Editing Geology of the Appalachians (section)

==== Grenville orogeny ====
[[File:Grenville extent.gif|thumb|Land added to Laurentia during the Grenville orogeny]]
The first mountain-building tectonic plate collision that initiated the construction of what are today the Appalachian Mountains occurred during the [[Mesoproterozoic|Mesoproterozoic era]] at least one billion years ago when the pre-North-American craton called [[Laurentia]] collided with other continental segments, notably [[Amazonian craton|Amazonia]]. All the other cratons of the Earth also collided at about this time to form the [[supercontinent]] Rodinia, which was surrounded by [[Mirovia|one single ocean]]. Mountain-building referred to as the [[Grenville orogeny]] occurred along the boundaries of the cratons. 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]].<ref name="Thomas 2021">{{Cite journal |last1=Thomas |first1=William A. |last2=Hatcher, Jr. |first2=Robert D. |date=2021 |title=Southern-Central Appalachians-Ouachitas Orogen |journal=Encyclopedia of Geology |volume=4 |quote=The foundations of the Appalachian-Ouachita orogen were laid when the assembly of supercontinent Rodinia was completed. The collisional events were accompanied by high-grade metamorphism and magmatism during the Grenville orogeny in the time span of 1300–950 Ma. |via=Elsevier Science Direct}}</ref>