The region was covered by sea several times, also in the beginning of the geohistorical antiquity and Middle Ages. The sediment of this latter is the dolomite that forms the majority of the Keszthelyi Mountains, which emerged from the surroundings much later – in the Pleistocene era- almost 2 million years ago. There have been periods, for example at the beginning of the Paleozoic and Mesozoic eras, when the area was covered with water, the sediments of which formed the dolomite, the material the majority of the hills consist of. The hills themselves emerged much later - about 2 million years ago.
In the meantime, however, during the middle Cretaceous period and the Miocene era, this region was a desert, later, in the upper Cretaceous period the climate became wetter, and as a consequence, the desert turned into wetland.
In the Pliocene epoch - about 5.5-1.8 million years ago, the territory was covered by the Pannon Sea, the sediment of which was the mica, to be found at the western edge of the Keszthely Hills. At the end of the period as a result of volcanic activities, the basaltic hills, characteristic of the upper Balaton region got formed.
The north-south layer movement broke the surface. Along these crevasses valleys appeared, which makes the countryside look spectacularly varied. The area used to be almost completely covered by forests. Human activity, however, managed to change it. On the hill-slopes nowadays one can only see vineyards. The remaining forests consist of mainly Austrian or Turkey oaks (Quercus cerris) and sessile oaks (Quercus petraea). The trees cut down were replaced by Austrian pines (Pinus nigra), on dry dolomite soil, which unfavourably influenced the original flora coverage, so the area occupied by these forests is not going to be enlarged any more.