抄録
Paleomagnetic directions from two sites at Mono Lake, California, 24000 years ago traced-out a well-defined counter-clockwise loop 25° in diameter. Major features of the loop can be explained by an inward directed radial dipole located at 0.5 Earth's radius, drifting eastward along a path 15° south of Mono Lake. Its longitudinal velocity was 0.10-0.19°/yr and its strength was 0.12-0.21 relative to the Earth's main dipole moment. The life-span of this perturbing source probably was similar to the period of the magnetic loop, about 850 years.
