The Western Falkland Islands are characterized by landforms and sediments of Quaternary age originating from the interplay of periglacial and marine processes. These have left their imprints on siliciclastic sediments and subbituminous coal, peatland, and podzolic soil. Our depositional study focuses on interpreting a stratigraphic sequence which contains white quartz sand with an interbedded coal seam by using petrography (coal petrography, carbon isotope analysis, sedimentary petrography, clay mineralogy, granulometric, morphometric studies), and geochemistry. The study of the coal-sand couple sheds some light on two contrasting sedimentary geological settings. Firstly, it broadens the knowledge of the regional geology at the southern tip of South America by examining how coal seams may be emplaced in a periglacial-microtidal environment. Secondly, the study is also relevant for applied geology by investigating how sand is processed in a coal-bearing paralic regime. The coal-sand couple evolved during 6 discrete stages. Stage I: The detrital parent material was derived from the Siluro-Carboniferous Gran Malvina Group. Stage II: From the Oligocene through the late Miocene under a warm tropical climate organic matter was accumulated in a paralic environment giving rise to subbituminous coal. Stage III: During the Pleistocene alternating erosion and deposition in a wave-dominated coastal-marine regime gave rise to the build-up of coal interbedded with sand. The hydrodynamic regime reduced the grain size to the level of medium to fine sand and enhanced its sorting coefficient causing the separation of minerals according to their specific gravity (mechanical processing). Stage IV: The coal seam has been reworked by the last glacial progradation. Stage V: Weathering by wind and waterworn sand grains into semispherical to spherical forms and the content of heavy minerals increased along backshore and in dune belt environments. Stage VI: Organic acids derived from the coal promoted chemical leaching and significantly contributed to the decrease of the labile constituents of arenites (feldspar, carbonate minerals, and calcareous tests of faunal remains). Chemical alteration was grinded to a halt by another sea level rise, which gradually destroyed the coal layer. The depositional environment most effective for the processing of sand is located in the microtidal setting. In the meso-to macrotidal hydrodynamic regime the chemical leaching becomes the only efficacious tool to improve the quality of the footwall rocks. Due to the predominance of argillaceous sediments there, the quality of clay is enhanced and kaolin deposits may come into existence. (C) 2017 Elsevier B.V. All rights reserved.