Editing Cambrian (section)

=== Laurentia ===
During the Cambrian, Laurentia lay across or close to the equator.  It drifted south and rotated c. 20° anticlockwise during the middle Cambrian, before drifting north again in the late Cambrian.<ref name="Torsvik-2017" />

After the Late Neoproterozoic (or mid-Cambrian) [[rift]]ing of Laurentia from Gondwana and the subsequent opening of the Iapetus Ocean, Laurentia was largely surrounded by [[passive margin]]s with much of the continent covered by shallow seas.<ref name="Torsvik-2017" />

As Laurentia separated from Gondwana, a sliver of continental [[terrane]] rifted from Laurentia with the narrow [[Taconic orogeny|Taconic seaway]] opening between them. The remains of this terrane are now found in southern Scotland, Ireland, and Newfoundland. Intra-oceanic [[subduction]] either to the southeast of this terrane in the Iapetus, or to its northwest in the Taconic seaway, resulted in the formation of an [[island arc]]. This [[Accretion (geology)|accreted]] to the terrane in the late Cambrian, triggering southeast-dipping subduction beneath the terrane itself and consequent closure of the marginal seaway. The terrane collided with Laurentia in the Early Ordovician.<ref name="Domeier-2016">{{Cite journal |last=Domeier |first=Mathew |date=2016 |title=A plate tectonic scenario for the Iapetus and Rheic oceans |url=https://linkinghub.elsevier.com/retrieve/pii/S1342937X15002014 |journal=Gondwana Research |language=en |volume=36 |pages=275–295 |doi=10.1016/j.gr.2015.08.003|bibcode=2016GondR..36..275D }}</ref>

Towards the end of the early Cambrian, rifting along Laurentia's southeastern margin led to the separation of [[Cuyania]] (now part of Argentina) from the [[Ouachita County, Arkansas|Ouachita]] embayment with a new ocean established that continued to widen through the Cambrian and Early Ordovician.<ref name="Domeier-2016" />