Approximately 500 million years ago, during the Cambrian period, the Iapetus seafloor began subducting into the Earth's mantle, creating volcanoes between the southern edge of the Laurentian land mass and the Iapetus ocean.
Approximately 500 million years ago, during the Cambrian period, the Iapetus seafloor began subducting into the Earth's mantle, creating volcanoes between the southern edge of the Laurentian land mass and the Iapetus ocean.