Nectarian Era

From Paleos

The Nectarian Era of the Hadean Eon: 3950 to 3850 million years ago

The Nectarian Era is named for the Mare Nectaris ("Sea of Nectar"), an old basin on the southwest part of the lunar Nearside. This region was formed approximately 3950 to 3850 Mya. The absolute dates vary considerably, but there is general agreement that the Nectarian was relatively short, lasting 75 to 100 My. The Nectaris Basin was created by the impact of perhaps thirteen large bodies within a region only 860 km wide. The current "best guess" is that these objects were derived from the breakup of the planet which produced the asteroid belt, a result of tidal stresses caused by a close approach to Jupiter. The basins of Nectarian age are the oldest surviving basins on the moon.

Given that the Earth has a substantially larger gravitational field, the effect of the Nectarian bombardment on the Earth was probably severe. Almost nothing from this era remains on Earth, so the geology is somewhat speculative. However, by churning and heating the outer regions of the Earth, these impacts would have promoted the density sorting that eventually produced "light" granite continents floating on the distinctly denser material of the mantle.