Science. 1967 Jul 7;157(3784):55-6. doi: 10.1126/science.157.3784.55.
Theoretical work on the magnetohydrodynamics of the earth's liquid core indicates (a) that horizontal variations in the properties of the core-mantle interface that would escape detection by modern seismological methods might nevertheless produce measurable geomagnetic effects; (b) that the rate of drift, relative to the earth's surface, of nonaxisymmetric features of the main geomagnetic field might be much faster than the average zonal speed of hydrodynamic motion of core material relative to the surrounding mantle; and (c) why magnetic astronomical bodies usually rotate. Among the consequences of (a) and (b) are the possibilities that (i) the shortest interval of time that can be resolved in paleomagnetic studies of the geocentric axial dipole component of the earth's magnetic field might be very much longer than the value often assumed by many paleomagnetic workers, (ii) reversals in sign of the geomagnetic dipole might be expected to show some degree of correlation with processes due to motions in the mantle (for example, tectonic activity, polar wandering), and (iii) variations in the length of the day that have hitherto been tentatively attributed to core motions may be due to some other cause.
(a) 尽管现代地震学方法可能无法探测到地核-地幔界面属性的水平变化，但这些变化可能会产生可测量的地磁效应；(b) 主地磁场非轴对称特征相对于地球表面的漂移速度可能远快于地核物质相对于周围地幔的平均经向流体运动速度；(c) 为什么磁天体通常会自转。(a) 和 (b) 的结果包括以下可能性：(i) 在对地球磁场的地心轴向偶极分量的古地磁研究中，可以分辨的最短时间间隔可能比许多古地磁工作者通常假设的时间长得多，(ii) 地磁偶极的反转可能与地幔运动（例如构造活动、极移）引起的过程有关，(iii) 迄今为止归因于地核运动的日长变化可能是由其他原因引起的。
