Abstract: The study aims to give a geological approach to the environmental problems of the Ortahisar town. Themajor problems encountered include the rockfalls from the castle, which symbdlizes the town ,and the possible failure ofthe roofs of the caves dwelled for accomodation purposes. The dominating- rock types of the area include the ash-flowtuffs ,and the pumice flows of Neogene age. The castle, which is made of the welded portions of ash-flow tuffs, had almostlost most of its strength due to excessive dwellings ,and now acts as a potential hazard for the buildings that surround it.For this reason, a fallout area is established around the castle ,and the levelling of this area is proposed. In order to avoidthe jump of the falling blocks, the fallout area must be covered with a blanket of pumice flows. The major causes of cavefailure include the seepage of rain water ,and the accumulation of small ponds on the floors of the caves, the runoff ,andthe surcharge load exerted by the newly built houses on topof the caves. It is thus necessary to drain the caves, to sealthe fractures to prevent seepage of rain water, to collect ,and canalize the runoff ,and to support the roofs of some caves.