High Quality Content by WIKIPEDIA articles! During the Late Archaen Eon repeated episodes of continental collisions, compressions and subductions generated a mountain-building episode known as the Algoman orogeny; it is known as the Kenoran orogeny in Canada. The Superior province and the Minnesota River Valley microcontinent collided about 2,700 to 2,500 million years ago. The collision folded the Earth's crust, and produced enough heat and pressure to metamorphize then-existing rock. This orogeny added landmass along a 1,200 km (750 mi) boundary that stretches discontinuously from present-day eastern South Dakota into the Lake Huron area. The Algoman orogeny brought the Archaen Eon to a close, about 2,500 million years ago; it lasted less than 100 million years and marks a major change in the development of the earth's crust. Prior to the orogeny thousands of feet of sedimentary layers had been laid down and they were metamorphosed by the heat and pressure.