over Greater London. This would also allow Yorkshire to create up to 200,000 jobs across the county and provide similar funding and autonomy to that enjoyed by Greater Manchester. Toponymy Geology Historically, the northern boundary of Yorkshire was the River Tees, the eastern boundary was the North Sea coast and the southern boundary was the Humber Estuary and Rivers Don and Sheaf. The western boundary meandered along the western slopes of the Pennine Hills to again meet the River Tees. It is bordered by several other historic counties: the county of Durham, Lincolnshire, Nottinghamshire, Derbyshire, Cheshire, Lancashire and Westmorland. In Yorkshire there is a very close relationship between the major topographical areas and the geological period in which they were formed. The Pennine chain of hills in the west is of Carboniferous origin. The central vale is Permo-Triassic. The North York Moors in the north-east of the county are Jurassic in age while the Yorkshire Wolds to the south east are Cretaceous chalk uplands. Yorkshire is drained by several rivers. In western and central Yorkshire the many rivers empty their waters into the River Ouse which reaches the North Sea via the Humber Estuary. The most northerly of the rivers in the Ouse system is the River Swale, which drains Swaledale before passing through Richmond and meandering across the Vale of Mowbray. Next, draining Wensleydale, is the River Ure, which the Swale joins east of Boroughbridge. Near Great Ouseburn the Ure is joined by the small Ouse Gill Beck, and below the confluence the river is known as the Ouse. The River Nidd rises on the edge of the Yorkshire Dales National Park and flows along Nidderdale before reaching the Vale of York and the Ouse. The River Wharfe, which drains Wharfedale, joins the Ouse upstream of Cawood. The Rivers Aire and Calder are more southerly contributors to the River Ouse and the most southerly Yorkshire tributary is the River Don, which flows northwards to join the main river at Goole. Further north and east the River Derwent rises on the North York Moors, flows south then westwards through the Vale of Pickering then turns south again to drain the eastern part of the Vale of York. It empties into the River Ouse at Barmby on the Marsh. In the far north of the county the River Tees flows eastwards through Teesdale and empties its waters into the North Sea