Hunter-gatherer occupations of the forests of Patagonia are still not well understood compared to those of the open steppe and the coasts. The paucity of forest sites with a thorough chronological framework and the incomplete picture of climate-human dynamics in such environments pose a challenge to understanding the occupations of such habitats. This paper presents recent work at the Las Quemas rockshelter, an archaeological site located in the Andean forests of the Aisén region (44°38’ S) dating between 6100 and 2400 cal B.P. We examine the context of the site, its rock art, and the technological and functional dimensions of its lithic assemblage. By comparing these records with local environmental reconstructions that report forest area fluctuations after the Post-Glacial period, this study provides novel data for a comprehensive regional-scale model of human occupations in central Patagonian forests. Following an initial mid-Holocene occupation, recurring occupational events at the site coincide with a significant contraction of forested area in the region during the late Holocene. The results are discussed in regard to regional archaeological data and current models of forest occupation in Patagonia.

Thermodynamic methods such as exergy analysis enable the evaluation of environmental load (environmental impacts) by quantifying entropy generation and exergy destruction associated with using renewable and non-renewable resources throughout a production system. Based on the principle that environmental impacts occur when exergy is dissipated into the environment, this study applies exergy analysis as a tool for assessing the sustainability of gold mining in Colombia. Two extraction technologies—open-pit and alluvial mining—are evaluated by calculating exergy efficiencies, cumulative exergy demand (CExD), and associated environmental impacts. The results reveal significant differences between the two methods: open-pit mining is heavily dependent on fossil fuels (53% of input exergy), with 99.62% of total exergy destroyed, resulting in an exergy efficiency of just 0.37% and a sustainability index (SI) of 1.00. In contrast, alluvial mining relies predominantly on water (94%), with 69% of input exergy destroyed, an exergy efficiency of 31%, and an SI of 1.46. Four strategies are proposed to reduce environmental burdens: improving efficiency, minimizing exergy losses, integrating renewable energy, and adopting circular economy principles. This study presents the first application of exergy analysis to comprehensively assess the exergy cost of gold production, from extraction through refining, casting, and molding, highlighting critical exergy hotspots and offering a thermodynamic foundation for optimizing resource use in mineral processing.

The aim of this study is to determine how energy resources are used in the production of unrefined sugar in Colombia. To do this, measurements were carried out in eight sugar mills that represent the typical production processes for unrefined sugar. These data were used to obtain first and second law balances, which were then used to calculate efficiencies and some energy use indicators. By comparing the mills it was found that technological improvements enable energy efficiency to be increased to acceptable levels due to better combustion processes and reductions in energy losses from exhaust gases and heat transfer to the walls. The effect of these improvements in second law efficiency is not significant, which suggests that cogeneration systems should be implemented in large-scale production processes in order to make a better use of the energy resources.