While low-lying coastal zones are frequently monitored for the risks associated with sea-level rise and flooding, rocky cliffs are increasingly being scrutinized for their erosive variability and instability. Historically, sediment fluxes have been extensively studied and constrained; however, recent advancements in remote sensing and UAV technology now facilitate more precise quantitative assessments of the volumes of crustal materials involved in these transfers. In this study, we analyze erosion and sediment transport in two sectors of the Penestin Peninsula in South Brittany using high-resolution and high-frequency drone imagery along the coastline. We integrate available aerial photographs, LIDAR data, and newly acquired high-frequency and high-resolution topographic data to perform a detailed photogrammetric analysis of approximately 900 meters of the Mine d'Or cliff. The resulting topographic and morphological differentials at the land-sea interface reveal significant erosion asymmetry between the southern and northern sectors of the beach, primarily influenced by gravitational forces and urban development at beach access points. Quantitatively, since 1952, the southern sector has experienced an average annual retreat of approximately 60 cm, whereas the northern slope has retreated at an average rate of 10 cm per year. Our mapping of the dynamics of coarse and medium sand stocks along the northern coast of the peninsula, spanning the period from 2010 to 2020, indicates that approximately 32,000 m3 of material from cliff erosion has contributed to sediment accumulation on the shore, particularly within the Branzais Marsh. Furthermore, while 10,000 m3 were lost from the beach due to littoral drift transport, approximately 12,000 m3 of sand and gravel were documented in transit to the northern coast. This quantitative analysis underscores the substantial impact of rocky coastal cliff erosion as a major sedimentary source in a context of limited external sediment supply. The sediment stock, made available for transit and deposition due to local hydrodynamic factors, is notably influenced by a northward longshore drift.