Sediment cores from Dyken and Shaver ponds on the Rensselaer Plateau, eastern New York state, USA, were analyzed for sediment chemistry, pollen, plant macrofossils, and diatoms to reconstruct the ecological and climate history since Laurentide ice sheet retreat of this previously unstudied region. Forests were established by 13,040 cal yr BP, and pollen records follow the well-documented northeastern U.S. sequence: Allerød interstade (mixed boreal and thermophilous taxa, including Tsuga), Younger Dryas stadial cooling (rise of Alnus, Betula, and Picea), Early Holocene warmth and dryness (Pinus dominance), increased moisture and Tsuga rise, Mid-Holocene Tsuga decline followed by Late Holocene recovery, neoglacial cooling in the past two millennia (Picea rise), and European settlement (Ambrosia rise). Superimposed on these longer-term trends are centennial- to sub-millennial-scale climate variations marked by shifts in vegetation and changes in diatom species abundance. The combined datasets indicate that Mid-Holocene Tsuga decline coincided with several severe droughts as well as climatic cooling events between ca. 6100 and ca. 3700 cal kyr BP.

The Little Ice Age (LIA, ∼1400–1850 CE) was characterized by colder winters and more frequent extreme weather events in the Northern Hemisphere. While changes in ocean circulation likely contributed to global cooling, the specific mechanisms remain poorly understood. Here, we investigate how ocean circulation changed before, during, and after the LIA using marine sediment cores from the Laurentian Channel in the lower St. Lawrence Estuary. We first established a Mg/Ca–temperature calibration for Globobulimina auriculata using instrumental temperature data and a century-old box core. Applying this calibration to a longer piston core, we reconstructed bottom-water temperatures during the LIA. Coupling these results with existing δ1⁸O calcite data allowed us to isolate the δ1⁸O seawater signal, which reflects changes in the relative contributions of the Labrador Current and Gulf Stream. Our results indicate an increase of fresh and cold Labrador Sea–derived waters around 1500 CE. Throughout most of the LIA, we observed a slow and steady warming of the bottom water associated with a gradual increase in the proportion of Atlantic-derived waters until ∼1850 CE. The ∼1800–1950 CE interval shows high-amplitude variability, including a sudden freshening event at the LIA’s end. After 1950 CE, regional warming dominates, consistent with previous studies documenting increased Atlantic influence over the Canadian shelf.

Conventional thought holds that in formerly glaciated areas straying of anadromous fish from nearby unglaciated areas established contemporary salmon populations. An additional explanation for patterns of salmon life-history diversity and population structure derives from isolation of populations in proglacial lakes. We evaluate evidence for these potentially complementary hypotheses in chum salmon from two previously glaciated North American regions: the southern Alaska Peninsula/upper Cook Inlet and the Salish Sea of northwestern Washington and southern British Columbia. Some chum salmon populations in the southern Alaska Peninsula are genetic outliers compared with other nearby populations, while Salish Sea chum salmon populations have greater region-wide genetic divergence and lower gene diversity. Within-population genetic diversity and among-population divergence in both study areas support a hypothesis of salmon persistence relying on cryptic isolation and freshwater-resident (trout-like) life histories in proglacial lakes. We find that ice age adaptation of salmon to a trout life history helps explain aspects of contemporary population structure and life-history diversity.

Thirty packrat (Neotoma spp.) middens collected from boulder fields near Cataviña, Baja California, Mexico, at 640–680 m elevation provide the first long chronology of macrofossils and pollen spanning the late Quaternary in the Central Desert of Baja California. Midden plant macrofossil and pollen assemblages document a rich chaparral/woodland assemblage during the last glacial and early Holocene dominated by Parry pinyon (Pinus quadrifolia) and California juniper (Juniperus californica) until 11,630 cal yr BP. This indicates chaparral/woodland had a much more extensive distribution in what are now desert elevations in northern and central Baja California. In contrast to late glacial and early Holocene midden records from northeastern Baja, the Cataviña middens of the same age lack plants adapted to warm season precipitation, suggesting that decreased temperatures and evapotranspiration during the growing season and enhanced winter precipitation, with little contribution from summer rains, supported the lowering of chaparral/woodland species distributions in central Baja California. Cataviña middens also record endemic desert plant taxa mixed in with chaparral/woodland species during the Pleistocene, persisting throughout the Holocene, followed by the quick arrival of other desert species after ∼11,000 cal yr BP. Baja California remains a high-potential yet poorly sampled area for packrat midden research in North America.

Slack-water deposits are archives of paleoflood frequency, magnitude, and provenance. In the eastern Himalaya, deposits along the Siang River document Quaternary outburst megafloods originating from southeastern Tibet. Here we present new observations of slack-water deposits within aggradational terraces of the Siyom River, the Siang’s largest tributary. Terrace stratigraphy reveals distinct, regionally extensive sedimentary facies including laminated sands, clays, and detrital organic-rich deposits consistent with slack-water deposition from temporarily impounded waters. Radiocarbon dates from clay and organic horizons range from 34,020 to 10,630 cal yr BP, overlapping with age constraints for Tibetan paleolake deposits. Detrital zircon (U-Th)/Pb geochronology confirms a local source for the underlying fluvial facies, whereas event-deposit silts contain young zircons derived from Tibet, supporting their interpretation as megaflood deposits. This evidence, combined with the deposits’ temporal overlap with Tibetan paleolakes and distinctive slack-water sedimentology, demonstrates that event facies formed through megaflood backflooding sourced from southeastern Tibet. The results point to the likelihood of similar deposits in other tributaries, providing a framework for regional investigation. Our findings further show that megafloods in steep terrain can produce substantial deposition and terrace formation tens of kilometers upstream in tributaries—far beyond the main stem floodway—revealing an overlooked geomorphic imprint of extreme floods.

Stable carbon isotopes in Holocene soils provide key insights into past climate and ecosystems. This study presents high-resolution isotope analyses of pedogenic carbonates and organic carbon from modern loess-derived soils in northern Iran across a strong precipitation gradient (150–850 mm mean annual precipitation [MAP]). Eight soil profiles span five soil orders: Alfisols, Mollisols, Inceptisols, Aridisols, and Entisols. The mean δ13Cpc values show strong linear relationships with MAP (δ13Cpc = −0.0093 × MAP + 1.8878; R2 = 0.98) and with the ratio of precipitation to potential evapotranspiration, P/PET (δ13Cpc = −8.6842 × P/PET + 1.608; R2 = 0.99), indicating that δ13Cpc reliably reflects moisture availability during carbonate formation. Values range from −6.2‰ in wetter sites to −0.1‰ in dry areas, reflecting changes in soil respiration and CO₂ flux. δ13Coc values (−25.6‰ to −23.3‰) indicate dominant C₃ vegetation and exhibit a bimodal response to precipitation, increasing from arid to semiarid zones and decreasing in wetter forests. Oxygen isotopes in carbonate (δ1⁸Opc = −7.9‰ to −6.6‰) show limited climate sensitivity, reflecting precipitation mainly from the Caspian Sea with minimal evaporative enrichment. Overall, δ13Cpc, δ13Coc, and δ1⁸Opc provide robust proxies for soil moisture, vegetation structure, and water sources, supporting paleoenvironmental reconstruction in loess systems.

Four new Pleistocene track-bearing aeolianite surfaces have been identified on South Africa’s Cape south coast, each portraying evidence of tortoise tracks. Together, they add to and buttress previous reports of tortoise tracks and trackways from the region. Globally, this remains the only area from which fossilized tortoise tracks have been recorded, and for the first time we illustrate the preservation of typical tortoise trackway morphology (involving a ‘tramline’ pattern with a wide straddle and closely spaced tracks), as observed in the trackways of extant tortoises. One site provides further evidence for the inferred presence of a very large tortoise trackmaker from the region during the Pleistocene. This tortoise was substantially larger than the largest extant tortoises in southern Africa, which bolsters the inference of either an extinct very large tortoise or a large chrono-subspecies of the extant leopard tortoise (Stigmochelys pardalis). The mismatch between the body fossil record and trace fossil record with respect to the presence of large tortoises in the southern Cape persists. One trackway was probably registered by a smaller leopard tortoise, and the other trackways may have been registered by an angulate tortoise (Chersina angulata).

New cosmogenic 10Be exposure ages and a proglacial lake sediment archive provide the first record of local ice cover following the deglaciation of the Cordilleran Ice Sheet (CIS) in southeast Alaska. Exposure ages from Necker Bay corroborate existing evidence for a CIS deglaciation age of ∼15–14 ka from the outer coast of Baranof Island. We date retreat farther inland on the western and eastern flanks of the island to the Early Holocene, providing evidence for an ice cap persisting on Baranof Island ∼3 ka after CIS retreat. Baranof Lake sediment cores document continued local ice cover until ∼10.4 ka, after which glaciers receded to their Holocene minima until ∼8 ka. Glaciers grew through the remainder of the Holocene, reaching their maxima during the last millennium before retreating rapidly during the last century. Remote sensing analysis of glacial change around Baranof Lake from 1948 to 2023 CE shows that the rate of glacier area loss increased by an order of magnitude after 1986 CE, from −0.03 km2/yr to −0.29 km2/yr. This trend in glacier area loss is reflected across Alaska and western Canada, highlighting the sensitivity of Beringian glaciers to climate changes and the significant contribution they will make to sea-level rise this century.

The 7.7-m loess–paleosol sequence in Trzebnica records a short (ca. 3 ka) but intense phase of loess accumulation that preceded the onset of the Weichselian Late Glacial (MIS 2). The stratigraphy contains a well-defined erosional unconformity, marking a hiatus prior to the deposition of the youngest loess unit (L1LL1). The Trzebnica loess contains numerous signals of slope redeposition, as evidenced by lithological indicators. In this paper, we present optically stimulated luminescence (OSL) and radiocarbon data for the Trzebnica site, as well as granulometric analyses and end-member modeling of grain-size data. Our findings refine the regional loess stratigraphy and challenge an earlier hypothesis regarding the age of the Trzebnica 2 archeological site, which pointed to its evolution beginning around MIS 11. Limitations of 14C dating and its comparison to OSL dates are discussed.

The efficacy of using luminescence dating on glacial deposits is tested for a portion of the Marine Isotope Stage (MIS) 6 Laurentide Ice Sheet margin in southwestern Indiana. We assess small-aliquot quartz optically stimulated luminescence (OSL) and feldspar infrared-stimulated luminescence (IRSL) dating of glaciofluvial, glaciodeltaic, and aeolian sediments against a well-established soil stratigraphy and a cosmogenic 10Be depth profile. Results indicate that standard blue-light OSL regenerative protocols used on MIS 2 glacial sediments in the region warrant caution when duplicated for MIS 6 sediments. Quartz OSL ages underestimate age by up to 50% compared with cosmogenic and feldspar post-IR IRSL200 ages. Presence of unstable or hard-to-bleach OSL signal components that cannot be removed with modified preheat protocols yields unreliable data. While dates obtained using post-IR IRSL200 protocols on feldspar are affected by partial bleaching and anomalous fading, these factors can be accounted for. Discrimination of negligible-fading small-aliquot data allowed us to obtain post-IR IRSL200 ages between 103 ± 12 and 241 ± 28 ka. Post-IR IRSL200 ages are mostly consistent with 10Be depth-profile dating and stratigraphic constraints and represent a viable option to study glaciofluvial sedimentation during MIS 6 and older glaciations in the region.

Bender’s Cave on the Edwards Plateau of Texas contains evidence of Late Pleistocene biodiversity that contrasts with the record from 17 regional sites dating to the last glacial interval, Marine Isotope Stage 2 (MIS 2). Bender’s Cave is a groundwater conduit system with an underground stream. Fossils occur in the cave primarily as an underwater lag assemblage and represent taxa that are typical of the Rancholabrean Land Mammal Age and common to central Texas (e.g., Bison, Mammuthus, Camelops). Megalonyx jeffersonii and Mammutidae also occur in Bender’s Cave but are rare elsewhere in the region. Other fossils provide the first regional records of Holmesina septentrionalis and a species of giant Hesperotestudo. The paleoecology of those novel taxa is inconsistent with regional paleoenvironmental proxies for MIS 2, which document a relatively open, dry grassland and cool climate. The novel composition of the assemblage may be the product of sample bias, and the fossils may be vastly time-averaged. However, the identified taxa frequently co-occur in other Texas sites interpreted as dating to interstadial/interglacial intervals of the late Pleistocene (i.e., MIS 3 or MIS 5), suggesting that fossils in Bender’s Cave may also date to one of those earlier warm periods.

The Mission Creek fault strand (MCF) of the San Andreas Fault is proposed to be the primary strand accommodating slip between the Pacific and North American plates in Southern California, but its Holocene activity northwest of Indio is debated. This study presents new depositional ages for alluvial deposits near the mouth of the Mission Creek drainage to investigate potential Holocene activity of the MCF. We estimate a mean depositional age of 0.7 ± 0.2 ka for the alluvium deposited in the drainage valley, contradicting previously inferred ages of >3–18 ka. The young ages for alluvium, often indistinguishable from the age of modern alluvium, suggest that grains are transported during high-energy flash flood–like events. A comparison of luminescence and cosmogenic 10Be ages from alluvial surfaces adjacent to the Mission Creek suggests a possible reworking event at ∼30 ka. Young alluvium ages, together with evidence for frequent flash floods, suggest that this site is rapidly resurfacing and therefore unlikely to preserve surficial rupture signatures older than a few hundred years. Therefore, the lack of observable offsets in deposits overlying the MCF does not imply Holocene inactivity.

Climate oscillations may strongly modify continental precipitation and temperature patterns, therefore understanding their history is relevant for comprehending effects of past and ongoing climate changes. For this purpose, temperature and precipitation reconstructions beyond the instrumental record are extremely useful. As widespread terrestrial archives, loess–paleosol sequences are viable targets for such analyses. Consequently, cost-efficient geophysical proxies have gained increasing attention, but little is known about their capability to reflect even narrow climatic differences. Here we assess the sensitivity of rock-magnetic and photo-spectrometric properties of topsoil samples (n = 50) along uncorrelated, mean annual precipitation (MAP: 525±1 mm/yr to 584±1 mm/yr) and mean annual temperature (MAT: 10.8±0.1 °C to 11.2±0.1 °C) gradients across the Bačka Loess Plateau (Serbia) and test a multivariate approach. Most proxies are sensitive to MAP <565±1 mm/yr, especially anhysteretic remanent magnetization (r2 = 0.81). Applying a multivariate approach to hysteresis data reveals a robust relationship between precipitation (r2 = 0.63), aridity (r2 = 0.67) and physical properties over the entire MAP range. Although the approach needs to be further tested considering different climates, regression analyses, and timescales, our study indicates that multi-proxy approaches may increase the robustness with respect to single-proxy measurements for MAP and aridity reconstructions.

Lake sediments record past hydrologic variability, but natural lakes are often sparse in semiarid and arid regions, making the calibration of paleohydrologic models a challenge. At Lake Elsinore, the largest of the few natural lakes in Southern California, we explore and develop a novel transfer function approach for reconstructing lake depth. Using 32 modern surface sediment samples spanning Lake Elsinore’s littoral to profundal zones, we establish a statistical relationship between lake depth and sediment elemental geochemistry composition analyzed via X-ray fluorescence (XRF). We develop lake depth transfer functions using weighted averaging-partial least squares (WA-PLS) and modern analog technique (MAT). Application of the WA-PLS C5 elemental geochemistry-based transfer function to Lake Elsinore sediment cores reveals a climatically sensitive and variable lake hydrology over the past 32,000 years. The reconstruction suggests a prolonged shallowing during an early Marine Isotope Stage 2 (MIS 2) mega-drought between 28,000 and 25,000 cal yr BP, a deep lake spanning the last glacial maximum, a wet–dry response to the Younger Dryas, and a highly dynamic MIS 1/Holocene lake. This single-lake elemental geochemistry technique may be useful in similar settings for reconstructing lake depth and inferring past hydrologic changes.

The prehistoric cultural material at the Lodoso Site, a Middle Archaic to Late Prehistoric campsite near Driscoll, Texas, is dominated by irregularly shaped heat-hardened fragments of earth called burned clay objects (BCOs). These artifacts are a common component of coastal plain archaeology in Texas and elsewhere in the state. Many such sites, especially those situated in sandy soils, do not preserve charcoal well, which renders dating the occupations challenging. The clayey matrix of the Lodoso Site does preserve charcoal, which presents an opportunity to assess the suitability of luminescence dating of burned clay objects by thermoluminescence (TL) and optically stimulated luminescence (OSL), and directly compare those results with charcoal collected from the same excavation provenience, as well as OSL dating of the sedimentary matrix. The TL and OSL results generally track together well but are consistently slightly older than charcoal collected from the same level. The charcoal dates suggest the midden formed between approximately 1500 and 2300 years ago, whereas the luminescence ages suggest formation occurred between 2000 and 3000 years ago. Where the luminescence ages occur out of stratigraphic order, so do the paired charcoal samples, indicating that this is a result of pedoturbation. The results of both radiocarbon and luminescence dating indicate that the midden is a diachronic feature resulting from use over a prolonged period rather than the product of a single burning event.

Luminescence dating has developed over the last ∼60 years as a powerful technique for placing environmental and anthropogenic change into a secure temporal framework. However, over time, many have forgotten, or were never introduced to, the history of how of the method developed, particularly the role of unique instruments built in-house that enabled key methodological advances. In this paper we provide a concise history of the technique’s evolution, drawing on our own experiences.

Understanding the local to regional history of extreme events such as debris flows and floods provides context to plan for and mitigate these hazards to life, property, and infrastructure. The Klamath Mountains of northwestern California have experienced both debris flows and devastating wildfires. Whiskeytown National Recreation Area (WHIS) is at the heart of this range and has a wealth of debris flow–related landforms. Gaining an understanding of prehistoric flows and their relationship with fire or other potential triggers can help mitigate future problems. Optically stimulated luminescence and radiocarbon analyses from sediment and entrained organics in undisturbed facies, including beneath partially buried boulders, establishes a chronology of paleo-events in WHIS. The levee deposits indicate a repetition of debris flows during the latest Holocene, every 125–150 years, since 850 yr. Larger flows occurred, with a record elucidated from debris-flow deposits along Clear Creek, with Middle Holocene ages, ca. 2600 to 5500 yr, most of which have sufficient concentrations of charcoal to indicate origins as postfire debris flows. Deposits at higher elevations show events from the latest Pleistocene ca. 13,000 yr. This geochronology indicates that these are not singular events but are relatively common and inherent to the geomorphic processes shaping this landscape.

Paleolake coring initiatives result in large datasets from various proxies taken at different resolutions, ranging from continuous scans to samples collected at coarser intervals. Higher-resolution data (e.g., core-scan X-ray fluorescence [XRF]) can detect short-duration changes in the paleolake and help identify unit boundaries with precision; however, interpreting the causes of such changes may require sampling and more intensive laboratory analysis like X-ray diffraction (XRD). This study applies a published wide and deep learning model, developed for the Olduvai Gorge Coring Project (OGCP) 2014 cores from the Pleistocene Olduvai basin, Tanzania, to reconstruct the mineral assemblages from saline-alkaline paleolake Olduvai using core-scan XRF data and core lithology. A classification model (predicting mineral presence or absence) and a regression model (predicting relative abundances of minerals) yielded predictions for two OGCP cores (2A and 3A), which were compared with published XRD mineral data and detailed core sedimentological descriptions. The models were excellent at identifying dolomite-rich layers, carbonate-rich intervals, intervals of sandstone within claystone, and altered tuffs within claystone and at predicting whether illitic or smectitic clays dominate. The models struggled with less-altered tuffs and with zeolites in non-tuff sediments, especially when XRD identified chabazite and erionite (rather than phillipsite) as the dominant, non-analcime zeolite.