The basaltic Nylgimelkin (also known as Atlasov) shield volcano and the topographically higher but smaller shield of Novagrablenova are dwarfed by their neighbor, the glacier-clad Pleistocene Khuvkhoitun, the highest Quaternary volcano of the northern Sredinny Range. The two youthful shields were constructed on the W and NW flanks of Khuvkhoitun. Lava flows from them extend primarily to the west. Cinder cones and a lava flow were erupted along a fissure at Nylgimelkin about 5,500 years ago.