorkshire almost without a break . The dale becomes bolder below Caldron Snout, and trees appear, contrasting with the broken rocks where the water dashes over High Force, one of the finest falls in England . The scenery becomes gentler but more picturesque as the river descends past Middleton-in-Teesdale (Durham), the terminus of a branch of the North-Eastern railway from Darlington . In this locality lead and ironstone are worked . The ancient town of Barnard Castle, Eggleston Abbey, and Rokeby Hall, well known through Sir Walter Scott's poem, are passed; and then the valley begins to open out, and the river traverses in sweeping curves the rich plain east and south of Darlington . The course of the valley hitherto has been generally E.S.E., but it now turns N.E. and, nearing the sea, becomes an important commercial waterway, having on its banks the ports of Stockton-on-Tees, Thornaby-on-Tees and Middlesbrough, and forming an outlet for the rich ironworking district of Cleveland in the North Riding of Yorkshire . It is also navigable for barges up to High Worsall, 11 m. above Stockton . For the last five miles the course, below Middlesbrough, is estuarine . The drainage area is 708 sq. m .

No important tributary is received .