The Planet Chronicles by Diatoms

E. I. Loseva, R. Crawford, A. Yu. Gladenkov, J. Smol, M. Douglas, M. Poulin, T. A. Grebennikova

Rapid development of diatoms resulted in bottom deposits enriched in silica at the expense of frustules of dead diatoms, which can stay fossilized for millions of years. In this way "diatomaceous" rocks form, some of which consist almost completely of diatom frustules, especially where calcium promoting dissolution of silica is in deficiency. Ancient sea diatomites, diatomaceous shales, and silts are known in many world regions, reaching several hundred meters thick in places.

Fossil complexes of diatoms allow us to reconstruct the paleogeographic situation of the past geological eras with a high degree of reliability, if the complexes contain extant species. Thus, revision of all known diatoms, both fossil and modern, carried out by scientists of the Komi Scientific Center of the Uralian Branch of the Russian Academy of Sciences, yielded a list of 995 species! As a result, the environments that existed at different stages of the Pleistocene have been reconstructed- a geological period embracing the latest 1.8 million years in the Earth history.

The information obtained from the areas where the deposits had been accumulated continuously is of special value. This is how a full geological record is formed, for example, in oceans or Lake Baikal, where the deposits of diatom frustules up to 600 meters thick embrace the time span of 8 million years! Unfortunately, the majority of diatom species have not survived, which is why their ecological features are inferred from comparison with findings of other organisms as well as with paleothermal, oxygen-isotope, and paleomagnetic scales.

More information on these and other subjects you can find in the printed version of our journal.