The geological structure of Goričko is not that diverse, but due to its fairly eventful history it is quite interesting. The entire territory of this part of Slovenia is made up mainly of Tertiary rock, between 66 and 1.6 million years old. The much older rocks which were formed in the sea approximately 400 million years ago are present only in the area of Sotina and Rdeči breg. They are an example of phyllitoid schist. Today they project through the softer Tertiary sediments and form the steepest slopes in the northwestern part of Goričko. The appearance of metamorphic phyllitoid schist in the geological history of Goričko was followed by a long period of dry land. It was only at the end of the Oligocene epoch, around 23 million years ago, that the land was submerged beneath the waters of the Pannonian Sea advancing from the east. Only the most northwestern part remained above sea-level. The land remained covered by the sea for the next 18 million years.

In the Pliocene era the original marine sediments (gravel, sand and clay which formed sandstone, sandy clay loam and clay loam) became increasingly freshwater. Due to the rising of the ground level, the Pannonian sea moved off toward the east.

In the early Pliocene, around 1.6 million years ago, a large volcano began to erupt near Klöch in Austria. The remains of its activity are also visible in Grad in Goričko, where layers of basalt tufa and silty tufa appear between partially adhered layers of red flint gravel, sand, marl and clay, while dark gray basalt appears southwest of Kaniža. In the past these rocks were used as building materials. Today they are interesting mostly from the mineralogical aspect, since the site in Grad is the only source of olivine garnets in Slovenia.

From the Holocene epoch to the present the area has been marked by the accumulation of sediments.

In the past, Goričko was also known for its clay, but the old crafts of pottery and brick-making by hand are dying out. The making of lime from marble and limestone is also no longer interesting from the economic standpoint.

Source:
Činč Juhant, B. & Planjšek, M. 2002. O geologiji Pomurja in Goričkega. Narava Slovenije. Mura in Prekmurje, Prirodoslovni muzej, Ljubljana.