During the Proterozoic terranes were accreted onto the province. These terranes accreted to Asia during Late Devonian and Permian. As the continent drifted West, terranes were accreted onto the west coast. Most of the land is made of terranes that have been accreted onto the margin. The prevailing explanation for metal-rich white dwarfs is that they have recently accreted rocky planetesimals. Sediments accreted to the forearc are another source of fluids. The rest might have been accreted from now defunct dwarf galaxies. These accreted together to form parent asteroids. During the Devonian, Chaitenia, an island arc, accreted to Patagonia. The material can be accreted by the white dwarf and pollute the atmosphere. The main alternative hypothesis is that the moons accreted in the present position. But, several arguments suggest that asteroids may not have accreted this way. Grains of matter accreted through electrostatic interaction. Their fibular bone has partially accreted with the tibia. It was later accreted to the continental margin of Laurasia.