Mount Kamuriki is southwest of the Nagano Basin and is a Quaternary intrusion into the central uplift zone and western sedimentary zone of northern Fossa Magna where the sandstone, conglomerate and tuff deposits of the Tertiary strata were deposited during the time the area was ocean floor. The summit is a bipyrite andesite eroded lava dome, and although no direct evidence of volcanic activity exists, columnar joints can be observed on the rock on the eastern slope of the summit. A large portion of the summit collapsed during the 1847 Nagano earthquake.