The Mountain is characterized by a variegated surface – steep sides, narrow valleys, undulating parts, plains and hills. In spite of its small area it is characterized by a varied geological construction, as the Somlyó is constituted of andesite tuff of volcanic origin, sea- and freshwater limestone and loess sandy sediments. The majority of the Somlyó used to be covered with the characteristic association of loess grounds called the Tatarian maple loess oaks, but only small patches of it can be seen mainly on the northern side. Because of the diversity of geology and formations, the flora of the mountain is also varied.
The cool deep valleys and the easily warming up southern sides of Mediterranean microclimate ensure the survival of montane and thermophile species as well. Several rare herbaceous plants of the Somlyó have been present since the warming up after the ice age: the Jerusalem sage, stemless milk-vetch, the (Compositae) etc., while the montane maidenhair spleenwort grows on the cooler areas. The outstandingly rich butterfly fauna of the Somlyó is the greatest asset of the area. More than half of the entire Hungarian large butterfly fauna is present, e.g. (Rileyana fovea) living only in Dalmatia besides Somlyó. The most precious is the zephyr blue (Plebejus sephirus) dwelling on the stemless milk-vetch, which besides the Somlyó, only lives in certain parts of Bulgaria. Almost all the lizard species can be found in the Somlyó, and the bee-eater, the kestrel (blood hawk) and the roller also hatch.