The geomagnetic polarity timescale records well-documented reversals of Earth's magnetic field through geologic time: the present normal-polarity interval, the Brunhes Chron, extends from the present back to approximately 0.78 Ma, while the preceding Matuyama Chron (approximately 0.78 to 2.58 Ma) is predominantly reversed polarity, punctuated by brief normal-polarity subchrons such as the Jaramillo subchron (approximately 0.99 to 1.07 Ma); the natural remanent magnetization (NRM) direction recorded in a sediment sample reflects the polarity of the geomagnetic field at the time the sediment was deposited and magnetized.