Aeolian Geomorphology Research Papers - Academia.edu (original) (raw)

morphology and style of accumulation. Dunes respond rapidly to changes in wind conditions and the resulting changes in dune morphology are represented by bounding surfaces that are common in aeolian sandstones. After deposition, aeolian... more

morphology and style of accumulation. Dunes respond rapidly to changes in wind conditions and the resulting changes in dune morphology are represented by bounding surfaces that are common in aeolian sandstones. After deposition, aeolian strata may undergo deformation or be reworked by bioturbation, which disturbs primary lamination and creates its own suite of sedimentary structures. The preservation of aeolian strata within sedimentary systems is discussed.

ABSTRACT The modern Great Basin of the interior western United States is characterized by surface winds with considerable spatial and temporal variabilities. Wind records from the second half of the 20th century for 12 Great Basin... more

ABSTRACT The modern Great Basin of the interior western United States is characterized by surface winds with considerable spatial and temporal variabilities. Wind records from the second half of the 20th century for 12 Great Basin localities, analyzed with standard aeolian-sediment transport methods developed elsewhere in the world, reflect this complexity. The drift potential (DP) for aeolian deposits is generally moderate (DP 200– 400) in the western Great Basin and weak (DP b 200) in the central Great Basin where winds are
predominantly west-southwesterly. DP is relatively high (DP N 300) at the eastern edge of the Great Basin where the dominant prevailing wind direction is south-southwesterly. Both DP and resultant drift direction (RDD) are consistent with synoptic meteorological observations of the evolution of cold fronts in the Great Basin. Meteorological observations show that effective winds to produce dunes are most commonly the result of late winter–early spring cyclogenesis. There has been considerable temporal variability of DP in the latter half of the 20th century. Most of the Great Basin has experienced decreasing wind strength since 1973, consistent with recent studies of wind strength in North America and elsewhere. Dune morphology matches both localized RDD and temporal variations in DP reasonably well in the Great Basin. The results demonstrate that local topography can have an important influence on wind directionality, thus providing a cautionary note on the interpretation of dune morphology in the paleoclimatic and stratigraphic record.

Flow dynamics and sediment transport responses over a large, vegetated foredune at Prince Edward Island, Canada, during an offshore wind event are examined. Data were collected along an instrumented transect that extended from the dune... more

Flow dynamics and sediment transport responses over a large, vegetated foredune at Prince Edward Island,
Canada, during an offshore wind event are examined. Data were collected along an instrumented transect that
extended from the dune crest, down the lee-side (seaward) slope of the dune, across a wave-cut scarp, and on
to the back-beach. When the wind direction at the dune crest was approximately crest-normal (less than
about 15° deviation), the mean near-surface flow directions along the dune slope and on the back beach were
generally onshore, indicating reversed (onshore) flow relative to the regional (offshore) wind direction.
Although flow patterns were consistent with a lee-side recirculation eddy, large excursions in flow direction
were also prevalent, suggesting that the eddy was unstable and alternated with highly turbulent wake flow. As
wind direction at the crest veered to greater than 20° from crest-normal, lee-side winds shifted toward strongly
alongshore flowwith minimal directionally variability. On the dune slope, the wind vectorswere slightly offshore
whereas on the back-beach they were slightly onshore.
Wind speeds and sediment transport were greatest at the foredune crest and declined rapidly downslope due to
flow expansion and deceleration in the wake zone as well as to the influence of a sparse vegetation layer. Mean
particle counts (averaged over a 15-min interval) derived from laser sensors positioned at the crest were large
(7.76 per second) in comparison to those measured in the immediate lee of the crest (0.52 per second) and
farther down the dune slope (b0.13 per second). In contrast, the values were as large as 25.62 per second on
the middle of the back-beach, declining rapidly to a value of only 0.24 per second at the dune toe. Transport
intensity was highly variable with the largest Activity Parameter (AP = 0.5) values at the dune crest and on
the back-beach, and with the smallest values (AP b 0.1) on the lee-side dune slope down to the top of the
scarp. Calculations of sediment (particle) flux divergence between instrument stations show that deposition
was significant immediately downwind of the dune crest but negligible across most of the lower dune slope.
Deposition was also prevalent on the dune ramp below the scarp.
These results demonstrate that sediment transport across the beach–dune system was spatially discontinuous
during this offshore wind event. Rebuilding of the dune ramp at the toe of the scarp occurred quite independently
of, and with a different sediment source than, the broadening of the dune crest, which was fed with sediment
from the landward side of the foredune. Such process ‘decoupling’ is an example of the complexity by which
foredunes evolve or are maintained, and as with previous research reinforces the importance of offshore and
alongshore wind events to beach–dune morphodynamics.

The formation and evolution of parabolic aeolian dunes depend on vegetation, and as such are particularly sensitive to changes in environmental controls (e.g., temperature, precipitation, and wind regime) as well as to human disturbances... more

The formation and evolution of parabolic aeolian dunes depend on vegetation, and as such are particularly sensitive to changes in environmental controls (e.g., temperature, precipitation, and wind regime) as well as to human disturbances (e.g., grazing, agriculture, and recreation). Parabolic dunes can develop from the stabilisation of highly mobile barchan dunes and transverse dunes as well as from blowouts, as a consequence of colonisationand establishment of vegetationwhen aeoliansandtransport is reduced and/orwhenwater stress is relieved (by increasing precipitation, for instance). Conversely, existing parabolic dunes can be activated and may be transformed into barchan dunes and/or transverse dunes when vegetation suffers environmental or anthropogenic stresses. Predicted increases in temperature and drought severity in various regions raise concerns that dune activation and transformations may intensify, and this intensification would have far-reaching implications for environmental, social, and economic sustainability. To date, a broad examination of the development of parabolic dunes and their related transformations across a variety of climate gradients has been absent. This paper reviews existing literature, compares data on the morphology and development of parabolic dunes in a comprehensive global inventory, and scrutinises the mechanisms of different dune transformations and the eco-geomorphic interactions involved. This knowledge is then integrated into a conceptual framework to facilitate understanding and prediction of potential aeolian dune transformations induced by changes in environmental controls and human activities. This conceptual framework can aid judicious land management policies for better adaptations to climatic changes.

TUGAS 7 INDIVIDU GEOMORFOLOGI (Bentuklahan Aeolian)

Praktikum lapang dimulai dengan pemberangkatan dari ATM Center IPB melewati Tol Jagorawi yang merupakan tol pertama di Indonesia pada daerah fluviovulkanik, yakni terbentuk dari proses lahar Gunung Pangrango yang mengalir dan mengalami... more

Praktikum lapang dimulai dengan pemberangkatan dari ATM Center IPB melewati Tol Jagorawi yang merupakan tol pertama di Indonesia pada daerah fluviovulkanik, yakni terbentuk dari proses lahar Gunung Pangrango yang mengalir dan mengalami proses fluvial hingga ke Jakarta.

The extant terrestrial Paleoindian sites on the Delmarva Peninsula suggest a hunting emphasis. Interpretations about Paleoindian lifestyles in the Middle Atlantic coastal plain are greatly biased by marine transgression. Research... more

The extant terrestrial Paleoindian sites on the Delmarva Peninsula suggest a hunting emphasis. Interpretations about Paleoindian lifestyles in the Middle Atlantic coastal plain are greatly biased by marine transgression. Research conducted over the past two years at 44NH233 offers new insights into Paleoindian adaptations near the developing Chesapeake Bay. The geologic investigations provide an opportunity to assess regional models explaining the formation of Mockhorn Island along the Atlantic coast of the Delmarva Peninsula. The investigations at 44NH233 also offer a better appreciation of the natural processes impacting archaeological sites during the transition from a terrestrial environment to a sub-aqueous offshore setting. (A detailed analysis of the stone tools found at this site will be published in 2016 as a book chapter. The reference is: Dennis Stanford, Darrin Lowery, Margaret Jodry, and Michael Frank; Mockhorn Island and Insights into Paleoindian Coastal Adaptations, pp. 58-95. Chapter to be included in the book entitled In The Eastern Fluted Point Tradition, Volume II, edited by Joseph A. M. Gingerich, University of Utah Press).

Penyebaran endapan batubara di Indonesia cukup meluas baik di Indonesia bagian barat maupun Indonesia bagian timur. Provinsi Kalimantan Selatan adalah salah satu daerah penghasil batubara terbesar di Indonesia yang beribu kota di... more

Penyebaran endapan batubara di Indonesia cukup meluas baik di Indonesia bagian barat maupun Indonesia bagian timur. Provinsi Kalimantan Selatan adalah salah satu daerah penghasil batubara terbesar di Indonesia yang beribu kota di Banjarmasin dan terletak di sebelah selatan pulau Kalimantan. Di Provinsi Kalimantan Selatan ini memiliki salah satu cekungan penghasil batubara yang cukup besar di Indonesia yaitu Cekungan Barito. Pada saat ini batubara merupakan salah satu alternatif bahan bakar yang efisien selain minyak bumi dan gas alam. Keterdapatan batubara pun sangat dipengaruhi oleh kondisi geologi yang terjadi pada lingkungan pengendapannya. Kondisi tersebut akan mempengaruhi kuantitas dari batubara yang mencangkup geometri dari batubara tersebut. Geometri batubara sangat penting untuk diketahui dan dikaji dikarenakan akan mempengaruhi model geologi dari batubara tersebut dan nilai ekonomi dari batubara tersebut.Geometri lapisan batubara menuntut suatu pendekatan yang menyeluruh terhadap faktor-faktor pengendalinya.

full citation: Ford, R.L., Gillman, S.J., Wilkins, D.E., Clement, W.P., and Nicoll, K. 2010. Geology and Geomorphology of Coral Pink Sand Dunes State Park, Utah. In Anderson, P.B.; Chidsey, T.C. and Sprinkel, D.A. (Eds) Geology of Utah's... more

Archaeological, geoarchaeological, and geomorphological investigations were conducted at the Harleigh Knoll Site in Talbot County, Maryland. The site is located at the headwaters of a small tidal tributary that drains into Trippe Creek.... more

Archaeological, geoarchaeological, and geomorphological investigations were conducted at the Harleigh Knoll Site in Talbot County, Maryland. The site is located at the headwaters of a small tidal tributary that drains into Trippe Creek. The site and the associated knoll had evidence of prior human occupation on the surface of the forest floor. The evidence included a scatter of shell, some lithic stone tool manufacture debris, and several anomalous rounded river cobbles or boulders. Soils analysis revealed that the knoll is an aeolian landform or wind deposited dune. The knoll was created as a result of sand erosion from the creek bed located north of the site being reworked by intense northerly winds. The reworked sands were redeposited south of two converging streams over many millennia building the topographically elevated knoll. Archaeological testing revealed stratified prehistoric deposits associated with the Early Archaic, Late Archaic, and Late Woodland periods. These investigations also revealed that the knoll was used as an historic 17th century period cemetery.

Despite widespread recognition that landforms are complex Earth systems with process-response linkages that span temporal scales from seconds to millennia and spatial scales from sand grains to landscapes, research that integrates... more

Despite widespread recognition that landforms are complex Earth systems with process-response linkages that span temporal scales from seconds to millennia and spatial scales from sand grains to landscapes, research that integrates knowledge across these scales is fairly uncommon. As a result, understanding of geomorphic systems is often scale-constrained due to a host of methodological, logistical, and theoretical factors that limit the scope of how Earth scientists study landforms and broader landscapes. This paper reviews recent advances in understanding of the geomorphology of beach-dune systems derived from over a decade of collaborative research from Prince Edward Island (PEI), Canada. A comprehensive summary of key findings is provided from short-term experiments embedded within a decade-long monitoring program and a multi-decadal reconstruction of coastal landscape change. Specific attention is paid to the challenges of scale integration and the contextual limitations research at specific spatial and/or temporal scales imposes. A conceptual framework is presented that integrates across key scales of investigation in geomorphology and is grounded in classic ideas in Earth surface sciences on the effectiveness of formative events at different scales. The paper uses this framework to organize the review of this body of research in a 'scale aware' way and, thereby, identifies many new advances in knowledge on the form and function of subaerial beach-dune systems. Finally, the paper offers a synopsis of how greater understanding of the complexities at different scales can be used to inform the development of predictive models, especially those at a temporal scale of decades to centuries, which are most relevant to coastal management issues. Models at this (landform) scale require an understanding of controls that exist at both 'landscape' and 'plot' scales. Landscape scale controls such as sea level change, regional climate, and the underlying geologic framework essentially provide bounding conditions for independent variables such as winds, waves, water levels, and littoral sediment supply. Similarly, a holistic understanding of the range of processes, feedbacks, and linkages at the finer plot scale is required to inform and verify the assumptions that underly the physical modelling of beach-dune interaction at the landform scale.

Inverse maximum gross bedform-normal transport (IMGBNT) analysis has been applied to Context Camera (CTX) images of the largest dune field in Ganges Chasma on Mars. The dune field was selected for its position in a likely complex,... more

Inverse maximum gross bedform-normal transport (IMGBNT) analysis has been applied to Context Camera (CTX) images of the largest dune field in Ganges Chasma on Mars. The dune field was selected for its position in a likely complex, multi-directional wind regime. Results indicate that four main winds are responsible for simultaneous construction of the dune field, including along chasma winds from the ESE, winds blowing down a nearby re-entrant from the NE, winds blowing down the adjacent chasma wall from the NW, and chasma floor winds from the SW. Each wind represents a transport vector that dominates dune morphology at its respective edge of the dune field, such that the central axis of the dune field reflects the convergence of the three most prominent winds (ESE, NW, and SW). The Mars Regional
Atmospheric Modeling System (MRAMS) was run at twelve times throughout the martian year to provide context for the local wind patterns. Potential sand fluxes calculated from MRAMS output show that three major air flows from the ENE–E, NNE–NE, and NNW–N converge near the location of the dune field. These
flows likely correspond to the ESE, NE, and NW winds identified from IMGBNT analysis, respectively. MRAMS output shows that the flows with major northerly components are produced by larger-scale Hadley return flow constructively combining with nighttime downslope winds; the flow with a major easterly
component is likely produced by equatorial easterly ‘‘trade’’ winds constructively combining with the diurnal tide and/or local topography. Although the model correctly predicts the major elements of the local wind pattern, some aspects are either over- or underrepresented, demonstrating the value of using aeolian morphological analysis to conclusively constrain the major sand-moving winds on Mars. Overlapping High Resolution Imaging Experiment (HiRISE) images of barchanoid dunes at the northernmost edge of the dune field indicate that these dunes are currently migrating southward at ~5 m/Mars year (~2.6 m/Earth year); the direction of migration is consistent with both MRAMS predictions in this location and the NW/NE winds found from IMGBNT analysis. Dune morphology suggests that sand in
the northwestern part of the dune field is likely to be derived from the adjacent chasma wall to the north and northwest, and sand in the southeastern part of the dune field was probably transported from farther east along the main chasma floor.

Dune management along developed coasts has traditionally focussed on the suppression of the geomor-phic dynamics of the foredune to improve its role in sea defence. Because a stabilized foredune acts as an almost total barrier to aeolian... more

Dune management along developed coasts has traditionally focussed on the suppression of the geomor-phic dynamics of the foredune to improve its role in sea defence. Because a stabilized foredune acts as an almost total barrier to aeolian transport from the beach, the habitat diversity in the more landward dunes has degraded. With the overarching objective to mitigate this undesirable loss in biodiversity, dune management projects nowadays increasingly intend to restore aeolian dynamics by reconnecting the beach-dune system with notches excavated through the foredune. Here, we use repeat topographic survey data to examine the geomorphic response of a coastal dune system in the Dutch National Park Zuid-Kennemerland to five notches excavated in 2012–2013 within an 850-m stretch of the 20-m high established foredune. The notches were dug in a V-shape (viewed onshore), with a width between approximately 50 and 100 m at the top, a (cross-dune) length between 100 and 200 m, and excavation depths between 9 and 12.5 m. The 1 Â 1 m digital terrain models, acquired with airborne Lidar and UAV photogrammetry, illustrate that during the 3-year survey period the notches developed into a U-shape because of wall deflation, and that up to 8-m thick and 150-m long depositional lobes formed landward of the notches. Sand budget computations showed that the sand volume of the entire study area increased by about 22,750 m 3 /year, which, given the 850-m width of the study area, corresponds to an aeolian input from the beach of approximately 26.5 m 3 /m/year. Between 2006 and 2012 all wind-blown beach sand deposited on the seaward side of the foredune; since 2013, the notches have caused 75% of the sand to be deposited landward of the foredune. This highlights that the notches are highly effective conduits for aeolian transport into the back dunes. Future monitoring is required to determine for how long the notches will stimulate aeolian dynamics and if (and when) vegetation eventually starts to regrow and enforces the degeneration of the notches.

In 1961, Dr. Ralph Solecki reported a Chesapeake Bay Paleo-Indian projectile point discovery in AMERICAN ANTIQUITY. Solecki postulated that the “fluted point found along the shoreline at Poplar Island could be explained in terms of... more

In 1961, Dr. Ralph Solecki reported a Chesapeake Bay Paleo-Indian projectile point discovery in AMERICAN ANTIQUITY. Solecki postulated that the “fluted point found along the shoreline at Poplar Island could be explained in terms of worldwide climatic shifts and lowered sea level.” The Chesapeake Bay at present encompasses approximately 4,479 square miles of estuarine water and it contains almost 12,000 linear miles of coastline. Numerous archaeological sites occur along the margins of the bay and its tributaries. Thousands of these sites are regularly threatened by the daily onslaught of wind and wave activity. The Delmarva Peninsula, which encompasses the eastern margins of the bay, has revealed approximately 350 Clovis-style fluted projectile points. Later and potentially earlier Paleo-American sites have also been discovered. Most of these sites and their associated assemblages have been found as a result of active coastal erosion. The purpose of this paper is to highlight the erosion threats observed at Paleoindian sites. A few of these rapidly disappearing sites have been partially investigated over the past 35 years and offer unique insights into regional Paleoindian adaptations. Finally, the presentation will outline how Dr. Dennis Stanford has contributed to the analysis of these rapidly disappearing coastal Paleo-American sites.

In central Saudi Arabia the redness of sands observed on satellite imagery, often related to iron oxide amount, was used to better interpret geomorphic processes operating in the area. To compare variations between dune and interdune... more

In central Saudi Arabia the redness of sands observed on satellite imagery, often related to iron oxide amount, was used to better interpret geomorphic processes operating in the area. To compare variations between dune and interdune morphology, linear and dome dunes, and an ephemeral river partly buried under the sand sea, Nafud Al-Thuwayrat, a multiscale approach was used to identify the spatial variation in causes of iron oxide amounts and colour. Macro-scale mapping of Image Spectral Redness identified that the extent and intensity of colour grading across the orientation of well-defined linear and dome dune types, interdunes and the Wadi Al-Rimah, indicated sediment mixing of different provenance. Meso-scale chemical, physical and colour analysis of surface samples indicated that iron oxide coated grains were present within all the samples and was not the sole control on Image Spectral Redness. The reddest sediments were the best sorted medium-to fine-quartz sands with iron oxide bearing chemistry and the paler sediments contained coarser sands with additional feldspars, calcite and gypsum. Micro-scale analysis of grain characteristics found dune-interdune contrasts and that the reddest sands with iron coatings were of aeolian origin and the paler sands contained larger fluvial material mixed with reworked aeolian deposits. Dust in the area consists of high amounts of iron oxide and appears to be a major contributor to redness in the sand dunes. These controls on colour show the sand seas are paler westwards because a major river and local drainage systems deliver fluvial sediments from the carbonate and sandstone bedrock into the quartz rich aeolian material from the linear dunes. Evaporite deposits dominate in the paler interdunes, and south of the Wadi the dome dunes are the reddest as they are not migrating but building up. This multiscale approach has provided a modern analogy of processes for palaeoenvironmental studies.

We report the results of thermoluminescence (TL) dating applied to sand samples from the dune in Kepa Kujawska, Poland. The emphasis is on the estimation of the residual TL. The tests for bleaching of natural TL with the use of daylight... more

We report the results of thermoluminescence (TL) dating applied to sand samples from the dune in Kepa Kujawska, Poland. The emphasis is on the estimation of the residual TL. The tests for bleaching of natural TL with the use of daylight and a bleach simulator were carried out. From the results it follows that the residual TL is a significant part of the natural TL. The equivalent doses were determined by the regeneration method with the residual TL assumed as a starting level. The annual doses were calculated by means of gamma spectrometry. The ages of the bottom and top layers of the dune are 10.6 ka +/- 2.4 ka and 2.1 ka +/- 0.6 ka, respectively.

The Nahal Oz Reservoirin the coastal, semi-arid southwestern Israel was designed to enhance local irrigation of crops using reclaimed sewage water during the dry summer months. On March 2001, part of the western dike of the reservoir was... more

The Nahal Oz Reservoirin the coastal, semi-arid southwestern Israel was designed to enhance local irrigation of crops using reclaimed sewage water during the dry summer months. On March 2001, part of the western dike of the reservoir was breached and generated a flow release of 3.5 * 10 6 m 3 of secondary irrigation water that was channeled down the 1st order ephemeral loess stream (Nahal Yare'akh). The consequent 12-hour flood surge, with an estimated peak discharge of 1000 m 3 s −1 , inflicted severe loess erosion, agricultural, property and infrastructural damage downstream ($6 million). Post-flood mapping documented the geomorphic response to the flood which included channel scour and widening along the initial 2 km downstream of the reservoir where a spillway channel was formed. The increase in the crosssectional area was about 60% and had an estimated 170,000 m 3 of sediment bed, bank and floodplain erosion. Calculated maximum shear stress and stream power along this section are estimated at 300 Nm −2 and 900 wm −2 , respectively. The peak discharge at the end of this segment was estimated at 800 m 3 s −1 indicating only minor attenuation along this segment. Two km downstream of the breach, a wide braided fan indicated deposition of the eroded sediments. At the end of this segment the floodwater diverged into several watercourses and inundated tilled agricultural fields and neighborhoods. Downstream, 9 km from the reservoir, the discharge attenuated to 100 m 3 s −1 , slightly above bankfull. Further downstream and upon reaching the large Shikma stream the flow was already very low. This reduction in discharge is attributed to the anthropogenic infrastructureroads, neighborhoods and agricultural fields and the large transmission losses typical of sandy ephemeral streams. The study shows that channels within erodible materials respond to high peak discharges very locally. Erosional thresholds that severely incised the channel are only maintained for 2 km below the breached reservoir and as distance from the source area increases, available energy is substantially reduced due to high transmission losses, gentler valley gradients, very wide shallow flow and the ability of the drainage network to accommodate large discharges. Consequently, the geomorphic impact was limited to the first 2.6 km with only minor erosional or depositional evidence downstream. The current natural flow regime has only minor impact on the newly formed channel geometry below the breached dam. Accordingly, the channel geometry may be preserved for a relatively long time. However, channel recovery in this segment was rapid and within a few years all bare loess surfaces exposed during the flood have been covered by dense vegetation. The analysis also shows that Nahal Oz Reservoir's dam-break flood transmission losses and flood attenuation rates were extreme in comparison to other case studies. This artificial flood event in a desert environment offers a rare opportunity to quantify channel and bank erosion evolution processes during an extremely high-magnitude flood within highly erodible fine sediment as well as to detect the recovery processes a few years later.

Swarms of barchan dunes are common in arid environments. Unlike immobile or slowly moving dunes whose stratigraphy can be used to reconstruct paleoenvironmental changes, the high migration rate of barchans seems to prohibit their use as... more

Swarms of barchan dunes are common in arid environments. Unlike immobile or slowly moving dunes whose stratigraphy can be used to reconstruct paleoenvironmental changes, the high migration rate of barchans seems to prohibit their use as geoarchives. In this paper, a possible use of barchan swarms for paleoenvironmental reconstructions is presented. The approach is based on dune migration. In a case study based on 500 dunes in the Pampa de Jaguay aeolian transport corridor in coastal southern Peru, middle to late Holocene changes in the supply of aeolian material are inferred from calculating the time of dune initiation at the coastline. Limitations posed by the assumptions underlying this approach are discussed.

Loess is common in the Mid-Atlantic region of the United States south of the Late Wisconsinan glacial border particularly along rivers draining the glaciated areas of Pennsylvania, New Jersey, and New York. The broadest deposits occur on... more

Loess is common in the Mid-Atlantic region of the United States south of the Late Wisconsinan glacial border particularly along rivers draining the glaciated areas of Pennsylvania, New Jersey, and New York. The broadest deposits occur on the flat landscapes of the Delmarva Peninsula in Maryland where two episodes of deposition have been identified. The earlier Miles Point Loess has a limited distribution and is buried by the more widespread Paw Paw Loess. OSL and 14C dates place deposition of the Miles Point Loess during MIS 3. The well developed paleosol formed in the Miles Point Loess acts as a stratigraphic marker. The Paw Paw Loess buries Clovis age cultural materials which date deposition to the end of the Pleistocene. Loess deposits and paleosols are critical in understanding regional landscape evolution, Late Pleistocene environments, and early North American cultural history. Mapping the extent of loess in the Mid-Atlantic using the Natural Resources Conservation Service's gSSURGO database overrepresents loess in some areas and underrepresents in others.

Sand control measures in any dune-covered area in the Thar desert are heavily dependent on the concept of vegetative propagation on the dunes. Mechanical and chemical control methods are not popular. The activities are often directed... more

Sand control measures in any dune-covered area in the Thar desert are heavily dependent on the concept of vegetative propagation on the dunes. Mechanical and chemical control methods are not popular. The activities are often directed towards planting of trees and shrubs on the reactivated slopes of the high dunes, especially the downwind end of the dunes. While these practices have shown some results, it is more appropriate if the sites and the types of control are decided on the basis of a knowledge on the dune types, their morphology and history of development, their mobility, the air and sand flow patterns over and around them, the expected changes upon any interference to the sand body, as well as the environmental set up of the dunes, including vegetation status, land use practices, etc. A great variety of dunes exist in the Thar desert, which can be broadly grouped under the "old" and the "new" dunes. The new dunes, especially the barchans and the barchanoids, are most mobile and can at best be tackled by mechanical means.

The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This article presents an extensive review of the physics of wind-blown sand and... more

The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This article presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other smallscale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan.

ABSTRACT This study identifies anthropogenically disturbed areas and barren playa surfaces as the two primary dust source types that repeatedly contribute to dust storm events in the eastern Great Basin of western Utah, U.S.A. This... more

ABSTRACT This study identifies anthropogenically disturbed areas and barren playa surfaces as the two primary dust source types that repeatedly contribute to dust storm events in the eastern Great Basin of western Utah, U.S.A. This semi-arid desert region is an important contributor to dust production in North America, with this study being the first to specifically identify and characterize regional dust sources. From 2004 to 2010, a total of 51 dust event days (DEDs) affected the air quality in Salt Lake City, UT. MODIS satellite imagery during 16 of these DEDs was analyzed to identify dust plumes, and assess the characteristics of dust source areas. A total of 168 plumes were identified, and showed mobilization of dust from Quaternary deposits located within the Bonneville Basin. This analysis identifies 4 major and 5 secondary source areas for dust in this region, which pro- duce dust primarily during the spring and fall months and during moderate or greater drought conditions, with a Palmer Drought Index (PDI) of −2 or less. The largest number of observed dust plumes (~60% of all plumes) originated from playas (ephemeral lakes) and are classified as barren land cover with a silty clay soil sediment surface. Playa surfaces in this region undergo numerous recurrent anthropogenic disturbances, including mili- tary operations and anthropogenic water withdrawal. Anthropogenic disturbance is necessary to produce dust from the vegetated landscape in the eastern Great Basin, as evidenced by the new dust source active from 2008 to 2010 in the area burned by the 2007 Milford Flat Fire; this fire was the largest in Utah's history due to extensive cover of invasive cheatgrass (Bromus tectorum) along with drought conditions. However, dust mobili- zation from the Milford Flat Burned Area was limited to regions that had been significantly disturbed by post-fire land management techniques that consisted of seeding, followed by chaining or tilling of the soil. Dust storms in the eastern Great Basin negatively impact air quality and transportation in the populated regions of Utah; this study details an improved forecasting protocol for dust storm events that will benefit transportation planning and improve public health.

This study highlights a significant methodological and practical issue involving the use of a magnetic compass in aeolian studies in the field. Geomagnetic declination can significantly affect field measurements of wind direction from... more

This study highlights a significant methodological and practical issue involving the use of a magnetic compass in aeolian studies in the field. Geomagnetic declination can significantly affect field measurements of wind direction from anemometers as well as measurement of the orientation of geomorphic features such as sand dunes, depending on geographic location. It is therefore surprising how often methodological descriptions of published aeolian studies, including those in southern Africa, neglect to describe any declination corrections applied to field measurements or instrumental records. This results in uncertainty in the validity of data reported in such studies, particularly where actual wind directions may be very different (>20° in some cases) from measured values. Drawing from examples in the literature from southern Africa and other key locations globally, this study discusses the need for greater clarity in the declination corrections applied when wind direction is being measured and reported, especially where wind datasets from different sources are being used or integrated, or when published studies are being compared.

Kiseiba Oasis and depression are located in southern Egypt between the Selima Sand Sheet to the west and the Nile to the east, an important area that hosted Late Cenozoic drainage, Middle Pleistocene lakes, and numerous Paleolithic and... more

Kiseiba Oasis and depression are located in southern Egypt between the Selima Sand Sheet to the west and the Nile to the east, an important area that hosted Late Cenozoic drainage, Middle Pleistocene lakes, and numerous Paleolithic and Neolithic cultural sites. A synthesis of orbital data, field surveying and near-surface stratigraphy provides new insights into the Quaternary history of this region. Shuttle Imaging Radar data show a complex of fluvial channels that are due to stringers of surficial fluvial lag, subsurface fluvial deposits, and areas of deep alluvium. Three topographic surfaces are described: 1) the Atmur El-Kibeish, above 230 m elevation, which displays a linear pattern of light radar returns, possibly formed from northeast drainage; 2) the Acheulean Surface, at 200 m elevation, that has dark radar patterns resulting from thick alluvium bounded by pebble sand and calcrete strata, and 3) the Kiseiba Surface, below 190 m, that has a complex series of surface and subsurface fluvial and aeolian sediments. Initial drainage from the Early through Middle Pleistocene was to the northeast, which may have lasted through the Last Interglacial. Later reworking of sediments during the Last Glacial Maximum and the Holocene resulted in topographic inversion, with any subsequent local drainage on the Kiseiba Surface to the southwest, towards the Kiseiba Scarp.

This paper discusses the advance of the speleothem luminescence research. Potential, resolution and limitations of high resolution luminescence speleothem proxy records of Paleotemperature, Solar Insolation, Solar... more

This paper discusses the advance of the speleothem luminescence
research. Potential, resolution and limitations of high resolution luminescence speleothem proxy records of
Paleotemperature, Solar Insolation, Solar Luminosity, Glaciations, Sea Level advances, Past Precipitation, Plants
Populations, Paleosoils, Past Karst Denudation, Chemical Pollution, Cosmic Rays Flux variations, Cosmogenic
Isotopes production and Supernova Eruptions in the Past, Advances of Hydrothermal Waters, and Techtonic Uplift are
discussed. It is demonstrated that speleothems allow extremely high resolution (higher than in any other paleoclimatic
terrestrial archives) and long duration of records. Some speleothems can be used as natural climatic stations for
obtaining of quantitative proxy records of Quaternary climates with annual resolution.

This field trip follows the evolution and encroachment route of aeolian (winddriven) sand and vegetated linear dunes (VLDs) into the northwestern (NW) Negev during the late Pleistocene, from the Egypt -Israel border to the dunes'... more

This field trip follows the evolution and encroachment route of aeolian (winddriven) sand and vegetated linear dunes (VLDs) into the northwestern (NW) Negev during the late Pleistocene, from the Egypt -Israel border to the dunes' easternmost location at Ramat Beqa. Along this excursion we will present the morphology, internal structure, chronostratigraphy, sedimentology and dynamics of the dunes and demonstrate the episodes of their mobilization, activity and quiescence. This will enable a comprehensive understanding of the forces that control vegetated linear dune elongation, accretion and stabilization.

This paper explores historical evolution of blowouts at Cape Cod National Seashore (CCNS), USA — a site that hosts one of the world's highest densities of active and stabilized blowouts. The Spatial–Temporal Analysis of Moving Polygons... more

This paper explores historical evolution of blowouts at Cape Cod National Seashore (CCNS), USA — a site that
hosts one of the world's highest densities of active and stabilized blowouts. The Spatial–Temporal Analysis of
Moving Polygons (STAMP) method is applied to a multi-decadal dataset of aerial photography and LiDAR to
extract patterns of two-dimensional movement andmorphometric changes in erosional deflation basins and depositional
lobes. Blowout development in CCNS is characterized by several geometric (overlap) and movement
(proximity) responses, including: i) generation and disappearance, ii) extension and contraction, iii) union or
division, iv) clustering and v) divergence by stabilization. Other possible movement events include migration,
amalgamation and proximal stabilization, but they were not observed in this study. Generation events were
more frequent than disappearance events; the former were highest between 1985 and 1994, while the latter
were highest between 2000 and 2005. High rates of areal change in erosional basins occurred between 1998
and 2000 (+3932 m2 a−1), the lowest rate (+333 m2 a−1) between 2005 and 2009, and the maximum rate
(+4589 m2 a−1) between 2009 and 2011. Union events occurred mostly in recent years (2000–2012), while
only one division was observed earlier (1985–1994). Net areal changes of lobes showed gradual growth from a
period of contraction (−1119 m2 a−1) between 1998 and 2000 to rapid extension (+2030 m2 a−1) by 2010,
which is roughly concurrent with rapid growth of erosional basins between 2005 and 2009. Blowouts extended
radially in this multi-modal wind regime and, despite odd shapes initially, they became simpler in form (more
circular) and larger over time. Net extension of erosional basins was toward ESE (109°) while depositional
lobes extended SSE (147°). Lobes were aligned with the strongest (winter) sand drift vector although their
magnitude of areal extension was only 33% that of the basins. These differences in extension responses likely
result from more complex and evolving flow-form interactions inside erosional basins. Historical photographs
and CCNS documents suggest that blowout evolution may be influenced by land-use changes, such as revegetation
campaigns in 1985 that were followed by high blowout generation. High magnitude regional storm events
(e.g., hurricanes) also play a role. The analytical framework presented provides a systematic means for twodimensional
geomorphic change detection and pattern analysis that can be applied to other landscapes.

The Cafayate depression is a dry valley located in the Pre-Andean region of northwest Argentina. The area shows the development of a large dune field. Its significance has been established from geomorphological and mineralogical evidence,... more

The Cafayate depression is a dry valley located in the Pre-Andean region of northwest Argentina. The area shows the development of a large dune field. Its significance has been established from geomorphological and mineralogical evidence, grain shape characteristics and chronological data (OSL dating, archaeological remains, and historical data. The dating results were between 1000-1100 AD to1740-1830 AD showing that the aeolian dynamics remained active during the last millennium. It was not possible to identify stabilized phases marked by ruptures or paleosol development. Nevertheless, other regional and local proxies from Northwest Argentina (archaeological, documentary, etc.) were used to complete the interpretative framework to propose the paleoenvironmental evolution of the area. In addition, human activity and land use must be considered as a complementary factor affecting aeolian dynamics during the most recent stage.

The White Sands Dune Field, New Mexico (USA), provides a unique opportunity to study sources and eolian transport of sand. End member mixing analysis provides unbiased correlation of the grain size distributions of populations that mix... more

The White Sands Dune Field, New Mexico (USA), provides a unique opportunity to study sources and eolian transport of sand. End member mixing analysis provides unbiased correlation of the grain size distributions of populations that mix sands from four different local source surface types. Textural differences between sources allow local transport paths to be deduced. In total, 1214 surface samples from 10 dunes and 2 downwind-oriented transects were collected. Neither elevation on the dune, lee or stoss location nor distance downwind correlated with mean grain size, coarsest 10% (D 90), or sorting. Instead, grain size distributions are controlled by mixing of locally sourced sand populations. Adjacent dunes can have different mean grain sizes, resulting from different local source populations. Local within-dune and between-dune variability resulting from different sand sources dominates any larger-scale trends across and within dunes. Four sand populations are identified, based on microscopically observable differences in grain size, shape and angularity. Each correlates with high loading of a different statistical factor, derived from End Member Mixing Analysis. End Member 1 (EM1) correlates with well-sorted populations of finer-grained, equant, rounded sands. EM2 correlates with samples that contain moderately sorted populations containing angular blades and crystal aggregates associated with erosional interdunes. EM3 is associated with samples of moderately to poorly sorted fine-grained sand containing fine sand-sized gypsum needles collected from areas of vegetated interdunes, and EM4 is associated with moderately well sorted coarse-and very coarse-grained sands collected from granule ripples. These results suggest that downwind mixing of different populations and segregation by different depositional processes influence grain size distributions in the dune field, rather than by dune-scale or erg-scale transport and sorting.

The Third International Planetary Dunes Workshop took place in Flagstaff, AZ, USA during June 12–15, 2012. This meeting brought together a diverse group of researchers to discuss recent advances in terrestrial and planetary research on... more

The Third International Planetary Dunes Workshop took place in Flagstaff, AZ, USA during June 12–15, 2012. This meeting brought together a diverse group of researchers to discuss recent advances in terrestrial and planetary research on aeolian bedforms. The workshop included two and a half days of oral and poster presentations, as well as one formal (and one informal) full-day field trip. Similar to its predecessors, the presented work provided new insight on the morphology, dynamics, composition, and origin of aeolian bedforms on Venus, Earth, Mars, and Titan, with some intriguing speculation about potential aeolian processes on Triton (a satellite of Neptune) and Pluto. Major advancements since the previous International Planetary Dunes Workshop include the introduction of several new data analysis and numerical tools and utilization of low-cost field instruments (most notably the time-lapse camera). Most presentations represented advancement towards research priorities identified in both of the prior two workshops, although some previously recommended research approaches were not discussed. In addition, this workshop provided a forum for participants to discuss the uncertain future of the Planetary Aeolian Laboratory; subsequent actions taken as a result of the decisions made during the workshop may lead to an expansion of funding opportunities to use the facilities, as well as other improvements. The interactions during this workshop contributed to the success of the Third International Planetary Dunes Workshop, further developing our understanding of aeolian processes on the aeolian worlds of the Solar System.

Holocene drift-sand activity in the northwest European sand belt is commonly directly linked to population pressure (agricultural activity) or to climate change (e.g. storminess). In the Pleistocene sand areas of the Netherlands,... more

Holocene drift-sand activity in the northwest European sand belt is commonly directly linked to population pressure (agricultural activity) or to climate change (e.g. storminess). In the Pleistocene sand areas of the Netherlands, small-scale Holocene drift-sand activity began in the Mesolithic, whereas largescale sand drifting started during the Middle Ages. This last phase not only coincides with the intensification of farming and demographic pressure but also is commonly associated with a colder climate and enhanced storminess. This raises the question to what extent drift-sand activity can be attributed to either human activities or natural forcing factors. In this study, we compare the spatial and temporal patterns of drift-sand occurrence for the four characteristic Pleistocene sand regions in the Netherlands for the period between 1000 BC and AD 1700. To this end, we compiled a new supra-regional overview of drift-sand activity based on age estimates (14C, optically stimulated luminescence (OSL), archaeological and historical ages). The occurrence of sand drifting was then compared in time and space with historical-route networks, relative vegetation openness and climate. Results indicate a constant but low drift-sand activity between 1000 BC and AD 1000, interrupted by a remarkable decrease in activity around the BC/AD transition. It is evident that human pressure on the landscape was most influential on initiating sand drifting: this is supported by more frequent occurrences close to routes and the uninterrupted increase of drift-sand activity from AD 900 onwards, a period of high population density and large-scale deforestation. Once triggered by human activities, this drift-sand
development was probably further intensified several centuries later during the cold and stormier ‘Little Ice Age’ (LIA; AD 1570–1850).

A B S T R A C T Dunefields are very common in the northern coastal zone of northeast Brazil. They have the potential to yield important information about paleoclimate, paleo-winds and regional winds and their response to sea-level... more

A B S T R A C T Dunefields are very common in the northern coastal zone of northeast Brazil. They have the potential to yield important information about paleoclimate, paleo-winds and regional winds and their response to sea-level fluctuations during the Holocene. We reconstructed the coastal dunes geochronological evolution of northwest Ceará State – Brazil, in the last 3000 cal yrs BP, using detailed analyses of lithostratigraphy, microfossil (for-aminifera), wind regime, dune monitoring and 8 radiocarbon dates. The chronology was based on 14 C dating in eolianites and monitoring transversal mobile dunes movement processes. Radiocarbon date results indicated that the dunes corresponding to eolianites revealed ages between 2760–2480 and 980–750 cal yrs BP, suggesting that the vast transversal mobile dunefields were formed after this period in similar condition to the current sea-level. We considered that the material transportation by the prevailing east winds towards the transversal dunes is estimated in the order of 11.0 m/year, thus the current aeolian system is less than 1000 yrs BP.

atmospheric dust loads. Poor agricultural practices were implicated for triggering widespread eolian erosion and heightened dust emissions, but this assumption is called into question. This study classified land surface changes in... more

atmospheric dust loads. Poor agricultural practices were implicated for triggering widespread eolian erosion and heightened dust emissions, but this assumption is called into question. This study classified land surface changes in southwest Kansas from aerial images taken in 1936 and 1939 to infer surficial processes, dust sources, and associated emissivity. In total, seven distinctive surface classes were identified from an ArcGIS analysis of spectral reflectance values connected to surface vegetation cover and eolian activity, demonstrating a strikingly heterogeneous landscape response to the drought. Stratigraphic studies indicate accumulation of up to 4 m of eolian sand in places with erosion of a subjacent silty pre-1930s soil surface. Potential dust
emissivity estimates for particulate matter were derived from the distribution of classified land surfaces and from empirical relations on analogous dust emissive surfaces in the western US. Over 60% of total suspended particles in 1939 were inferred to be derived from uncultivated sandy surfaces and eolian landforms within the study area, with the remainder from human-modified surfaces. The PM2.5 and PM10 emissivity estimates for a single dust event with winds over 6 m s−1 in the study area were 510–4514 and 4700–41,607 μg m−3 d−1, respectively, similar in magnitude to current dust storm events
from North Africa and East Asia. Drought frequency is forecast to increase in late 21st century, potentially with greater severity than the Dust Bowl and may be associated with magnitude increase in atmospheric dust loads.

The interaction of wind and water over time is arguably the key influence upon the contemporary geomorphology and longer-term landscape development of arid regions of the world. Aeolian processes in arid and semi-arid areas need constant... more

The interaction of wind and water over time is arguably the key influence upon the contemporary geomorphology and longer-term landscape development of arid regions of the world. Aeolian processes in arid and semi-arid areas need constant monitoring, as they often translate into sand encroachment, a common form of land degradation. The monitoring of aeolian geomorphic units is rendered through repeated and objective mapping in order to detect change. For this purpose we employed Landsat historical and present imagery data (from 1984 to 2014) in a hybrid-automated classification method involving visual interpretation and a customised classification scheme, proposed for this particular study. The entire analysis is supported by thorough ground truth data, including spectral field measurements of sand accumulations and psamophyte vegetation, using a full-range Vis/NIR field spectroradiometer and 30 m resolution digital elevation data of Shuttle Radar Topography Mission (SRTM, freely available from US Geological Survey web tools). The final objective is to argue driving forces, anthropic vs. natural, source areas and to understand the trend metrics of this desertification process. In the Oum Zessar study area, in Tunisia, the overall results show that there was substantial change in several landscape components in the last decades, related to increased anthropic pressure and settlement, agricultural policies and national development strategies. One of the concerning aspects is the increase of sand units coverage over the last three decades by 21%. This study is part of the WADIS-MAR Demonstration Project, funded by the European Commission through the Sustainable Water Integrated Management (SWIM) Programme (www.wadismar.eu).

The results from three years of surveying and monitoring a dynamic foredune and dunefield restoration effort on Vancouver Island, Canada is presented. Complete removal of foredune vegetation occurred in three phases spaced a year apart in... more

The results from three years of surveying and monitoring a dynamic foredune and dunefield restoration effort on Vancouver Island, Canada is presented. Complete removal of foredune vegetation occurred in three phases spaced a year apart in an effort to control invasive Ammophila spp. The collection of airborne LIDAR, orthophotographs, and bi-monthly topographic surveys provided a means to quantify and examine sediment budgets and geomorphic responses. Three survey swaths, corresponding with each phase of vegetation removal, were established to provide detailed topographic coverage over the impacted beach, foredune, and dunefield landscape units. The swath corresponding with the first phase of removal recorded a positive sediment budget of 1.3 m3 m−2 after 3 years. A control swath, with data collected for a year prior and two years following removal, exhibited a distinct pulse of sediment delivery into the dunefield unit with a maximum gain of 0.03 m3 m−2 pre-removal compared to 0.11 m3 m−2 post-removal. Vegetation analysis zones, associated with each of the three swaths, demonstrate a range of vegetation responses due to variation in the vegetation removal and subsequent re-invasion or removal methods employed. The first site to be cleared of vegetation, received ongoing invasive re-growth control, and three years following removal vegetation cover dropped from 57% in 2009 to 13% in 2012 (-44%). An adjacent site was cleared of vegetation two years later (only 1 year of recovery) but experienced rapid Ammophila re-invasion and percent cover changed from from 61% in 2009 to 26% in 2012 (-35%). The data presented provides insights for improving the application of sediment budget monitoring in dynamic restorations and discusses the potential for detailed spatial-temporal survey data to improve our understanding of meso-scale landscape morphodynamics following foredune disturbance. Overall, the vegetation removal treatments reduced the extent of invasive grass and increased dunefield mobility and dynamic activity.

In present day Polish coastal dunes' development, heavy storms and human activity play a significant role. Natural or almost natural dune processes and accumulation of the coast is observed only in a few places, such as the S ´ wina Gate... more

In present day Polish coastal dunes' development, heavy storms and human activity play a significant role. Natural or almost natural dune processes and accumulation of the coast is observed only in a few places, such as the S ´ wina Gate Sandbar (also called barrier). As far as the spit number and morphology of the youngest ridges is concerned, they are different in the western, the middle and the eastern part. In the western part, ridges are smaller and closer to each other, thus depressions between them are narrower. Moreover, beach is widely covered by small hillocks. In the middle part, ridges are higher but narrower. Likewise, depressions between them are wider. The beach is wide and covered by large numbers of plants and dune hillocks. In the eastern part, dunes are also high but tend to be narrow, with steep seaside slope having the most frequent occurrence. Depressions and beach are narrow. The number of plants is not considerable compared with other parts. Since 1997 an increase of the new dune ridge on the still developing beach has been observed. Each year the beach is becoming wider and covered by larger number of plants. Plants lead to the development of new dunes and increase of the sandbar. The new foredune ridge consists of several hillocks joined into irregular ridge. This new first ridge is also shaped by storm waves but still becomes a real ridge. This development may be caused by continuous sand supply and by very strong north and west winds. A lot of different dune psammophyties on the beach are in favour of sand fixing on the increasing beach far from the first ridge. Only on part of spit with a tendency to erosion, accumulation of the dunes is not to be observed. Additionally, human activity stops aeolian accumulation and plant growth on the beach.

Evidence from a field study on wind flow and sediment transport across a beach–dune system under onshore and offshore conditions (including oblique approach angles) indicates that sediment transport response on the back-beach and stoss... more

Evidence from a field study on wind flow and sediment transport across a beach–dune system under onshore and
offshore conditions (including oblique approach angles) indicates that sediment transport response on the back-beach and stoss
slope of the foredune can be exceedingly complex. The upper-air flow – measured by a sonic anemometer at the top of a 35m tower
located on the dune crest – is similar to regional wind records obtained from a nearby meteorological station, but quite different from
the near-surface flow field measured locally across the beach–dune profile by sonic anemometers positioned 20 cm above the sand
surface. Flow–form interaction at macro and micro scales leads to strong modulation of the near-surface wind vectors, including
wind speed reductions (due to surface roughness drag and adverse pressure effects induced by the dune) and wind speed increases
(due to flow compression toward the top of the dune) as well as pronounced topographic steering during oblique wind approach
angles.
A conceptual model is proposed, building on the ideas of Sweet and Kocurek (Sedimentology 37: 1023–1038, 1990), Walker and
Nickling (Earth Surface Processes and Landforms 28: 111–1124, 2002), and Lynch et al. (Earth Surface Processes and Landforms 33:
991–1005, 2008, Geomorphology 105: 139–146, 2010), which shows how near-surface wind vectors are altered for four regional
wind conditions: (a) onshore, detached; (b) onshore-oblique, attached and deflected; (c) offshore, detached; and (d) offshore-oblique,
attached and deflected. High-frequency measurements of sediment transport intensity during these different events demonstrate that
predictions of sediment flux using standard equations driven by regional wind statistics would by unreliable and misleading. It is
recommended that field studies routinely implement experimental designs that treat the near-surface wind field as comprising true
vector quantities (with speed and direction) in order that a more robust linkage between the regional (upper air) wind field and the sediment transport response across the beach–dune profile be established.

Equilibrium concepts are widespread in aeolian geomorphology, especially those incorporating time-averaged parameterizations of fluid flow and sediment transport. The main objective of this chapter is to reflect critically on whether a... more

Equilibrium concepts are widespread in aeolian geomorphology, especially those incorporating time-averaged parameterizations of fluid flow and sediment transport. The main objective of this chapter is to reflect critically on whether a new paradigm based on coherent flow structures (CFS) is emerging as a viable alternative to the traditional steady-state perspective on aeolian processes. A survey of recent research addressing the existence and nature of CFS in aeolian systems indicates that: (i) there is as yet no convincing evidence in support of the classic bursting process or of any discrete flow structure with a characteristic topology (e.g., hairpin vortex) for the case of near-surface boundary layer flow over flat sandy surfaces (with or without saltation); (ii) there are instances in which near-surface vortices of varying geometry are found in association with small obstacles (e.g., logs, pebbles, vegetation clumps) on sandy surfaces, but it is not always apparent what the pattern of erosion or deposition in the vicinity of the obstacle will be, given that there are additional controls that involve surface hardness and sediment delivery from upwind; (iii) flow over aeolian dunes is generally well understood and very similar to flow over fluvial dunes with characteristic zonation, including flow acceleration and streamline compression on the stoss slope and a recirculation eddy and wake region in the lee; and (iv) the importance of these dune-related flow zones to sediment transport response is more reliably understood through examination of a range of turbulence parameters (e.g., Reynolds stress, turbulent kinetic energy) in addition to the time-averaged flow quantities alone. In order to advance our understanding of CFS in aeolian geomorphology, it will be essential to develop better technologies for high-frequency monitoring of wind and sediment flux, to focus attention on sediment transport events with specific topologies (e.g., streamers) rather than attempt to capture flow events and hope that there is an accompanying transport signal, to move beyond simple quadrant analysis and adopt analytical methods that elucidate the time-history of event signatures, and to reformulate existing time-averaged parameterizations of sediment flux to incorporate event-based information.

The study of active and stabilized late Quaternary aeolian landforms provides important proxies for past climate events and environmental transitions. Despite an overall increase in the study of aeolian landforms in previously glaciated... more

The study of active and stabilized late Quaternary aeolian landforms provides important proxies for past climate events and environmental transitions. Despite an overall increase in the study of aeolian landforms in previously glaciated and coastal settings in eastern North America, the history of aeolian sedimentation in many unglaciated inland alluvial settings remain poorly understood. This study reports on the geochronology and depositional history of aeolian landforms and sediments in the unglaciated upper Ohio Valley at the Sandy Springs site. Aeolian landforms and sediments include complex, linear, barchan-like, and climbing dunes; an interdune sand sheet; and sandy loess that blankets high valley surfaces. At Sandy Springs, aeolian dune sands and sandy loess are restricted to intermediate (S2) and higher (S3) geomorphic surfaces. Eight optically stimulated luminescence age estimates constrain the initiation of aeolian processes on the S2 surface to sometime after 17 ka and episodic deposition on the S2 and S3 surfaces between 11 and 1.4 ka. The distribution of aeolian sediments at Sandy Springs is influenced by several past factors including local wind fetch potential, sediment availability, and underlying alluvial topography. Sediment availability is interpreted as the primary factor controlling aeolian processes and appear linked to several pan-regional paleoclimate events. Sandy loess deposition at ca. 8.2 ka on the S3 surface may reflect hydrologic variability and cooling, associated with the final pulse of meltwater into the North Atlantic from the Laurentide Ice Sheet. Dune reactivation and erosion at ca. 4.5 ka on the S2 surface indicate enhanced sediment availability possibly associated with drought conditions. These results illustrate that the deciphering the coupled fluvial-aeolian records in this catchment of the Ohio River provides new insight into the nature of changing surface processes against the backdrop of climate variability over the past ca. 20 ka.

Numerous palaeoenvironmental and archaeological studies from southern Arabia (Yemen and Oman) have revealed strong relations between phases of human settlements and climate change linked to the Indian monsoon system. Analyses on... more

Numerous palaeoenvironmental and archaeological studies from southern Arabia (Yemen and Oman) have revealed strong relations between phases of human settlements and climate change linked to the Indian monsoon system. Analyses on speleothems, cave fills, lacustrine deposits and palaeo-mangroves have shown that during the Early to Mid-Holocene, a humid Optimum culminated around 9000e8000 cal BP. New results on inland speleothems and cave sediments from the Jebel Qara (southern Oman) are crucial in our depiction of Early and Mid-Holocene climatic evolution and cultural dynamics of the region. These aspects are discussed here, based on new archaeological surveys, excavations, geoarchaeological and micromorphological studies, aiming to better understand connections with Terminal Pleistocene and Early Holocene autochthonous cultures of southern Arabia. Our results suggest that the final Pleistocene was marked by strong aridity, which promoted a widespread thermoclastism within rock shelter and deposition of aeolian sand; in contrast, the transition towards the Holocene is marked (since c.12,000 cal BP) by a progressive increasing in environmental humidity, which permitted the formation of thick strata of peridesert loess. After this phase, the environmental humidity of the Jebel increased and permitted the existence of a large community of land snails; the latter were exploited by Early Holocene hunteregatherers who lived in the rock shelters between c. 10,500e9500 cal BP and left consistent accumulations of land shells (escargoti eres). The maximum of Holocene humidity was reached between 9000 and 8000 cal BP; regional aquifer were recharged and the deposition of calcareous tufa at the entrance of caves started, lasting up to c. 4500 cal BP. C and O stable isotopes from calcareous tufa highlights, in accordance with several regional records, the progressive decline of the intensity of the Indian Ocean monsoon and the transition towards arid conditions. In this phase, the area was abandoned and archaeological communities possibly relocated along the coast of central and southern Oman, where they exploited the mangrove environment.

Dune pattern, grain-size gradients and geochemistry were used to investigate the sources and dynamics of aeolian deposition during the last glacial in southwest France. The coversands form widespread fields of low-amplitude ridges... more

Dune pattern, grain-size gradients and geochemistry were used to investigate the sources and dynamics of aeolian deposition during the last glacial in southwest France. The coversands form widespread fields of low-amplitude ridges (zibars), whereas Younger Dryas parabolic dunes mainly concentrate in corridors and along rivers. Spatial modelling of grain-size gradients combined with geochemical analysis points to a genetic relationship between coversands and loess, the latter resulting primarily from dust produced by aeolian abrasion of the coversands. The alluvium of the Garonne river provided also significant amounts of dust at a more local scale. The geochemical composition of loess shows much lower scattering than that of coversands, due to stronger homogenisation during transport in the atmosphere. Overall, sandy loess and loess deposits decrease in thickness away from the coversands. Dune orientation and grain-size gradients suggest that the efficient winds blew respectively from the W to the NW during the glacial, and the W-SW during the Younger Dryas. A comparison between the wind directions derived from the proxy data and those provided by palaeoclimatic simulations suggests a change of the main transport season. Ground surface conditions and their evolution throughout the year, i.e. the length of the season with snow and frozen or moist topsoil, and the seasonal distribution of wind speeds able to cause deflation are thought to have been the main factors that controlled the transport season in the study area.