In Summer and Fall 2019, The Commander Islands Nature and Biosphere Reserve hosts field research of geological formations on Bering Island. Geologist Alexey Perelygin analyses rock formations on the coastline to understand what the islands looked like during upper Oligocene and early Miocene. He will also create a collection of minerals and subsurface rocks for a permanent geological exposition in our museum.

The research started around Tolsty Cape on the South-East coast of Bering Island. Here lies the most ancient Dikovsky complex of volcanic and sedimentary rocks. It appeared in the upper Oligocene about 23 million years ago and is a part of suite formation of Tolsty Cape, which mainly consist of tufogenic sediments: conglomerates, malmrocks, silt stones and mudstones.

“Volcanic sediments of Tolsty Cape suite formation have a major role in the composition of the Commander Islands, occupying over 70% of Bering Island surface. It is oldest rocks, which create a kind of a fundament for the island,” said Alexey.  

Tolsty Cape. Coastal outcrops of sudimental rocks of Dikovsky complex. Photo by Alexey Perelygin

Sediments sometimes contain parts or imprints of mollusks and even petrified wood and parts of plants, which is the most curious. These plants are no longer living on the Commander Islands.

“Petrified wood and leaves of Oligocene era are very common, including Tolsty Cape area. We can suppose that this place was a forest 23 million years ago. It is hard to believe today, as there no more high trees on the Commander Islands. Still, the findings are the evidence,” said Alexey.

Petrified wood, Severo-Zapadny Cape, Bering Island. Photo by Alexey Perelygin

The research continues in Ozernaya Bay, where the so far the most interesting sample was found. It is an imprint of a large unknown plant. Moreover, Alexey plans to move to Lisinskaya Bay afterwards to look into sediments there, as many fossilized animals and plants had been found there before.

Imprint of an unknown plant found in Ozernaya Bay region

The research project will give us a deeper understanding of rock composition, landscape, flora and fauna in the end of Paleogene – beginning of Neogene, the period when the majority of Bering Island was formed. Some of the collected samples will be exhibited in the visitor center museum of the nature reserve.