NATS 1880 Lecture 13: Part 6
17 Dec 2018
School
Department
Course
Professor
Document Summary
A fossil is any evidence of past life and rarely contains organic material. Mineral replacement occurs and sometimes results in complete transformations (petrified forests, trees of stone). Less and less fossils exist the further back in time we go. Eons, eras, periods, epochs and ages help define the order and development of events (including life) on earth. The phanerozoic eon ( visible life ) represents the most recent events in earth"s history and is the richest in fossil life (and thus detail). The oldest known evidence in the geological record is roughly 4. 02 billion years ago, long after the birth of earth. Zircons, zirconium silicate crystals formed in the early solar system, help place the date of earth to as far back as 4. 38 billion years. Samples of the lunar regolith yield rocks dating to 4. 4 billion years ago. Samples of meteorites place the age of the solar system at roughly 4. 57 years.
