Landscape Evolution Research Papers - Academia.edu (original) (raw)

We present palaeoenvironmental, geomorphological, archaeological, and place-name data which allow a holistic assessment of the history of landscape change on Sandoy, Faroe Islands, especially in terms of the changes that occurred in... more

We present palaeoenvironmental, geomorphological, archaeological, and place-name data which allow a holistic assessment of the history of landscape change on Sandoy, Faroe Islands, especially in terms of the changes that occurred in response to the colonization of the island by humans. In contrast to other situations in the North Atlantic region, there is considerable continuity in the patterns and processes of landscape evolution across the initial

1] The HiRISE camera features a 0.5 m diameter primary mirror, 12 m effective focal length, and a focal plane system that can acquire images containing up to 28 Gb (gigabits) of data in as little as 6 seconds. HiRISE will provide detailed... more

1] The HiRISE camera features a 0.5 m diameter primary mirror, 12 m effective focal length, and a focal plane system that can acquire images containing up to 28 Gb (gigabits) of data in as little as 6 seconds. HiRISE will provide detailed images (0.25 to 1.3 m/pixel) covering 11% of the Martian surface during the 2-year Primary Science Phase (PSP) beginning November 2006. Most images will include color data covering 20% of the potential field of view. A top priority is to acquire 11000 stereo pairs and apply precision geometric corrections to enable topographic measurements to better than 25 cm vertical precision. We expect to return more than 12 Tb of HiRISE data during the 2-year PSP, and use pixel binning, conversion from 14 to 8 bit values, and a lossless compression system to increase coverage. HiRISE images are acquired via 14 CCD detectors, each with 2 output channels, and with multiple choices for pixel binning and number of Time Delay and Integration lines. HiRISE will support Mars exploration by locating and characterizing past, present, and future landing sites, unsuccessful landing sites, and past and potentially future rover traverses. We will investigate cratering, volcanism, tectonism, hydrology, sedimentary processes, stratigraphy, aeolian processes, mass wasting, landscape evolution, seasonal processes, climate change, spectrophotometry, glacial and periglacial processes, polar geology, and regolith properties. An Internet Web site (HiWeb) will enable anyone in the world to suggest HiRISE targets on Mars and to easily locate, view, and download HiRISE data products.

During the Last Glacial Maximum (LGM), the San Juan Mountains of southern Colorado, USA were covered by one of the largest ice caps in North America. The deposits formed subsequent to LGM retreat provide a record of the interaction... more

During the Last Glacial Maximum (LGM), the San Juan Mountains of southern Colorado, USA were covered by one of the largest ice caps in North America. The deposits formed subsequent to LGM retreat provide a record of the interaction between post-LGM climate change and late Quaternary landscape evolution. In order to determine the role of post-LGM climate change in alpine landscape modification, a high resolution surficial geologic map was produced for the four primary tributaries and the main stem of the upper Conejos River watershed in the southeastern San Juan Mountains.

Studies on denudation rates can provide insight into the influence of climate change, tectonics, and human activities on landscape evolution. Research performed in Central Italy has shown considerable spatial variability of denudation... more

Studies on denudation rates can provide insight into the influence of climate change, tectonics, and human activities on landscape evolution. Research performed in Central Italy has shown considerable spatial variability of denudation rates in the major river basins. These studies have focused mainly on the Tyrrhenian side of the Italian peninsula, where Plio-Pleistocene marine deposits filling NW–SE elongated sedimentary basins have been uplifted during the Quaternary up to several hundreds of meters above present sea level. Small sub-catchments developed on clays are affected by sharp- and/or rounded-edged badlands (i.e. calanchi and biancane), representing denudation “hot spots” in the present-day morphoclimatic framework.In this paper, we analyze the relationships between indirectly estimated denudation rates at the catchment scale and field monitoring data at the hillslope scale. We attempt to better understand and quantify all hillslope processes that contribute to seasonal variability of denudation, to help with predicting the net input from “hot spots” to the overall estimated sediment yield at the basin outlets. At the hillslope scale, we discuss, in particular, the variability of denudation rates at calanchi and biancane badlands as a function of their different morphoevolution.

Glacial outburst floods (jökulhlaups) have a significant role for landscape evolution in NE Iceland. A number of jökulhlaups have routed from the northern margin of Vatnajökull during the Holocene. In this study, reconstruction of the... more

Glacial outburst floods (jökulhlaups) have a significant role for landscape evolution in NE Iceland. A number of jökulhlaups have routed from the northern margin of Vatnajökull during the Holocene. In this study, reconstruction of the largest Holocene jökulhlaup along Jökulsá á Fjöllum, NE Iceland was undertaken using the HEC-RAS hydraulic modelling and HEC-GeoRAS flood mapping techniques with a Digital Elevation Model (DEM) derived from ERS-InSAR data and field-based wash limit evidence. The largest jökulhlaup produced extensive erosional and depositional landforms across an inundated area of ˜1390 km2 and is calculated to have had a peak discharge of 0.9×106 m3 s-1. Power per unit area within this jökulhlaup varied from 6 to 46,000 W m-2. Jökulhlaup hydraulics are related to geomorphogical evidence at three key sites: in Vaðalda, Upptyppingar and Möðrudalur sub-areas in order to explain the abrupt spatial variation of the flood characteristics on a regional scale and to relate erosional and depositional features to spatial variations in jökulhlaup hydraulics. These process-form relationships of the largest jökulhlaup along the Jökulsá á Fjöllum are compared with large outburst floods elsewhere. The largest Jökulsá á Fjöllum jökulhlaup had a factor of ˜20 times smaller discharge and ˜a factor of 20 times lower power per unit area than Altai palaeoflood—the largest known flood on the Earth.

The Warratta Inlier is located in northwestern New South Wales, approximately 20 km south of Tibooburra. The Inlier is bound on its northeastern side by the Warratta Fault and it has been suggested that this is an extension of the... more

The Warratta Inlier is located in northwestern New South Wales, approximately 20 km south of Tibooburra. The Inlier is bound on its northeastern side by the Warratta Fault and it has been suggested that this is an extension of the Olepoloko Fault (Stevens 1985), a major terrain boundary between the Thomson Fold Belt and the Lachlan Fold Belt of the Tasmanides. This study incorporated potential field geophysics and regolithlandform mapping to determine possible models for the landscape evolution of the area, based on ...

Triangulated irregular networks (TIN) in landscape evolution models have the advantage of representing geologic processes that involve a horizontal component, such as faulting and river meandering, due to their adaptive remeshing... more

Triangulated irregular networks (TIN) in landscape evolution models have the advantage of representing geologic processes that involve a horizontal component, such as faulting and river meandering, due to their adaptive remeshing capability of moving, adding and deleting nodes. However, the moving node feature is difficult to integrate with the accumulation of a three-dimensional (3D) subsurface stratigraphy, because it requires 3D subsurface interpolation, which results in stratigraphic data loss due to heterogeneity of the subsurface and averaging effects. We present a simple algorithm that maps any changes in the configuration of TIN landscape nodes onto a static grid, facilitating the creation of a fixed stratigraphic record of TIN surface change. The algorithm provides a practical solution not only for the stratigraphic problem, but also for other problems that involve linking of models that use TIN and raster discretization schemes. An example application is presented using the river meandering module incorporated in the CHILD landscape evolution model. Examples are shown of cross-sections, and voxel distributions and geo-archaeological depth-age maps. These illustrate the type of insights that can be obtained from process-based modeling of subsurface fluvial architecture, and highlight potential applications of stratigraphic simulation. r

Dating the time of abandonment of geomorphic surfaces in the arid mid latitudes is necessary for studies ranging from tectonics, landscape evolution and paleoclimate. It has often been hampered by the limited material suitable for... more

Dating the time of abandonment of geomorphic surfaces in the arid mid latitudes is necessary for studies ranging from tectonics, landscape evolution and paleoclimate. It has often been hampered by the limited material suitable for conventional isotopic methods and the uncertainties inherent in cosmogenic radionuclide methods. We propose luminescence dating as a suitable method for dating the time of abandonment of aggradational geomorphic surfaces in the hyperarid regions. We dated the top of such surfaces with different age ranges and geomorphic settings in a sequence of alluvial fans in Nahal Shehoret in the southern Negev and in a sequence of terraces in Nahal Ze'elim and in Nahal Zin, two adjacent drainage basins in the Judean Desert, Israel. Samples were collected from beneath the gypsic horizon at a depth of 0.3-0.7 m, below which sand grains do not penetrate. Depositional ages for the uppermost beds of the landforms, which are proxies for abandonment, range from w90 ka to w5 ka. In all three basins, the ages are in morphostratigraphic order and agree well with relative age estimates based on soil chronosequences and on Lake Lisan levels. Abandonment ages for an individual alluvial fan cluster within AE10-20%, therefore it is possible to distinguish between surfaces with ages differing by more than 20%. Thus, in hyperarid areas, the luminescence methods can be used for surface dating.

Landscapes evolve in response to external forces, such as tectonics and climate, that influence surface processes of erosion and weathering. Internal feedbacks between erosion and weathering also play an integral role in regulating the... more

Landscapes evolve in response to external forces, such as tectonics and climate, that influence surface processes of erosion and weathering. Internal feedbacks between erosion and weathering also play an integral role in regulating the landscapes response. Our understanding of these internal and external feedbacks is limited to a handful of field-based studies, only a few of which have explicitly examined saprolite weathering. Here, we report rates of erosion and weathering in saprolite and soil to quantify how climate influences denudation, by focusing on an elevation transect in the western Sierra Nevada Mountains, California. We use an adapted mass balance approach and couple soil-production rates from the cosmogenic radionuclide (CRN) 10 Be with zirconium concentrations in rock, saprolite and soil. Our approach includes deep saprolite weathering and suggests that previous studies may have underestimated denudation rates across similar landscapes. Along the studied climate gradient, chemical weathering rates peak at middle elevations (1200-2000 m), averaging 112·3 ± 9·7 t km -2 y -1 compared to high and low elevation sites (46·8 ± 5·2 t km −2 y −1 ). Measured weathering rates follow similar patterns with climate as those of predicted silica fluxes, modeled using an Arrhenius temperature relationship and a linear relationship between flux and precipitation. Furthermore, chemical weathering and erosion are tightly correlated across our sites, and physical erosion rates increase with both saprolite weathering rates and intensity. Unexpectedly, saprolite and soil weathering intensities are inversely related, such that more weathered saprolites are overlain by weakly weathered soils. These data quantify exciting links between climate, weathering and erosion, and together suggest that climate controls chemical weathering via temperature and moisture control on chemical reaction rates. Our results also suggest that saprolite weathering reduces bedrock coherence, leading to faster rates of soil transport that, in turn, decrease material residence times in the soil column and limit soil weathering. a Rock [Zr] measured from exposed tor or bedrock beneath soil at each site: BG (61 ppm), BM (78 ppm), PC (61 ppm), KR (99 ppm), WB (95 ppm). b Where saprolite [Zr] exceeds soil concentrations, saprolite CDF would be negative. In these, we adjust CDF sap to zero.

The plain of Thessaloniki is an important area from a historical standpoint. Numerous reigns and empires have occupied the area, leaving behind numerous archaeological remains. The literature and historical evidences show that the city of... more

The plain of Thessaloniki is an important area from a historical standpoint. Numerous reigns and empires have occupied the area, leaving behind numerous archaeological remains. The literature and historical evidences show that the city of Pella was located near the sea and its harbor was the starting point of various conquests of famous kings such as Philip the 2nd and Alexander the Great. At present, the ancient capital is located 28 km inland the large fertile plain of Thessaloniki.

We propose a radiometric chronology bracket for the last glacial advance/retreat, called the Marquette readvance, in the Upper Peninsula of Michigan (Upper Peninsula) using organic material from kettle lakes and previously published age... more

We propose a radiometric chronology bracket for the last glacial advance/retreat, called the Marquette readvance, in the Upper Peninsula of Michigan (Upper Peninsula) using organic material from kettle lakes and previously published age determinations on wood buried by glaciofluvial sediments. The lakes are located both inside and outside the ice-contact margin of the Marquette readvance. Wood buried in glaciofluvial sediments from the Marquette readvance was previously dated at 10,025 ± 100 14 C yr BP . Ackerman Lake, a kettle lake located inside the ice-contact margin, yielded a basal radiocarbon date of 9,495 ± 70 14 C yr BP representing the time of organic accumulation after ice retreat. These dates above and below the glacial deposit bracket the age of the Marquette readvance/retreat to 360-700 14 C yr, or the midpoint of 530 14 C yr. Ackerman Lake yielded multiple radiocarbon dates, including an average date of 8,811 ± 11 14 C yr BP (9,736-9,913 cal yr BP) at a change in stratigraphy from red clay to gray silt. This transition along the northern Upper Peninsula is interpreted to represent ice sheet retreat into Lake Superior and the reworking of older glacial sediments by ~8,500 14 C yr BP. Organic material from the kettle lake sediments spanning multiple geomorphic locations (both inside and outside of the ice-contact margin) and previous radiocarbon dates from the entire Upper Peninsula yielded dates concentrating around 9,500 14C yr BP. We attribute this synchronous organic accumulation in the Upper Peninsula to be a result of climatic signature corresponding with the Preboreal Oscillation, so the duration of the Marquette glacial cover may have been less then implied by the Ackerman Lake basal age. , and is of particular interest when reconstructing ice-sheet dynamics and the timing of advance/retreat cycles (e.g., . These previous studies not withstanding, the radiometric chronology of ice retreat in parts of the region is not well-established.

Gråtådalen valley, Svartisen, north Norway is a hanging tributary to a larger valley, where the junction is perched on erosion-resistant schists. Marble bands further up-valley contain numerous caves at various levels above the valley... more

Gråtådalen valley, Svartisen, north Norway is a hanging tributary to a larger valley, where the junction is perched on erosion-resistant schists. Marble bands further up-valley contain numerous caves at various levels above the valley floor. This situation is ideal for testing the possible connection between stages in valley downcutting and corresponding morphological signatures in the caves. The caves are subject to accurate re-surveying, allowing a thorough speleogenetic and speleochronological analysis. This is part of an ongoing master thesis at the University of Bergen, Norway and further details will be given in the oral presentation.

The cosmogenic nuclide exposure history method is undergoing major developments in analytical, theoretical, and applied areas. The capability to routinely measure low concentrations of stable and radioactive cosmogenic nuclides has led to... more

The cosmogenic nuclide exposure history method is undergoing major developments in analytical, theoretical, and applied areas. The capability to routinely measure low concentrations of stable and radioactive cosmogenic nuclides has led to new methods for addressing long-standing geologic questions and has provided insights into rates and styles of sur"cial processes. The di!erent physical and chemical properties of the six most widely used nuclides: He, Be, C, Ne, Al, and Cl, make it possible to apply the surface exposure dating methods on rock surfaces of virtually any lithology at any latitude and altitude, for exposures ranging from 10 to 10 years. The terrestrial in situ cosmogenic nuclide method is beginning to revolutionize the manner in which we study landscape evolution. Single or multiple nuclides can be measured in a single rock surface to obtain erosion rates on boulder and bedrock surfaces, #uvial incision rates, denudation rates of individual landforms or entire drainage basins, burial histories of rock surfaces and sediment, scarp retreat, fault slip rates, paleoseismology, and paleoaltimetry. Ages of climatic variations recorded by moraine and alluvium sediments are being directly determined. Advances in our understanding of how cosmic radiation interacts with the geomagnetic "eld and atmosphere will improve numerical simulations of cosmic-ray interactions over any exposure duration and complement additional empirical measurements of nuclide production rates. The total uncertainty in the exposure ages is continually improving. This article presents the theory necessary for interpreting cosmogenic nuclide data, reviews estimates of parameters, describes strategies and practical considerations in "eld applications, and assesses sources of error in interpreting cosmogenic nuclide measurements.

The Five Islands of south central Louisiana are piercement-type salt domes uplifted from several kilometers depth as the surrounding strata experiences regional subsidence. In general, the domes are nearly circular in plan with maximum... more

The Five Islands of south central Louisiana are piercement-type salt domes uplifted from several kilometers depth as the surrounding strata experiences regional subsidence. In general, the domes are nearly circular in plan with maximum land surface elevations 23-52 m asl. Geomorphic evidence of salt-induced uplift includes surface lineations, aligned gullies, excessively steep land surface topography, and shear fractures in surficial sediments. Evidence of subsidence includes sinkhole ponds a few hectares in area, broad topographic saddles over tens of hectares in size, and kilometer-scale collapse structures. On each of the Five Islands, Peoria Loess and silty colluvium bury a paleosol developed in the Late Pleistocene Prairie Complex of the Lower Mississippi Valley. The loess represents a single genetic unit of eolian origin, is typically thickest on lower side slopes, and is thin or absent on ridge crests. The silty colluvium around the perimeter of the islands is a reworked loess derived from higher elevations. Shear fractures with high-angle average dips occur in both Peoria Loess and the Prairie Complex. Conjugate shear pairs probably develop from extensional stress associated with vertical uplift of the underlying salt. Prairie Complex deposition and initial soil development in a low-relief alluvial plain of the Mississippi River predates the latest emergence of the Five Islands. Loess and colluvial stratigraphy indicate that the domes were emergent during loess deposition. Gully incision, shearing of Quaternary sediments, and the distribution of colluvium indicate continued uplift after loess deposition. Sinkholes and collapse structures are influenced by salt dissolution and corrasion, whereas broad subsidence areas and topographic saddles form over areas of structural weakness within the salt. Five Islands landscape evolution is controlled by the interaction of driving and resisting forces that operate over various time scales. Diapiric uplift is a driving force of net upwards motion, and the external and internal salt dome hydrology are driving forces of solution and corrasion. The structure and lithology of the internal salt stocks and the surrounding sediments are heterogeneous and have variable strength. Collectively, this interaction produces both uplift and subsidence features across the salt dome landscape. Resource use at the Five Islands correlate with instability of both underground facilities and the surface landscape. Uplift of the Five Islands has continued since at least the Late Pleistocene, is probably still active at present, and periods of tectonic and geomorphic instability are possible in the future. Sediments overlying salt domes record discrete periods of surface uplift and periods of episodic and incremental subsidence that is common where salt domes pierce surficial sediment. The rate, magnitude, and pattern of landscape modification by salt domes have implications for the safe utilization of mineral extraction and geostorage facilities. Geomorphic evaluation of salt dome landscapes can help to develop policies that ensure safe salt dome utilization. Salt dome resource planning should include detailed characterization of internal and external stratigraphy and

In present-day alluvial environments, the impact of vegetation on sedimentological processes and deposits is well known. A vegetated catchment may decrease sediment yield, sediment erodibility, Hortonian overland flow, aeolian winnowing... more

In present-day alluvial environments, the impact of vegetation on sedimentological processes and deposits is well known. A vegetated catchment may decrease sediment yield, sediment erodibility, Hortonian overland flow, aeolian winnowing of fines, the proportion of sediment transported as bedload, and may increase bank stability, infiltration into substrates, and bed roughness. Vegetation also promotes the production of chemically-weathered clays and soils and the adoption of a meandering style. It is generally understood that, prior to the evolution of terrestrial vegetation during the Early Palaeozoic, ancient alluvial systems were markedly different from modern systems, with many systems adopting a "sheet-braided" style. This understanding has previously informed the interpretations of many Precambrian pre-vegetation alluvial successions, but there has been relatively little work regarding Early Palaeozoic alluvial successions laid down prior to and during the initial colonization of the Earth's surface by plants.

Assessing the impacts of climatic and, in particular, land use changes on rates of soil erosion by water is the objective of many national and international research projects. However, over the last decades, most research dealing with... more

Assessing the impacts of climatic and, in particular, land use changes on rates of soil erosion by water is the objective of many national and international research projects. However, over the last decades, most research dealing with soil erosion by water has concentrated on sheet (interrill) and rill erosion processes operating at the (runoff) plot scale. Relatively few studies have been conducted on gully erosion operating at larger spatial scales.

Soils chronosequences are valuable tools for investigating rates and directions of soil and landscape evolution. Post-incisive chronosequences are the most common type of chronosequence. They are found in many landscapes, including sand... more

Soils chronosequences are valuable tools for investigating rates and directions of soil and landscape evolution. Post-incisive chronosequences are the most common type of chronosequence. They are found in many landscapes, including sand dunes, glacial moraines, landslide scars, old pasture, burnt landscape patches, old mining areas, lava flows, alluvial fans, floodplains, river terraces, and marine terraces. They register pedogenic change over time-scales ranging from years to millions of years. Soil chronosequences help in testing rival theories of pedogenesis. Traditional soil formation theory sees a soil developing progressively under the influence of the environmental state factors until it is in equilibrium with prevailing environmental conditions. This developmental view of pedogenesis is supported by the classic soil chronosequence studies. A new evolutionary view of pedogenesis, which was prompted by the omnipresent inconstancy of environmental conditions and the notions of multidirectional changes and multiple steady states Ž . as predicted by non-linear dynamics , proposes that environmental inconstancy and non-linear behaviour in soil-landscapes lead to soil evolution, rather than to soil development. Soils 'evolve' through continual creation and destruction at all scales, and may progress, stay the same, or retrogress, depending on the environmental circumstances. Some recent soil and vegetation chronosequence investigations support an evolutionary view of pedogenesis. It is concluded that soil chronosequences are still potent instruments for pedological investigations and that they have a starring role to play in the testing of pedological theories. q

This paper focuses on analysing tillage as a mechanism for the transformation of soil spatial variability, soil morphology, superficial soil properties and development of soil -landscape relationships in agricultural lands. A new... more

This paper focuses on analysing tillage as a mechanism for the transformation of soil spatial variability, soil morphology, superficial soil properties and development of soil -landscape relationships in agricultural lands. A new theoretical two-dimensional model of soil catena evolution due to soil redistribution by tillage is presented. Soil profile truncation occurs through loss of soil mass on convexities and in the upper areas of the cultivated hillslopes; while the opposite effect takes place in concavities and the lower areas of the field where the original soil profile becomes buried. At sectors of rectilinear morphology in the hillslope (backslope positions), a null balance of soil translocation takes place, independent of the slope gradient and of the rate of downslope soil translocation. As a result, in those backslope areas, a substitution of soil material in the surface horizon with material coming from upslope areas takes place. This substituted material can produce an inversion of soil horizons in the original soil profile and sometimes, the formation of ''false truncated soil''. In the Skogstad agricultural field (Cyrus, MN) spatial patterns of soil properties (soil calcium carbonate content) in the surface soil horizons and soil morphology along several slope transects were analyzed. These spatial patterns are compared with those estimated for soil redistribution (areas of erosion and deposition) due to tillage using the Soil Redistribution by Tillage (SORET) model and water erosion using the models Water Erosion Prediction Project (WEPP) and Universal Soil Loss Equation (Usle2D). Results show that tillage was the predominant process of soil redistribution in the studied agricultural field. Finally, some practical implications of the proposed model of soil landscape modification by tillage are discussed. Nomographs to 0341-8162/$ -see front matter D (S. De Alba). www.elsevier.com/locate/catena Catena 58 (2004) 77 -100 calculated the intensity of the expansion process of the eroded soil units by tillage are proposed for three different patterns of tillage. D

It is commonly accepted that, following the end of the Pleistocene, semi-arid deciduous oak woodlands did not spread in the Irano-Anatolian region of Southwest Asia as quickly as they did in the Levantine Mediterranean littoral, despite... more

It is commonly accepted that, following the end of the Pleistocene, semi-arid deciduous oak woodlands did not spread in the Irano-Anatolian region of Southwest Asia as quickly as they did in the Levantine Mediterranean littoral, despite the fact that climatic improvement occurred broadly at the same time in both regions. Prehistoric impacts on woodland vegetation (such as woodcutting, burning and clearance for cultivation), the harsh continental climate of inland Southwest Asia and its distance from late Pleistocene arboreal refugia have all been discussed in the literature as likely causes of the delay. In this paper we argue that semi-arid deciduous oak woodlands should not be viewed as part of the “natural” vegetation of the Irano-Anatolian region that has been progressively destroyed by millennia of human activities since the Neolithic. They represent instead one of the earliest anthropogenic vegetation types in Southwest Asia, one that owes its very existence to prehistoric landscape practices other scholars commonly label as “destructive”. Drawing on anthracological, pollen and modern vegetation data from central Anatolia we describe how the post-Pleistocene species-rich and structurally diverse temperate semi-arid savanna grasslands were gradually substituted by low-diversity, even-aged Quercus-dominated parklands and wood pastures in the course of the early Holocene. Economic strategies that encouraged the establishment and spread of deciduous oaks included sheep herding that impacted on grass and forb vegetation, the controlling of competing arboreal vegetation through woodcutting, and woodland management practices such as coppicing, pollarding and shredding that enhanced Quercus vegetative propagation, crown and stem growth. Understanding the origin and evolution of the Irano-Anatolian semi-arid oak woodlands of Southwest Asia is of critical importance for reconstructing the changing ecologies and geographical distributions of the progenitors of domesticated crop species, and the nature and scale of early agricultural impacts on the landscape.

Assessing the impacts of climatic and, in particular, land use changes on rates of soil erosion by water is the objective of many national and international research projects. However, over the last decades, most research dealing with... more

Assessing the impacts of climatic and, in particular, land use changes on rates of soil erosion by water is the objective of many national and international research projects. However, over the last decades, most research dealing with soil erosion by water has concentrated on sheet (interrill) and rill erosion processes operating at the (runoff) plot scale. Relatively few studies have been conducted on gully erosion operating at larger spatial scales.

Geomorphic models such as the glacial buzz saw and denudational unloading and understanding the significance of active tectonics on geomorphic systems can be elucidated by quantitatively defining rates of erosion and sediment transfer in... more

Geomorphic models such as the glacial buzz saw and denudational unloading and understanding the significance of active tectonics on geomorphic systems can be elucidated by quantitatively defining rates of erosion and sediment transfer in active mountain systems. To this end, we examine the topographically and morphometrically asymmetrical Ladakh Range to quantify the significance of tectonic influence on geomorphic systems. Morphometric analysis and10Be cosmogenic radionuclide dating of 13 fluvial sediment samples from active channels was undertaken in 6 catchments to define erosion rates. North facing catchments of the central Ladakh Range have erosion rates of 0.056±0.012 mm/yr and 0.074±0.011 mm/yr, while south facing catchments have rates of 0.020±0.003 mm/yr, 0.020±0.003 mm/yr, and 0.039±0.008 mm/yr. Rates of erosion in north facing catchments are approximately two times higher than rates of erosion in south facing catchments. This data confirms that the tectonic tilting of the Ladakh Range and active rock uplift (~ 1 mm/yr) on the northern side of the range has had a significant impact on the rate of erosive geomorphic processes. However, the increased erosion on the northern side of the range is not keeping pace with rock uplift on the northern side of the range. Morphometric analysis shows that the maximum and average elevations increase at nearly the same rate across the Ladakh Range with higher elevation on the northern side. This precludes the possibility of long-term denudational unloading from having a significant feedback into the tectonic tilting of the range.

Palynological archives dating from the Pleistocene–Holocene transition are scarce in the arid zone of the southern Levant. Anthracological remains (the carbonized residues of wood fuel use found in archaeological habitation sites) provide... more

Palynological archives dating from the Pleistocene–Holocene transition are scarce in the arid zone of the southern Levant. Anthracological remains (the carbonized residues of wood fuel use found in archaeological habitation sites) provide an alternative source of information about past vegetation. This paper discusses new and previously available anthracological datasets retrieved from excavated habitation sites in the southern Levant dating to the Pre- Pottery Neolithic (PPN) period. The available evidence indicates the existence of distinct arboreal floras growing in different ecological niches, which occupied areas that today are either treeless or very sparsely wooded. The anthracological data provide independent confirmation of the hypothesis that early Holocene climate in the southern Levant was significantly moister than at present. Clear North–South and East–West precipitation and associated woodland composition gradients are evidenced. Far from deducing widespread anthropogenic degradation of the regional vegetation, it is suggested that woodland expansion in the semi-arid interiors of the Levant may be attributed to the intensive management of Pistacia woodlands for food, fuel and pasture.

Soil development and landscape evolution were studied in the basin-shaped Phobjikha Valley at 2900-3200 m a.s.l., to the west of the Black Mountain Range, West Central Bhutan. The local environmental setting with strong along-valley... more

Soil development and landscape evolution were studied in the basin-shaped Phobjikha Valley at 2900-3200 m a.s.l., to the west of the Black Mountain Range, West Central Bhutan. The local environmental setting with strong along-valley winds, frequent freeze-thaw cycles, extensive dry periods and sparse vegetation cover seems to encourage the generation and short-distance transport of silt-sized particles. The effects of this process are evidenced in the smooth valley morphology and in the nature of the examined pedons. Their involvement in continuing redistribution of local sediments is reflected by a homogeneous silty-clayey and stone-free texture, varying profile depths, buried topsoils and weakly developed recent A horizons. In protected locations, in situ weathering of metamorphic parent materials results in alu-andic features with bulk densities <0.9 g cm À3 , (Al o + ½Fe o ) > 2%, and phosphate retention >95%. Dominance by Al-hydroxy interlayered clay minerals and large amounts of well-crystallised iron oxides indicate an advanced stage of weathering. In areas of preferred eolian deposition, argic and ferralic features emerge, with clay contents of up to 60% and surface areas of >50 m 2 g À1 . Under forest, umbric horizons can develop. CEC eff is below 10 cmol c kg À1 at all sites. Cluster and factor analyses of soil chemical and physical parameters confirm the redistribution of local sediments as a dominant factor behind the measured variables. No clear indication of glacial activities in the area was found, whereas the massive silty sediments in the lower parts of most profiles, the presence of debris slopes, and the asymmetric cross sections of the side valleys suggest periglacial conditions. Buried topsoils dated at about 2000 conventional 14 C years BP indicate a weakening or absence of sediment influx under wetter conditions towards the end of the Holocene climate optimum. Charcoal on top of paleosols suggests that human activities of deforestation, grazing and arable agriculture may have contributed to the reactivation of local sediment redistribution until today.

We review the role of landslides in current concepts of the topographic development of mountain ranges. We find that many studies in this field address basin-or orogen-scale competition between rock uplift and fluvial bedrock erosion.... more

We review the role of landslides in current concepts of the topographic development of mountain ranges. We find that many studies in this field address basin-or orogen-scale competition between rock uplift and fluvial bedrock erosion. Hillslopes in general, and bedrock landslides in particular, are often assumed to respond rapidly to incision and development of the fluvial drainage network. This leads to a one-sided view of the geomorphic coupling between hillslopes and rivers that emphasizes the fluvial control of hillslopes, but ignores the alternative view that landslides can affect the fluvial network. There is growing evidence that landslides are a dominant source of sediment in mountain belts and that they exert a direct geomorphic control on fluvial processes. Landslides can influence the river network in a variety of ways, from determining basin area and drainage divide positions, to setting streamwise variations in sediment load and calibre. The geomorphic legacy of large landslides on hillslope and channel morphologies may persist for up to 10 4 yr, adding considerable variability to fluvial erosion and sedimentation patterns over these timescales. We identify a number of questions for future research and conclude that a better understanding and quantification of the geomorphic feedbacks between landslides and river channels builds an important link between short-term (< 10 1 yr) process studies and long-term (> 10 5 yr) landscape evolution models.

The fluvial systems and landscape of the drylands of western India have preserved evidence of Late Quaternary environmental and tectonic changes. Data on the fluvial systems of Mainland Gujarat, Saurashtra and Kachchh have been... more

The fluvial systems and landscape of the drylands of western India have preserved evidence of Late Quaternary environmental and tectonic changes. Data on the fluvial systems of Mainland Gujarat, Saurashtra and Kachchh have been synthesised to evaluate the roles of geological factors in the evolution of these drylands. Mainland Gujarat is largely underlain by the flat alluvial plain, and has a structurally controlled fluvial system that originates in the eastern uplands. The fluvial system of Mainland Gujarat shows deeply incised valleys, entrenched meanders, extensively developed ravines and uplifted terraces, which have preserved a Late Quaternary succession of continental (fluvial and aeolian) and marine sediments dating back to B125 ka: Marine sediments correspond to the transgressive phases of the last interglacial ðB125 kaÞ and post-glacial maximum ð6 kaÞ: The overlying alluvial sediments suggest deposition by ephemeral rivers in varied fluvial depositional environments under a semi-arid to sub-humid climatic regime with periods of intense pedogenesis. The sedimentation can be correlated with marine isotopic stages (MIS) 5 and 3. The fluvial sediments are buried under a thick blanket of aeolian sediments, which are indicative of enhanced dune building activity in the Thar Desert and are correlatable to the global arid phase of the last glacial maximum. The post-aeolian tectonic uplift triggered severe erosion of Late Pleistocene sediments and 40-50 m deep incised fluvial valleys were formed. This erosional phase suggests a resumption of fluvial activity, which coincided with the rapidly rising sea level on the west coast during the Early Holocene. The Holocene marine and fluvial aggradation was initiated within the incised fluvial valleys around 6 ka and continued uninterrupted until B2 ka: These sediments now occur as raised valley fill terraces suggesting a Late Holocene uplift further corroborated by low to moderate seismic activity during historical times. The landscape of Saurashtra is marked by flat-topped basaltic (trappean) ridges and a highly varied coastline where a narrow belt of low ridges and cliffs of miliolite limestones and other shore deposits are found. The fluvial system of Saurashtra shows a radial drainage pattern. The channels have steep banks in the hilly regions and show significant deflections before meeting the sea. Evidence of last interglacial high sea levels ðB125 kaÞ are found on the coastal cliffs of southern Saurashtra in the form of oyster reefs and notches of various types which now occur at higher levels. A net sea level rise of þ7 m consistent with the global sea level estimates at 125 ka has been obtained by recent studies after decoupling the tectonic component. Dating of Late Pleistocene and Holocene sea levels on this coast suggest continued uplift of Saurashtra since 125 ka even though the sea level continued to fluctuate. The Holocene high sea submerged a considerable stretch of land including the Okha Rann on the northern Saurashtra coast and isolated patches in and around the river mouths on the southern coast. The short, straight and parallel courses of rivers in the direction of tectonic slope, incised and confined channel belts also suggest a strong component of tectonic uplift. The continental sediments exposed in these river valleys have however remained uninvestigated leading to lack of palaeoclimatic data. A remarkable control of structure on landscape evolution is depicted by the Kachchh peninsula. The fluvial system exhibits the characteristics of drainage flowing along tectonically provided slopes. The overall drainage pattern of Kachchh shows excellent correlation with N-S trending transverse fault patterns. The transverse fault system has brought out changes in the landscape of Kachchh though the Kachchh rift basin evolved along E-W latitudinal faults. The Quaternary deposits occur in the form of miliolite limestones, colluvial and alluvial fans, fluvial sands and silts, and Rann sediments. Significant sedimentologic details on these sediments are lacking. However, the marine incursions seem to correlate with the adjacent Saurashtra and Mainland Gujarat.

The coastal plain located between Figueira da Foz and Nazaré (western central Portugal) has a general low slope towards west, with altitudes below 200 m, and constitutes an important geomophological unit that is usually called “Littoral... more

The coastal plain located between Figueira da Foz and Nazaré (western central Portugal) has a general low slope towards west, with altitudes below 200 m, and constitutes an important geomophological unit that is usually called “Littoral Platform”. At north, east and south, the platform is limited by the limestones relieves of the Serra da Boa Viagem – Verride arc, Sicó Massif and Estremenho Massif.
These relieves are characterized by high slope values and altitude > 200 m. The fluvial incision produced narrow valleys, that in the study area comprise the distal sectors of the Mondego and Lis drainage basins. Regionally six territorial units were distinguished which, given the characteristics of the natural systems and the development of human activities, determine different areas of risk: the limestone hills, sandy hills, floodplains, coastal plain, littoral and the probable neotectonic structures.
The limestone hills are particularly sensitive to geomorphological risks (landslides), the sandy hills are vulnerable not only to geomorphological risks (landslides, streams, erosion by land and water) but also to forest fires, alluvial plains are vulnerable to floods and flooding, coastal plain and its field of eolian dunes vulnerable to forest fires, the coast with high vulnerability to erosion of different types according to morphology of the coast and, finally, the probably active tectonic structures, particularly
those that are related to diapiric structures, are a source of seismic risk. The detailed geomorphological maps created were a very important tool for the localization and identification of the mineral resources outcrops and to improve the susceptibility maps also created.

Paraglacial geomorphology is the study of earth-surface processes, sediments, landforms, landsystems and landscapes that are directly conditioned by former glaciation and deglaciation. The withdrawal of glacier ice exposes landscapes that... more

Paraglacial geomorphology is the study of earth-surface processes, sediments, landforms, landsystems and landscapes that are directly conditioned by former glaciation and deglaciation. The withdrawal of glacier ice exposes landscapes that are in an unstable or metastable state, and consequently liable to modification, erosion and sediment release at rates greatly exceeding background denudation rates. This paper (1) reviews research on paraglacial processes, landforms and landscape change in a range of geomorphological settings; (2) explores the importance of paraglacial landscape modification and sediment recycling as a component of alternating glacial/nonglacial landscape evolution; (3) assesses the nature and significance of paraglacial facies in Quaternary stratigraphic sequences; and (4) develops a general model of the sequence of paraglacial landscape modification and the changing nature of paraglacial landsystems. Six paraglacial landsystems are identified: rock slopes, drift-mantled slopes, glacier forelands, and alluvial, lacustrine and coastal systems. Each contains a wide range of paraglacial landforms and sediment facies. Collectively these landforms and sediments (e.g. talus accumulations, debris cones, alluvial fans, valley fills, deltas and coastal barrier structures) can be conceptualised as storage components of an interrupted sediment cascade with four primary sources (rockwalls, drift-mantled slopes, valley-floor glacigenic deposits and coastal glacigenic deposits) and four terminal sediment sinks (alluvial valley-fill deposits, lacustrine deposits, coastal/ nearshore deposits and shelf/offshore deposits). Paraglacial sediment stores and sinks may form major sources of readily erodible sediment during the early stages of glacial cycles, leading to high rates of sediment transport during periods of glacier or ice-sheet expansion. Probably because of the limited preservation potential of paraglacial sediments that were subsequently overrun by glacier ice, identification of paraglacial facies in both terrestrial and marine settings has been almost exclusively limited to sequences that postdate the Last Glacial Maximum. The unifying concept of paraglacial geomorphology is that of glacially conditioned sediment availability. Relaxation of landscape elements to nonglacial conditions operates over timescales of 10 1->10 4 years, and is conditioned by both process and spatial scale. Rate of sediment reworking can be described by an exhaustion model. In the case of primary reworking of glacigenic sediment, the rate of reworking declines approximately exponentially through time, though extrinsic perturbation may rejuvenate paraglacial sediment flux long after termination of the initial period of paraglacial adjustment. Landscape-scale (particularly alluvial and coastal) systems may exhibit intrinsically complex responses due to reworking of secondary paraglacial sediment stores. The long relaxation time of such systems implies that many areas deglaciated in the Late Pleistocene or Early Holocene have still not fully adjusted (in terms of sediment supply) to nonglacial conditions.

Terrain features in Kachchh district, both inland and along the coast, are very much influenced by repeated Quaternary tectonic events, as well as by climate change. While the Great Rann of Kachchh and the Little Rann are the remnants of... more

Terrain features in Kachchh district, both inland and along the coast, are very much influenced by repeated Quaternary tectonic events, as well as by climate change. While the Great Rann of Kachchh and the Little Rann are the remnants of the receded Arabian Sea, the vast delta in the west has ceased to grow because of stream derangement related to tectonism. The coastal tract has features of submergence and emergence, which suggest eustatic changes and tectonism, while the landforms and streams inland bear testimony to many tectonic events. This paper discusses the geomorphic processes and landforms in the district, and assesses the potentials of landforms for land resources development.

Australia has numerous landforms and features, some unique, that provide a useful reference for interpreting the results of spacecraft orbiting Mars and exploring the martian surface. Examples of desert landforms, impact structures,... more

Australia has numerous landforms and features, some unique, that provide a useful reference for interpreting the results of spacecraft orbiting Mars and exploring the martian surface. Examples of desert landforms, impact structures, relief inversion, long-term landscape evolution and hydrothermal systems that are relevant to Mars are outlined and the relevant literature reviewed. The Mars analogue value of Australia's acid lakes, hypersaline embayments and mound spring complexes is highlighted along with the Pilbara region, where the oldest convincing evidence of life guides exploration for early life on Mars. The distinctive characteristics of the Arkaroola Mars Analogue Region are also assessed and opportunities for future work in Australia are outlined.

Detailed lithostratigraphic, geochemical, pedological, micromorphological and archaeological analyses were carried out at a stratigraphic sequence of Scafati, about 3 km east of ancient Pompeii. It comprises roughly the last 22,000 years... more

Detailed lithostratigraphic, geochemical, pedological, micromorphological and archaeological analyses were carried out at a stratigraphic sequence of Scafati, about 3 km east of ancient Pompeii. It comprises roughly the last 22,000 years of landscape history consisting of a multilayered succession of repeated volcanic deposition and pedogenesis. The former is caused by several phases of volcanic activity of Somma-Vesuvius, Campi Flegrei and Ischia, reflecting a large spectrum of eruption types including Plinian, sub-Plinian, Strombolian to Vulcanian and effusive volcanic events. The latter contains phases of volcanic quiescence leading to soil formations of different durations, intensities and soil-forming environments. Furthermore, the paleosols repeatedly reveal clear evidence of anthropogenic activity such as agriculture. Using this multiproxy approach, a holistic landscape evolution model was developed reconstructing the late Pleistocene and Holocene history of volcanic activity, soil formation and land use in the hinterland of Pompeii. This was correlated with the larger-scale climatic and human history of the Campania region.

This study presents a multiproxy record of Holocene environmental change in the region East of the Pechora Delta. A peat plateau profile (Ortino II) is analyzed for plant macrofossils, sediment type, loss on ignition, and radiocarbon... more

This study presents a multiproxy record of Holocene environmental change in the region East of the Pechora Delta. A peat plateau profile (Ortino II) is analyzed for plant macrofossils, sediment type, loss on ignition, and radiocarbon dating. A paleosol profile (Ortino III) is described and radiocarbon dated. A previously published peat plateau profile (Ortino I) was analyzed for pollen and conifer stomata, loss on ignition, and radiocarbon dating. The interpretation of the latter site is reassessed in view of new evidence. Spruce immigrated to the study area at about 8900 14 C yr B.P. Peatland development started at approximately the same time. During the Early Holocene Hypsithermal taiga forests occupied most of the present East-European tundra and peatlands were permafrost free. Cooling started after 5000 14 C yr B.P., resulting in a retreat of forests and permafrost aggradation. Remaining forests disappeared from the study area around 3000 14 C yr B.P., coinciding with more permafrost aggradation. The retreat of forests resulted in landscape instability and the redistribution of sand by eolian activity. The displacement of the Arctic forest line and permafrost zones indicates a warming of at least 2-3°C in mean July and annual temperatures during the Early Holocene. At least two cooling periods can be recognized for the second half of the Holocene, starting at about 4800 and 3000 14 C yr B.P.

In semi-arid areas vegetation is scarce and often dominated by individual shrubs on raised mounds. The processes of formation of these mounds are diverse and still debated. Often, shrub mound formation is directly related to the formation... more

In semi-arid areas vegetation is scarce and often dominated by individual shrubs on raised mounds. The processes of formation of these mounds are diverse and still debated. Often, shrub mound formation is directly related to the formation of vegetation patterns, thereby assuming that shrub mound formation is driven by biological interactions. We hypothesize that water-related erosion and sedimentation are also important drivers of shrub mound formation in the Northern Negev Desert of Israel. We test this hypothesis by combining field observations with model simulations. We studied shrub mounds in the semi-arid catchment of Sayeret Shaked in the Northern Negev Desert (200 mm annual precipitation). Height and diameter of shrub-canopy and shrub mounds were measured and micro-morphological techniques were used to reconstruct the formation of the shrub mounds. We used landscape evolution model LAPSUS to simulate shrub mound formation at short (single precipitation event) and longer (100 years) timescales at different slope angles. Both field and model results indicate that shrub mounds in Sayeret Shaked are at least partly formed by redeposition of eroded material below the shrubs, and by erosion and lowering of the surrounding crust. Additional model simulations suggest that mounds are formed most under low shrub density and large shrub-canopy diameter. Shrub mound formation increases with slope. In dryer and wetter climates than the studied 200 mm rainfall semi-arid climate zone, shrub mound formation is less likely.

The Brecon Beacons in southern Wales is a large upland area (900 km2) close to the periphery of the former British–Irish Ice Sheet. The geomorphology of the Brecon Beacons highlands and surrounding areas was mapped using satellite imagery... more

The Brecon Beacons in southern Wales is a large upland area (900 km2) close to the periphery of the former British–Irish Ice Sheet. The geomorphology of the Brecon Beacons highlands and surrounding areas was mapped using satellite imagery and a digital elevation model (DEM). A fragmentary pattern of glacial lineations is inferred to represent ice build-up in the mountains. A more

Human habitation patterns are constrained by natural resources and processes. Any regional archaeological project must therefore first determine the primary resources provided by the natural setting, including the availability of fresh... more

Human habitation patterns are constrained by natural resources and processes. Any regional archaeological project must therefore first determine the primary resources provided by the natural setting, including the availability of fresh water, arable land, mineral deposits, building stones, and natural harbors, and, second, investigate the geological processes that may have distorted the original archaeological record, including erosion, deposition, tectonic movement, and coastal progradation and regression. Only when the quality and quantity of these factors are known will archaeological field projects be able to establish site size, function, and duration and reconstruct and interpret the historic interrelation between human habitation and landscape evolution.

The privileged location of Venezuela along an active interplate deformation belt, despite of being a "so-called" developing country, has led to a long paleoseismic tradition as attested by 45 trench assessments since 1968. Since then, a... more

The privileged location of Venezuela along an active interplate deformation belt, despite of being a "so-called" developing country, has led to a long paleoseismic tradition as attested by 45 trench assessments since 1968. Since then, a first 2-trench study was carried out by the American Woodward-Clyde company across the Oca fault at Sinamaica. Since 1980, all further paleoseismic studies have been performed by FUNVISIS and the Uribante-Caparo hydroelectric project (southern Mérida Andes) became their first assessment where 22 huge trenches were bulldozer-dug. Except for these Compañía Anónima de Administración y Fomento Eléctrico (CADAFE) financed trenches and two others, all other assessments were for Petróleos de Venezuela S. A. —PDVSA-. In this paper, geographic and geologic factors, as well as logistic limitations, conditioning success in paleoseismic studies by trenching, shall be discussed based on the Venezuelan experience developed over the years. The scientific contribution of this approach refer to: confirmation of Holocene fault activity, slip-per-event and average slip rate of a given fault (or segment), seismic potential (repeat of maximum credible earthquakes) of known faults, fault segmentation, fault interaction as consequence of stress loading by stick-slip on contiguous faults, time-space distribution of seismic activity along a given tectonic feature, seismotectonic association of historical earthquakes and landscape evolution on the short term and its implications on the long-term evolution (poorly discussed since this is really part of the field of Neotectonics). In recent years (since 1999), a new approach has been introduced in Venezuela consisting in complementing the seismic history derived from trenching studies with the evaluation of seismically induced perturbations in the continuous Quaternary sedimentary record of (either active or fossil) lakes. The future of this discipline in Venezuela heads to more trenching and lake coring in order to gather more data on the previously mentioned aspects. Other paleoseismic approaches have been developed very little in Venezuela since either climate or the geodynamic setting do not favor their application.