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.

Colluvial sediments of talus relicts (“talus flatirons”) around mesas preserve a record that sheds light on slope-forming processes at temporal scales > 103 yr. The sedimentology and soil stratigraphy of two groups of talus flatirons in the northeastern hyperarid Negev desert reveal four deposition events in the younger talus and at least two in the older one. Numerical modeling of high-resolution 10Be depth profiles suggests that these taluses were deposited during the middle Pleistocene; the younger talus group first depositional event occurred at 551 − 142+ 80 ka and its abandonment occurred at 270 − 38+ 17 ka. The abandonment of the older talus group and stabilization of its surface occurred at 497 − 114+ 176 ka. These ages indicate that the development of the studied talus sequence is not specifically associated with Pleistocene glacial–interglacial cycles. The 10Be modeled concentrations indicate significant differences in the average inheritance of talus flatirons of different groups. These differences can be attributed to variability in the transport distance and duration of gravel exposure during transport but could also reflect some temporal variability in cliff retreat. Our results also demonstrate that talus slopes in hyperarid areas, despite their steepness, can store sediment for long periods (~ 500 ka) and thus constitute a valuable archive.

Of numerous theories of drumlin genesis, none has been widely accepted. It seems evident, however, that some form of positive feedback process is involved. Under certain circumstances perturbations are amplified. Herein we suggest that patchy areas of frozen bed provide the initial perturbation. Such frozen patches may occur in local areas underlain by material of lower thermal conductivity or on slight topographic highs. Drag exerted by the frozen patch deflects ice flow into its lee, dragging with it mobile till eroded from the thawed area. The energy balance is such that this till likely refreezes, either producing a topographic perturbation or amplifying an existing one. The resulting topography then deflects more of the geothermal heat away from the developing hill and into the adjacent trough, resulting in a positive feedback. Once the thermal perturbation exceeds a critical (though as yet undefined) level, melting may decouple the ice from the bed, preventing further entrainment of till from thawed areas, and thus limiting the height and length of the drumlin.

Magnetic grain-size variations have been used as sensitive paleoclimate proxies to investigate the evolution of the East Asian summer monsoon, but their relationship with temperature and precipitation is not entirely clear. Here we find that two magnetic grain-size proxy records (χARM/χLF and χARM/SIRM, where χARM, χLF and SIRM are anhysteretic remanent magnetization susceptibility, magnetic susceptibility measured at 470 Hz and saturation isothermal remanent magnetization, respectively) of Chinese loess and red-clay sediments co-vary during the last 6 Ma, except between ~ 4.5 and 2.6 Ma, when these two records had opposite trends. We attribute this disparate behavior to the different responses of χARM/χLF and χARM/SIRM to temperature and precipitation during ~ 4.5–2.6 Ma, when temperature and precipitation on the Chinese Loess Plateau were decoupled. A comparison of the loess and red-clay χARM/χLF and χARM/SIRM records with the global ice-volume proxy records reveals that χARM/χLF is more sensitive to temperature variations than χARM/SIRM. The results suggest that temperature on the Chinese Loess Plateau had a cooling trend from ~ 4.5 to ~ 2.6 Ma, whereas rainfall tended to increase. Our studies demonstrate that joint analysis of loess χARM/χLF and χARM/SIRM records can reveal paleoclimatic information that cannot be revealed by a single parameter.

The highly fossiliferous sediments of the Tolomosa Formation from Tarija, southern Bolivia, represent one of the most important localities in South America that documents the Great American Biotic Interchange. Over the past several decades, chronostratigraphic studies have indicated a middle Pleistocene age for the Tolomosa Formation from ~ 1.1 to 0.7 Ma. This interval correlates to the Ensenadan South American Land Mammal Age as it is characterized from classic localities in Argentina. Recently, however, a new interpretation based on AMS 14C ages indicates that the fossiliferous sediments from Tarija are latest Pleistocene, i.e., < 44 ka, and thus of Lujanian age. Here we report a new age of 0.76 ± 0.03 Ma (2σ) based on 11 U–Th/Pb and U–Th/He individual determinations from the Tolomosa Formation. This is indistinguishable from the age published from the same ash in 1983, and was originally used to calibrate the magnetostratigraphic section at Tarija. The new age confirms that the age of the Tolomosa Formation is middle Pleistocene, and not latest Pleistocene. The age of the Tarija Fauna has significant implications with regard to the stage of evolution biochronology for Pleistocene fossil mammals in South America, and in particular, the classic and important reference sections in Argentina.

Geographically isolated environments such as the conifer forests atop the Madrean “sky islands” in southeastern Arizona provide natural laboratories for studying factors involved in speciation and origins of biodiversity. Using molecular and geospatial analyses, we examine beetle population phylogeny, regional climate records, and the Quaternary paleobiogeography of forests to evaluate four hypothetical scenarios regarding the current geographic and population genetic patterns of Scaphinotus petersi. Scaphinotus petersi is a large, flightless beetle that resides in the Madrean conifer forests above ~ 1900 m asl. Our results do not support the current hypothesis that S. petersi populations found on seven separate mountain ranges are genetically distinct and separated as temperatures warmed after the Last Glacial Maximum (LGM). Rather, we show that only some of the ranges hold genetically distinct populations, and the timing of separation among the populations does not appear to coincide with specific climatic events such as warming trends. In addition, we show that predicted changes to the climate of the Madrean sky islands may result in the disappearance of S. petersi from some of the lower ranges by the end of this century.

The Rb/Sr ratio of lake sediments has been demonstrated to be a potential indicator of chemical weathering by increasing work. However, Rb and Sr in lake sediments are derived from both chemical weathering and physical erosion. Rb and Sr of different forms in lake sediments may record different environmental processes and information. In this study, the variation patterns of Rb and Sr of different forms in sediments of Daihai Lake were investigated. The results show that Rb and Sr of different forms display noticeably different variation patterns due to their different sources and associated environmental processes. Using the Rb/Sr ratios of bulk lake sediments to reflect chemical weathering is not accurate. The non-residual Sr of the sediments without detrital carbonates, representing the Sr leached from the catchment, can be used as an index of chemical weathering because the weathering of Sr minerals is very sensitive to climate change, and the non-residual Sr content of the sediment is determined more by Sr2 + influx than by the physicochemical conditions of lake water. The correspondence between the non-residual Sr and TIC/TOC in Daihai Lake also indicates that the non-residual Sr of the sediments is a good indicator of chemical weathering in the catchment.

Environmental isotopes and noble gases in groundwater samples from the Kazan Trona Ore Field are studied to establish the temperature change between the Holocene and the late Pleistocene. Noble gas temperatures (NGTs) presented in this study add an important facet to the global paleotemperature map in the region between Europe and North Africa. The groundwater system under investigation consists of three different aquifers named shallow, middle and deep in which δ18O and δ2H vary from − 8.10‰ to − 12.80‰ and from − 60.89‰ to − 92.60‰ VSMOW, respectively. The average isotopic depletion between unconfined and confined parts of the system is − 2.5‰ in δ18O and − 20‰ in δ2H. It is not possible to explain this depletion solely with the elevation effect. Recharge temperatures derived from dissolved atmospheric noble gases reflect the current average yearly ground temperatures (13°C) for samples collected near the recharge area but are 3 to 8°C lower than today's temperatures in the deep aquifer system. Low 14C activities and high He excesses in the confined parts of the aquifer system suggest that the water in the deep aquifer was recharged during the last Pleistocene under considerably cooler climatic conditions.