Kotelny Island
Kotelny Island consists of sedimentary rocks and sediments ranging in age from Early Paleozoic to Late Cenozoic. The oldest rocks fossiliferous shallow- to deep-water marine, Ordovician to Early Devonian limestones and dolomites. Middle Devonian to Carboniferous interbedded limestones, dolomites, sandstones, and conglomerates overlie these sedimentary strata. The Permian to Jurassic strata exposed within Kotelny Island consist of interbedded, fossiliferous mudstones, siltstones, and sandstones. All of these sedimentary rocks are faulted, folded into complex anticlines and synclines, and intruded by thin diabase dikes. Pleistocene to Holocene fluvial sediments, which range in age from 1,500 to greater than 55,000 radiocarbon years BP, underlie stream terraces that lie within the Balyktakh and Dragotsennaya River valleys. Thick permafrost has developed in these sediments.