How many major chrons were there in the Quaternary?

• A. 3
• B. 4
• C. 5
• D. 6

Answer: (B)

Major chrons are the long blocks of time defined by the direction of Earth’s magnetic field as recorded in rocks. In the Quaternary, the standard magnetostratigraphic record shows four distinct polarity intervals that are commonly named: Matuyama reversed, Olduvai Subchron reversed, Jaramillo normal, and Brunhes normal. The Brunhes chron is the current polarity and extends to the present. The Olduvai Subchron is a relatively brief reversed interval, and the Jaramillo normal is a notable normal interval that occurred after Olduvai in the sequence. Because these four named intervals constitute the major polarity episodes recorded during the Quaternary, the correct count is four.