Editing Appalachian Mountains (section)

===Grenville Orogeny and formation of Supercontinent Rodinia===
The first mountain-building tectonic plate collision that initiated the construction of what are today the Appalachians occurred at least a billion years ago when the pre-North American [[craton]] called [[Laurentia]] collided with at least one other craton - [[Amazonian craton|Amazonia]]. All the other cratons of the earth also collided at about this time to form the supercontinent [[Rodinia]] and were surrounded by one single ocean.  (It is possible that the cratons of [[Kalahari craton|Kalahari]], and [[Río de la Plata craton|Rio Plato]], were also part of that early collision since they were present as Rodinia broke up). Mountain-building referred to as the [[Grenville Orogeny]] occurred along the boundaries of the cratons.<ref name="Thomas 2021"/><ref name="auto">{{Cite book |last=Clark |first=Sandra H. B. |url=https://pubs.usgs.gov/gip/birth/birth.pdf |title=Birth of the Mountains: The Geologic Story of the Southern Appalachian Mountains |publisher=United States Geologic Survey |year=1996 |pages=4 }}</ref> The present Appalachian Mountains have at least two areas which are made from rock formations that were formed during this orogeny - the  [[Blue Ridge Mountains]] and the [[Adirondack Mountains|Adirondacks]].
[[File:Grenville extent.gif|thumb|Land added to Laurentia during the Grenville orogeny]]