Editing Upper Rhine (section)

== Geology ==
{{Main|Rhine Rift # Formation}}
Around 35 million years ago, a [[rift valley]] of about {{convert|300|km|mi}} long and {{convert|50|km|mi}} wide came into being between the present cities of Basel and [[Frankfurt]].  This was due to tensile stresses in the [[Earth's crust]] and [[mantle (geology)|mantle]], which resulted in lowering the earth's surface.  The moat has been partially filled up again by [[sedimentation]].  On the edges we find mountain ridges, the so-called "rift flanks".  On the eastern side, they are the [[Black Forest]] and [[Odenwald]] mountains, in the west the [[Vosges Mountains|Vosges]] and [[Palatinate Forest]].  During the [[Tertiary]], the High Rhine continued west from Basel and flowed via the [[Doubs]] and the [[Saône]], into the [[Rhône]].  The rift diverted the Rhine into the newly formed [[Upper Rhine Valley]].

The [[Rhine knee]] at Basel marks the transition from the High Rhine to the Upper Rhine with a change of direction from West to North and a change of landscape from the relatively small-chamber high-Rhine [[cuesta]] landscape to the wide rift zone of the Upper Rhine Rift Valley.  The two largest tributaries come from the right: the [[Neckar]] in [[Mannheim]], the [[Main (river)|Main]] across from [[Mainz]].  In the northwest corner of the Upper Rhine Valley, at Rhine-kilometre 529.1, near Bingen, where the [[Nahe (Rhine)|Nahe]] flows into the Rhine, the Rhine flows into a gorge in the [[Rhenish Massif]] and thereby changes into the [[Middle Rhine]].<ref>{{Cite web |url=http://www2.hmuelv.hessen.de/umwelt/wasser/wrrl/stadtlandfluss/oberrhein/ |title=Hessian Ministry of Environment, Energy, Agriculture and Consumer Protection |access-date=2011-05-20 |archive-url=https://web.archive.org/web/20121029014957/http://www2.hmuelv.hessen.de/umwelt/wasser/wrrl/stadtlandfluss/oberrhein/ |archive-date=2012-10-29 |url-status=dead }}</ref>