Volcanoes of Kamchatka. The Tolbachicks

The volcanoes Ostriy (Pointed) and Ploskiy (Flat) Tolbachicks occupy all the south-western area of the Klutchevskaya Volcanic Groups. The accrete constructions of Ostriy and Ploskiy Tolbachicks are a huge united volcanic massif for nowadays, although each construction can be differentiated externally by eye.

Ostriy Tolbachick is a pyramid-shaped pointed icy summit with a huge circus of destruction below and well seen barrancoses. The volcano is extinct, the height takes 3682 meters.

Ploskiy Tolbachick is formed with changing stratums of lava and slag and demonstrates a flat summit with the diameter of 3 km approximately. The height of the top plateau is 3085 meters. The caldera is totally filled with ice and products of eruptions, what makes the landscape looking similar to a mountain plateau. In the western part there is a crater with the diameter of 1,8 km and the depth up to 450 m. The volcano uses to be active rarely, but the periods of the activity are rather significant. Since 1740 there were 10 eruptions recorded, including four strong ones. One of the character traits of the volcano is long periods of stagnation between strong eruptions. Another character trait is a rather liquid consistence of lava. The boiling lava is in that liquid state to be a little bit gushing. There are no lavas like that nowhere in Kamchatka among active volcanoes. One more feature of the Ploskiy Tolbachick’s lava flows is a wavy surface of some of them. It gives an impression of seeing a hardened river stream with small waves and air bulbs on the surface.

The volcano also demonstrates the «Pele’s hairs» (Pele is a goodness of fire honored by aborigines of Hawaii). The «Pele's hairs» are thin (from 2 to 5 mm) throws of glass, which length varies in a wide range from 6 to 1,5 m. The throws can be light-brown, glassy-transparent with a dark brown tinge.

In the lavas of Ploskiy Tolbachick one can recognize the imprints of trunks o wood. That indicates of the fact that the lava flow crossed a forested area. The forest was destroyed, but the imprints of trees, well seen at the crushed pieces of basalts, got safe for many centuries.

Thus, both Tolbachicks are very impressive externally and can give especial insight to the character of eruptions, taking place in Kamchatka.