Editing Ruhr (section)

==Geography==
[[File:Ruhr area-map.png|thumb|300px|Map of the Ruhr area; in Green is a stricter or narrower definition of the Ruhr, comprising municipalities that are members of the Ruhr regional institution.]]

The urban landscape of the Ruhr extends from the Lower Rhine Basin east to the Westphalian Plain and south to the hills of the [[Rhenish Massif]]. Through the centre of the Ruhr runs a segment of the [[loess]] belt that extends across Germany from west to east. Historically, this loess belt has underlain some of Germany's richest agricultural regions.

Geologically, the region is defined by [[coal]]-bearing layers from the upper [[Carboniferous]] period. The coal seams reach the surface in a strip along the river Ruhr and dip downward from the river to the north. Beneath the Lippe, the coal seams lie at a depth of 600 to 800 metres (2,000 to 2,600 feet). The thickness of the coal layers ranges from one to three metres (three to ten feet). This geological feature played a decisive role in the development of coal mining in the Ruhr.

According to the Regionalverband Ruhr (RVR, Ruhr Regional Association), 37.6% of the region's area is built up. A total of 40.7% of the region's land remains in agricultural use. Forests account for 17.6%, and bodies of water and other types of land use occupy the rest. The inclusion of four mainly rural districts in the otherwise mainly industrial Ruhr helps to explain the large proportion of agricultural and forested land. In addition, the city boroughs of the Ruhr region have outlying districts with a rural character.

Seen on a map, the Ruhr could be considered a single city, since there are no visible breaks between the individual city boroughs. Thus the Ruhr is described as a polycentric urban area, which shares a similar history of urban and economic development.

Because of its history, the Ruhr is structured differently from monocentric urban regions such as [[Munich]], which developed through the rapid absorption of smaller towns and villages by the most significant city among them. Instead in the Ruhr, the individual city boroughs and urban districts of the Ruhr grew in a rapid and parallel fashion independently of one another during the [[Industrial Revolution]]. The population density of the central Ruhr is about 2,100 inhabitants per square kilometre (about 5,400 per square mile)—not too high compared to other German cities.

Between the constituent urban areas are relatively open suburbs and even some open land with agricultural fields. In many places however, the borders between cities in the central Ruhr are unrecognizable, blending into one urban landscape due to continuous development across them.

The replanting of [[brownfield land]] has created new parks and recreation areas in recent decades. The Emscher Landschaftspark (Emscher Landscape Park) lies along the river [[Emscher]], formerly virtually an open sewer, parts of which have undergone natural restoration. This park connects strips of parkland running from north to south, which were developed through regional planning in the 1920s, to form a green belt between the Ruhr cities from east to west.