The End of the Archean and beginning of the Proterozoic
2,600,000,000 to 2,200,000,000 years ago
(2.6 to 2.2 billion years ago)
This is a relatively quite time in Wisconsin geologically speaking an there is intense weathering of the rocks. Mountains that formed during earlier parts of the Archean are quickly eroded down to flat, rolling granitic plains called peneplains. At this time there are no plants or animals. The continents are bare rock. With no plants or ground cover, erosion is intense and quick. Much of the original Archean terranes are eroded into pebbles, sand and clay, destroying much of the Archean mountains and original crust. These sediments are washed into the ocean and deposited on the ocean floor.