Gornja Rijeka

The geological structure of Kalnik and recent knowledge about the tectonic past of the Alpine-Dinaric system have changed the earlier opinions about Kalnik. While it was previously thought to belong to the chain of the Eastern Alps, today it is thought to be a remnant of the former Oriental Continent, which in the Mesozoic era played a significant role in the tectonic processes between the Alpine and Dinaric systems. The appearance of thermal and mineral waters (Apatovačka kiselica under the southern slope) is connected with tectonic movements in the area of this mountain. The extreme outcrops of the mountain range are covered with deposits from the Pleistocene, which are mainly clays and clay loams.

The erosive activity of numerous streams, as well as other forms of erosion, in the Pleistocene and Holocene greatly furrowed and dissected the relief. Tertiary sediments of the central Kalnik area are significant, with deposits of coal, conglomerate, clay, sandstone, marl, and in places tufa. Numerous alluvial stream valleys have cut into the structure of the relief, directed towards the Glogovnica valley, and in the lower reaches they are swampy and mostly agriculturally unattractive. Considering the petrographic composition of the relief as well as the possibility of erosive action, the pedological composition and properties of the soil are not the most suitable for agricultural exploitation.

The greater part of the southern Kalnik prigorje is covered by types of podzolized soils, which differ from each other in the degree of podzolization and the development of the profile. These are mostly less valuable soils, somewhat acidic and poor in nutrients, and in parts of Pleistocene clays, difficult to cultivate.

Despite these natural characteristics of the soil, throughout history the Kalničko prigorje was relatively densely populated, so the natural forest cover was mostly cleared, and the podzolic soils were mostly cultivated, thus gradually turning into humus anthropogenic soils.