Like the Udokan plateau, Jom-Bolok is a volcanic field part of the Baikal rift which has been volcanically active during the Holocene. Volcanism there may be the consequence either of passive rifting or mantle plume activity and has been ongoing since the Mesozoic. The basement of this area was heavily folded and altered during the Tertiary, which was also affected by river incision and earlier eruptive activity. During the late Pleistocene, thick glaciers formed in the Jom-Bolok valley and other adjacent valleys.