Gypsum cave notches and their palaeoenvironmental significance: A combined morphometric study using terrestrial laser scanning, traditional cave mapping, and geomorphological observations

Abstract

Terrestrial laser scanning has shown to be a very powerful method for the study and monitoring of caves. The high density of acquired points allows geostatistical methods to be used in the elaboration of large datasets on different depositional and erosional morphologies on cave walls, roof and floor. Here we describe a multidisciplinary morphometric study on cave wall morphologies and sediments in a multi-level gypsum cave system in the northern Apennines (Italy) with the objective of finding the direction of water flow that created these passages over hundred thousand years ago. The analysis of the traditional cave map (in long profile) suggests an overall, albeit very low, north-west inclination of the cave passages. However, other definitive indicators of flow direction, such as scallops, are absent which restricts the verification of this interpretation. The laser scanner-derived 3D point clouds of the cave wall notches of the main level have been analysed using different methods to verify the paleocurrent direction. However, statistical analyses of the point cloud data have yielded inconclusive results, even if most flow-related morphologies appear to be gently sloping towards north-west, where the present main cave entrance is found. Imbrication of fluvial sediments prevalently indicates the same direction. While no single method provided conclusive results on its own, the collective evidence strongly suggests an ESE to WNW paleocurrent flow, confirming the ancient resurgence nature of the cave gallery.