The glacier-capped Alney-Chashakondzha complex, one of the largest volcanoes of the Sredinny Range, consists of two large mostly Pleistocene andesitic stratovolcanoes constructed on a large Pliocene shield volcano.  Both 2598-m-high Alney on the north and 2526-m-high Chashakondzha on the south are capped with andesitic lava domes.  Three rhyodacitic-to-rhyolitic lava domes and associated lava flows were emplaced along ring faults enclosing a 15 x 20 km area.  Two cinder cones on the east flanks of Alney and Chashakondzha volcanoes erupted about 2600 years ago and produced lava flows, one of which traveled as far as 9 km down the eastern flanks of the complex.  Alney is one of the few large stratovolcanoes in the Sredinny Range known to have been active throughout the Holocene, with more than 30 documented pyroclastic deposits.  The last intense eruption took place about 350 years ago.