Izvor – špilja Ričina nalazi se na širem području zaseoka Vrilo u blizini Tomislavgrada. Dio je većega kompleksa, točnije riječ je o tri špiljska ulaza međusobno povezana špiljskim kanalima koji su nastali korozivnim djelovanjem snažnoga podzemnog toka. Za vrijeme viših vodostaja akumulacijskoga jezera kompleks, ali i područje uokolo je potopljeno. Špiljski kompleks je već prije speleološki dokumentiran, a prilikom jednoga posjeta speleolozi su ispred špilje uočili ostatke kremenoga oruđa. Pronalazak je potaknuo arheološka istraživanja prilikom kojih je, ispred ulaza u pećinu, pronađeno mjesto izrade litičkih predmeta. Tanki kulturni sloj i prostorna dispozicija nalaza asocira na sekundarni položaj nalaza, ali geomorfološke karakteristike terena pokazuju da je, ipak, riječ o izvornoj zoni litičke obrade. Postojanje gotovo svih faza lanca operacija (nedostaje jedino faza prikupljanja sirovine) ukazuje kako se cjelokupni proces obrade odvijao na ovome mjestu. Iako kronološke analize za sada nisu moguće, tipološke i tehnološke karakteristike, uz pojavu obrađenih sječiva, grebala i pločica s hrptom, sasvim jasno ukazuju na epigravetijensku kulturu. Time nalazište na izvoru Ričine postaje prvo paleolitičko nalazište na prostoru zapadne Hercegovine The Ričina spring cave is located in the wider region of the Vrilo hamlet in the vicinity of Tomislavgrad. It is a part of a larger complex, more precisely there are three cave entrances mutually connected with cave channels, created as a consequence of the corrosive activity of a strong underground stream. The complex and the surrounding region are flooded when there is a high water level in the reservoir. The cave complex has already been documented speleologically, and remains of stone tools were noticed by speleologists in one of their visits to the cave. This discovery incited archaeological research that resulted in the identification of a place in front of the cave where lithic objects were made. The thin cultural layer and spatial disposition of the finds imply their secondary position, but the geomorphological characteristics of the terrain indicate that it was the original zone of lithic production. The presence of almost all the phases of the operational sequence (only the collection of raw material is missing) indicates that the entire process of production happened at this spot. Though chronological analyses are unavailable for the time being, typological and technological characteristics, along with the presence of retouched blades, end scrapers and backed bladelets, clearly indicate the Epigravettian culture. It means that the site at the source of Ričina is the first Palaeolithic site in the western Herzegovina region