It consists of a large igneous province with an area of 105,000 km2 (41,000 sq mi) that was constructed about 620 million years ago when Laurentia broke-up from Baltica.
[1] Its formation might have occurred when the ancient Iapetus Ocean began to open.
[2] Long Range is the oldest of a series of magmatic events that occurred along the eastern margin of Laurentia 620–560 Ma, before the opening of the Iapetus Ocean.
It was followed by the 590 Ma Grenville-Adirondack swarm, Upstate New York, associated with separation from Amazonia and the 563 Ma Sept Îles, Quebec, layered intrusions (coeval with the Catoctin large igneous province) associated with the break-up of the Dashwoods microcontinent of West Newfoundland.
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