Earth through the Ages (Starting with the earliest Earth at the back) 1.   4.5 Ga  (1 Ga = 1 thousand million years) Molten ball of rock growing in primordial dust. 2.   4.5Ga   Molten ball of rock, being bombarded. 3.   4 Ga Arrival of water (from meteorites & comets), Showing continued bombardment bringing water, craters filled with. 4.   3.5 Ga  Cloudy Earth, due to steam from hot rocks/volcanoes etc. 5.   3 Ga  Earth covered with oceans with scattering of small volcanic islands. Microscopic life flourishes. 6.   2.5 Ga Snowball Earth. 7.   2.1 Ga Long interval of microscopic life in the ocean. 8.   0.75 Ga Snowball Earth again. 9.   0.35 Ga Carboniferous continental period. 10. 0 Ga Modern Earth.