The rock-hewn churches in the Zelve and Göreme valleys were dug out of volcanic rock and are conical in shape; they served first as places of meditation before being used as impregnable places of refuge during the successive invasions. All the various Byzantine styles are to be found in their architecture and wall paintings. The area has suffered very badly from the effect of rain and landslides, and emergency measures are to be taken to arrest the deterioration, particularly in the case of the churches of El Nasar, Elmali and Karanlik. -- AATA