Magnetic anomaly lineations that lie just north of northwestern Australia in the eastern Indian Ocean are correlated with the Late Jurassic magnetic reversal sequence. Magnetic lineations M–22 to M–25 trend east-northeast with the oldest anomaly against the stable Australian margin. This correlation agrees with the age of the Oxfordian basement recovered from Deep Sea Drilling Project Site 261 in the area and with the geology of the Australian margin. It suggests that a landmass was rifted away from northwestern Australia about 155 m.y. ago.