The only event the time almanac has listed under the heading 4.5 billion b.c. is this formed

Below you can find the The only event the time almanac has listed under the heading 4.5 billion b.c. is this formed Jeopardy Words Answer. The answer to The only event the time almanac has listed under the heading 4.5 billion b.c. is this formed has 5 letters. This clue belongs to the A billion reasons category and is part of Jeopardy Word Level 1652. If you scroll near the bottom you will find other clues and answers part of level 1652