In 2000, geologist dr. Bogdan Jurkovšek examined the Jarešca stream in Jarčja Dolina near Žiri. In the vicinity of the farm Lukač, he found a new limestone layer in the riverbed, which was previously revealed by the storm. Laboratory analyses have shown that the layers were formed 252 million years ago in the shallow sea, in the last period of the Paleozoic and at the beginning of Mesozoic (Permian-Triassic boundary). During that time, Earth's greatest catastrophe in the last 550 million years happened. Up to 96% of all marine invertebrate species and 70% of genera of terrestrial vertebrate species probably disappeared in the great extinction of living beings. The extinction was most likely the result of volcanic eruptions in today's Siberia and China, which sent huge amounts of gases and dust into the atmosphere and sea. Earth's regulating mechanisms were denied. The temperature of the atmosphere and the seas increased. Aridity on the land and toxic hydrogen sulfite, as well as a lack of oxygen in the seas were probable causes of the extinction. There is still a lot of ambiguity about that time. Some of them were clarified by the exploration of the rock from the Jarča Dolina.
The investigation of the geological site was an international project of geologists from Slovenia, Croatia, USA and other countries and was published in scientific literature. Geologists guided a visit to the geological site during the European Heritage Days on September 30th, 2016.