Mount Erciyes is an inactive volcano in Kayseri Province, Turkey. It is a large stratovolcano surrounded by many monogenetic vents and lava domes, and one maar. The bulk of the volcano is formed by lava flows of andesitic and dacitic composition. At some time in the past, part of the summit collapsed towards the east. The volcano began to form in the Miocene. At first, a volcano farther east named Koç Dağ formed from lava flows.