Cenozoic
(66 million years until present)

BACK

CENOZOIC is divided into Tertiary and Quaternary


Tertiary (66 million years to 1.6 million years ago)

Tertiary sediments occupy the largest area of the Park. They surround the central area built of igneous and metamorphic rocks. In smaller part they are represented with Paleocene layers (fine clastic layers, clayey and sandy marls ) alternating with sandstones.

The most significant tertiary rocks are Tortonian, Lithothamnium limestone which are most abundant in the area of Bizek and Vrapčak stream. Quarry Bizek contains very rich fossil remains of the fauna of shallow sea. Lithothamnium limestone is important since it builds Zagreb 's cathedral, and many portals of downtown houses.

Lithothamnium limestone and Triassic dolomites form a unique carbonate zone in the western part of the Park . In that way was formed an isolated karst pocket, surrounded by non-karst area. Present are numerous karst forms such as caves, karst sinkholes and valleys. Geomorphologic monument of nature, Veternica cave, is located in this area, and it was formed along the contact between dolomite and calceraus layers. Horvat's steps and calceraus area of Lipa and Rog have similar significance.


Horvat's steps

About 66 million years ago when two eras exchanged, early Cenozoic and late Mesozoic, we find traces that witness a mass extinction of species .

Some time later we find ourselves in vast Tethys ocean in which sediments is a lot of material from not so distant land with fragments of mostly very old rocks that are even today unchanged and located in the body of Medvednica, and a lot of biogenic material.

In this relatively young age of Earth's geological history strong tectonic activity were present in whole Europe . In that way Dinarids, Alps and Carpats were emerged and formed. At that time Medvednica was mostly land, and only during a short Otnangian period freshwater lakes. Near village Planina one can find lake sediment conglomerates, sandstones, marls and limestone where fossils of bivalve congeria , small ostracods and leaves of terrestrial plants were found.

24 million years ago deep sea was everywhere and dramatic changes occurred such as the collapse of Mediterranean Sea Tethys with formation of early Paratethys.

20 million years before that last volcanoes existed in today's eastern part of Medvednica, and swamps where coal near Planina will be formed.

Approximately 20 million years ago Carpatian Sea penetrates into today's Pannonian valley, and central parts of Medvednica rise as an island in the sea called Paratethys, more known as Pannonian Sea. In sandstones one can find brachiopod Terebratural and cephalopod Aturia, while in marls foraminifera were found.

Cephalopod Aturia

During Baden when shallow and warm sea was present, corals reefs and red algae Lithothamnium grew which can be seen in Veternica cave, while in the zone of strong waves lived bivalves with thick shells like Pecten and large sea-urchins Clypeaster (most of these fossils can be seen when visiting Veternica). All of them were found in rich biogene calcereus sediment, which used to be excavated in the middle ages in quarry Gornje Vrapče, and later in Dolje and Bizek.

Zagreb’s cathedral and the west part of Banski dvori are built from Litothamnium limestone, as well as portals of downtown houses.


Algae Lithotamnium


Sea-urchin Clypeaster Shell Pecten

The main emerging of the mountain occurred some 12 million years ago, when along old faults parallel with Dinarid spread emerged mountain - horst, whose parts are next to today's' Medvednica, Samobor's mountain on one side and Kalnik on the other. During the main emerging the connection between former seas probably broke, which led to its later collapse. From the geological standpoint, formed mountain massive took the form of horst by emerging from the central part of today's Medvednica, which begun at the beginning of Tortonian. It kept this structure until the end of Dacianian when this structure was partially destroyed, because of reverse faulting and movement of central parts towards northwest, which led to overthusting and folding .

Along Medvednica coast which rose as an island in the real sea Paratethys characteristic littoral sediments settled, more or less filled with splintered fragments of older rocks. In them we can finds splinters of practically all rocks that formed the island of those times, and on which we step today, during our walks on Medvednica. That shore area can be followed today, but on the northern side it is significantly lower now, which can be explained by strong tectonics that occurred later . A noticeable step between downtown and upper Zagreb is a witness of these refractions and emerging.

Near Podsused and Dolje many fossil fish, fossil bones of whale, bones of manatee, and shark teeth were found.

Reconstruction of whale in Podsused

Well known laminated quartz marl, so called Tripoli was formed in the sea through the activities of algae Diatomea , which were very small, so that we can see them only magnified 800 times.

Sramatian trees used to grow on the land whose leaves reached the sea by wind, and were found fossilized in marls of Pannonian Sea near village Dolje. Common tree species can be found like oak, willow, beech, but Mediterranean plants as well like laurel, Ficus, cinnamon tree, which point out that climate was warmer then.

Changes occurred after that because Pannonian Sea lost its connection with opened Mediterranean Sea , and the salinity in Pannonian Sea was reduced. Many sea organisms become extinct, but some of them adapted to the life in brackish water, such as shell Cardium which is now called Limnocardium. During this period ( Pannonian ) other species of shells, snails Melanopsis, and Theodoxus lived, whose fossil remains we can find in layers in the surrounding of Markuševac.

During Pontian period Pannonian pool turned into a number of freshwater lakes where new organisms were formed; for example snails with bloated last twist ( Limnaea, Zagrabica, Boskovicia, Lytostoma, Valenciennesia ), small snails Micreomelania, new genus of ribbed shells ( Limnocardium, Paradacna, Pteradacna, Didacna ). Edged shells Congeria rhomboidea shaped like a rhombus lived here.

During the last century in the surrounding of Okrugljak in Rhomboidea layers ( sandy and clayey marls and loose sands) a rich collection of these fossils was found.

Five million years ago the lakes that remained from Pannonian pool drained out and Medvednica finally become land.

Quaternary (1.6 million years until today)

Further on we enter an ice-age, a repeated alternation of warm and cold periods which lasted 2 million years, known as Pleistocene. The last de-icing period called glacial Würm lasted about one hundred thousand years 43 thousand years ago, when Neanderthal hunter from Mousterian chased out cave bears from Veternice cave and settled it, could be accounted for as a beginning of today's Zagreb . Sedimentation of fine-grained sediment which was brought in by wind, so called loess, is connected with ice-age in these parts .

Northeast part of the mountain is still restless which is indicated by many earthquakes with the epicenter near Kašina. Here we can find surprising terrain evidence, streams Suhopot, today right confluent of Kašine, and Vukov Dol, that used to be a part of Hrvatsko zagorje basin. The cause for their current flow on the other side is recent emerging of their hinterland. It is interesting as well that river Sava perforated its corridor, overcoming the barrier near Podsused, approximately 10 thousand years ago, or more simply said at the end of the last ice-age. At that point, once long and single massive divided into three smaller geographical entities: Samobors' mountain, Medvednica and Kalnik. Since that time until today Sava has accumulated vast amounts of gravel and sand along its entire valley, and somewhere the layer is up to 40 m deep.