Lake sediments are key archives for paleoenvironmental investigation as they provide continuous records of the depositional history of the lake and its watershed. Lake Futalaufquen (42.8°S) is an oligotrophic waterbody located in Los Alerces National Park in the Andes of northern Patagonia, South America. A sedimentary sequence covering 1600 years was recovered to analyze the potential for paleoenvironmental reconstructions of the last millennia. Integration of different geochemical and mineralogical parameters and comparison with climatic reconstructions from other Patagonian records give clues for the identification of a warm period around AD 800–1000, associated with the Medieval Climatic Anomaly. The high frequency of tephra layers beginning in the mid-sixteenth century precludes identification of the Little Ice Age, recorded in northern Patagonia as a cold period from the fourteenth to the eighteenth century. Furthermore, the parameters analysed do not provide evidence of late-twentieth-century global warming. However, Zn deposition, a long-distance atmospheric transport process of anthropogenic origin, was identified during the last century.

Seismic-reflection surveys of the Isle Royale sub-basin, central Lake Superior, reveal two large end moraines and associated glacial sediments deposited during the last cycle of the Laurentide Ice Sheet in the basin. The Isle Royale moraines directly overlie bedrock and are cored with dense, acoustically massive till intercalated down-ice with acoustically stratified outwash. Till and outwash are overlain by glacial varves, a lower red unit and an upper gray unit.

The maximum extent of late Younger Dryas-age readvance into the western Lake Superior basin is uncertain, but it was probably controlled by both ice dynamics and climate. Our data indicate that during retreat from the maximum, the ice paused just long enough to construct the outer of the two moraines, >100 m high, and then retreated to the inner moraine, during which time most of the lower glacial-lacustrine sequence (red varves) was deposited. Retreat from the inner moraine coincided with a marked flux of icebergs at the calving margin and a change to gray varves. Rapid retreat may be related to both an influx of meltwater from Glacial Lake Agassiz about 10,500 cal yr BP and retreat of the calving margin down an adverse slope into the Isle Royale sub-basin.

We analyzed the δ2H composition of n-alkanes isolated from Laguna Zoncho, a small lake in southern Pacific Costa Rica, to reconstruct paleohydrology. Using a core that spans the past 3600 years, we found evidence of dry periods, most notably during the Terminal Classic Drought (TCD; ~1200 cal yr BP) and the Little Ice Age (~400 cal yr BP). Previous work at Laguna Zoncho, using bulk sedimentary δ13C and geochemical analysis, found that agriculture began to decline during the TCD. Our δ2H records confirm the occurrence of arid conditions coincident with the TCD at Laguna Zoncho and show that, despite receiving more than 3000 mm of precipitation per year, this region is susceptible to multidecadal droughts.

Reconstructing routes of ancient long-distance voyaging, long a topic of speculation, has become possible thanks to advances in the geochemical sourcing of archaeological artifacts. Of particular interest are islands classified as Polynesian Outliers, where people speak Polynesian languages and have distinctly Polynesian cultural traits, but are located within the Melanesian or Micronesian cultural areas. While the classification of these groups as Polynesian is not in dispute, the material evidence for the movement between Polynesia and the Polynesian Outliers is exceedingly rare, unconfirmed, and in most cases, nonexistent. We report on the first comprehensive sourcing (using a portable X-ray fluorescence spectrometer) of obsidian and volcanic glass artifacts recovered from excavations on the Polynesian Outlier island of Tikopia. We find evidence for: (1) initial settlement followed by continued voyages between Tikopia and an island Melanesian homeland; (2) long-distance voyaging becoming much less frequent and continuing to decline; and (3) later voyaging from Polynesia marked by imports of volcanic glass from Tonga beginning at 765 cal yr BP (±54 yr). Later long-distance voyages from Polynesia were surprisingly rare, given the strong cultural and linguistic influences of Polynesia, and we suggest, may indicate that Tikopia was targeted by Tongans for political expansion.

A distinct feature of many of the earliest archaeological sites (13,000-11,200 cal yr BP) at the core of the Atacama Desert is that they lie at or just below the surface, often encased in desert pavements. In this study, we compare these sites and undisturbed desert pavements to understand archaeological site formation and pavement development and recovery. Our results indicate these pavements and their soils are poorly developed regardless of their age. We propose that this is because of sustained lack of rain and extreme physical breakdown of clasts by salt expansion. Thus, the core of the Atacama provides an example of the lower limits of rainfall (<50 mm/yr) needed to form desert pavements. At site Quebrada Maní 12 (QM12), humans destroyed the pavement. After abandonment, human-made depressions were filled with eolian sands, incorporating artifacts in shallow deposits. Small and medium-sized artifacts preferentially migrated upwards, perhaps due to earthquakes and the action of salts. These artifacts, which now form palimpsests at the surface, helped – along with older clasts - to restore surface clast cover. Larger archaeological features remained undisturbed on top of a deeper Byzm horizon. The vesicular A horizons (Av horizons) have not regenerated on the archaeological sites due to extreme scarcity of rainfall during the Holocene.

The timing of the Neanderthal-associated Middle Palaeolithic demise and a possible overlap with anatomically modern humans (AMH) in some regions of Eurasia continues to be debated. The Iberian Peninsula is considered a possible refuge zone for the last Neanderthals, but the chronology of the later Middle Palaeolithic record has undergone revision and has increased the debate on the timing of Neanderthal extinction. Here we report on a study of the 5-m-thick archaeological stratigraphy of the Cardina-Salto do Boi, an open-air site located in inland Iberia, from which optically stimulated luminescence (OSL) ages were obtained for Middle and Upper Palaeolithic occupations preserved in overbank alluvial deposits. Geomorphology, archaeostratigraphy, stone-tool evolution, and OSL dating support the persistence of Neanderthals after 41 ka in central Iberia; the transition between the Middle Palaeolithic material culture and the AMH-associated Aurignacian blade and bladelet production is estimated to lie between 34.0 ± 2.0 ka and 38.4 ± 1.9 ka. Our results demonstrate that investigations focusing on different geomorphological situations are necessary to overcome the current limitations of the evidence and to establish more consistent models for Neanderthal disappearance and AMH expansion in the Iberian Peninsula.