14 - Permafrost evolution in the Earth's history

Summary

History of the development of permafrost and its distribution on the planet

The evolution of the Earth extends over almost 5 billion years. Its history can be divided into three significant stages which are basically responsible for the present state of the lithosphere. These are the initial or Archaean (2 x 10⁹ years), Proterozoic (on the order of 2 x 10⁹ years) and Phanerozoic (0.6 x 10⁹ years) stages of the development of the geosphere and lithogenesis. During the Archaean stage of the Earth's development the vulcanogenic type of lithogenesis, characterized by accumulation of lava and loose ash material on the sea bottom with a low content of weathered terrigenous sediments, was dominant. The differentiation of the lithogenetic types is likely to have begun only at the end of the Archaean stage, being most apparent in the Proterozoic-Riphean stage with the formation of humid, arid, volcanogenic-sedimentary and glacial or cryogenic types of sedimentary rock. The first certain glacial drift of the continental type is referred to this stage. The expansion of the area of the continents caused not only glaciation and formation of specific deposits of the cryogenic type but also considerable increase of deposition of detrital and dissolved material in oceans (especially of carbonates) with the predominance of exogenous lithogenesis over the volcanogenic-sedimentary.

The cryogenic type of lithogenesis in the Proterozoic is the latest and it becomes more and more important as the recent epoch is approached. An increase in climatic severity and frequency of glaciation supports this.