Four sets of microstructural measurements of surface fracturing were taken at different locations in the NW sector of the Ciumerna Plateau.

The measurements were recorded using the FieldMove Clino app installed on a mobile device (Midland Valley Exploration Ltd., 2014) and verified with a Freiberger geological compass. The collected data were subsequently processed using the TectonicsFP software (Reiter & Acs, 2020).

The geomorphological investigation of the surface karst consisted of mapping the dolines, uvalas, and ponors. Particular attention was paid to the plateau sector above the cave and the uvala nearby.

By combining fieldwork and morphometric analysis, we produced a consistent dataset and geomorphological maps that aid in interpreting the evolution of the drainage system and the resulting karst landforms. LiDAR data from ANCPI (LAKI II Project) were instrumental in conducting the analysis in ArcGIS Pro software.

The cave survey and mapping were carried out by a team consisting of Laura Tîrlă, Ionuț Mirea, Gabriela Călin, and Andrei Mărghescu. The collected data were entered into the Compass software (Fish, 2022) and subsequently used to produce a detailed map and longitudinal profile, enabling the depositional context of the sediments and their fossil content to be identified.

We are grateful to Cosmin and Cristina Berghean from the Polaris Speleological Association (Blaj) for their technical assistance during this activity.

The systematic excavation of the cave deposit located in the sediment trap, at the lower level of the cave, was carried out in four excavation units measuring 1 × 1 m in plan and reaching depths of up to 2 m.

Excavations were conducted through the gradual removal of sediment using fine tools, with each sample recorded in the field notebook. Samples were initially photographed in situ to document their taphonomic context.

Sediment samples and bones were collected in plastic bags and transported to the “Emil Racoviță” Institute of Speleology in Bucharest, the curatorial institution responsible for the paleontological collection.

Sediment was sampled for grain size analysis, geochemistry and OSL dating.

After sieving, the sediment from a selected quadrant was sorted and examined for the recovery of small mammal paleontological remains. These remains will be identified in order to establish mammalian assemblages characteristic of particular climatic conditions (e.g., warm and humid, cold and dry, cold and humid). The results will contribute to reconstructing the paleoclimatic variability that controlled the depositional phases of sediment accumulation.

During this stage, almost the entire quantity of sediment extracted since the beginning of the investigations was washed and sorted. The activity was coordinated by Dr. Alexandru Petculescu, and the working team benefited from the help and assistance of colleagues from the “Emil Racoviță” Institute of Speleology, Cluj branch: Dr. Traian Brad, Dr. Oana Moldovan, and researcher Marius Kenesz.

The sediment and paleontological material excavated during the previous field campaign was transported to the cave entrance, where it was sorted in order to identify small-sized paleontological remains. Most members of the project team, as well as collaborators and volunteers, participated in this activity.

The recovered fossil material was washed, labeled, and identified in the Paleontology Laboratory of the “Emil Racoviță” Institute of Speleology in Bucharest.

All bone samples were entered and organized in an electronic database. For each element, the following information was recorded: excavation unit, stratigraphic level, sample code, degree of fragmentation, type, anatomical position, number of identified fragments, approximate age of the individual, taxonomy, and the presence of mechanical cut marks.

Radiocarbon dating of fossil bone and charcoal samples was conducted at the Radiocarbon Laboratory in Vilnius (Lithuania). Bone samples were selected from specimens with a high probability of preserving significant collagen content (metapodials, phalanges, M1 molars, mandible – Ursus spelaeus, herbivores).

Speleothem samples (calcite crusts) were submitted for U–Th dating (²³⁰Th/²³⁴U) at the CENIEH (Burgos, Spain).

For preliminary geochemical analysis of the sediments, samples were dried, crushed, encapsulated and analyzed using the Itrax Core Scanner at the Orșova Geographical Research Station (University of Bucharest), an instrument acquired through the LIFEWATCH Romania project.