What is Orosirian?
The '''Orosirian''' is the third [[geology|geological]] [[Period (geology)|period]] in the [[Palaeoproterozoic]]. It began 2.05 [[billion]] years ago (bya) and ended at 1.8 bya. The latter half of the period was a time of [[Orogeny|mountain-building]] on nearly all [[continent]]s. It was the time when the supercontinent [[Columbia (continent)|Columbia]] began to form. Two of the largest known [[impact event]]s on [[Earth]] happened during the Orosirian. At the beginning of the period, 2023 million years ago (mya), a large [[asteroid]] hit the earth and created the [[Vredefort crater|Vredefort impact structure]]. The event that created the [[Sudbury Basin]] structure happened near the end of the period about 1850 mya. {{Geologic history}} [[Category:Palaeoproterozoic]] {{sci-stub}}