Geophysics, Geodynamics and Tectonics
Global Continental Reconstructions
The objectives of my work are to synthesise and evaluate the available geological and geophysical data to make plausible global continental reconstructions as far back in time as possible. Unless reasonably precise base maps are available the paleoclimate and paleoceanography of past periods cannot be modelled.
Mesozoic and Cenozoic positions of the major continents relative to one another are known in many cases to better 1° and relative to the spin axis to within 5°, but the uncertainties in Paleozoic reconstructions may in some cases amount to 30° of latitude or more. The uncertainties are largely due to the difficulties of evaluating the paleomagnetic data.
The notion of a 'snowball Earth' is based on the fact that several 'high quality' paleomagnetic poles place many ice-covered continental areas in low latitudes during the Vendian period, or about 600-545 Ma. There are major problems in trying to account for an ice-covered Earth and how it eventually recovered from such a state.
An alternative Vendian continental configuration that uses other 'high quality' poles places the ice-covered areas in much higher latitudes, in agreement with their latitudinal distribution throughout the whole of Phanerozoic time. The differences in interpretation are due to the differences in the paleomagnetic data, in turn most probably related to the ages assigned to the poles.
Older Publications by Dr Alan Smith