[5] Although little crustal material from this period survives, the oldest dated specimen is a zircon mineral of 4.404 ± 0.008 Ga enclosed in a metamorphosed sandstone conglomerate in the Jack Hills of the Narryer Gneiss terrane of Western Australia.
[6] The earliest supracrustals (such as the Isua greenstone belt) date from the latter half of this period, about 3.8 Ga, around the same time as peak Late Heavy Bombardment.
[11][10] Nonetheless, within the first billion years of the formation of Earth,[12][13][14][15] life appeared in its oceans and began to affect its atmosphere and surface, promoting the proliferation of aerobic as well as anaerobic organisms.
Since then, the combination of Earth's distance from the Sun, its physical properties and its geological history have allowed life to emerge, develop photosynthesis, and, later, evolve further and thrive.
[16][17][18] Earlier possible evidence of life includes graphite, which may have a biogenic origin, in 3.7-billion-year-old metasedimentary rocks discovered in southwestern Greenland[19] and 4.1-billion-year-old zircon grains in Western Australia.