Stratigraphic insights and geospatial reconnaissance of Ta’ Ghammar Hill, Gozo : unravelling earth’s chronological tapestry through advanced remote sensing illuminating millennia of mystery : where cutting edge technology meets the timeless story of stone

Abstract

This research examines the geological structure of Ta’ Ghammar Hill, an underexplored hill in Gozo, Malta. The geological stratigraphy of these sites remains poorly documented, despite its critical role in the formation of perched aquifers. These aquifers, present in Gozo’s smaller hills, remain uncontaminated due to the absence of agricultural and industrial activity on the plateaus, many of which have been abandoned altogether. Sites like Gelmus, Ta’ Kuljat, Ghar Ilma, Nuffara and the study area, should all contain the necessary geological members needed for this aquifer to naturally form, but their subsurface structure remains largely unknown. For detailed subsurface stratigraphy analysis, the study integrates Unmanned Aerial Vehicle (UAV)-based photogrammetry and the (Horizontal to Vertical Ratio (H/V)) methods, ensuring high-resolution mapping of geological formations. The research successfully delineates the boundary between the Upper Coralline Limestone and the underlying Blue Clay Formation, a crucial interface for perched aquifer development. Validation against Planning Authority LiDAR and orthophotos datasets demonstrates both accuracy and feasibility of the methodology of the photogrammetry results and the H/V curves which contain a level of uniformity within all the results and also conform to other studies done in Malta. The findings from the photogrammetry, H/V and synthetic H/V reveal a coherent geological structure which in theory is capable to store water, a fact corroborated by numerous of vegetative indicators such as the dense giant reed growth, suggesting active groundwater retention present at ta’Ghammar. These insights offer a compelling case for including small hills like Ta’ Ghammar in water resource planning and conservation strategies in Malta. More broadly, the study highlights a replicable and most importantly cost-effective methodology of identifying the stratigraphy