Geoheritage Assessment of Volcanic Landforms on the Biga Peninsula (NW Türkiye) Using UAV-Based Geomorphological and Mineralogical Analyses

Volcanic landforms constitute important components of geoheritage because they record both primary magmatic processes and subsequent surface weathering dynamics. This study investigates two distinct volcanic landforms on the Biga Peninsula (NW Türkiye): tafoni-bearing dacitic tuffs in the Karaömerler area and columnar basalts in the Akköy area. The aim of this research is to evaluate how lithological characteristics, geomorphological processes, and morphometric parameters contribute to volcanic geoheritage assessment. An interdisciplinary methodology integrating field observations, petrographic and mineralogical analyses, meteorological data (2005–2024), and Unmanned Aerial Vehicle (UAV)-based photogrammetry was applied. High-resolution orthophotos, digital elevation models, and three-dimensional surface models were generated using Structure-from-Motion (SfM) techniques, with positional accuracy validated by RTK-GNSS ground control points. UAV-derived morphometric parameters (including slope, surface roughness, and curvature) were calculated to quantify microtopographic variability and identify geomorphological processes controlling landform development, providing quantitative indicators relevant for geoheritage characterization. In the Karaömerler tuffs, tafoni cavities exhibit a mean aperture diameter of 0.45 m, a mean depth of 0.32 m, and an average depth-to-width ratio of 0.71, with spatial densities reaching up to 15 cavities m⁻². These morphometric features indicate advanced cavernous weathering associated with lithological porosity. Meteorological data supported the interpretation of weathering processes shaping the geomorphology of the volcanic landforms. In contrast, the Akköy basalt outcrops display well-developed polygonal columnar jointing with an average column diameter of approximately 35 cm and step-like micro-relief variations of 15–20 cm between adjacent columns, reflecting structure-dominated volcanic morphology formed by cooling-induced contraction. Geoheritage significance was evaluated using the criteria-based framework of Brilha (2016), incorporating scientific, educational, aesthetic, accessibility, and geotourism values. The results indicate that the Karaömerler tuffs represent process-dominated volcanic geoheritage shaped by surface weathering dynamics, whereas the Akköy basalts represent structure-dominated geoheritage controlled by primary volcanic cooling processes. The integration of UAV-derived morphometric metrics with qualitative geoheritage assessment improves the objectivity and reproducibility of volcanic geoheritage evaluation. This study establishes a transferable and integrated methodological framework for the documentation and assessment of volcanic geoheritage.