Few people recognize, as they travel down a highway or hike along a mountain trail, that the rocks they see around them have rich and varied histories. Unless they are geologists, they have probably not been trained to identify a particular cliff as rock formed on a beech of an ancient ocean, frozen lava flow, of a dormant volcano, coral reef grown in tropical turquoise water, or other miracles preserved on the stony walls. We live in a modern, urbanized, industrial world, with all benefits which come from unrecoverable sources, and hardly have time to pay attention to such secret beauties and values which could be easily destroyed and not restored again.
Croatia is a part of European complex geology, situated between two orogenic mobile belts, Dinarides and Carpathiens, remnants of the Tethyan ocean, which squeezed Tisia, microplate of European affinities. Papuk Geopark has a unique position within the collision zone of two macroplates African and Eurasian. The rocks in the Park were formed in a variety of geological settings and consequently there is a great variety of lithology, stratigraphic age, and structural characteristics throughout the Park.
Papuk contains rock formations of outstanding geological interest, which span over 600 million years to include some of the oldest rocks in Croatia.
Geologically, Papuk is situated in the southernmost part of the Tisia tectonic Unit, which forms part of the Pre-Neogene crystalline basement of the Pannonian Basin. Most of Papuk Mountain is composed of metamorphic and igneous Pre-Alpine rocks which are considered to be the best outcrops of the Tisia Unit in the wider Pannonian Basin area.
The crystalline basement is overlain by Permian-Mesozoic age sediments and by Neogene - Quaternary deposits, all of which form part of the Pannonian Basin. Information concerning the age of metamorphic (phyllites, chlorite schists, gneisses, migmatites and amphibolites) and granitic rocks are sparse and their ages have been the subject of frequent speculation: they are generally considered to be of Precambrian or Lower Paleozoic age.
Mesozoic formations are represented by carbonate rocks, in which typical karst features, such as abysses, sinkholes and caves are abundant. These are found right up to the crest of Papuk Mountain.
The Cenozoic geological period is represented by fossiliferous sediments, particularly of Miocene age [16 million years old], when Papuk was an island in the “Pannonian sea”. Final tectonic elevation and ongoing erosion of the rocks in the Slavonian Mountains generated large volumes of sedimentary detritus, now preserved as more than one-kilometre thick deposits in the Sava and Drava river valleys.