The following statements describe key interactions and feedback loops within Earth's systems (the biosphere, geosphere, atmosphere, and hydrosphere) during the Great Oxidation Event (GOE).

The statements are not in the correct chronological order:

1. Atmospheric methane (${CH}_4$), a potent greenhouse gas, is oxidised by rising oxygen levels to form carbon dioxide (${CO}_2$) and water.
2. Dissolved iron (${Fe}^{2+}$) in the oceans reacts with dissolved oxygen, precipitating out as insoluble iron oxides to form Banded Iron Formations (BIFs).
3. The drastic reduction in greenhouse warming plunges the planet into a global ice age (the Huronian glaciation).
4. Photosynthetic cyanobacteria evolve in the oceans, producing molecular oxygen ($O_2$) as a metabolic byproduct.
5. Stratospheric oxygen levels reach a threshold that allows the formation of a protective ozone layer ($O_3$).
6. Chemical sinks in the oceans and crust become saturated, allowing free oxygen ($O_2$) to accumulate rapidly in the atmosphere.

What is the correct chronological sequence of these Earth system interactions?