A review of palaeomagnetism

Abstract

Palaeomagnetic data published up to the end of 1968 plus some published in 1969 and early 1970 are tabulated according to the continent of origin and age. The following tentative conclusions may be drawn: Pangea existed as a single unit from the Early-Middle Palaeozoic (i.e. possibly from the end of the Ordovician Period) until the end of the Triassic. During this interval of geological time, the south pole wandered across Pangea, from northeast Brazil in a southeasterly direction across South Africa continuing across the Antarctican part of Gondwanaland over an angular distance of about 90°. (3) There were three apparently rapid shifts. The first occurred during the Silurian or Early Devonian, the second during the Middle Carboniferous and the third in the Late Permian. (4) Pangea started to disintegrate at the end of the Triassic when North America drifted away from northwest Africa. Also some movement of Australia relative to the rest of Gondwanaland occurred in the Late Permian. (5) The most intense phase of dispersal of the continents which were formerly part of Gondwanaland took place during the Late Mesozoic and Tertiary. (6) There is some evidence, as yet rather tenuous, that the single landmass, Pangea, was created during the Early Palaeozoic possibly during the Ordovician-Silurian. (7) There is evidence of relative movements between component parts of Pangea before the Early Mesozoic, but there was no tendency for the parts to disperse until then. (8) Plate tectonics as well as polar shifts have to be invoked to interpret the data.