Pollen analysis of a 9.03-m-long lake sediment core from Pender Island on the south coast of British Columbia was used to reconstruct the island's vegetation history over the last 10,000 years. The early Holocene was characterized by open mixed woodlands with abundant Pseudotsuga menziesii and a diverse understory including Salix and Rosaceae shrubs and Pteridium aquilinum ferns. The establishment of Quercus garryana savanna-woodland with P. menziesii and Acer macrophyllum followed deposition of the Mazama tephra until ~ 5500 cal yr BP, when these communities gave way to modern mixed P. menziesii forest. Charcoal analyses of the uppermost sediments revealed low charcoal accumulation over the last 1300 years with a mean fire return interval (mFRI) of 88 years. Fires were more frequent (mFRI = 50 yr) during the Medieval Climate Anomaly (MCA) with warm, dry conditions facilitating a higher fire frequency than during the Little Ice Age, when fires were infrequent. Given the projected warming for the next 50–100 years, land managers considering the reintroduction of fire to the Gulf Islands National Park Reserve may want to consider using the mFRI of the MCA as a baseline reference in prescribed burning strategies.

A paleoenvironmental time-series spanning the Holocene was constructed using 29 radiocarbon ages and 149 standardized δ13Csom values from alluvial terrace profiles along the middle Delaware River valley. There is good agreement between increasing δ13Csom and Panicoideae phytolith concentrations, suggesting that variations in C4 biomass are a major contributor to changes in the soil δ13C. A measurement error deconvolution curve over time reveals two isotope stages (II–I), with nine sub-stages exhibiting variations in average δ13Csom (average %C4). Stage II, ~ 10.7–4.3 ka, shows above-average δ13Csom (increase %C4) values with evidence of an early Holocene warming and dry interval (sub-stage IIb, 9.8–8.3 ka) that coincides with rapid warming and cool-dry abrupt climate-change events. Sub-stage IId, 7.0–4.3 ka, is an above average δ13Csom (increase %C4) interval associated with the mid-Holocene warm-dry hypsithermal. The Stage II–I shift at 4.3 ka documents a transition toward below average δ13Csom (decrease %C4) values and coincides with decreasing insolation and hydroclimatic change. Sub-stages Ib and Id (above average %C4) coincide with the first documented occurrence of maize in the northeastern USA and a substantial increase in human population during the Late Woodland. These associations suggest that people influenced δ13Csom during the late Holocene.

Late Pleistocene carbon isotope (δ13C) records from a paleolithic sedimentary sequence collected from Baeki, Hongcheon, central Korea, show long-term changes with superimposed short-term isotopic excursions. The δ13C value of the sedimentary organic matter, a proxy for past vegetation change, varied from − 26‰ to − 23‰ for the period between 30 and 90 ka, with a long-term variation similar to insolation changes. High-amplitude (− 1‰ to approximately − 1.5‰) fluctuations superimposed on the long-term changes in the δ13C values decreased during stronger summer monsoon intervals but increased during the weakened summer monsoon. This millennial-scale pattern is generally similar to Greenland Dansgaard–Oeschger (D–O) cycles. The possible connection between the Hongcheon area, Korea and high latitudes may be explained by atmospheric circulation changing in response to the D–O oscillations in the Northern Hemisphere.

Dating middle Pleistocene hominin occupations alongside the reconstruction of paleoenvironments in China between 700 and 100 ka has always been a challenging task. In this paper, we report thermally transferred optically stimulated luminescence (TT-OSL) dating results for a Middle Paleolithic site in the Luonan Basin, central China, which we have named Longyadong Cave. The results suggest that the age of cave infilling and the deposition of sediments outside the cave range between 389 ± 18 and 274 ± 14 ka. These deposits are stratigraphically and geochronologically correlated with the L4 loess and S3 paleosol units of the typical loess–paleosol sequence of the Chinese Loess Plateau, and with Marine Isotope Stages (MIS) 10 to 9, respectively. On the basis of these new ages and the available paleoenvironmental data, it is suggested that the Longyadong hominins might have occupied the site both in glacial and interglacial periods, demonstrating that they coped well with environmental change in this mountainous region in warm/wet and cold/dry climates. The study further implies that the hominins abandoned the Longyadong Cave between 274 ± 14 and 205 ± 19 ka, when it was sealed by alluvial and slope deposits.

In this paper we use radiocarbon dates to evaluate the signature of the Younger Dryas Chronozone (YDC) in eastern North America. Using an approach that examines radiocarbon dates by region, we argue that the northeastern United States shows a better overall representation of radiocarbon dates when compared to the Mid-Atlantic and Southeast. These data result in a peak in summed probability distributions during the YDC, which is often interpreted as evidence of population growth. Further examination of these distributions, however, illustrates that differential standard deviations, varying sample size, and the effect of taphonomic and research biases likely overwhelm any demographic signatures in our study sample. Consequently, the frequency of radiocarbon dates by itself is insufficient for understanding the relationship between climate, culture and demography in eastern North America.

A series of environmental changes from late-glacial ice recession through the early Holocene are revealed in a 7000-yr-long record of pollen, charcoal, geochemistry, and stable isotopes from Blacktail Pond, a closed-basin lake in Yellowstone National Park. Prior to 11,500 cal yr BP, cool conditions dominated, fire activity was low, and alpine tundra and Picea parkland grew on the landscape. A step-like climate change to warm summer conditions occurred at 11,500 cal yr BP. In response, fire activity increased facilitating a transition from Picea parkland to closed Pinus forest. From 11,500 to 8280 cal yr BP, warm summers and abundant moisture mostly likely from high winter snowfall supported closed Pinus contorta forests. Cooler drier summer conditions prevailed beginning 8280 cal yr BP due to decreased summer insolation and winter snowpack, and lower parkland developed. The timing of vegetation change in the Blacktail Pond record is similar to other low- and middle-elevation sites in the northern Rocky Mountains during the late-glacial period, suggesting local plant communities responded to regional-scale climate change; however, the timing of vegetation changes was spatially variable during the early and middle Holocene due to the varying influences of strengthened summer monsoons and subtropical high on regional precipitation patterns.

During the Pleistocene a fauna composed of large (biomass > 44 kg) and giant mammals (biomass > 1000 kg) that are usually associated with open environments lived in the Brazilian Intertropical Region. We present here new information concerning the paleoecology and chronology of some species of this megafauna. Carbon isotope analyses were performed for a better understanding of the paleoecology of the species Eremotherium laurillardi (Lund, 1842), Notiomastodon platensis (Ameghino, 1888) and Toxodon platensis (Owen, 1849). The δ13C data allow attributing a generalist diet to these species, which varied according to the kind of habitat in which they lived. In more open habitats all species were grazers; in mixed habitats E. laurillardi and T. platensis were mixed feeders, and N. platensis was grazer; and in more closed habitats all species were mixed feeders.

Aeolian deposits at four sites in the Gonghe Basin were used to reconstruct the history of aeolian activity over the late Quaternary. These deposits include well-sorted aeolian sand, paleosols and/or loess. Aeolian sand represents dune-field expansion and/or dune buildup, whereas paleosols indicate stabilization of dunes, accompanying ameliorated vegetation cover. On the basis of 25 dates by optically stimulated luminescence (OSL), it appears that aeolian activities occurred episodically at 33.5, 20.3, 13.9, 11.8–11.0, 9.4, 7.8, and 5.7 (5.5) ka, which is largely consistent with the recent findings from the adjacent semi-arid areas. Aeolian sand mobility occurring during the early to mid Holocene conflicts with a climatic optimum inferred from lacustrine records in the northeastern Qinghai-Tibetan Plateau. This inconsistency may be resolved by interpreting aeolian activity as a response to decreased effective moisture due to enhanced evaporation, induced by higher summer insolation at that time, together with local terrain and its effects on moisture. Our results suggest that aeolian sand and paleosol cannot be simply ascribed to regional dry and wet climates, respectively, and they most likely reflect changes in effective moisture.

Knowledge about vegetation dynamics during the last glacial and deglacial periods in southeastern North America is under-constrained owing to low site density and problematic chronologies. New pollen records from two classic sites, Anderson Pond, TN, and Jackson Pond, KY, supported by AMS 14C age models, span 25.2–13.7 ka and 31.0–15.4 ka, respectively. A transition from Pinus dominance to Picea dominance is recorded at Jackson Pond ca. 26.2 ka, ~ coincident with Heinrich Event H2. Anderson and Jackson Ponds record a transition from conifer to deciduous-tree dominance ~ 15.9 and 15.4 ka, respectively, marking the development of no-analog vegetation characterized by moderate to high abundances of Picea, Quercus, Carya, Ulmus, Fraxinus, Ostrya/Carpinus, Cyperaceae, and Poaceae, and preceding by ~ 2000 yr the advent of similar no-analog vegetation in glaciated terrain to the north. No-analog vegetation developed as a time-transgressive, south-to-north pattern, mediated by climatic warming. Sporormiella abundances are consistently low throughout the Jackson and Anderson Pond records, suggesting that megafaunal abundances and effects on vegetation varied regionally or possibly that the Sporormiella signal was not well-expressed at these sites. Additional records with well-constrained chronologies are necessary to assess patterns and mechanisms of vegetation dynamics during the last glacial and deglacial periods.

For the first time, electron spin resonance optical dating (ESROD) has been conducted on littorally transported and aeolian siliciclastic sediments in Florida. ESROD utilizes light-sensitive radiation-sensitive defects at silicon sites that have been replaced by aluminum and titanium atoms to give rise to a time-dependant signal. These defects saturate at higher levels of radiation dose, compared to optically stimulated luminescence, and therefore extend the optical dating range back into the millions of years. Our results show that the Trail Ridge Sequence is a multi-depositional unit that began deposition around 2.2 Ma and continued until 6 ka. The Osceola Cape, of the Effingham Sequence, was deposited around 1.5 Ma, and the Chatham Sequence was a multi-depositional terrace with at least three events preserved.

Data from multiple ice and sediment cores in the North Atlantic show that Marine Oxygen Isotope Stage 3 (MIS 3) was characterized by recurring millennial-scale variations in climate, but the periodic behavior of the well-known millennial-scale variations, Heinrich events and Dansgaard–Oeschger events, is uncertain. We use oxygen isotope values from the Greenland Ice Sheet Project 2 (GISP2) and North Greenland Ice Core Project (NGRIP) ice cores and estimated sea-surface temperature derived from a Bermuda Rise marine sediment core as climate proxies to assess the periodic behavior of Heinrich events and Dansgaard–Oeschger events using Lomb–Scargle spectral decomposition and continuous time autoregressive models. We find that continuous time autoregressive models produce less variable estimates of periodicity for Heinrich events than Lomb–Scargle methods. Heinrich events during MIS 3 are periodic with an estimated periodicity of 6.29–6.49 ka in the GISP 2 ice core, 6.71–6.76 ka in the marine sediment core, and 7.89–8.23 ka in the NGRIP core. There is insufficient evidence from these data to conclude that Dansgaard–Oeschger events exhibit a single periodicity during MIS 3. We also find that the periodic behavior of millennial-scale variations depends on the observational time frame.

We present the first study of the distribution, genesis and paleoenvironmental significance of late Pleistocene loess in northeastern Wisconsin and adjacent parts of Michigan's Upper Peninsula. Loess here is commonly 25–70 cm thick. Upland areas that were deglaciated early and remained geomorphically stable preferentially accumulated loess by providing sites that were efficient at trapping and retaining eolian sediment. Data from 419 such sites indicate that the loess was mainly derived from proglacial outwash plains and to a lesser extent, hummocky end moraines within and near the region, particularly those toward the east of the loess deposits. Most of the loess was transported on katabatic winds coming off the ice sheet, which entrained and transported both silt and fine sands. The loess fines markedly, and is better sorted, distal to these source regions. Only minimal amounts of loess were deposited in this area via westerly winds. This research (1) reinforces the observation that outwash plains and end moraines can be significant loess sources, (2) provides evidence for katabatic winds as significant eolian transport vectors, and (3) demonstrates that the loess record may be variously preserved across landscapes, depending on where and when geomorphically stable sites became available for loess accumulation.

Alluvial and lacustrine sediments exposed beneath late Pleistocene glaciolacustrine silt and clay at two sites along the Old Crow River, northern Yukon Territory, are rich in fossils and contain tephra beds. Surprise Creek tephra (SZt) occurs in the lower part of the alluvial sequence at CRH47 and Little Timber tephra (LTt) is present near the base of the exposure at CRH94. Surprise Creek tephra has a glass fission-track age of 0.17 ± 0.07 Ma and Little Timber tephra is 1.37 ± 0.12 Ma. All sediments at CRH47 have a normal remanent magnetic polarity and those near LTt at CRH94 have a reversed polarity — in agreement with the geomagnetic time scale. Small mammal remains from sediments near LTt support an Early Pleistocene age but the chronology is not so clear at CRH47 because of the large error associated with the SZt age determination. Tephrochronological and paleomagnetic considerations point to an MIS 7 age for the interglacial beds just below SZt at CRH47 and at Chester Bluffs in east-central Alaska, but mammalian fossils recovered from sediments close to SZt suggest a late Irvingtonian age, therefore older than MIS 7. Further studies are needed to resolve this problem.

The Fairmead Landfill locality contains a diverse middle Irvingtonian, (0.78–0.55 Ma), vertebrate fauna that includes three sloths, Megalonyx wheatleyi, Nothrotheriops shastensis and Paramylodon harlani. The co-occurrence of these three genera in a single fauna is relatively rare in both the Irvingtonian and Rancholabrean and this is only the fourth documented Irvingtonian fauna to contain all three sloth genera. The presence of the three different sloths, each of which had different ecological requirements, indicates the presence of a variety of different habitats at this time and a heterogeneous landscape. Preliminary analysis of pollen from the site supports the interpretation of the existence of a mosaic of plant communities, but a landscape dominated by a mesic grassland. This interpretation is also supported by the total faunal diversity that includes taxa associated with woodlands as well as open habitat and taphonomic differences in the preservation and relative abundance of the different sloths. Evolutionarily the Fairmead Landfill sloths show a suite of morphological, size and proportional characters that indicate they represent transitional populations between older and younger members of their respective lineages.

The distribution of marine-influenced oxygen isotope stage (OIS) 5 to OIS 1 sediments was examined in several late Quaternary boreholes from the southern Changjiang (Yangtze) delta plain, China, using different dating methods including OSL, U-series, AMS 14C and paleomagnetism. Results demonstrate that coastal and estuarine deposition during OIS 5 and OIS 3 occurred throughout the study area. However, Holocene transgressive sediments were absent on the Taihu block. The burial depth of intertidal to subtidal sediment deposited during OIS 5e records 30–80 m subsidence caused by sediment compaction and tectonic movement since that time. However, coastal sediments formed during the late phase of OIS 3 were buried to a depth of ca. 6–15 m in the Taihu Lake area, while the burial depth increased eastward to ca. 45–60 m on the coastal plain. This phenomenon, combined with the distribution of Holocene marine strata, indicates at least 25–30 m uplift of the Taihu block since the end of OIS 3. We suggest that this uplift was mainly caused by the differential subsidence due to substantial amount of post-glacial deposition by the Changjiang and Huanghe Rivers on the continental shelf of east China marginal sea.

Plio-Pleistocene deposits of the Lower Colorado River (LCR) and tributary alluvial fans emanating from the Black Mountains near Golden Shores, Arizona record six cycles of Late Cenozoic aggradation and incision of the LCR and its adjacent alluvial fans. Cosmogenic 3He (3Hec) ages of basalt boulders on fan terraces yield age ranges of: 3.3–2.2 Ma, 2.2–1.1 Ma, 1.1 Ma to 110 ka, < 350 ka, < 150 ka, and < 63 ka. T1 and Q1 fans are especially significant, because they overlie Bullhead Alluvium, i.e. the first alluvial deposit of the LCR since its inception ca. 4.2 Ma. 3Hec data suggest that the LCR began downcutting into the Bullhead Alluvium as early as 3.3 Ma and as late as 2.2 Ma. Younger Q2a to Q4 fans very broadly correlate in number and age with alluvial terraces elsewhere in the southwestern USA. Large uncertainties in 3Hec ages preclude a temporal link between the genesis of the Black Mountain fans and specific climate transitions. Fan-terrace morphology and the absence of significant Plio-Quaternary faulting in the area, however, indicate regional, episodic increases in sediment supply, and that climate change has possibly played a role in Late Cenozoic piedmont and valley-floor aggradation in the LCR valley.

Cosmogenic nuclide (CN) apparent exposure dating has become a widely used method for determining the age of glacial landforms on the Tibetan Plateau with > 1200 published ages. We present the first 10Be exposure ages from the Dalijia Shan, the most northeastern formerly glaciated mountain range on the Tibetan Plateau. The moraine groups identified from field and remote sensing imagery mapping record four glacial events at 37.07 ± 3.70 to 52.96 ± 4.70 ka (MIS 3), 20.17 ± 1.79 to 26.99 ± 2.47 ka (MIS 2), 16.92 ± 1.49 to 18.76 ± 1.88 ka (MIS 2), and 11.56 ± 1.03 to 11.89 ± 1.06 ka (Younger Dryas). These ages indicate that glaciation in the northeastern Tibetan Plateau is much younger than previously thought. In addition, this record is consistent with many other regions on the Tibetan Plateau, with a local last glacial maximum during MIS 3 asynchronous with Northern Hemisphere last glacial maximum during MIS 2. The Dalijia Shan might also include an event of Younger Dryas age, but this needs to be tested in future studies.

Two fundamental issues for tephrostratigraphic work are the differentiation of primary from reworked tephra and the characterization of reworking mechanisms. We study the depositional processes of four deposits of Youngest Toba Tuff in the Lenggong valley, Malaysia. We focus on site stratigraphy, particle-size distributions, magnetic susceptibility and mineralogical associations. Reworked tephra display variable sedimentological characteristics including polymodal and unimodal, very fine to coarse-grained distributions, and variable concentrations of ash. Particle-size distributions from this study are similar to published analyses for primary deposits, demonstrating that particle size alone cannot distinguish primary from secondary tephra. The tephra sequences are associated with fluvial and colluvial deposition. Three facies are identified: flood flow, mudflow and slumping. The ash accumulated rapidly, over a period of a few days to months. In this valley the ideal site for paleoenvironmental reconstructions is Kampung Luat 3, where ash accumulated at least in two distinct phases. Despite the rapid accumulation, the Lenggong sites are not well-suited for paleoenvironmental studies of the YTT impact. The time lag between the primary deposition and the floods is unknown and the records could have been modified by site-specific characteristics. Such variables should be considered when proposing paleo-environmental reconstructions based on reworked tephra.

Last interglacial and mid Wisconsinan pollen data from sedimentary sequences of Cape Breton Island in Atlantic Canada were analyzed to reconstruct biome and climate conditions. Our results show warm and humid climate with mean annual temperature 6–7°C higher than today, up to 15–20% more sunshine and significantly longer growing season that fostered growth of temperate trees during the optimum of the last interglacial. The northern limit of the deciduous forest biome was then about 500 km north of its modern limit. Towards the end of the interglacial the deciduous forest was replaced by conifer/hardwood forest and boreal forest. Climate was then similar to modern. The transition from interglacial to glacial was marked by a change towards coniferous forest related to colder and dryer conditions. During the mid Wisconsinan, the development of forest tundra to boreal forest reflects migration of the Arctic Front and significant cooling with mean annual temperature anomalies of − 8 to − 12°C. The overall time series reflect large amplitude climate changes that point to high sensitivity of the southeastern Canadian margins, likely as a response to latitudinal shifts of the Gulf Stream and variable strength of the Labrador Current together with changes in large-scale atmospheric circulation pattern.