History of the Earth

(4410) Latest appearance of water - By this time, water could be found Earth's surface, though it would have been highly acidic. (4000) Formation of the magnetic field - The magnetic field was active by this time, though about 10-50% of its strength today. (2500) Great Oxygenation Event - Oxygen begins to accumulate in the atmosphere as a result of the success of cyanobacteria.

(2450) Oceans turn red - As a result of the new abundance of oxygen in the atmosphere, BIFs may have caused the entire planet's oceans to rust. (2050) Anoxic Catastrophe - A relatively recently-discovered extinction caused by declining oxygen levels that saw the extinction of 99. 5% of all microbial life.

It may have paved the way for extreme anoxic conditions for the next billion years. (2023) Vredefort impact - This impact is the largest confirmed crater on Earth at 300 km wide. It is found in South Africa.

(2000) Oklo nuclear reactor active - Located in Gabon, a lower concentration of uranium-235 in uranium ore was found here. At the time, U-235 concentration would have been about 3%, the same as a modern-day reactor. With ground water acting as control for neutrons, the Oklo reactor would have been active for several thousand years, producing about 100 kW of energy.

(1800) Beginning of the Boring Billion - Named due to the relative stability in the Earth’s environment, for the next billion years, the Earth would be marked by low oxygen levels and high sulfur in the oceans, called the Canfield ocean. (1600) Oceans turn purple - The oceans at this time may have been rich in sulfur, allowing for purple and green sulfur bacteria to thrive. (1250) Formation of the inner core - Though estimates vary wildly depending on sources, the solid inner core is likely to have formed by this time, coinciding with a strong increase in the strength of the magnetic field.

(600) Formation of the ozone layer - Oxygen levels at this time became high enough for a protective layer of ozone to first form. First fire - Oxygen was abundant enough to fuel fires, indicated by the appearance of charcoal. (50) Paleocene–Eocene Thermal Maximum - The warmest period in the Cenozoic era was caused by increased levels of carbon as a result of extensive magmatism.

(5. 96) Messinian salinity crisis - The closure of the Straits of Gibraltar causes the Mediterranean Sea to completely dry up, leaving a deep inhospitable desert with temperatures of >50°C and pressures twice that of sea level. (5.

33) Zanclean flood - With the reopening of the Straits of Gibraltar, the dry Mediterranean Sea catastrophically refills within a few months or years.