 Rodinia broke up   Life became more complex and thrived

 Laurentia splits from Rodinia and experiences no tectonic movement (no mountain ranges)  Laurentia is surrounded by passive margins (edges of continents without plate movement)

 Ocean tides wash sand onto a shoreline creating beaches ◦ Deposited sand becomes sandstone  Offshore clay is also deposited ◦ Clay becomes shale  Calcium carbonate deposits occur farther from the shoreline ◦ calcium carbonate becomes limestone

 As sea levels rise and fall the pattern of deposition shifts  A rise of sea level (transgression) causes clay sediment to deposit over beaches  A falling of sea level (regression) causes clay sediment to deposit over limstone

 During the Ordovician, Laurentia collided with the Taconic Island Arc (Taconic Orogeny)

 Laurentia was further transformed during the Silurian when Laurentia collided with Baltica and Avalonia

 Laurentia collided with Gondwana (Ouachita orogeny) during the carboniferous period

 As Gondwana pushed into Laurentia, Alleghenian orogeny took place (creating the Appalachian mountains and finally assembling the Earth’s second supercontinent)

 Read pp to make notes on the Cambrian explosion, Ordovician extinction, Devonian extinction, terrestrial plants, coal deposits and Permian changes  Q: 1, 2, 3, 4, 6