Events 4.6 Ga Planet accretes.
Basaltic crust forms intercrater plains.
4.6-3.9 Ga Heavy bombardment forms basins and densely cratered terrain. Most of atmosphere lost Water freezes to form polar caps and permafrost. Water released from chaotic terrain forms outflow channels. 2.0 Ga-present Tharsis uplift Large volcanoes and volcanic plains form. Valles Marineris forms.