Soils in similar geomorphic settings in hyperarid deserts (< 50 mm yr−1) should have similar characteristics because a negative moisture balance controls their development. However, Reg soils in the hyperarid southern Negev and Namib deserts are distinctly different. Soils developed on stable alluvial surfaces with only direct input of rainfall and dust depend heavily on rainfall characteristics. Annual rainfall amount can be similar (15–30 mm), but storm duration can drastically alter Reg soil properties in deserts. The cooler fall/winter and dry hot summers of the southern Negev Desert with a predominance brief (≤ 1 day) rainstorms result in gypsic-saline soils without any calcic soil horizon. Although the Namib Desert receives only 50–60% of the southern Negev annual rainfall, its rainstorm duration is commonly 2–4 days. This improves leaching of the top soil under even lower annual rainfall amount and results in weeks-long grass cover. The long-term cumulative effect of these rare rain-grass relationships produces a calcic-gypsic-saline soil. The development of these different kinds of desert soils highlights the importance of daily to seasonal rainfall characteristics in influencing soil-moisture regime in deserts, and has important implications for the use of key desert soil properties as proxies in paleoclimatology.

The Sierra los Cuchumatanes (3837 m), Guatemala, supported a plateau ice cap and valley glaciers around Montaña San Juan (3784 m) that totaled ∼ 43 km2 in area during the last local glacial maximum. Former ice limits are defined by sharp-crested lateral and terminal moraines that extend to elevations of ∼ 3450 m along the ice cap margin, and to ca. 3000–3300 m for the valley glaciers. Equilibrium-line altitudes (ELAs) estimated using the area–altitude balance ratio method for the maximum late Quaternary glaciation reached as low as 3470 m for the valley glaciers and 3670 m for the Mayan Ice Cap. Relative to the modern altitude of the 0°C isotherm of ∼ 4840 m, we determined ELA depressions of 1110–1436 m. If interpreted in terms of a depression of the freezing level during maximal glaciation along the modern lapse rate of − 5.3°C km–1, this ΔELA indicates tropical highland cooling of ∼ 5.9 to 7.6 ± 1.2°C. Our data support greater glacial highland cooling than at sea level, implying a high tropical sensitivity to global climate changes. The large magnitude of ELA depression in Guatemala may have been partially forced by enhanced wetness associated with southward excursions of the boreal winter polar air mass.

Palynological records in cores C4 and B106 from the Gulf of Tonkin reveal signals of paleo-monsoon and paleoenvironmental change during the late Pleistocene and Holocene. Before ∼ 13.4 cal kyr BP, the Gulf of Tonkin was exposed to the atmosphere and covered by grassland. Starting at ∼ 11.7 cal kyr BP, the Gulf of Tonkin was inundated by brackish water, indicated by the appearance of the brackish algae Cleistosphaeridium, Sentusidinium and Spiniferites, a decrease of herb content, and an increase of Pinus. After Hainan Island was completely separated from the Leizhou Peninsula by Qiongzhou Strait at ∼ 8.5 cal kyr BP, a continuous marine sedimentary environment was found. The current patterns were similar to those of the present, with a general trend of current homogenization reflected by gradually decreasing quantities of Quercus pollen and a narrowing gap between the palynological concentrations of the southern and northern parts of the region. The data suggest that three short periods of strengthened winter monsoons and currents were centered at ∼ 6.0 cal kyr BP, ∼ 2.7 cal kyr BP and ∼ 0.2 cal kyr BP and that two short periods of strengthened summer monsoons and currents were centered at ∼ 7.5 cal kyr BP and ∼ 3.4 cal kyr BP.

The 1959 discovery of the hominin fossil Zinjanthropus boisei brought the world's attention to the rich records at Olduvai Gorge, Tanzania. Subsequent excavations of archaeological level 22 (FLK Zinj) Bed I uncovered remains of Homo habilis and a high-density collection of fossils and Oldowan stone tools. The occurrence of this unusual collection of bones and tools at this specific location has been controversial for decades. We present paleoecological data that provide new insights into the origin of FLK Zinj. Our recent excavations 200 m north of the site uncovered a 0.5-m-thick tufa mound draped by Tuff IC, in the same stratigraphic horizon as level 22. Stable isotope analyses indicate that the carbonates were deposited by a freshwater spring. Phytolith analysis of the waxy clay under Tuff IC revealed abundant woody dicotyledon and palm phytoliths, indicating that the site was wooded to densely wooded. The time equivalency and close physical proximity of the two environments indicate the two are related. This study has provided the first documented evidence of springs in Bed I and these data have important implications for the interpretation of hominin behavior in meat acquisition and the ongoing debate on scavenging versus hunting.

We examined the hydroclimatic signal in a record of annual lamina (varve) thickness from High Arctic Lake A, Ellesmere Island (83°00.00′N, 75°30.00′W). In this unglacierized catchment, nival melt is the dominant source for meltwater and transport of sediment to the lake, and autumn snowfall is highly influential on varve thickness through the amount of snow available for melt in the following year. For the period during which climatic data are available, varve thickness in Lake A was significantly correlated (r = 0.50, p < 0.01) with the cumulative snowfall from August to October (ASO) during the previous year and to a lesser extent, ASO mean daily temperature (r = 0.39, p < 0.01) at Alert, Nunavut (175 km east). The varve thickness record, interpreted as a proxy record of ASO snowfall and by extension, ASO temperature, indicated above-mean conditions during five periods of the past millennium, including most of the 20th century. These results corresponded well to other available high-resolution proxy climate records from the region, with some discrepancies prior to AD 1500 and during the period AD 1700–1900.

Renewed excavations at FLK Zinj and its surrounding landscape have yielded valuable information regarding its paleoecological situation and the prehistoric behavioral function of the site. The density of materials at the main cluster of the site excavated by Leakey contrasts with the bone and lithic scatters surrounding the site. The location of FLK Zinj, situated a few hundred meters away from a freshwater spring, would have enabled hominins access to water, plants and game. The appeal of the spot for hominins (also explained by the presence of a wooded habitat) is confirmed by inferences of its redundant use prior and during the formation of the FLK Zinj paleosol, as witnessed by materials accumulated both under and on the waxy clay deposit that constitutes the FLK Zinj stratum. The single-cluster nature of the site indicates central-place behavior and evidence is provided that hominins occupied the site at a time of very low predation hazards in the area.

The valley floor of a 33.9 km2 watershed in western Colorado experienced gradual sedimentation from before ∼ 6765 to ∼ 500 cal yr BP followed by deep incision, renewed aggradation, and secondary incision. In contrast, at least four terraces and widespread cut-and-fill architecture in the valley floor downstream indicate multiple episodes of incision and deposition occurred during the same time interval. The upper valley fill history is atypical compared to other drainages in the Colorado Plateau.

One possible reason for these differences is that a bedrock canyon between the upper and lower valley prevented headward erosion from reaching the upper valley fill. Another possibility is that widespread, sand-rich, clay-poor lithologies in the upper drainage limited surface runoff and generally favored alluviation, whereas more clay-rich lithologies in the lower drainage resulted in increased surface runoff and more frequent incision. Twenty-two dates from valley fill charcoal indicate an approximate forest fire recurrence interval of several hundred years, similar to that from other studies in juniper–piñon woodlands. Results show that closely spaced vertical sampling of alluvium in headwater valleys where linkages between hillslope processes and fluvial activity are relatively direct can provide insight about the role of fires in alluvial chronologies of semi-arid watersheds.

The southwest Yukon Territory, Canada, is an important region for recovering sensitive records of Holocene paleoclimatic change. More information is needed, however, to constrain the timing of the major Holocene climatic transitions, and to understand associated impacts on different ecosystems. For example, paleolimnological studies have focused on small lakes and ponds, but the history of large lakes has received little study. We analyzed diatom assemblages, species richness, valve concentrations, and biogenic silica, in the sediments of Kusawa Lake (60°16.5'N; 136°10.9'W; 671 m a.s.l.) to reconstruct the responses of this large (surface area = 142 km2), deep (Zmax = 135 m) freshwater ecosystem to Holocene climatic transitions. Diatoms colonized the lake soon after ice retreat, around 11,000 cal yr BP; assemblages throughout the record were dominated by planktonic types. Diatom concentrations and biogenic silica were high during the Holocene Thermal Maximum between 10,700 and 7300 cal yr BP, then began to decrease in response to cooling associated with orbitally driven reductions in insolation. Diatom assemblages shifted towards taxa with lower surface water temperature optima after 8300 cal yr BP, perhaps in response to abrupt and progressive cooling. Our study confirms that diatom assemblages in large lakes are sensitive to regional-scale paleoclimatic changes.

The alluvial deposits near Gibala-Tell Tweini provide a unique record of environmental history and food availability estimates covering the Late Bronze Age and the Early Iron Age. The refined pollen-derived climatic proxy suggests that drier climatic conditions occurred in the Mediterranean belt of Syria from the late 13th/early 12th centuries BC to the 9th century BC. This period corresponds with the time frame of the Late Bronze Age collapse and the subsequent Dark Age. The abrupt climate change at the end of the Late Bronze Age caused region-wide crop failures, leading towards socio-economic crises and unsustainability, forcing regional habitat-tracking. Archaeological data show that the first conflagration of Gibala occurred simultaneously with the destruction of the capital city Ugarit currently dated between 1194 and 1175 BC. Gibala redeveloped shortly after this destruction, with large-scale urbanization visible in two main architectural phases during the Early Iron Age I. The later Iron Age I city was destroyed during a second conflagration, which is radiocarbon-dated at circa 2950 cal yr BP. The data from Gibala-Tell Tweini provide evidence in support of the drought hypothesis as a triggering factor behind the Late Bronze Age collapse in the Eastern Mediterranean.

The history of glacial advances and retreats of the East Antarctic ice sheet during the Holocene is not well-known, due to limited field evidence in both the marine and terrestrial realm. A 257-cm-long sediment core was recovered from a marine inlet in the Rauer Group, East Antarctica, 1.8 km in front of the present ice-sheet margin. Radiocarbon dating and lithological characteristics reveal that the core comprises a complete marine record since 4500 yr. A significant ice-sheet expansion beyond present ice margins therefore did not occur during this period.

The records of early hominins are commonly localized both temporally and spatially even in archaeologically rich basins like Olduvai Gorge, Tanzania. The FLK North site was discovered in 1960, but the reason for the exact location of this dense concentration of fossils and stone tools on a lake-margin flat has not been explained. We present new geological and geochemical information from six excavations in upper Bed I, which revealed up to 1.4-m-thick carbonate deposits, attesting to the presence of freshwater springs in the area surrounding FLK North. The δ18O signatures of the tufa are typical for meteoric water that has evolved during evaporation. Tuff IF that caps the sequence was deposited on uneven topography with the highest area a low-relief ridge between two faults at the archaeological site and lowest areas being sites of groundwater discharge. The model proposed here is that rainfall on adjacent highlands was transported to the basin where faults acted as conduits for water. Similar hydrogeological settings at modern lakes Manyara and Eyasi, currently support lush groundwater forest and woodland despite arid climate. FLK North may have been an “oasis” offering freshwater and shelter for consuming meat by both carnivores and hominins.

The phytolith content of 10 samples collected immediately under Tuff IF (~ 1.785 Ma) at FLK N and other surrounding localities (~ 2 km²) provides a direct botanical evidence for woody vegetation in the eastern margin of Olduvai Gorge during uppermost Bed I time. Observation and counting of 143 phytolith types (5 to >150 μ) reveal dense but heterogeneous woody cover (~ 40–90%) of unidentified trees and/or shrubs and palms associated to the freshwater springs surrounding FLK N, and more open formation (presumably ~ 25–70% woody cover) in the southeast at localities VEK, HWK W and HWK E. The paleovegetation is best described as groundwater palm forest/woodland or bushland, which current analogue may be found near Lake Manyara in similar hydrogeological context (freshwater springs near saline/alkaline lake). Re-evaluating the published pollen data based on this analogy shows that 70% of the pollen signal at FLK N may be attributed to thicket-woodland, Acacia groundwater woodland, gallery and groundwater forests; while < 30% is attributed to swamp herbage and grasslands. Micro-botanical, isotopic, and taphonomical studies of faunal remains converge on the same conclusion that the area surrounding FLK N, which attracted both carnivores and hominins in the early Pleistocene, was densely wooded during uppermost Bed I time.

Scholars attribute the growth and decline of Classic period (AD 200–900) settlements in the semi-arid northern frontier zone of Mesoamerica to rainfall cycles that controlled the extent of arable land. However, there is little empirical evidence to support this claim. We present phytolith, organic carbon, and magnetic susceptibility analyses of a 4000-yr alluvial record of climate and human land use from the Malpaso Valley, the site of one such Classic frontier community. The earliest farming occupation is detected around 500 BC and appears related to a slight increase of aridity, similar to the level of the modern day valley. By AD 500, the valley's Classic period Mesoamerican settlements were founded under these same dry conditions, which continued into the Postclassic period. This indicates that the La Quemada occupation did not develop during a period of increased rainfall, but rather an arid phase. The most dramatic changes detected in the valley resulted from the erosion associated with Spanish Colonial grazing and deforestation that began in the 16th century. The landscape of the modern Malpaso Valley is thus primarily the product of a series of intense and rapid transformations that were concentrated within the last 400 yr.

Vegetation changes are reconstructed based on more than 51,000 charcoal fragments of more than 380 samples from nine Bronze Age sites in northern Syria and southern Turkey. In addition to fragment proportions, special attention was paid to the frequency of Pistacia relative to Quercus and Populus/Salix relative to Tamarix, fruit-tree ubiquity, and riverine diversity in order to gain an improved understanding of the human versus climatic impact on the vegetation. The results indicate that human impacts first took place within the riverine forest. This phase was followed by land clearing within the woodland steppe, especially in the northern portion of the study area. In the south near Emar, the woodland steppe probably disappeared by the Late Bronze Age. It is uncertain whether this was caused by aridification and/or human clearing. The northward shift of the Pistacia-woodland steppe is very likely a result of climatic drying that occurred throughout the entire period under investigation. Although increased deforestation is evident through time, the small proportions of imported wood indicate that local resources were still available.

This paper presents a case study that assessed spatial variations in the tectonic uplift rates of beach deposits in the relict Kujukuri strand plain, situated on the northeastern coast of the Boso Peninsula, eastern Japan. The southern Boso Peninsula is tilted downward to the northeast due to plate subduction along the Sagami Trough. However, the cause of the northeastern coast uplift creating the relict strand plain is unclear, due to the absence of a Holocene raised marine terrace sequence. Elevations and ages of beach deposits were collected from drilled cores and ground-penetrating radar profiles along three shore-normal sections in the southern Kujukuri strand plain. From this, alongshore variations in the relative sea level since the mid-Holocene could be seen. These corresponded to north-to-northeast downward tilting at a rate of 0.4 m/ka for an interval 10 km and are concordant with the longer term tilting of the last interglacial marine terrace surrounding the plain. Although it is difficult to assess shore-normal variations of uplift based on the present dataset, the recognized tilting apparently continues to the tilting of the southern Boso Peninsula, implying the Sagami Trough probably affects the uplift of the Kujukuri coast.

From excavation at FLK North levels 1–2 in 1960–1962, Mary Leakey reported approximately 1200 Oldowan artifacts and 3300 large mammal fossils as a hominin “living floor”. Preliminary taphonomic analysis by Bunn seemed supportive, based on the presence of some cut-marked bones, the concentration of several dozen bovid individuals, and the relative abundance of limbs and mandibles over other axial elements. Recent taphonomic analysis of Leakey's entire fossil assemblage by Domínguez-Rodrigo and Barba, however, documents a minor hominin role at the site, contrasted to the dominant role of carnivores. Felids brought prey animals; hyenas scavenged from abandoned felid meals. At different times, hominins butchered several bovids and discarded artifacts at this dynamic location. Since 2006, renewed excavations at FLK North and other sites by the Olduvai Paleoanthropology and Paleoecology Project (TOPPP) have expanded artifact and fossil samples and implemented new analytical approaches to clarify taphonomic histories of the Olduvai paleolandscape. At FLK North, > 1000 new large mammal fossils from levels 1 to 2 show minimal butchery evidence amid abundant evidence of carnivore gnawing/fracture, rodent gnawing, and sediment abrasion. To help guide future excavation and analyses, we have developed several alternative working hypotheses of site formation.