Hadean
The Hadean () is a geologic eon of the Earth pre-dating the Archean. It began with the formation of the Earth about 4.6 billion years ago and ended, as defined by the ICS, 4 billion years ago. , the ICS describes its status as ""informal"". Geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks on Earth. W. Brian Harland later coined an almost synonymous term, the "Priscoan period", from "priscus", the Latin word for "ancient". Other, older texts simply refer to the eon as the Pre-Archean.
Timeline of Arda
The Years of the Sun begin with the Awakening of Men in about V.Y. 5000. 
From this time, the First Age lasts for another 590 years.
The Second Age extends to 3441 years, beginning with the foundation of Mithlond (the Grey Havens) under Círdan, and Lindon as the Noldorin Kingdom under Gil-galad, and ending with the defeat of Sauron at the hands of the Last Alliance of Elves and Men.
The Third Age extends to 3021 years, ending with the final defeat of Sauron in the War of the Ring and the establishment of the Reunited Kingdom of Arnor and Gondor.
The Fourth Age is mainly outside the scope of Tolkien's legendarium, beginning the suggested transition to the historical period, but Tolkien gives a summary of the first two centuries of the Fourth Age.