Editing Lake Constance (section)

=== Emergence and future ===
The present-day shape of Lake Constance has resulted from the combination of several factors:
* The [[tectonic]] Lake Constance Basin between the Alps and the Jura was created in the [[Jurassic]] and [[Tertiary]] periods.
* The current [[Alpine Rhine]] was initially a tributary of the Danube.
* Over time, the basin was [[stream capture|captured]] by the [[High Rhine]] as a result of [[headward erosion]] ([[fluvial erosion]]).
** The capture was not always only along the present Rhine valley; [[Lake Überlingen]] marks part of an older valley course.
* The river valleys were deepened during several [[cold period]]s by the [[Rhine Glacier]] from the valley of the Alpine Rhine ([[glacial erosion]]).
* Behind the present impressive traces of the [[Würm Ice Age]], the effects of older cold periods can no longer be explored in any detail. Lake Constance now represents, above all, a [[zungenbecken]] or [[glacial lake]] of the Würm Glaciation.<ref>quaternary-science.publiss.net/articles/452/download Albert Schreiner: ''Zur Entstehung des Bodenseebeckens'' (Quaternary Science Journal, pdf)</ref>
* During a later phase of the ice age, only the Obersee was glaciated. As the glacier retreated further, the [[glacial meltwater]]s flowed out of the emerging Überlingen See through the older more northerly valley into the present High Rhine valley.
* Due to the advancing headward erosion, the present course of the High Rhine was finally (again) reconnected to Lake Constance.<ref>[http://www.landeskunde-online.de/rhein/bodensee/geologie.htm Geology of Lake Constance] at landeskunde-online.de. Retrieved 31 August 2017.</ref> <!-- It is questionable whether there has ever been an undivided Lake Constance -->

Like any glacial lake, Lake Constance will also silt up by [[sedimentation]]. This process can best be observed at the mouths of the larger rivers, especially that of the Alpine Rhine. The [[silting up]] process is accelerated by ever-increasing erosion by the Rhine and the associated reduction in the level of the lake.