title: An Explanation for Earth's Long-Term Rotational Stability
abstract: Paleomagnetic data show less than approximately 1000 kilometers of motion between the paleomagnetic and hotspot reference frames-that is, true polar wander-during the past 100 million years, which implies that Earth's rotation axis has been very stable. This long-term rotational stability can be explained by the slow rate of change in the large-scale pattern of plate tectonic motions during Cenozoic and late Mesozoic time, provided that subducted lithosphere is a major component of the mantle density heterogeneity generated by convection. Therefore, it is unnecessary to invoke other mechanisms, such as sluggish readjustment of the rotational bulge, to explain the observed low rate of true polar wander.
authors.affiliation: M. A. Richards, Department of Geology and Geophysics, University of California, Berkeley, CA 94720, USA. Y. Ricard, Departement de Geologie, Ecole Normale Superieure, Lyon, France. C. Lithgow-Bertelloni, Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015-1305, USA. G. Spada, Dipartimento di Fisica, Settore Geofisica, Universita di Bologna, Bologna, Italy. R. Sabadini, Dipartimento di Scienze della Terra, Sezione Geofisica, Universita di Milano, Milano, Italy.
authors.initials: MA
authors.lastname: Richards
authors.initials: Y
authors.lastname: Ricard
authors.initials: C
authors.lastname: Lithgow-Bertelloni
authors.initials: G
authors.lastname: Spada
authors.initials: R
authors.lastname: Sabadini