Palaeomagnetic constraints on the distribution of continents in the late Silurian and early Devonian
Silurian and Devonian palaeomagnetic data are reviewed and used to orient continental fragments in a global map-frame. In some cases longitude separations have been estimated from palaeontological data. The resulting maps show a possible evolution of the continents in Silurian and Devonian time. A 10° present-day latitude-longitude grid has been rotated to past positions and the extent of areas involved in subsequent deformation are shown. Two internally consistent alternatives are presented for the Silurian-Devonian boundary reconstruction. The first draws on North American and Baltic data, mostly from cratonic sediments; the second uses British data obtained mostly from igneous rocks, and admits poles from SE Australia in positioning Gondwanaland. Choosing between these alternatives depends on having better data from Gondwanaland and on evaluating the hypothesis of large-scale remagnetization of red beds