Actualism as a methodological principle in tectonics

Abstract

The influence of Actualism, Uniformitarianism an Evotutionism in Tectonics is discussed. A review of the evofution of these concepts shows the existence of dose relationship between several currents of geological thoughl.  The methods used to reconstruct the Earth's crustal evolution analyzed with emphasis to the modem views of Actualism and Evo!ulionism show that several aspects of the Phanerozoic evolution of the crust can be regarded as closely analogous to certain present-day tectonic models. The main features of pre-Phanerozoic mobile belts are summarized and the foles played by severa! auxiliary hypotheses to the theory of Global Tectonics are discussed. It is possible to recognize: (1) file generalized rejection of lhe most radical form of the Uniformitarianism, (2) the almost complete acceptance of Evolutionism as a principIe in the study of file past and, finally, (3) lhe adoption, in variable degree. of Actualism as a quiding principIe in Tectonics, From this discussion it can be observed that Tectonics is influenced by Actualism not only as a physical science but it relays also on it as a necessary basis to a method (i.e. a strategy) to the tectonic study of the geologic past. or. ma broader sense, to the study of the Historical-Geologic Process.