How do geologists determine the age of rocks?
Geologists determine the age of rocks by measuring their radioactivity with special detectors.
What significant events occurred during the Hadean eon?
During the Hadean eon, the Earth was hot, had many volcanoes, and experienced collisions with comets and meteors. There was no oxygen in the atmosphere.
What important development in the Earth's atmosphere happened during the Proterozoic eon?
During the Proterozoic eon, oxygen began to build up in the Earth's atmosphere.