Paleomagnetic secular variation curve for the past two thousand years

Paleomagnetic secular variation curve for the past two thousand years. Label dates are mean ages before present (B.P.) or Anno Domini (AD), with gray circles indicating estimated error. Note that the magnetic field changes in declination (horizontal arched lines) and inclination (angled vertical lines) over time. Diagram is a section of an equal-area net where symbols indicate directions projected from the lower hemisphere.