The incorporation of trace metals into land snail shells may record the ambient environmental conditions, yet this potential remains largely unexplored. In this study, we analyzed modern snail shells (Cathaica sp.) collected from 16 sites across the Chinese Loess Plateau to investigate their trace metal compositions. Our results show that both the Sr/Ca and Ba/Ca ratios exhibit minimal intra-shell variability and small inter-shell variability at individual sites. A significant positive correlation is observed between the shell Sr/Ca and Ba/Ca ratios across the plateau, with higher values being recorded in the northwestern sites where less monsoonal rainfall is received. We propose that shell Sr/Ca and Ba/Ca ratios, which record the composition of soil solution, may be controlled by the Rayleigh distillation in response to prior calcite precipitation. Higher rainfall amounts may lead to a lower degree of Rayleigh distillation and thus lower shell Sr/Ca and Ba/Ca ratios. This is supported by the distinct negative correlation between summer precipitation and shell Sr/Ca and Ba/Ca ratios, enabling us to reconstruct summer precipitation amounts using the Sr/Ca and Ba/Ca ratios of Cathaica sp. shells. The potential application of these novel proxies may also be promising for other terrestrial mollusks living in the loess deposits globally.

Identifying use-related residues from stone artefacts has become increasingly important in determining starchy plant exploitation over time and in different locales. Standard methods for processing residues samples are widely available but there is no clear consensus on suitable methods for attributing unknown starch grains to known plant taxa. We revisit the case study of a flaked stone artefact (K/76/S29B) recovered from Phase 1 (c. 10,000 ka) at Kuk Swamp in Papua New Guinea (PNG). Starch grains from taro (Colocasia esculenta) were identified in the residue extraction, but there were other grains that could not be attributed a plant origin at that time. The new analysis applied robust statistical methods, categorial attributes and expert input. In addition to C. esculenta, kudzu bean (Pueraria montana var. lobata) was identified, representing the earliest use of kudzu bean in the PNG highlands. Importantly, we also determined that starch grains from C. esculenta and Dioscorea esculenta are morphologically indistinguishable. We turned to other attributes of potential contributing plant taxa in determining distinguishing features: habit/growing requirements; the sedimentary context of the archaeological find; and environmental settings. Cultural use of both plants, artefacts and artefact technologies can be critical elements in confident identification outcomes, as exemplified here.

Woodrats of the genus Neotoma are an important study system for ecological and paleoecological research. However, paleontological studies are often hindered by the difficulty of identifying woodrat remains to species. We address this limitation by using 2D landmark-based geometric morphometrics to classify 199 lower first molars (m1s) of five extant western North American Neotoma species (N. albigula, N. cinerea, N. fuscipes, N. lepida, and N. macrotis) collected throughout California. We then use discriminant analysis of principal components (DAPC) models to identify Late Pleistocene fossils of unknown species from the Rancho La Brea Tar Pits in Los Angeles, California. DAPC correctly identifies ∼85–90% of extant individuals to species, with most misclassifications occurring between sister taxa N. fuscipes and N. macrotis. Most fossil m1s are classified as N. macrotis by DAPC, which may be the first confirmation of N. macrotis in the fossil record. We show that landmark-based geometric morphometric analyses are generally effective at differentiating m1s of extant Neotoma species in California and they are an auspicious method for unknown fossil identification. Further applications of this method across a broader range of geographic locations and species will better contextualize its utility.

This study from the Luoxiao Mountains, southeastern China, combines historical information with paleoecological data from two wetlands, yielding a detailed reconstruction of landscape changes over recent centuries. The historical record suggests that people first settled in the region in the late Tang dynasty (618 to 907 CE), and wetland sediments show an increase in charcoal from about this time. During the Qing dynasty in the mid-seventeenth century, a temple complex and a Tea and Salt trade road were constructed near the study sites. Greater impacts are recorded in the wetland closer to the temple site. In the last few hundred years, pollen data show a regional decline of forest cover and the expansion of open vegetation as nearby lowland areas were settled and cleared for agriculture. Proxies for erosion show human impacts in the vicinity of the wetlands. Changes in charcoal inputs reflect regional fire activity, with elevated values around 1500 CE, low values during the Qing dynasty, and a subsequent peak during the twentieth century.

Ozette Lake, located on the Olympic Peninsula of western Washington, is ideally situated to provide a sedimentary record of past earthquakes along the northern portion of the Cascadia subduction zone. The lake stratigraphy is punctuated by turbidites, with characteristics typical of those triggered by earthquake shaking as seen in other lakes worldwide. Sediments deposited in Ozette Lake over the past 1300 years between earthquake events show decadal-scale variations in color, magnetic susceptibility, clay content, organic carbon content, density, and computed tomography (CT) intensity. Applying the dynamic time warping technique reveals a strong correlation of CT intensity to historical, instrumental measurements of regional cool-season precipitation, indicating that sediments in the lake preserve a high-fidelity record of decadally averaged fluvial sediment discharge and climate. Correlation of CT intensity patterns from older strata preserved deeper in the lake stratigraphy to two independent, regional paleo-precipitation reconstructions similarly suggests that the sediments record decadal variations in hydroclimate. We provide radiocarbon-independent dates for the past four northern Cascadia subduction earthquakes that are within the uncertainty of a radiocarbon age-depth model but are more precisely estimated by placing earthquake-triggered turbidites in the context of wet and dry periods in these tree-ring- and oxygen-isotope-based reconstructions. Paleoclimate-based constraints on the age of event layers in this and other regional lakes have the potential to help address ongoing questions about past ruptures on the Cascadia subduction margin.

A 13,500-year-old record from Langohr Wetland in the Gallatin Range of southwestern Montana offers new insights into the vegetation and fire history at middle elevations within the Greater Yellowstone Ecosystem. Pollen data suggest that following deglaciation, a tundra–steppe established until warmer and wetter conditions than before could support Picea parkland. The development of an open, predominantly Pinus mixed-conifer forest from ca. 9300–7000 cal yr BP suggests warming summer temperatures led to an increase in forest cover and fire activity; the increase in tree abundance supported infrequent, stand-replacing fires approximately every 600 years. Picea and Pseudotsuga increased their presence at ca. 7000 cal yr BP, and the mixed-conifer forest became denser during the Mid- and Late Holocene, suggesting summers became cooler and wetter. The additional fuel load led to increased fire activity, with stand-replacing fires occurring approximately every 350 years in the Late Holocene. The forest surrounding Langohr Wetland experienced less change in vegetation composition and structure and fewer fire episodes than other low- and high-elevation sites in the Greater Yellowstone Ecosystem. The stability of this forested ecosystem over thousands of years is likely a result of its cool mesic mid-elevation setting, limiting the frequency of intense fire episodes.

While geological and paleoanthropological studies at Laetoli have focused on the relatively fossiliferous Ndolanya and Laetolil beds, Laetoli’s younger Naibadad and Olpiro beds provide an important record of Pleistocene volcanism, tectonics, and landscape evolution in northern Tanzania. This study documents the mineralogical and geochemical compositions of their tephra using EPMA of glass and phenocrysts, and their ages using 40Ar/39Ar geochronology. Naibadad Beds tephra is rhyolitic or trachytic, compositionally distinct from the underlying Ndolanya and overlying Olpiro beds in their mineral assemblages and glass and phenocryst compositions. The Naibadad Beds can be divided into chronostratigraphic clusters as follows: Lower (2.189–2.154 Ma), Middle (2.115–2.104 Ma), and Upper (2.036–2.004 Ma). Most Naibadad Beds tephra could not be compositionally differentiated, although the basal Naibadad Beds tuff is unique in having both trachytic glass and andradite garnet. The uppermost Naibadad Beds tuff at Locality 23 has rhyolitic glass and aenigmatite like Olduvai Gorge’s Naabi ignimbrite and a similar age (2.033 Ma and 2.004 Ma, respectively), although they differ in feldspar and augite composition and are likely not from the same eruption. The lack of direct correlatives between Olduvai and Laetoli, which both derived tephra from Ngorongoro over the same time interval, is likely explained by paleotopography.

Ice-sheet volume during Marine Isotope Stage (MIS) 3 (57–29 ka) is controversial. Several recent studies have proposed that the Greenland Ice Sheet was smaller during MIS 3 than it is today based on radiocarbon ages of molluscan bivalve shells reworked into sedimentary deposits adjacent to the present ice margin. Such a result contrasts with available records of MIS 3 climate, ice volume, and sea level. We revisited a site previously interpreted as containing evidence for smaller than present ice during MIS 3. We collected marine bivalve shells and combined progressive acid dissolution in preparation for radiocarbon dating with new-generation amino acid analysis, which focuses on aspartic acid racemization. Our results suggest that contamination by young carbon yields finite radiocarbon ages despite bivalve shells likely dating to MIS 5e (∼125 ka) or even older. This result should be further tested, which could be accomplished with additional studies of this kind in combination with ice-sheet modeling and additional paleoclimate data generated from adjacent seas.

Distinguishing early domesticates from their wild progenitors presents a significant obstacle for understanding human-mediated effects in the past. The origin of dogs is particularly controversial because potential early dog remains often lack corroborating evidence that can provide secure links between proposed dog remains and human activity. The Tumat Puppies, two permafrost-preserved Late Pleistocene canids, have been hypothesized to have been littermates and early domesticates due to a physical association with putatively butchered mammoth bones. Through a combination of osteometry, stable isotope analysis, plant macrofossil analysis, and genomic and metagenomic analyses, this study exploits the unique properties of the naturally mummified Tumat Puppies to examine their familial relationship and to determine whether dietary information links them to human activities. The multifaceted analysis reveals that the 14,965–14,046 cal yr BP Tumat Puppies were littermates who inhabited a dry and relatively mild environment with heterogeneous vegetation and consumed a diverse diet, including woolly rhinoceros in their final days. However, because there is no evidence of mammoth consumption, these data do not establish a link between the canids and ancient humans.

Rare earth elements (REEs) preserved in speleothems have garnered increasing attention as ideal proxies for the paleoenvironmental reconstruction. However, due to their typically low contents in stalagmites, the availability of stalagmite-based REE records remains limited. Here we present high-resolution REEs alongside oxygen isotope (δ18O) records in stalagmite SX15a from Sanxing Cave, southwestern China (110.1–103.3 ka). This study demonstrates that REE records could provide useful information for the provenance and formation process of the stalagmite, due to consistent distribution pattern across different periods indicating stable provenance. More interestingly, the total REE (ΣREE) record could serve as an effective indicator to reflect local hydrological processes associated with monsoonal precipitation. During Marine Isotopic Stage (MIS) 5d, a relatively low ΣREE content is consistent with the positive SX15a δ18O and negative NGRIP δ18O, reflecting a dry-cold environment; while during MIS 5c, a generally high ΣREE content suggests a humid-warm circumstance. Furthermore, the ΣREE record captured four prominent sub-millennial fluctuations within the Greenland interstadial 24 event, implying a combined influence by the regional climate and local soil redox conditions. Our findings indicate that the stalagmite-based REE records would be a useful proxy for better understanding of past climate and environment changes.

Alluvial fans associated with eolian fields are common geomorphic features that reflect complex interactions in which the alluvial or eolian system acts as both a sedimentary source and a modifier. The semi-arid region of the São Francisco River is notable in Quaternary studies for its alluvial system and the largest Quaternary inland eolian field in Brazil. Fluvial fans are present on the western margin of the river and to the south of the eolian field. To characterize these fans, we used remote sensing, fieldwork, sedimentology, and OSL dating. We identified three fluvial fans: two asymmetric (> 185 km2) and one circular (8.5 km2). The eolian deposits played a critical role in both sediment supply and formation of the fluvial fans. Fan spreading occurred due to the difference in gradient between the eolian field and the river terraces. Fan deposits were dated to 4.5 ± 0.6 ka, and overlap with other systems, which suggests the system was active before 4 ka. Currently, these fans are degrading and being reworked by wind, and the drainages that exist across them are ephemeral. The Xique-Xique fluvial fans are now fossil systems, preserving evidence of past increased rainfall and base level lowering in the Late Holocene.

At the end of the last glaciation aeolian processes promoted the development of the European Sand Belt, generating one of the largest areas of cold-climate dune fields in the world. Specific processes that led to the development and stabilization of these dunes remain poorly understood because there have been limited attempts to reconstruct the Belt’s past aeolian environments. New paleoenvironmental information can now be provided through an assessment of residual dune ridges (RDRs), landforms that are characteristic of wet dune systems. We recently identified almost 2,000 RDRs within the Kampinos Forest dune field (central Poland) and examined them through detailed morphometric analysis. That search showed that the development of the RDRs was driven by seasonally increased fluvial runoff and, in the longer term, by climate amelioration—apparently during the Bølling–Allerød interstadial. The high density of dunes protected ridges from deflation, so was crucial towards RDR preservation. The study proved that the RDRs can exist for more than 10 ka years, thus they can be used as environmental proxies. Additionally, they can be used as an indicator of past flood-event frequency and magnitude, as well as act as repositories of information on past-dune transformation.

Loess–paleosol outcrops were logged and dated to trace loess cover during the Pleistocene in a low-elevation mountainous area. The exposed successions were a maximum of 15 m thick and stratigraphically fragmentary. Still, results suggest that loess was deposited in all climatically suitable periods within the limits of the dating methods (ca. 400 ka), and probably also beyond this. Luminescence measurements provided numerical ages from ca. 18 ka to ca. 200 ka and minimum ages of up to >267 ka. Loess accumulation was also active during the relatively mild MIS 3. A new occurrence of a well-preserved Quaternary tephra was documented, correlative with the middle Pleistocene Bag Tephra (ca. 340 or 368 ka). The dating of loess successions provided valuable data on geomorphic evolution as well, identifying hydrological changes and constraining a maximum incision and uplift rate of 0.008–0.035 mm/yr for the western part of the area. The low thickness of loess–paleosol successions and the stratigraphic gaps seem to be a consequence of repeated erosion during the Pleistocene rather than a result of non-deposition. The mountains probably have been covered with loess for most of the time during the past 1 Ma. This should be taken into consideration in studies influenced by the loess cover of an area.