The Steens Basalt captured a highly detailed record of the earth's magnetic reversal that occurred roughly 15 million years ago. Over a period, more than 130 flows solidified – roughly one flow every 75 years. As each flow cooled below about , it captured the magnetic field's orientation-normal, reversed, or in one of several intermediate positions. Most of the flows froze with a single magnetic orientation. However, several of the flows, which freeze from both the upper and lower surfaces, progressively toward the center, captured substantial variations in magnetic field direction as they froze. The observed change in direction was reported as 50⁰ over 15 days.