Late Pleistocene Terrace Research Articles

Enhancing the Identification and Mapping of Fluvial Terraces Combining Geomorphological Field Survey with Land-Surface Quantitative Analysis

A methodological approach to refining the identification and mapping of fluvial terraces has been applied, combining geomorphological field surveys with the computation and assessment of different morphometric parameters (local, statistical, and object-oriented), derived from a high-resolution digital terrain model (DTM) obtained from a LiDAR survey. The mid-sector floodplain of the Misa River basins was taken as a valid example of the main river valleys draining the northern Marche Apennines (Italy) and was considered an ideal site to test a combination of different geomorphological techniques for enhancing fluvial terraces’ detection and mapping. In this area, late Pleistocene–Holocene fluvial terraces are well exposed, and their geomorphological and geochronological characteristics have largely already been studied. However, a reliable distinction of the different Holocene terrace levels, including a detailed geomorphological mapping of different terrace features, is still lacking due to the very complex terrace geometry and the lack of good-quality deposit outcrops. Land-surface quantitative (LSQ) analysis has been coupled with the available outcomes of previous studies and ad-hoc geomorphological field surveys to enhance the identification and mapping of fluvial terraces. The results of this work provided information for the discernment of terrace remnants belonging to the full-glacial fill terrace generation (late Pleistocene) as well as reconstruction of the terrace top–surface, and can be used to distinguish the inner terrace limits coinciding with the margin of the floodplain. It has also been possible to identify and delimit the late Pleistocene terrace from a staircase of three younger strath terraces formed during the Holocene. The results of this study demonstrated that the investigation of fluvial landforms, at different scales, can strongly benefit from the integration of field surveys and quantitative geomorphic analysis based on high-resolution digital topographic datasets. In particular, the integration of LSQ analysis with ground-truth geomorphological data can be dramatically helpful for the identification and mapping of fluvial terraces.

Further evidence in support of the recognition of the Freshwater Turtle Elseya oneiros (Testudines: Chelidae) from the Nicholson and Gregory Rivers of Northern Queensland

Thomson et al. (1997) proposed that the extant Elseya from the Nicholson-Gregory drainages in northwestern Queensland was conspecific with the holotype of Elseya lavarackorum, which comprised a fossil carapace and associated plastron excavated from the late Pleistocene Terrace Site at Riversleigh. Analysis of additional fossil material, and examination of a suite of 16 scute characters (eight for each of the carapace and plastron) by Joseph-Ouni et al. (2020) concluded that the two species were distinct and represented separate Elseya lineages and proposed the new name Elseya oneiros for the extant lineage. Recently, the Turtle Taxonomy Working Group (TTWG) in their 9th edition Checklist of Turtles of the World (TTWG 2021) questioned the status of E. oneiros and placed it in the synonymy of E. lavarackorum, making the claim, amongst others, that the skeletal characters of Thomson et al. (1997) were not addressed. Here we fully address the claims made and evaluate those skeletal characters. We also assess an additional nine thoracic skeletal characters of the pertinent Elseya species, including E. dentata sensu stricto. The results again do not support the conclusions of Thomson et al. (1997) of the holotype of Elseya lavarackorum being conspecific with the extant Elseya from the Nicholson-Gregory Rivers, reaffirms the proposal offered by Joseph-Ouni et al. (2020) for the placement of E. lavarackorum in the subgenus Elseya, and the status of E. oneiros in the Nicholson-Gregory drainages as a distinct species.

Soils and soilscapes of the Upper Volturno basin: a detailed survey of a large intermontane basin in the Central-Southern Apennines, Italy

ABSTRACT Soils of the Upper Volturno basin in the Central-Southern Apennines (Molise, Italy) were surveyed in detail. Trends in development are described with focus on the contrast between the mountain soils and the soils of the basin. Mountain soils are shallow and poorly developed. Topsoils in the central and eastern areas and on N-facing slopes have a large Late Pleistocene tephra component (Campi Flegrei) and are Andic. Basin soils from a distinct chronosequence: early Mid-Pleistocene deep highly weathered Chromic Luvisols/Nitosols in old surfaces of the fluvio-lacustrine fill, less developed soils in Late Pleistocene terraces and fans, and recent Fluvisols in the Holocene sediments of the Volturno River and tributaries. In the basin, Mid-Pleistocene Roccamonfina tephra play an important role. In the SW, it occurs as thick layers, blanketing the fluvio-lacustrine/fan deposits. The soil pattern clearly reflects the complex geological history of the basin, with prominent subsidence in the SW.

Late Quaternary landscape evolution and bioclimatic change in the central Great Plains, USA

AbstractA systematic study of floodplains, terraces, and alluvial fans in the Republican River valley of south-central Nebraska provided a well-dated, detailed reconstruction of late Quaternary landscape evolution and resolved outstanding issues related to previously proposed Holocene terrace sequences. Stable carbon isotope (δ13C) values determined on soil organic matter from buried soils in alluvial landforms were used to reconstruct the structure of vegetation communities and provided a means to investigate the relationships between bioclimatic change and fluvial activity for the period of record. Our study serves as a model for geomorphological and geoarcheological investigations in stream valleys throughout the central Great Plains and wherever loess-derived late Quaternary alluvial fans occur, in particular.Holocene alluvial landforms in the river valley include a broad floodplain complex (T-0a, T-0b, and T-0c), a single alluvial terrace (T-1), and alluvial fans that mostly grade to the T-1 (AF-1) and T-0c (AF-0c) surfaces. Remnants of a late Pleistocene terrace (T-2), mantled by Holocene (Bignell) loess, are also preserved, and some Holocene alluvial fans (AF-2) grade to T-2 surfaces.Radiocarbon ages suggest that the T-1 fill and AF-1 fans aggraded between ca. 9000–1000 yr B.P. Hence, nearly all of the Holocene alluvium in the river valley is stored in these landforms. Sedimentation, however, was interrupted by several periods of landscape stability and soil formation. Radiocarbon ages from the upper A horizons of buried soils in the T-1 and AF-1 fills, indicating approximate burial ages, cluster at ca. 6500, 4500, 3500, and 1000 yr B.P. Also, based on the radiocarbon ages, the T-0c fill and AF-0c fans were aggrading between ca. 2000–900 yr B.P. Given that the T-0c fill and upper parts of the T-1 fill were both aggrading after ca. 2000 yr B.P., we suggest that the T-1 surface was abandoned between ca. 4500–3500 yr B.P., but subsequent aggradation of both the T-1 and T-0c fills occurred due to large-magnitude flood events during the late Holocene.The δ13C data indicate a shift from ∼40% C4 biomass at ca. 6000 to ∼85% at ca. 4500 yr B.P. We propose a scenario where (1) a reduction in C3 vegetation after 6000 yr B.P. destabilized the uplands, resulting in an increase in sediment supply and aggradation of the T-1 fill and AF-1 fans, and (2) the establishment of C4 vegetation by ca. 4500 yr B.P. stabilized the uplands, resulting in a reduction in sediment supply and subsequent incision and abandonment of the T-1 and most AF-1 surfaces. The proposed timing and nature of landscape and bioclimatic change are consistent with regional records from the central Great Plains.

ИСТОРИЯ ПЕРЕСТРОЙКИ РУСЛОВЫХ СИСТЕМ КАМСКО-КЕЛЬТМИНСКОЙ НИЗМЕННОСТИ В ПОЗДНЕМ ПЛЕЙСТОЦЕНЕ – ГОЛОЦЕНЕ

The analysis of the actual data on the age and stages of the channel systems formation in the Kama-Keltma lowland was based on the altitudinal differentiation of different stages of the relief and the results of radiocarbon dating of organics from the channel and floodplain facies. Late Pleistocene lake terrace is the highest level in the Upper Kama depression and Keltma hollow. The research into the geomorphological structure and age of deposited materials, with a particular focus on separate elements of the Kama-Keltma lowland erosive and accumulative relief, indicates the existence of six stages of the channel systems formation (reorganization). The first stage (end of the Kalinin stadial) is the Chepets hollow formation. The hollow was preserved after large-scale changes in the bottom relief of the Upper Kama depression. The second stage (Mologa-Sheksna interstadial) is the first Kama terrace formation. The third stage (Ostashkov stadial, 20-18 ka) is the period of the runoff hollow formation (including the ‘large terrace hollow’), which actively dissected the surface of aeolian landforms. The fourth stage (LGM, 18-10 ka) is the formation of the macromeanders of the South Keltma, Pilva, and Timsher, as well as the multi-arm channel of the Kama during alternating periods of relatively short-term warming and cooling. The fifth stage is the wide Kama floodplain formation in the Preboreal – Subboreal, represented by segmental generations. The sixth stage (modern) is characterized by the ‘straightening’ of the Kama channel – the formation of a relatively straight channel throughout the Kama-Keltma lowland.

Holocene slip rate of the frontal thrust in the western Qilian Shan, NE Tibetan Plateau

SUMMARY The activities of frontal thrusts in the northern Qilian Shan are critical for understanding the deformation of the Qilian Shan and the northeastern Tibetan Plateau. In this study, we estimate the slip rate of the active Fodongmiao–Hongyazi thrust along the northern margin of the Qilian Shan. High-resolution satellite imagery interpretations and detailed field investigations suggest that the fault displaced late Pleistocene terraces and formed fresh prominent north-facing fault scarps. To quantify the slip rate of the fault, we measured the displacements along the fault scarps using an unmanned aerial vehicle system and dated the displaced geomorphic surfaces using optically stimulated luminescence (OSL) and 14C methods. The vertical slip rate of the fault is estimated at 1.0 ± 0.3 mm yr−1 for the western segment. The slip rates for two branches in the eastern segment are 0.3 ± 0.1 and 0.6 ± 0.1 mm yr−1. Using a fault dip of 40 ± 10°, we constrain the corresponding shortening rates to 1.4 ± 0.5 and 1.2 ± 0.4 mm yr−1, respectively. The rates are consistent with values over different timescales, which suggests steady rock uplift and northeastward growth of the western Qilian Shan. Crustal shortening occurs mainly on the range-bounding frontal thrust.

Late Middle Pleistocene ecology and climate in Northeastern Thailand inferred from the stable isotope analysis of Khok Sung herbivore tooth enamel and the land mammal cenogram

Paleoecological and paleoclimatic records based on the stable isotopes of mammalian tooth enamel are poorly known in mainland Southeast Asia during the Pleistocene. Khok Sung in Northeastern Thailand is a late Middle Pleistocene terrace deposit, tentatively dated either as 213 ka or 188 ka, yielding 15 described mammalian taxa with especially abundant and complete fossil remains. To investigate paleodiets and habitats of these ancient mammals and to understand the corresponding regional climate, we performed an analysis of stable carbon and oxygen isotopes extracted from tooth enamel carbonate of various mammalian taxa, coupled with the cenogram method. The enamel δ13C values of Khok Sung mammals indicate a variety of diets, ranging from pure C3 to C4 plants, suggesting that C4 grasses were a major component of local Thai ecosystems during the late Middle Pleistocene. The stable isotopic distinction between C3 and C4 plants suggests that the Pleistocene wildlife habitats ranged from closed forests to open grasslands for the Khok Sung area. Moreover, differences within sympatric Pleistocene herbivores such as proboscideans, rhinoceroses, and cervids characterize possible niche partitioning by minimizing interspecific overlap. Paleoclimatic interpretations based on the intra-tooth variability in enamel δ18O values from large mammals and on the cenogram analysis reflect significant seasonal variations in precipitation and temperature, and humid conditions, for the Khok Sung locality. Compared to modern environments in Thailand, it is apparent that C4-dominated grasslands were more widespread at that time when anthropic impacts on the ecosystems were presumably absent or minimal.

Holocene internal shortening within the northwest Sub‐Himalaya: Out‐of‐sequence faulting of the Jwalamukhi Thrust, India

AbstractThe southernmost thrust of the Himalayan orogenic wedge that separates the foreland from the orogen, the Main Frontal Thrust, is thought to accommodate most of the ongoing crustal shortening in the Sub‐Himalaya. Steepened longitudinal river profile segments, terrace offsets, and back‐tilted fluvial terraces within the Kangra reentrant of the NW Sub‐Himalaya suggest Holocene activity of the Jwalamukhi Thrust (JMT) and other thrust faults that may be associated with strain partitioning along the toe of the Himalayan wedge. To assess the shortening accommodated by the JMT, we combine morphometric terrain analyses with in situ 10Be‐based surface‐exposure dating of the deformed terraces. Incision into upper Pleistocene sediments within the Kangra Basin created two late Pleistocene terrace levels (T1 and T2). Subsequent early Holocene aggradation shortly before ~10 ka was followed by episodic reincision, which created four cut‐and‐fill terrace levels, the oldest of which (T3) was formed at 10.1 ± 0.9 ka. A vertical offset of 44 ± 5 m of terrace T3 across the JMT indicates a shortening rate of 5.6 ± 0.8 to 7.5 ± 1.1 mm a−1 over the last ~10 ka. This result suggests that thrusting along the JMT accommodates 40–60% of the total Sub‐Himalayan shortening in the Kangra reentrant over the Holocene. We speculate that this out‐of‐sequence shortening may have been triggered or at least enhanced by late Pleistocene and Holocene erosion of sediments from the Kangra Basin.

Кореляція терас річкових долин Волинської височини на основі морфологічних та літологічних ознак

River valleys of Volhynian Upland are characterized by a larger number of terraces and a greater depth of their downcutting compared with neighbouring Polissia and Male Polissia. We established that the major rivers of Volhynian Upland have floodplain and mostly three terraces. The valley of the Horyn River is different from others by presence of fourth terrace. According to received information, the age of forming of the highest terrace (revealed only in the Horyn Valley) can be considered as Early Pleistocene, the third terrace – Middle Pleistocene, and the two lowest terraces – Late Pleistocene. Relief of the Early and Middle Pleistocene terraces is characterized by high degree of dissection and presence of sufficiently thick loess cover. At higher Late Pleistocene terrace loess cover isn’t revealed everywhere and has a small thickness (typically up to 5 m). The lowest terrace in most valleys has local distribution and it is composed mainly of sandy material. The surface of this terrace is located on several hypsometric levels. Floodplain usually has two high-rise levels. It formed in the Holocene. Key words: river valley, terrace, floodplain, Volhynian Upland, Horyn River, Styr River, Zakhidnyi Buh River.

Geomorphic and sedimentary responses of the Bull Creek Valley (Southern High Plains, USA) to Pleistocene and Holocene environmental change

Fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions. This study examines the response of Bull Creek, a small ephemeral creek in the Oklahoma panhandle, to environmental conditions through the late Pleistocene and Holocene. Fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley. Based on their elevations, terraces were broadly grouped into a late-Pleistocene fill terrace (T3) and two Holocene fill-cut terrace sets (T2 and T1). Terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time. Sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the Younger Dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late Holocene. The highest rates of aeolian accumulation within the valley occurred during the early to middle Holocene. Our data provide significant new information regarding the late-Pleistocene and Holocene environmental history for this region, located between the well-studied Southern and Central High Plains of North America.

The symmetry of handaxes from the Danjiangkou Reservoir Region (central China): A methodological consideration

In this paper, we present a three-dimensional (3D) quantitative approach to measure the degree of symmetry of handaxes from the Danjiangkou Reservoir Region (DRR), central China. Our analysis provides not only information on the bilateral symmetry, as most previous studies have done, but also on the symmetry of the profile view. The results show that the overall degree of symmetry of handaxes in plan view is much higher than for profile views in the DRR assemblages. However, the range of values for deviation from absolute symmetry for each specimen indicates that both plan and profile views possess great variability in symmetry. Comparisons of handaxes from two terraces (the Middle Pleistocene Terrace 3 and the early Late Pleistocene Terrace 2) demonstrate that the degree of symmetry did not increase over time in these two samples. Both the type of blank and the type of shaping play roles in determining the final degree of symmetry of the DRR handaxes. According to these results, we argue that there is no strictly imposed final symmetrical shape for the DRR handaxes, and the degree of symmetry is most likely related to some basic factors (e.g., bilateral and bifacial shaping and blank types). However, although a mental template for a preferred end product is absent, a conceptual standardization did indeed exist.

Geologic Records of Net Littoral Drift, Beach Plain Development, and Paleotsunami Runup, North Sand Point, Olympic Peninsula, Washington, USA

A geologic cross-section was constructed across a narrow late Holocene beach plain in a small southwest-facing pocket beach in North Sand Point. Olympic National Park, Washington, to test hypotheses about net littoral drift, potential tectonic uplift, and paleotsunami runup height. Twenty topographic stations (0–12 m elevation NAVD88) and eight auger core sites (2–5 m depth) were examined to establish the stratigraphic development of the narrow beach plain (120 m width). Existing radiocarbon dates and new optically stimulated luminescence (OSL) analyses were used to establish the onset (∼1.5 ka) and termination (∼0.6 ka) of net beach progradation, confirming net northward littoral drift in latest Holocene time. The anomalous high elevations of the beach plain resulted from an abandoned foredune ridge (9 m elevation) developed above the prograded beach deposits (6 m elevation). No tectonic uplift is required to account for the beach plain elevations. A fine gravel layer (5–30 cm thickness) draped the top of the dune ridge at 7–9 m elevation, but it is not traced to 11–12 m elevation in the adjacent late Pleistocene terrace. The gravel layer is attributed to catastrophic marine surge deposition (10 ± 0.5 m elevation) from a nearfield or locally produced Cascadia paleotsunami at ∼1.3 ka. The short duration of the recorded beach plain progradation (about one thousand years), together with a range of OSL grain bleaching ages (11.1–2.3 ka) that pre-date the beach plain deposition, attest to prior pocket beach instabilities and/or sand recycling in the high wave-energy beaches of the northwest Olympic Peninsula coastline.

A Late Bronze Age site and fluvial environmental context in the Middle Euphrates Valley (Northeast Syria)

Alluvial sediments provide records of environmental changes when early civilisations were born on Mesopotamian floodplains during approximately 6 kyr BP. In this work, we study and date the alluvial infill of a palaeochannel and sediments of a neighbouring wadi that flowed into the Middle Euphrates. Such a palaeochannel is alongside an archaeological site, abandoned in the late Bronze Age II. It was a strategic control point of the river transit in that period, when a single meandering channel existed. We hypothesise that the site was not reoccupied after destruction by a fire because of the loss of geostrategic interest, as it remained far from the new river channel. The main river channel was moved, and the palaeochannel filled with flash-flood sediments, possibly because of natural or human-induced environmental changes. Optically stimulated luminescence (OSL) allows direct dating of alluvial sediments, but it has been little tested in this area, while both radiocarbon and pottery style dating have been preferred. We used OSL to date the palaeochannel infill, wadi sidewall sediments and the late-Pleistocene terrace incised by the wadi. Our ages allow us to make a correlation between the palaeochannel infill process and significant environmental events. As a result, meandering is a highly probable cause of the lack of reoccupation of the site, but anthropological causes such as changes in spatial strategies cannot be completely discarded.

The Late Paleoindian Occupation of the Western Ouachita Mountains of Southeast Oklahoma: The Archaeology of Component V at the Quince Site (34AT134)

The Quince site (34AT134) is a well-preserved and relatively deeply stratified Ouachita Mountains archaeological site in Atoka County in southeastern Oklahoma. The site’s archaeological deposits are buried in Late Pleistocene and Holocene alluvial terrace deposits of McGee Creek, a tributary to Muddy Boggy Creek, itself a southern-flowing tributary to the Red River, that cuts through the western edge of the mountains. Excavated in 1982 and 1983 prior to the creation of McGee Creek Reservoir by the Bureau of Reclamation, the 3.0 m deep archaeological deposits at the Quince site contained a record of prehistoric occupations spanning most of the Holocene period (from ca. 10,500 B.P to 1000 radiocarbon years B.P., or ca. 12,590 to 927 calibrated years B.P.) Woodland (Component I), Late Archaic (Components II and III), and Middle Archaic (Component IV) period occupational deposits are present in good stratigraphic order within the upper 1 m of McGee Creek alluvium. There are also a series of buried Late Paleoindian occupations (in what is defined as Component V) with features and chipped stone lithic tools recovered in situ that are recognized beginning from about 1.10 m to 3.0 m in depth below the surface. In this article, I discuss the archaeological evidence for use of the Western Ouachita Mountains by Late Paleoindian foragers as seen principally from the micro-scale; that is, from the perspective of this one well-preserved and stratified Late Paleoindian site. Paleoindian occupations with good stratigraphic context are apparently quite rare in the Ouachita Mountains and along the edge of the Southeastern woodlands and the Great Plains in the eastern and eastcentral part of the state of Oklahoma. Much of the archaeological research dealing with Late Paleoindian peoples in this region has dealt primarily with the description and classification of isolated temporally diagnostic projectile points (and the kinds of lithic raw materials employed in projectile point manufacture) found on the surface or in mixed and relatively shallow stratigraphic contexts. The Quince site Late Paleoindian archaeological deposits provide direct and compelling evidence for the long-term and recurrent use of the western Ouachita Mountains by hunter-gatherer groups.

Climatic and tectonic control on fluvial and alluvial fan sequence formation in the Central Makran Range, SE-Iran

The geomorphic evolution of the Makran Range of SE-Iran and SW-Pakistan has been controlled by the prevailing SW-Asian monsoon and Mediterranean winter rainfall climate and the surface uplift processes resulting from the Arabia–Eurasia collision. The impact of climate on Quaternary fluvial and alluvial sequence formation and their regional correlation has been little investigated due to limited age control of these sequences. Using 10Be cosmogenic nuclide exposure ages we established a Middle to Late Pleistocene terrace chronology. Our record tentatively indicates that terrace levels were abandoned towards the transition to or during warmer/pluvial periods (interglacials and/or interstadials) back to Marine Isotope Stage (MIS) 7, but abandoned ages show a large spread. It is hypothesized that pluvial phases correspond with times of enhanced SW-monsoons and a northward shift of the Intertropical Convergence Zone (ITCZ). Furthermore, orbital periodicities can be deduced on frequencies related to obliquity and precession cycles. Overall, caution has to be placed in sampling and interpreting alluvial deposits, which may have complex inheritance patterns and spatially and temporarily variable catchment erosion histories and terrace-channel dynamics.Beside the dominant climate control on terrace formation, elevated channel steepness indices around major thrusts and numerous knickpoints indicate an additionally tectonic influence on terrace formation. Local incision rates (mean ~0.6–0.8mm·a−1) are variable in space and time but are similar to uplift rates obtained from coastal terraces and thus suggest a regional surface uplift.

An Integrated Geoarchaeology of a Late Woodland Sand Mound

AbstractThe Graveline Mound (22JA503) is a sand platform mound in Jackson County, Mississippi, built on a low, late Pleistocene terrace on the Mississippi Sound. The Late Woodland mound (A.D. 590–780) is composed of local soils, and its presence today is a testament to the ancient builders’ knowledge of earthen construction materials and methods. Central to the study of the mound is an integrated geoarchaeological approach that uses stratigraphy and micromorphology to decipher material source and selection, construction techniques, and periodicity, in combination with more traditional artifacts, revealing the activities that created this ultimately monumental space. The mound was built in three rapid stages beginning with a low earthwork demarcating a ritual precinct used during late spring/early summer. Stage II quickly followed with a series of alternating zoned fills, sealing the space that was then subsequently covered by Stage III, a massive hard red surface that marked the location with a platform mound.

Climatic, geomorphic, and archaeological implications of a late Quaternary alluvial chronology for the lower Salt River, Arizona, USA

Recent archaeological excavations along the lower Salt River, Arizona resulted in the unexpected discovery of buried late Pleistocene soils and cultural features dating 5800–7100cal YBP (Early Archaic), the latter representing the earliest evidence of human activity in the lower Salt River floodplain thus far identified. Because the lower Salt River floodplain has been heavily impacted by recent agriculture and urbanization and contains few stratigraphic exposures, our understanding of the river's geological history is limited. Here we present a late Quaternary alluvial chronology for a segment of the lower Salt River based on 19 accelerator mass spectrometry 14C and four optically stimulated luminescence ages obtained during two previous geoarchaeological investigations. Deposits are organized into allostratigraphic units and reveal a buried late Pleistocene terrace inset into middle-to-late Pleistocene terrace deposits. Holocene terrace fill deposits unconformably cap the late Pleistocene terrace tread in the site area, and the lower portion of this fill contains the Early Archaic archaeological features. Channel entrenchment and widening ~900cal YBP eroded much of the older terrace deposits, leaving only a remnant of fill containing the buried latest Pleistocene and middle-to-late Holocene deposits preserved in the site area. Subsequent overbank deposition and channel filling associated with a braided channel system resulted in the burial of the site by a thin layer of flood sediments. Our study confirms that the lower Salt River is a complex mosaic of late Quaternary alluvium formed through vertical and lateral accretion, with isolated patches of buried soils preserved through channel avulsion. Although channel avulsion is linked to changes in sediment load and discharge and may have climatic linkages, intrinsic geomorphic and local base level controls limit direct correlations of lower Salt River stratigraphy to other large rivers in the North American Southwest.

Palynological analysis of the Late Pleistocene terrace deposits of Lake Van, eastern Turkey: Reconstruction of paleovegetation and paleoclimate

Paleovegetation and paleoclimate reconstruction of a Late Pleistocene terrace of Lake Van (northern part of lake; Erciş Çelebibağı region) was based on pollen analysis from continuous laminated sediments. According to the pollen analysis, NAP pollen values are predominantly abundant. Chenopodiaceae, Artemisia and Poaceae were the prevailing plants, and Chenopodiaceae was the dominant paleoflora element during Late Pleistocene. Pollen data indicate halophyte vegetation. Climate was colder and drier.

Holocene geomorphic processes and landscape evolution in the lower reaches of the Orkhon River (northern Mongolia)

Abstract Geomorphological and sedimentological investigations in the lower reaches of the Orkhon River in northern Mongolia provide evidence for Late Pleistocene terraces, Holocene soil development, aeolian accumulation, soil erosion and slope wash. Optically stimulated luminescence (OSL) and radiocarbon dating of aeolian and colluvial sediments including paleosols show different sedimentation and soil formation periods. Luminescence data of 12.3 ka and 11.0 ka were obtained for basal sand deposits overlying slope bedrock and the Pleistocene terraces of the Orkhon River. OSL and radiocarbon data from aeolian sediments and paleosols indicated soil formation at around 11–10 ka, 7–6 ka and 3 ka. These periods can be associated with more humidity found in other areas of Central Asia as well.

Geomorphic evidence of active tectonics in the Sierra Alhamilla (eastern Betics, SE Spain)

Active tectonic deformation influencing the streams and hillslopes of the Sierra Alhamilla ridge (anticlinorium) in southeast Spain is related to the dextral-reverse Polopos Fault Zone to the north and east of the ridge and to normal faulting in the southern side of the ridge. A fault segmentation and fluvial terrace mapping is presented in this paper. The following geomorphic indices were calculated in the area: the mountain-front sinuosity, valley floor width-to-height ratio, drainage basin asymmetry factor, basin hypsometric curve and integral, longitudinal river profile and stream-length gradient index normalized by the graded river gradient (SLk index). The SLk map shows two sets of high anomalies: a) an E–W-striking anomaly, due to the dextral-reverse Polopos Fault Zone located in the northern limb of the anticlinorium; b) a group of NNW–SSE-striking anomalies, associated with Pliocene–Quaternary NW–SE- to NNW–SSE-striking high-angle normal faults that cut the southern limb. Late Pleistocene–Holocene activity occurred along the North Alhamilla Reverse Fault and the dextral transpressive South Gafarillos Fault, two segments in the Polopos Fault Zone. The former fault produces rejuvenation of the streams at the base of the northern slope. In this area, mountain-front sinuosity and valley floor width-to-height ratio suggest Quaternary uplift rates between 0.05 and 0.5mky−1. Holocene to present-day activity of the South Gafarillos Fault is demonstrated by faulted late Pleistocene terraces and Holocene colluvial deposits and suggested by deflected streams that have complex or convex hypsometric curves. Pliocene–Quaternary high-angle normal faults control the relief in the southern limb and the western end of the Sierra Alhamilla. These faults produce low mountain-front sinuosity and valley floor width-to-height ratio indices typical of uplift rates quite higher than field-based rates from some other studies.