The area of Monte della Guardia is characterized by triassic limestone. Towards monte Armetta, on the slopes facing the Tanaro valley, stands a large cave known as Grotta dei Dighè or Garb del Dighea. It was surveyed at the end of the 19th century by entomologysts that detected an interesting troglofauna with Plectogona sanfilippoi, subsp. Digheae, an arthropod endemic of Tanaro valley.