7 julio 2015
The Earth’s magnetic field experiences reversals such that north becomes south. The age of the latest reversal is unclear. Researchers have dated volcanic ash that was formed immediately before the last reversal. This result and chronology of the associated sedimentary rock identifies the age of the reversal as 780,000 years ago. This new age will contribute calibrating the geological time scale.
http://feeds.sciencedaily.com/~r/sciencedaily/~3/w5bq_grNFXw/150707101952.htm
