11. Most importantly, they sequentially replaced one another as dominant groups during the Phanerozoic . 12. Oldest to newest these are the Hadean, Archean, Proterozoic, and Phanerozoic . 13. Phanerozoic ironstones generally have a different genesis.14. It is likely that the group has evolved minimally over the course of the Phanerozoic . 15. In the Sahara they are mostly covered by more recent sediments from the Phanerozoic Eon. 16. Pellets occur in Precambrian through Phanerozoic strata. 17. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. 18. Prior to the Phanerozoic ( before 544 Ma ), it is believed that continental shelves. 19. Frenchman Mountain exposes a sequence of Phanerozoic strata equivalent to those found in the Grand Canyon. 20. These first appear after the boundary between the Proterozoic and Phanerozoic eons or Ediacaran and Cambrian periods.
