GEOLOGY
Today’s image of Kozjansko Park is just a glimpse of a long geological history, measured in millions of years. In terms of geology, Kozjansko is a very small area, but many researchers have found beautiful, well-preserved and also research-worthy geological natural values here.
The territory of Kozjansko Park is made up of Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Tertiary, and Quaternary rocks.
It is marked by stacks of Triassic rocks and Tertiary strata, with Jurassic, Cretaceous, and Permian-Carboniferous strata occurring here and there.
They are most widespread in the area of the new Earth era rocks that make up the hills of Kozjansko.
In several places, there are rich deposits of fossils found in Mesozoic and, more often, Cenozoic rocks. Preserved as fossils are shells of mussels, snail shells, sea urchins, cephalopod remains, microfossils – forams. A very interesting find is a fossil fish – one of the most beautiful finds in our area.
The area has a very complex tectonic composition, which belongs to the Dinarides and Pannonides geotectonic units. With its numerous fault lines, it is divided into larger and smaller clumps that were pushed up or down along the faults. There are traces of convergence in several places.
Today, earthquakes, mineral springs, and hydrothermal ore deposits confirm the vibrant tectonic activity.
Several synclines and anticlines run from west to east, resulting in a landscape of valleys and ridges. From north to south, the Rudnik-Ivanjica anticline, the Planina-Desinić syncline, the Litija anticline, the Senovo syncline, the Orlica anticline, and the Bizeljsko-Zagorje syncline follow each other (Aničić, Juriša, 1985).
The varied rock composition is largely reflected in the rugged surface at the junction of the Pre-Alpine and Pannonian worlds. The Kozjansko Regional Park is made up of three relief units: hills, mountains, and valleys. The heavily dissected mountains are characterised by narrow valleys, gorges, and ravines with steep slopes. The hills, with flatter slopes and wider valleys, continue into the plain along the Sotla.
The hills in the Triassic dolomites of the Orlica area and in the Triassic dolomites and shales and claystones of the Vetrnik area are between 500 and 800m above sea level. The highest point is Oslica in the western part of Vetrnik at 860m above sea level.
The hills are mainly made of lithothamnion limestones, Miocene lapis and Pliocene sediments, with altitudes ranging from 200 to 400m above sea level.
Rich fossil deposits are represented in several places. They are found in Mesozoic and, more commonly, Cenozoic rocks.
The Triassic rocks contain shells, snail houses, cephalopod remains, megalodontid shells, and microfossils such as foraminifera (forams).
Most of the fossil remains are Palaeogene and Neogene. The most interesting is the finding of a fish from the Lates genus, found on the south slope of Rudnica. Sea urchins, clams, snails, crabs, and shark teeth and bones are very common among macrofossils.
