Landscape Morphology Research Articles

Hydrogeophysical comparison of hillslope critical zone architecture for different geologic substrates

The belowground architecture of the critical zone (CZ) consists of soil and rock in various stages of weathering and wetness that acts as a medium for biological growth, mediates chemical reactions, and controls partitioning of hydrologic fluxes. Hydrogeophysical imaging provides unique insights into the geometries and properties of earth materials that are present in the CZ and beyond the reach of direct observation beside sparse wellbores. An improved understanding of CZ architecture can be achieved by leveraging the geophysical measurements of the subsurface. Creating categorical models of the CZ is valuable for driving hydrologic models and comparing belowground architectures between different sites to interpret weathering processes. The CZ architecture is revealed through a novel comparison of hillslopes by applying facies classification in the elastic-electric domain driven by surface-based hydrogeophysical measurements. Three pairs of hillslopes grouped according to common geologic substrates — granite, volcanic extrusive, and glacially altered — are classified by five different hydrofacies classes to reveal the relative wetness and weathering states. The hydrofacies classifications are robust to the choice of initial mean values used in the classification and noncontemporaneous timing of geophysical data acquisition. These results will lead to improved interdisciplinary models of CZ processes at various scales and to an increased ability to predict the hydrologic timing and partitioning. Beyond the hillslope scale, this enhanced capability to compare CZ architecture can also be exploited at the catchment scale with implications for improved understanding of the link between rock weathering, hydrochemical fluxes, and landscape morphology.

Structural Disorder and Collective Behavior of Two-Dimensional Magnetic Nanostructures.

Structural disorder has been shown to be responsible for profound changes of the interaction-energy landscapes and collective dynamics of two-dimensional (2D) magnetic nanostructures. Weakly-disordered 2D ensembles have a few particularly stable magnetic configurations with large basins of attraction from which the higher-energy metastable configurations are separated by only small downward barriers. In contrast, strongly-disordered ensembles have rough energy landscapes with a large number of low-energy local minima separated by relatively large energy barriers. Consequently, the former show good-structure-seeker behavior with an unhindered relaxation dynamics that is funnelled towards the global minimum, whereas the latter show a time evolution involving multiple time scales and trapping which is reminiscent of glasses. Although these general trends have been clearly established, a detailed assessment of the extent of these effects in specific nanostructure realizations remains elusive. The present study quantifies the disorder-induced changes in the interaction-energy landscape of two-dimensional dipole-coupled magnetic nanoparticles as a function of the magnetic configuration of the ensembles. Representative examples of weakly-disordered square-lattice arrangements, showing good structure-seeker behavior, and of strongly-disordered arrangements, showing spin-glass-like behavior, are considered. The topology of the kinetic networks of metastable magnetic configurations is analyzed. The consequences of disorder on the morphology of the interaction-energy landscapes are revealed by contrasting the corresponding disconnectivity graphs. The correlations between the characteristics of the energy landscapes and the Markovian dynamics of the various magnetic nanostructures are quantified by calculating the field-free relaxation time evolution after either magnetic saturation or thermal quenching and by comparing them with the corresponding averages over a large number of structural arrangements. Common trends and system-specific features are identified and discussed.

Differences in Potamogeton praelongus Morphology and Habitats in Europe

AbstractOne of the most southern European occurrences ofPotamogeton praelongusis in the Czech Republic (CR), with only one native population in the Orlice River floodplain in Eastern Bohemia, the only surviving site from 10 Czech localities known 45 years ago. This species is critically endangered in the CR and needs to be actively protected with a rescue program. The number ofP. praelongussites increases along a latitudinal gradient, from Central to North Europe (CR, Poland, Sweden, and Norway), and correlates with improving conditions (water transparency and nutrient content in water) for this species along this gradient. Although differences in site conditions between Central and North Europe were caused by changes in landscape geomorphology and vegetation during the glacial and postglacial eras, presently, anthropogenic impact is primarily observed.The Czech sites forP. praelongushave distinctly lower water depth and transparency, and conversely, higher conductivity, temperature, and shade levels than the Nordic ones. These extreme conditions in most biotopes of this light-demanding and mesotrophic species in the CR result in lower fitness and different morphological parameters in the Czech populations. These changes lead to decreased competitive ability against filamentous algae and more competitive aquatic plant species and increase the impact of animals.The Nordic nonintensively managed landscape provides numerous large, deep lakes, which are optimal for this aquatic species. In the CR,P. praelonguscan currently only survive in rivers and their oxbows, but these are heavily influenced by intensive landscape management and fishing. Comparison of the populations and their site conditions in the CR and other European countries showed that all Czech native and artificially established sites are exposed to eutrophication and its consequences, which are the most important factors affecting the survival ofP. praelongus.

Profiles of Near‐Surface Rock Mass Strength Across Gradients in Burial, Erosion, and Time

AbstractRock mass strength is recognized as an important control on landscape morphology and evolution. However, the controls on rock strength in mountainous topography remain poorly characterized, in part because strength remains challenging to quantify at spatial scales relevant to geomorphology. Here we quantify the mechanical properties of rock masses using subsurface S‐wave velocities, Schmidt hammer hardness values, and Geological Strength Index (GSI) observations. We produce shallow depth profiles of rock mass shear strength using intact rock hardness as measured from a Schmidt hammer, and assessment of the structure and surface conditions of fractures using GSI. We apply these techniques to the Western Transverse Ranges, southern California, USA, where gradients in stratigraphic age and erosion rate allow us to evaluate our methodology. We resolve strength differences of 200 kPa to ∼5 MPa that appear to be related to diagenetic changes associated with the maximum burial depth of young clastic sedimentary rocks. For rocks of the same lithologic type, stratigraphic age, and inferred burial histories, we resolve smaller differences in strength (300 kPa–1.5 MPa) that appear to be positively correlated with mean erosion rates. We suggest that the increase in strength with increasing erosion rate reflects decreased residence time in the weathering zone for ranges experiencing faster fault slip rates. These findings demonstrate up to an order of magnitude variability in strength with respect to burial, erosion, and time for lithologically similar rocks. As such, lithology alone is unlikely to adequately capture the role of rock strength in landscape evolution.

Spatial Behavior Characteristics of Land Use Based on Fractal Theory: Taking Poyang Lake Area as an Example

Landscape morphology can reflect the spatial behavior of land use. Using the Poyang Lake area as an example, the landscape pattern characteristics in 1995, 2000, 2015, and 2018 are determined by calculating the fractal dimension, fractal stability, patch density, patch shape fragmentation, and landscape isolation, and fractal theory is used to analyze the spatial behavior of land use. The results show that building land was the land use type which consistently had the highest fractal dimension, but the fractal dimension of building land shows a downward trend, indicating that the spatial form of building land gradually developed in an orderly direction under the action of land use spatial behavior. Paddy, dryland, and forested land were the land use types which always had the lowest fractal dimension, and they are in unstable states. The calculation results of patch density, patch shape fragmentation index, and landscape isolation index supported the conclusions of the fractal analysis. One recommendation for realizing the rational layout of the land is to reduce the fractal dimension of building land through scientific and reasonable planning and to guide the orderly development of building land. For natural landscapes such as forested land, shrub forest land, high-coverage grassland, and water area, their fractal dimensions should be increased to reduce human interference and maintain their stability. Finally, the results of this study suggest that the fractal dimension should be introduced into the National Spatial Planning, and used as an index for evaluating the rationality of the regional land use pattern.

Comparing Patterns of Hurricane Washover into Built and Unbuilt Environments

AbstractExtreme geohazard events can change landscape morphology by redistributing huge volumes of sediment. Event‐driven sediment deposition is typically studied in unbuilt settings – despite the ubiquity of occurrence and high economic cost of these geohazard impacts in built environments. Moreover, sedimentary consequences of extreme events in built settings tend to go unrecorded because they are rapidly cleared, at significant expense, from streets and roads to facilitate emergency response. Reducing disaster costs requires an ability to predict disaster impacts, which itself requires comprehensive measurement and study of the physical consequences of geohazard events. Here, using a database of poststorm aerial imagery, we measure plan‐view geometric characteristics of sandy washover deposits in built and unbuilt settings following five different hurricane strikes along the Atlantic and Gulf Coasts of the US since 2011. We identify systematic similarities and differences between washover morphology in built and unbuilt environments, which we further explore with a simplified numerical model. Our findings suggest that spatial characteristics of the built environment (termed “fabric”) – specifically, the built fraction of the depositional zone – exerts a fundamental control on the form of large deposits. Accounting for the influence of built fabric on the morphodynamics of flow‐driven geohazards is a tractable step toward improved forecasts of hazard impacts and disaster risk reduction.

Urban growth and freight transport: From sprawl to distension

This paper aims at discussing the effects of the urban growth on freight mobility through the analysis of urban activities localisation. Thanks to the results of this work, we lay the basics of an original concept that synthetizes logistics sprawl and other localisation dynamics taking into principal consideration the mobility of freight in general: the logistics distension.Through the spatial analysis of activities and population localisation between 1982 and 2012 in Lyon's urban area, we show the evolution of the socio-economic morphology and evolution of the freight landscape. Through freight movements modelling, we show the evolution of freight mobility in the conurbation of Lyon with regard to the modifications of the urban fabric.

Impact of deforestation on soil iron chemistry and isotope signatures in Amazonia

We examined the consequences of soil erosion processes following deforestation and long-term pasture establishment for soil chemical and physical properties and Fe isotope compositions within two distinct areas in the Eastern and Central parts of Amazonia (near Rio Capim, Para, Brazil and Lake Balbina/Rio Uatuma, Amazonas, Brazil).For each area studied, soils selected under forest cover and pasture or after recent slash-and-burn practices were investigated. In both forest ecosystems studied, pedogenesis along slopes reflects the evolution of lateritic crust bearing soils (Ferralsol) into iron depleted soils after leaching (Acrisol) and redox processes (Gleysol). Measurements performed by plasma source mass spectrometry show a large range of iron isotope signature within the soil profiles studied at the bottom of the slopes (i.e. foot slope and/or valley soils), under both forest and pasture. Iron isotopic signature in foot slope soils under forest cover (δ57FeIRMM-14 ~ +0.2 to +0.6‰) and pasture (δ57FeIRMM-14 ~ +0.3‰) are significantly heavier than both the continental crust baseline and the reference ferralitic soils from the top of the hill (δ57FeIRMM-14 ~ +0.1‰). This enrichment in heavy isotopes is attributed to the preferential mobilisation and loss of light iron during pedogenesis that involves redox processes in areas periodically flooded at the foot slope and valley soils. Under forest, light iron depletion (where ~90% of the iron was leached in the first metre of the soil) has greater influence on the soil isotopes signature, particularly in foot slope sand-rich soils close to the river system with a remaining Fe having δ57Fe IRMM-14 ~ +0.6‰. Under pasture where soils experienced erosion processes, iron depletion in foot slope and riverside soils is less important (where only a little more than half of the iron was leached in the first metre of the soil) and the resulting δ57FeIRMM-14 ~ +0.4‰ suggests an input of light iron isotopes via colluvic material deposition. This difference indicates that geomorphological changes due to erosion processes following deforestation (i.e. colluvic processes) lead to an “isotopic rejuvenation” of the soils in the valley, mostly apparent within the riverside soils.For comparison, we investigated isotopic changes in a recently deforested small watershed, near Lake Balbina, Central Amazonia, focusing on riverside soils. Results confirm that the isotopic rejuvenation effect appears within a few months following the first stage of deforestation as a consequence of erosion processes following slash-and-burn practices. Erosion can remove isotopically lighter (i.e. close to the continental crust value of ~0.1‰ in δ57Fe) iron bearing soil material from the top of the hill. When such colluvial soil material accumulates in the bottom of the hills on soils that were initially depleted in light iron isotopes, again due to podzolisation as described in the previous site, it induces an “isotopic rejuvenation” (tending again towards a lighter, continental crust-like δ57Fe signature) of the foot slope and riverside soils, besides changes in landscape morphology, water drainage and soil functioning (i.e. hydromorphic processes). Hence, this study illustrates that Fe isotopes can be used to identify erosion within a deforestation context through “isotope rejuvenation”, even when soil textures make it challenging to unravel.

Influence of pre-existing structure on pluton emplacement and geomorphology: The Merrimac plutons, northern Sierra Nevada, California, USA

AbstractIn much of the western Cordillera of North America, the geologic framework of crustal structure generated in the Mesozoic leaves an imprint on later plutonic emplacement, subsequent structural setting, and present landscape morphology. The Merrimac plutons in the northern Sierra Nevada (California, USA) are a good example of the influence of pre-existing structure at a larger scale. This paper updates and refines earlier studies of the Merrimac plutons, with the addition of analysis of gravity and magnetic data and new 206Pb/238U zircon dates. The gravity and magnetic data not only confirm the presence of two different neighboring plutons, but also (1) support the presence of a third pluton, (2) refine the nature of the contact between the Merrimac plutons as being structurally controlled, and (3) estimate the depth extent of the plutons to be ∼4–5 km. The zircon 206Pb/238U dates indicate that the two main plutons have statistically different crystallization ages nearly 4 m.y. apart. Geomorphic analyses, including estimates of relief, roughness and drainage density and generation of chi plots, indicate that the two main plutons are characterized by different elevations with large longitudinal channel knickpoints that we speculatively attribute to possible reactivation of pre-existing structure in addition to lithologic variations influencing relative erosion susceptibility in response to prior accelerated surface uplift.

Aerial Geotourism: New Branch of Geotourism for Promoting Geoconservation (Examples from Iran)

Aerial geotourism is a result of the combination of earth science, tourism, and aviation together, that is the tourism use of geodiversity, geoheritage, and especially geomorphological landscapes through various flying vehicles. In fact, aerial geotourism includes various aspects of tourism, recreation, aesthetics, education, interpretation, understanding, geohistorical, and geoconservation by flying over geological landscapes in natural, urban, and rural areas. Due to the impressive growth of geotourism, the extraordinary advancement of the aviation industry, and the use of various flight vehicles, it is necessary to consider the potentials, strategies, and development plans of aerial geotourism. In this study, for the first time, aerial geotourism has been introduced as a new field of research and a new branch of geotourism through four examples in Iran, and both aerial and terrestrial field experiences. The first example (Lut Desert World Heritage) showed that aerial geotourism is practically carrying out, but only based on the recreation and landscape beauty, without knowledge of the geodiversity and geotourism. The second example was the Tehran-Qeshm flight route, which aircraft flying over diverse geomorphological landscapes, and due to the type of these travels and various restrictions, aerial geotourism cannot be proposed; however, it can be considered as a new product to provide more services to passengers by airlines. The third and fourth examples were the Damavand volcano and the Dasht-e Kavir desert, which, as representatives of other natural areas, showed great potential for the development of aerial geotourism. Eventually, aerial geotourism can play a key role in geoconservation and geoeducation through decreasing physical contact pressure on geosites and geomorphosites, and promoting the understanding of geodiversity. Nevertheless, there are many issues that need to be addressed by researchers for a successful aerial geotourism.

Gold enrichment characteristics and exploration prospects in Zambia: Based on 1 ∶ 1000000 geochemical mapping

The 1∶1000000 geochemical mapping of Zambia provides catchment sediment geochemical data for 58 elements including Au from 746 sediment samples at 736 sampling sites, corresponding to a sampling density of about one site per 1000 km2. Under strict quality control using field duplicates, certified reference materials, and analytical replicate samples, the Au was determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The detection limit of Au was 0.20 × 10−9. The 95% range (2.5%–97.5%) of Au concentrations was from 0.24 × 10−9 to 1.36 × 10−9, and the median value was 0.40 × 10−9. The most noticeable Au distribution patterns shown on the map are mainly located between Lusaka and Ndola (Lufilian Arc Belt). In addition, several high Au value areas occurred in Mansa, Muyombe, Chipata, and Livingstone. The spatial distribution patterns of Au in tectonic units, drainage basins, and geomorphological landscapes could be related to the Lufilian Arc Belt and Bangweulu Block. The Au concentrations show metallogenic belts between Muyombe and Mbala areas, between Mansa and Ndola areas, and between Lusaka and Kasempa areas.© 2022 China Geology Editorial Office.

Geomorphologic Domination on Urban Sprawl of Southern Riyadh, Saudi Arabia Using Differential Interferometric Synthetic Aperture Radar (DInSAR)

This study tests the southern part of the Riyadh City growth domination by the Early Quaternary-Holocene trans-tensional Central Arabian graben system reactivation and the subsequent dissolution-induced collapses and karstification. This study utilizes Synthetic Aperture Radar (SAR) and Differential Interferometric Synthetic Aperture Radar (DinSAR) to examine the morphology of arid landscape, south of Riyadh. Eight Single Look Complex (SLC) amplitude images are calibrated, filtered, georeferenced and orthorectified at a resolution of 20 meters, and compared with one another by producing 17 diachronic images of the pairs at different intervals (1996, 2003-2005, 2008). The diachronic SAR intensity imageries suggest a downthrown displacement reaching 600 m and eastward tilting at the bottoms of the grabens. Also, the structurally-controlled valleys are developing an eastward-running drainage system towards the oasis of Al-Kharj and capturing an older hydrologic system. Moreover, a 12-year period (1996-2008) of the SAR data was obtained to examine the average annual rate of southern Riyadh’s urban sprawl, which is estimated at approximately 390 metres/year over the 12 years and constrained by geomorphological features towards the deformed area. DInSAR imageries show the primary results obtained from the 26 May 2004 and 31 Jan. 2005 pair of images, merged with 30 m resolution DEM-SRTM data for the arid region south of Riyadh to eliminate the influence of topography. DInSAR is applied in this study for its ability to detect small displacements at the centimetre scale (1/2 wavelength). Although the DInSAR’s coherence and phase imageries suggest a fairly stable region since the last tectonic and subsequent geomorphic events, erosional and artificial changes are observed, bounded within the valleys and depressions, primarily due to aeolian and fluvial processes and agriculture. It is highly recommended to preserve the area for sustainability and economy.

The role of landscape morphology on soil moisture variability in semi‐arid ecosystems

AbstractPrevious studies on semi‐arid ecosystems have shown high values of soil moisture variability (SMV) primarily induced by the combined effects of non‐uniform precipitation, incoming solar radiation, and soil and vegetation properties. However, the relative impact of these various factors on SMV has been difficult to evaluate due to limited availability of field data. In addition, only a limited number of studies have analysed the role of landscape morphology on SMV. Here we use numerical simulations of a simple hydrological model, the Bucket Grassland Model, to systematically analyse the effect of each contributing factor on SMV on two different landscape morphologies. The two different landform morphologies represent landscapes dominated respectively by either diffusive erosion or fluvial erosion processes. We conducted various simulations driven by a stochastically generated 100‐year climate time series, which is long enough to capture climatic fluctuations, in order to understand the effect of various soil moisture controlling factors on the spatiotemporal SMV. Our modelling results show that the fluvial dominated landscapes promote higher spatial SMV than the diffusive dominated ones. Further, the role of landform morphology on SMV is more pronounced in regions where the spatial variability of incoming solar radiation and precipitation is high.

Geodiversity of the Togean Islands National Park, Central Sulawesi Province for Geopark Assessment

The Togean Islands National Park is located at the Gulf of Tomini, Central Sulawesi Province, Indonesia. The islands officially become National Park in 2007, initiated by the government of the Tojo Una-Una district in 2004. There is a variety of geodiversity within the Togean Islands National Park, such as active volcano, ophiolitic pillow lava, beautiful beaches and islands formed by lithology of volcanic deposits, igneous intrusions and quaternary limestone formation. Four geodiversity areas are provided within the national park, according to lithological and geomorphological aspects. Those are the Una-Una Island active volcano, karst topography of limestone around the Batudaka Island, the lava dome at the Togean Island and the ophiolite complex of Walea Islands. The Una-Una volcano island is unique based on the location and anomaly in magma affinities. The Soliter volcano separated from the volcanic belt along the North Sulawesi Arm and has the adakite signature compared to tholeiitic - calk-alkaline as dominant affinities from the North Sulawesi island arc province. The Batudaka Island - karst topography offers sailing and cruiser to the beautiful shape and scenery of karst topography of limestone formation, cave, sandy beaches and blue ocean. The lava dome of the Togean Island: provides a geomorphological landscape that represents the dome of trachytic igneous rock above sea level. The Walea ophiolite: of a geoheritage showing rock formation, consists of ophiolitic pillow lava and the tectonic fossil of subduction between tectonic plates around Sulawesi Islands. Overall, the Togean Islands National Park proposes many adventure sites for diving, snorkelling, surfing, fishing, sea birds and dolphin watching and also conservation of reef, fish and geoheritage sites. Several facilities are already available inside of the National Park, such as resorts and cottages for accommodation, sailing and diving rental for leisure activities.

Is there an autochthonous “Tyrolean Modernism”?

"This article examines, on the basis of two residential buildings by Franz Baumann, the status of the postulate of an autochthonous “Tyrolean Modernism”. Often mentioned together, five architects are among the main representatives of classical modernism in the Austrian province of Tyrol: Clemens Holzmeister, Lois Welzenbacher, Theodor Prachensky, Franz Baumann and Sigfried Mazagg. Even if they did not form a close circle because of their life paths, there is a strong link between them, mostly in their artistic background and their way of representing architecture. Architecture was a detour from a first aim to pursue an artistic career for all of them, with the exception of Welzenbacher. Architects like Franz Baumann not only “modernized” well-known typologies, but also regionalized elementary components of internationally widespread building traditions. The “Tyrolean Modernism” was repeatedly regarded as an “autochthonous” movement, even if the regional scene was not detached at all from the international development. The alpine environment, in particular, offered a framework of conditions that challenged the architects to top performance. They were able to plan for locations that were uncharted territory in many respects: exposed in the mountains or high mountain areas. In this context, the architects of “Tyrolean Modernism” benefited from their painterly- trained eye for the morphology of Alpine landscapes."

The shaping of erosional landscapes by internal dynamics

Erosional landscapes transport sediment downstream, host natural hazards and are geologically active. While perturbations in external forcing, particularly climate and tectonics, sculpt erosional landscapes, similar landforms can be created by internal dynamics, that is, feedbacks between topography, erosion and sediment transport that occur independent of external perturbations. Internal system responses, termed autogenic dynamics, can remain active as landscapes adjust to perturbations in forcing, allowing for complex responses to external perturbations that potentially obscure links between external forcing, topographic form and sedimentary archives. Autogenic dynamics are being increasingly recognized in depositional systems, yet understanding of autogenic dynamics in erosional landscapes is nascent. In this Review, we discuss the mechanisms that contribute to internal dynamics in erosional landscapes. We use examples of autogenic terrace formation, knickpoint formation and river-basin reorganization to show how autogenic dynamics that occur over spatial scales of metres and temporal scales of hours can influence the evolution of mountain ranges over Myr periods. Unravelling the mechanics of autogenic processes allows the interplay of internal dynamics and external forcing to be explored and provides a framework to assess the influence of erosional processes in the geologic record. The morphology of erosional landscapes is often considered to be set by climate and/or tectonics; however, similar topographic features can arise through internal processes and feedbacks. This Review considers how the internal and external processes drive landscapes evolution, and how such processes can be differentiated in topographic and stratigraphic records.

High potential for loss of permafrost landforms in a changing climate

The presence of ground ice in Arctic soils exerts a major effect on permafrost hydrology and ecology, and factors prominently into geomorphic landform development. As most ground ice has accumulated in near-surface permafrost, it is sensitive to variations in atmospheric conditions. Typical and regionally widespread permafrost landforms such as pingos, ice-wedge polygons, and rock glaciers are closely tied to ground ice. However, under ongoing climate change, suitable environmental spaces for preserving landforms associated with ice-rich permafrost may be rapidly disappearing. We deploy a statistical ensemble approach to model, for the first time, the current and potential future environmental conditions of three typical permafrost landforms, pingos, ice-wedge polygons and rock glaciers across the Northern Hemisphere. We show that by midcentury, the landforms are projected to lose more than one-fifth of their suitable environments under a moderate climate scenario (RCP4.5) and on average around one-third under a very high baseline emission scenario (RCP8.5), even when projected new suitable areas for occurrence are considered. By 2061–2080, on average more than 50% of the recent suitable conditions can be lost (RCP8.5). In the case of pingos and ice-wedge polygons, geographical changes are mainly attributed to alterations in thawing-season precipitation and air temperatures. Rock glaciers show air temperature-induced regional changes in suitable conditions strongly constrained by topography and soil properties. The predicted losses could have important implications for Arctic hydrology, geo- and biodiversity, and to the global climate system through changes in biogeochemical cycles governed by the geomorphology of permafrost landscapes. Moreover, our projections provide insights into the circumpolar distribution of various ground ice types and help inventory permafrost landforms in unmapped regions.

Coupling of tectonic factors and precipitation variability as a driver of Late Quaternary aggradation in Northeast Brazil

AbstractThe coupling between tectonic factors and climate processes is a key element in understanding landscape evolution. However, few studies address this issue in the context of unglaciated tropical areas in passive continental margins. Thus, this research aimed to understand the origins and evolution of the geomorphological landscape in the eastern sector of Northeast Brazil along the Late Quaternary, between the Last Interstadial (Marine Isotopic State 3) and the Upper Holocene. The morphostratigraphic approach, coupled with sedimentological analyses and optically stimulated luminescence dating of sediments, showed that the depositional record stored in the landscape ranges from at least 60 000 years BP until the Upper Holocene. Depositional intervals suggest that there were moments of climatic instability followed by moments of relative geomorphological quiescence. Such active moments coincide chronologically with Heinrich and Dansgaard‐Oeschger events, which are likely linked to changes in paleo‐pluviosity that might respond to the dismantling of elluvial covers and colluvial deposition in the area. Likewise, reworking of hillslope materials led to increased deposition in the fluvial realm. In addition, such deposits might have been affected by the neotectonic complexity of the area, responsible for the creation of non‐concatenated accommodation spaces, indicating a dynamics of uplifting and subsidence of blocks typical of passive margin taphrogenic environments. Therefore, the formative processes that led to the Late Quaternary deposition of sediments in a platform margin context reflect a coupling between tectonic and climatic factors. The former, driven by precipitation variability on a regional scale, triggered fluvial and high‐energy hillslope processes that resulted in ubiquitous valley floor and piedmont aggradation, whereas the latter led to the dismantling of local base levels, transforming depositional units into new denudational landforms subject to the current climate dynamics. © 2020 John Wiley & Sons, Ltd.

GIS-based approach for the measurement of variability in tectonomorphic signatures using DEM's data: a case study from the Habo Dome in the Kachchh area, India

The Kachchh region of western India is located in a plate interior region, but falls under one of the highest seismic zones of India, having very active crustal deformation and erosion. The drainage system, as well as the geomorphic evolution of the region under a semi-arid climate zone with high to very high strength of rocks in areas with high relief, is dominantly controlled by the seismic instability associated with continual tectonics. In the present paper, we have analysed a block close to the epicentre of the 2001 Bhuj earthquake to understand the role of relative active tectonics in the evolution of domal landscape morphology. Shuttle Radar Topographic Mission Digital Elevation Model data were used to extract drainage network in the GIS platform and evaluate active tectonics using different geomorphic indices of the Habo Hill, the second largest domal structure situated in Northern Hill Range of the Kachchh region. The average cumulative weightage of different geomorphic indices provides a quantitative tool, Index of Relative Active Tectonics (IRAT), which shows significant variations in and around the Habo Dome. Activation of earlier lineaments and generation of new lineaments controlled the morphometric evolution of the fault bound block of the region to form the Habo Dome. The undulating topography in addition to the domal shape of the study area resulted from the differential movements along several active transverse faults striking NE–SW, N–S, and NW–SE, and the regional faults striking E–W (the Kachchh Mainland Fault, the Kas Fault, and the Jikadi Fault). Stress propagations from the Himalayan range in the northeast and Suleiman range in the northwest are identified to be the causative factors for active tectonics and drainage anomalies in the area.

Geosites for Geotourism, Geoheritage, and Geoconservation of the Khnefiss National Park, Southern Morocco

Khnefiss National Park has a very unique advantage of presenting three landscape morphologies of high quality: the coastal band, where the sea, dunes and cliffs mix; the lagoon zone, with its multiple interlacing water, algae and sand; and the vast desert, with its regs, hamadas, krebs, and dune extensions. It is unique and original at the world level for a protected area to retain in a single perimeter these three major ecosystems, which therefore gives this national park an exceptional quality. Khnefiss national park faces numerous natural, human-induced, institutional, organizational, and legal constraints. Hence, there is a need for a practical tool that would reconcile the imperatives of conservation, the demands of the local population, and tourism, and at the same time positively address the constraints that hamper the management of this geosite. Indeed, we will highlight a reflection that aims at clarifying the sense of this new trajectory in which Morocco is positioned in terms of interest development of geological heritage, the emergence of consumption of natural assets, and potentialities phenomenon according to regions. Therefore, all actions are based on values of citizenship, participative, responsibility, ethicality, and fairness. Indeed, the geosites have small to large scale characteristics (from ten meters to more than 10 km). The geosite inventory is based on the geoconservation strategy. Qualitative and quantitative assessments were carried out on the basis of geoheritage values of international significance. Thene, geoconservation efforts should be made in all these geosites for many reasons, such as valorization of academic research, preservation of natural resources, and promotion of geotourism in Khnefiss national park.