Terrace Levels Research Articles

Modeling Climate and Tectonic Controls on Bias in Measured River Incision Rates

AbstractRates of land surface processes provide insights into climatic and tectonic influences on topography. Bedrock incision rates are estimated by dating perched landforms such as strath terraces, assuming a constant bedrock incision rate from terrace abandonment to the next terrace level or present river level. These estimates express biases from the stochastic nature of sediment and water discharge in controlling river incision as well as from using a mobile channel elevation as a reference frame, leading to different incision rates when calculated over different timeframes. We introduce a 1‐D model incorporating fluvial mechanics, tectonics, sediment, and climate variability to predict these biases and assess their sensitivity to climate and tectonics. Findings suggest biases intensify under highly variable climates and slow rock uplift, with climate periodicity being a primary control for our modeled scenarios. Our model provides a mechanism to improve river incision measurement uncertainty, impacting paleoclimate and tectonic geomorphology reconstructions.

Exploring the role of microtopography in the spatial pattern of soil water at the hillslope scale based on high-resolution observation

Terraces have consistently been regarded as crucial measures for water conservation and vegetation restoration, particularly in mountainous environments. However, the hydrological effects of terraces in artificial forests have been rarely studied. In this study, detailed topography, soil properties and high-resolution (30 sites) soil water data (0–70 cm) observed from March 2015 to March 2016 were collected at hillslope scale (0.2 ha). The effects of static (soil properties and topography) and dynamic factors (precipitation) on the dynamics and variability of soil water content (SWC) were studied based on statistical methods, temporal stability and variance decomposition methods. The results showed that slope, topographic wetness index (TWI) and microtopography were the main control factors of different soil layers (shallow, middle and deep layer), which explained 37.2 %, 48.6 % and 47.3 % of the total variance of corresponding soil layers, respectively. Microtopography primarily affects deep layer soil water (40–70 cm). Level terraces show significantly higher soil water content (SWC) (30.89 ± 5.28 %) compared to gentle slopes (25.40 ± 5.33 %), steep slopes (27.05 ± 5.74 %), and scarps (19.71 ± 4.43 %) (P<0.05). Temporal stability of soil water varied across different depths, with shallow layer soil water exhibiting significantly weaker stability compared to other depths, the most representative point of different soil layers was located on relatively flat terraces. Decomposition of spatial variance revealed that the time-invariant component was the primary contributor to the total spatial variance, with a mean value over 70 %. These results highlight that microtopography could weaken the influence of soil-terrain factors on soil water, and the implementation of level terraces can enhance hillslope hydrological conditions in the Rocky Mountain area.

Vertical Deformation Along a Strike‐Slip Plate Boundary: The Uplifted Marine Terraces of the Gulf of Aqaba and Tiran Island, at the Southern End of the Dead Sea Fault

AbstractClose to its southern end where it connects to the Red Sea rift, the Dead Sea strike‐slip fault (DSF) becomes trans‐tensional in the Gulf of Aqaba. Details of this transition, however, remain difficult to unravel as most of the active tectonic structures are located off‐shore. This study focuses on uplifted marine terraces located in the Gulf of Aqaba and on Tiran Island. Using high‐resolution tri‐stereo Pleiades satellite imagery, we build a Digital Surface Model (DSM) at a 0.5‐m resolution of the eastern coast of the gulf and Tiran Island to map 19 levels of marine terraces. The terraces are preserved at elevations from 1 m to almost 500 m above the current sea level. Correlating laterally U‐Th ages obtained along the gulf with the lower levels found on Tiran Island, we build an age model to estimate the ages of the upper terraces on the island. Combining this with the terrace heights from our DSM, we derive the uplift rate affecting the terraces. The geographic extent of the terraces along the gulf suggests that the DSF is responsible for uplift along the entire eastern coastline of the gulf at a rate of about 0.14 ± 0.03 mm/year at least over the Quaternary. The uplift rate of Tiran Island, located closer to the Red Sea rift, is faster at 0.21 ± 0.02 mm/year over the past 2.4 Myr. This faster uplift rate suggests a combined tectonic uplift related to both the Dead Sea strike‐slip fault system and the Red Sea rift.

Unraveling the deposition and incision paces of alluvial fan-river system by using single grain K-feldspar luminescence dating

Alluvial river in the piedmont area deposits and incises cyclically, in response to both exogenetic and endogenetic forcing across a range of timescales. The paces of these processes unveil the mechanisms governing the evolution of alluvial fan-river system and affect the policy for river management. Numerical simulation suggests that the incision of alluvial river is much faster than the deposition process. However, the field observations are rare. Alluvial rivers entrench up to 300 m into the alluvial fans built pre-Holocene on the northern piedmont of Chinese Tianshan, which provide ideal sites to unveil the pace of alluvial fan-river evolution. Jingou River is one of these rivers, with four levels of terraces identified at the downstream area. These terrace deposits are characterized by a complex of upper very coarse gravels and cobble (VCGC) unit and lower medium and coarse gravels (MCG) unit. In this study, potassium-feldspar (K-feldspar) single grain pIR110IR170 luminescence dating procedure was employed to date the samples taken from sandy lens of both upper VCGC and lower MCG units, for which the depositional ages are supposed to be associated with the fan-building and river incision processes, respectively. The luminescence ages of the lower MCG unit suggests a gradual fan building phase between 16 ± 1.9 ka and 8.1 ± 0.9 ka, while the ages of the upper VCGC unit cluster around ∼5.2 ka rather than a monotonic decrease towards low level terraces. Several scenarios are discussed with respect to the attained age sequences to unravel the pace of deposition and incision of Jingou River, of which the asymmetric aggradation and incision is more preferred and echoes to the finding of previous numerical investigation.

Quaternary tectonic and climatic forcing on the spatio-temporal evolution of the Meuse fluvial terrace staircase

The Quaternary is characterized by pronounced alterations between cold and warm climatic states, with the Mid-Pleistocene Transition marking a strong increase in the intensity of cold-climate conditions. River systems are sensitive to environmental perturbation (e.g., climate, tectonics, base level) and are expected to respond to such profound changes. This study uses a combination of terrace mapping and analysis of a dense borehole database to investigate the Meuse terrace staircase (and its deposits), and gain insight on how it reflects climatic and tectonic perturbations during the Quaternary. The lower reaches of the Meuse river, which has both its main water and sediment source in the Ardennes displays a well-developed terrace staircase that was sculpted mainly throughout the Quaternary. The staircase is located near the cities of Maastricht (southern Netherlands) and Liège (northwestern Belgium). About 30 terrace levels reflect signals of environmental perturbations in the lithological composition, gradients, thicknesses, and spatial distribution. The terraces are organized in groups, based on their morphological position, from old to young; these are the East Meuse terrace group and West Meuse High-, Middle- and Low terrace groups. Our findings show a consistent increase in the gravel content from older to younger terraces. The sandier composition of the deposits of the oldest terraces (Early Pleistocene) is closely related to the supply of the Miocene-Pliocene weathered material from the Ardennes. Younger terraces (Middle and Late Pleistocene) are much richer in gravel, evidencing sediment input from fresh or partially weathered bedrock. These changes point to a downstream migration of the gravel front throughout the Quaternary. The mean thickness of the terrace groups shows a slight increase, even though the same trend is not clear when each terrace is analyzed on an individual basis. The anomalous thickness of the Caberg 1 terrace suggests increased sediment input during the cold climatic conditions of the Elsterian (MIS 12), the first Quaternary glacial during which an ice sheet extended into the northern Netherlands. Reconstruction of terrace gradients reveals that older East Meuse terraces show a (reversed) gradient opposite to reconstructed palaeo flow directions, which is attributed to a combination of low gradients during terrace formation and footwall back-tilting of the Feldbiss Fault Zone. In our analysis we do not see clear evidence for the imprint of the Mid-Pleistocene Transition, which suggests that due to its gradual nature, its signal is either buffered or assimilated by the overall climatic signal of the Quaternary. This study offers a first complete temporal analysis of the Meuse terrace staircase, providing an important basis for better understanding the effects of Quaternary climatic change and tectonics, and their resulting effects in other river systems worldwide.

The role of long-term preparatory factors in mass rock creep deforming slopes: insights from the Zagros Mts. belt (Iran)

The long-term evolution of slopes affected by Mass Rock Creep deformations is controlled by both time-invariant predisposing factors, such as the geo-structural inheritance, and time-dependent preparatory conditions, including regional uplift and landscape evolution rates. However, the relationship among Deep-seated Gravitational Slope Deformations, drainage network evolution, and tectonics remains poorly defined. Here, we focused on an undocumented Deep-seated Gravitational Slope Deformation affecting an area of about 8 km2 in the SE tip termination of the Siah Kuh anticline in the Lorestan arc (Zagros Mts., Iran), upstream to the Mountain Front Fault. To assess the evolution processes which involved the slope up to the present, we integrated quantitative geomorphic analysis, optically stimulated luminescence dating of geomorphic markers, and SAR interferometry techniques. In detail, we semi-automatically extracted the river terrace treads to which we associated an elevation above the thalweg based on the Relative Elevation Model allowing the order definition. The plano-altimetric distribution of the treads and the OSL ages of two levels of strath terraces sampled in the field have been correlated along the river longitudinal profile, allowing the estimation of an uplift rate of 2.8 ± 0.2 mm year−1 and 0.42 ± 0.03 mm year−1, respectively upstream and downstream of the Mountain Front Fault. SAR interferometry was used to spot present-day shallow ground displacements associated with the ongoing slope deformation, by processing 279 satellite Sentinel-1 (A and B) radar images of the ascending and descending orbit spanning from 06 October 2014 to 31 March 2019. Different landslide mechanisms were distinguished across the fold axis, rototranslative to lateral spreading interpreted as two different evolutionary stages of the same process transposed spatially through the fold axis. Indeed, the rototranslative mechanism represents an advanced stage of the strain evolution while the lateral spreading is an earlier one. Finally, we infer that the variability in the spatial distribution of the slope deformation styles and patterns in the Lorestan arc is strictly related to the coupled evolution of the drainage system and tectonics. Involved volumes (from 0.6 up to 44 km3), local relief (from 400 up to 2000 m), incision rates (from 0.8 to 2.8 ± 0.2 mm year−1), and persistence time (from 104 to 105 years) represent the most important preparatory conditions and are predisposed by a moderately dipping downslope (from 8 to 25°) sedimentary sequence characterised by units with significantly different rheological behaviour.

Lithological controls on the timing of strath terrace staircase formation in a collisional mountain belt

AbstractIn mountain belts, strath terrace staircases serve as markers for deriving river incision rates and erosional patterns. Distinguishing between terrace patterns influenced by external perturbations like changes in climate and tectonics and those driven by internal dynamics including feedbacks between topography, erosion and sediment transport remains challenging. We demonstrate that in a collisional mountain belt, lithology can act as a first‐order control on the spatial and temporal scales of strath terrace formation. Here, we investigate the role of lithology in modulating internal dynamics and the formation of strath terraces in the Mgoun River catchment of the High Atlas in Morocco, a region characterised by constant low‐rate rock uplift, a cyclical cool‐warm/arid‐humid Quaternary climate history and contrasting bedrock lithologies. By collecting (1) modern river and terrace clast data, (2) bedrock strath and strath‐top sediment elevations of four terrace levels, (3) terrace sedimentology and (4) integration with published terrace chronology, we found a dominance of local sediment input from hillslopes, mostly from recycled bedrock conglomerates. Additionally, we found valley width, controlled by the stratigraphic and structural configuration of lithological erodibility, significantly impacts sediment connectivity. The isolation between valleys with varying widths results in varied timescales of river channel response to hillslope coupling, with hillslope‐derived stochastic sediment gravity flows preserved in fluvial terraces in some river reaches and not in others. Furthermore, asynchronous terrace formation and abandonment ages result from the low longitudinal river connectivity between multiple valleys formed in erodible rock separated by gorges in high‐strength rock. These gorges limit knickpoint migration rates, inhibiting the ability of terraces formed in one valley to spread through the catchment. These findings can inform future research distinguishing between autogenic and external signals in erosional landscapes and help carefully derive river incision rates and climate insights from terraces.

Combining geomorphological and kinematic models to analyze tectonic deformation rates: A case study of the Bayin anticline in the eastern Tian Shan Mountains

Quantitatively characterizing the geometry, kinematics, and deformation rate of fold-thrust belts in intermontane basins is the key to understanding strain partitioning within the Tian Shan range. This work focuses on the Bayin anticline in the Youludusi Basin, a typical intermontane basin located within the eastern Tian Shan. The Kaidu River cuts through the Bayin anticline and has developed three levels of terraces (T1–T3) across the structure. By using cosmogenic nuclide and optically stimulated luminescence dating methods, the formation ages of terraces T1 and T3 are constrained to 11.54 ± 0.55 ka and 42 + 7.0/−7.1 ka, respectively. When applying a listric thrust fault model to the Bayin anticline and using terraces as references, the vertical displacements are estimated to be 16.45 + 6.46/−3.19 m (T1), 32.08 + 12.85/−6.19 m (T2), and 95.93 + 38.94/−18.6 m (T3), and the shortening amounts are 10.56 + 8.33/−5.04 m (T1), 20.46 + 16.68/−9.64 m (T2), and 61.24 + 50.22/−28.93 m (T3). Based on this listric thrust fault model and terrace T1–T3 ages, the rate of fault slip controlling the growth of the Bayin anticline is determined to be 1.6 ± 1.0 mm/yr, and the crustal shortening rate of the anticline is 1.0 + 0.7/−0.6 mm/yr. The estimated crustal shortening deformation of the Bayin anticline accounts for ∼12 % of the total deformation in the Youludusi Basin. In terms of the entire orogenic belt, the crustal shortening absorbed in the southern, central, and northern parts accounts for 24 %–56 %, 46 %–71 %, and 19 %–74 %, respectively, of the total strain across the eastern Tian Shan. Therefore, we believe that the Eastern Tianshan undergoes uniform deformation.

Active tectonics along the mountain front around the easternmost part of the Himalayan Range: Implications for geomorphic evolution

The frontal part of the easternmost zone of the Himalayas is tectonically active, which can be ascertained from different quaternary deformation features like tilted terraces, differential upliftment of terraces, and steep scarps. Along the mountain front, four and three levels of terraces are present on the right and left bank of the Siang River respectively with a maximum elevation of 303 m. Different levels of Quaternary terraces indicate episodic upliftment of the area. On the left bank of the Siang River, 300 m upstream from Dhobighat, the terrace deposits are present at an elevation of 150 m above the Siwalik Group, and 100 m downstream, tilted quaternary deposits are observed. Steep scarps near Mairam, indicate the presence of Himalayan Frontal Thrust (HFT), and based on convincing field evidence, HFT can be categorized into HFT-1 and HFT-2. Total eighteen basins are mapped which are elongated and aligned along the NW-SE direction, parallel to the trend of cross faults present in the area along the Siang River course. The mountain front sinuosity index, SL value, and elongation ratio reflect further that the area is tectonically active. Furthermore, the asymmetry factor and transverse topographic symmetry factor illustrate that all the basins are asymmetric and tilted. Most of the valley profiles are V-shaped, and the valley floor width-to-height ratio is low, indicating rapid upliftment of the area. Lineament maps show a similar trend of the orientation with the major structural features of the area and further, confirm that the area is tectonically active.

Evolution of the Júcar-Cabriel fluvial system on the Mediterranean watershed of the Iberian Peninsula (Valencia, eastern Spain)

This study presents the characterization and chronology of the Quaternary terrace sequence developed in the confluence zone of the Júcar and Cabriel river valleys. The study area covers a radius of 10 km from the confluence of the two valleys near the locality of Cofrentes (Valencia). It is located in the northern zone of the Ayora-Cofrentes Graben in the northeastern sector of the External Prebetic Zone adjacent to southern Iberian Chain. This N-S graben is an inherited tectonic feature with an axial salt wall subject to different periods of fluvial dissection and refilling since at least the end of the Messinian Salinity Crisis (MSC). Regional isostatic uplift and local uplift and subsidence processes related to salt flow and dissolution during the Quaternary period, favored by fluvial entrenchment and terrace development. The terrace system and the previous pre-incision erosional and depositional surfaces are analyzed from a geomorphological point of view. The terrace system only develops within the soft Mio-Pliocene sedimentary fill of the graben, whilst upstream and downstream this zone the studied valleys develop important gorges (canyons) carved in the Cretaceous tablelands (Caroch Massif) and Mio-Pliocene deposits (Llanura Manchega). The geochronological control is established from 20 numerical ages obtained by different dating methods, such us Electron Spin Resonance (ESR), Optically Stimulated Luminescence (OSL) in detrital sequences and Th/U series in calcareous tufa deposits. Additionally, four K/Ar dates available for volcanic materials disrupting the upper and oldest terrace have been considered. A total of 14 terrace levels were identified between +130–135 m (T1) and +3–4 m (T14) of relative height above the river thalwegs. The T1 has an approximate age of c. 1.6–2.0 M.a. as indicate the age of the volcanic materials from the Agras Volcano intruded in the terrace, marking the onset of Quaternary fluvial dissection in the zone. The obtained geochronological data indicate that the Lower-Middle Pleistocene boundary is slightly above T6 (+60–65 m), which has an ESR age of 577 ± 43 ka. This terrace also documents the onset of the most important period of rise of the salt within the graben interfering drainage development. The geochronological data indicate the occurrence of a second eruptive event during the second half of the Middle Pleistocene related to the terraces T7 (+50 m) and T8 (+35–40 m), updating the volcanic activity in the zone. The beginning of the Upper Pleistocene is recorded by the top sequences of the T9 terrace (+25–30 m) where numerous OSL and Th/U data have been obtained with ages between ca. 105 and 81 ka (MIS 5). However, these young terraces (T8 to T13) are thickened (8–10 m) recording Middle Pleistocene sediments in their basal sequences with ages between ca. 193 and 137 ka (MIS 6). The study provides important data on valley evolution under the interference of volcanic activity, salt –related deformation (diapirism, solution subsidence) and fluvial incision fostered by the rise of the axial diapir (salt wall) protruding the graben since at least the Brunhes-Matuyama boundary. The analyzed fluvial evolution documents interesting cases of river capture, drainage antecedence and tectonic adaptation of the drainage throughout the Quaternary Period. The paper also poses interesting geochronological data on the long-term Quaternary evolution of Mediterranean valleys in the Iberian Peninsula, poorly explored to the date.

Early Holocene transgression in the central of Svalbard: research results and problems of reconstruction

The report presents the results of the study of Holocene marine sediments and terrace levels in the central part of West Spitsbergen Island. The results of the study showed that the postglacial transgression in the study area reached marks of 30-35 m and 40-45 m in the north and south of the study area, respectively. The early Holocene marine sediments were formed in shallow-water, predominantly ice-sea conditions with an unstable coastline. The sea level retreat was rapid and was accompanied by a general cooling.

СУЧАСНИЙ ТА ДАВНІЙ РЕЛЬЄФ ГЕОАРХЕОЛОГІЧНОЇ ПАМ'ЯТКИ МЕЖИРІЧ

Background. Comprehensive geoarchaeological studies of prehistoric and historic human settlements involve analyzing all components of the ancient natural environment, including topography and landforming processes. However, insufficient attention to documenting these crucial characteristics, as well as arbitrary use of geomorphological terms, complicates their further interpretation. The research aims to revise existing geomorphological descriptions and paleogeomorphological reconstructions of the Mezhyrich geoarchaeological site, refining and detailing its position within the modern and ancient land surface structure. Methods. The research was conducted using cartographic methods and decoding materials from aerial photography. Additionally, a thorough bibliographic analysis of scientific publications related to paleogeographical reconstructions of the study area was carried out. Results. Discrepancies have been identified in precisely determining the geomorphological context of this site. The study delves into contentious issues surrounding various approaches to numbering the floodplain terraces. These debates stem from the use of different stratigraphic schemes for Ukraine's Quaternary deposits when dating alluvium. Additionally, the debate extends to criteria for terrace numbering. Through the analysis of satellite imagery, hypsometric and geomorphological diagrams, and other geological-geomorphological materials, the contemporary geomorphological situation has been refined, and the peculiarities of the ancient terrain have been unearthed. The role of morphostructural position, the spectrum of processes, and the dynamics of morpholithogenesis have been pinpointed. Conclusions. The conducted research substantiates the pivotal role of terrain in the selection and organization of safe living spaces for ancient humans. To address the issue of linking the Mezhyrich geoarchaeological site to the terrace level, the proposal is to number the terraces based on morphological features, thereby avoiding divergent interpretations of the ages of correlated deposits and discrepancies in terrace designations. Furthermore, there is potential for utilizing the geomorphological information from the investigated Late Paleolithic settlement as a search criterion for locating other ancient human settlements under similar physiogeographic and geological-structural conditions.

Неотектоника и геодинамика зоны сочленения Северо-Западного Кавказа и Черноморской впадины (район г. Геленджика)

Relevance of the work. In the junction zone of the neotectonic structures of the North-West Caucasus and the Black Sea depression, structures of different types in strike and morphological-kinematic type are developed. Determining the structural-geomorphological and neotectonic zoning, including modern ones, and its connection with the sources of tectonic forces and stresses is relevant. Such studies are necessary to ensure the geodynamic safety of engineering structures in the city of Gelendzhik, the territory of which is subject to negative geological processes. The purpose of the research is to identify the structural-geomorphological, neotectonic modern zoning with an assessment of the modern geodynamic conditions of its formation in connection with ensuring the safety of engineering drainage routes in the Gelendzhik region. The research method is structural-geomorphological, with the construction of profiles and geomorphological steps with an assessment of their age and deformations. The work used neotectonic and structural-geodynamic approaches aimed at identifying structures and identifying the sources of stress and deformation fields. The research methodology is the recognition of heterogeneity, different ranks and different ages of stresses and deformations. As a result of the work, erosion-denudation stages of different ages and marine terrace levels and neotectonic structures were identified with an assessment of modern geodynamic conditions. For the first time, a cross-structural plan has been established, in which all-Ural and anti-Caucasian structures intersect. Their origin is associated with the superposition of heterogeneous forces and stresses. Compression stress is generated in connection with collision processes of lithospheric plates and microplates (blocks), tension is generated in connection with the activity of the deep East Black Sea geodynamic system. It considers as a mechanism the upper mantle convection directed from the Black Sea depression towards the orogen of the North-Eastern Caucasus. The superposition of faults of different ages and different types on top of each other causes increased activity in them. Late orogenic faults, consistent with early Alpine (early orogenic) reverse faults, are characterized by increased displacement amplitudes and wide dislocation zones. It is dangerous for engineering routes to cross such gaps. The pipeline at the intersection with the zone of active ruptures will be equipped with special hinge-type devices to prevent dangerous deformations in it.

Rapid terrace incision and Quaternary landscape evolution in central Patagonia

AbstractThe debate over isostatic uplift versus discharge as drivers of Quaternary river incision is explored here through geospatial analysis of a ~250‐m‐relief terrace sequence from the Río Pinturas (Argentine Patagonia). The geomorphic setting of the Cañadon Caracoles reach allows evaluation of discharge as a driver of terrace incision because advancing ice during Pleistocene glaciations blocked Pacific drainage and routed meltwater from an expanded ~104‐km2 catchment to the Atlantic through the dryland steppe of the study area. Twenty‐two terrace levels, some assigned to previously dated ice margins [Marine Isotope Stage (MIS) 32–36, MIS 16, MIS 8 and MIS 2], were identified. Average net incision since 800 ka (~0.34 m ka−1) exceeded regional uplift rates. The MIS 2 terraces, with ante quem and post quem age constraint on the timing of terrace formation, show that terrace incision was episodic and faster still during a transitional warming climate. Glacier recession and proglacial lake formation at ~18 ka led to rapid incision of ~11.7 m ka−1 over a few millennia. River capture and negligible flow from ~15.0 ka caused fan‐dammed lake formation on the valley floor and vertical stability during MIS 1. The Pinturas terraces demonstrate rapid incision can be driven by discharge and sediment dynamics.

ON THE QUESTION OF USING GIS TOOLS IN THE STUDY OF PALEOVALLEY IN THE VERCHNY PRUT BASIN

This article is devoted to the complex issue of the use of GIS in the study of the stages of the formation of the water network of the rivers of the Ukrainian Carpathians, the identification and study of ancient flow valleys, morphogenesis and features of high terrace levels and paleovalleys in different periods of their formation. It is the use of new modern methods of digital mapping and geo-informational tools in research that allows us to look in a new way at the seemingly already known and defined problematic issues of the clarity of the stages of the origin and formation of the basins of the river systems of the Ukrainian Carpathians and their gradual stabilization within modern limits. It would seem that the position of leading specialists, Ukrainian geomorphologists (P. M. Tsis, K. I. Gerenchuk, M. S. Kozhurinoi, Y.S. Kravchuk, V. M. Klapchuk and others) has been clearly formulated for a long time thanks to the use of new geoinformation technologies and accessibility to modern software opens up new opportunities for its review and refinement. Currently, an important aspect of the study of basin systems of mountain regions, such as the territory of the Ukrainian Carpathians, is the application of not just a cartographic research method, with the corresponding results of visualization, zoning or the creation of appropriate map schemes, but the use of system analysis, thanks to GIS applications (TIN interpolation qgis) and the creation of appropriate models, which allows us to reveal in more detail the complex issues of the transformation of ancient valleys and their modern reflection in the relief of this territory. It is the ambiguous conclusions and results of previous researchers that encourage the use of new, more progressive methods, which will make it possible to better substantiate and determine how the processes of restructuring of the river network of the southeastern macroslope of the Ukrainian Carpathians took place, as well as to reveal the reasons for these changes. It is especially important to take into account and rely on changes in the configuration of the Upper Prut river system network at various stages of its functioning and development. This complex and not fully resolved issue, the transformation of ancient flow valleys in the Pliocene–Pleistocene period, is extremely important for the understanding of modern channel processes on the rivers of the Upper Pruth basin, as it still has a significant impact on the perception of the modern view of the river network of the studied basin and the inherited nature of macroforms riverbed in its separate sections. Keywords: GIS; digital topographic base of the Earth: SRTM; paleogeomorphological analysis; paleovalley Chornyy Cheremosh river; paleovalley Chornа Tysa river; paleovalley of the Lyuchka and Oslava rivers.

Slope instabilities and evolution of tectonic geomorphology along the strike of the Main Boundary Thrust zone in the western Himalaya, India

The Main Boundary Thrust (MBT) and Main Boundary Fault (MBF) zones of the southeast Himachal Himalaya are susceptible to various types of mass movement. Several active and in-active landslides are observed along the strike of the MBT. The landslides are mainly controlled by the brecciated and highly fractured nature of the bedrocks, and the intersecting joint sets form wedges. The movements are taking place along the fault planes, fracture planes, and bedding planes; and the types of failure are wedge failure, planar failure, toppling, rock falls, and complex landslides. The various morphotectonic features observed in the study area include fault traces, fault scarps, strath terraces, paleochannels and structurally controlled channels. Fault traces and their associated deformed landforms are the most spectacular tectonic landforms in the area. Along the strike length of the fault traces several linearly arranged sag ponds have formed, in the western segment the fault trace is observed along the MBF and the fault scarp dips south, with a maximum height of about 34 ​m. In the eastern segment the fault trace cut across the MBT, the fault trace is also displaced by transverse faults. Paleochannels and multiple levels of strath and fill terraces collectively indicate the river channel's disequilibrium state concerning the ongoing tectonic activity. The cross-cutting relation and displacement pattern of fault traces indicate later phases of tectonic activity.

River terraces assessment to evaluate the regional tectonic activity of the fore parts of Mishmi Block and Manabhum Anticline, North-east India: A conjunctive approach using Field Mapping and Satellite imagery

Terraces are the remains of a river's old floodplain. They are created when a river channel is downcut into its former floodplain, which is then deserted and subjected to lateral erosion. A former floodplain's downcutting, abandonment and lateral erosion can be caused by local or regional tectonic uplift, changes in the climate and changes in the river's discharge or a combination of these. The 1950 Mw 8.6 Great Assam Earthquake, which completely wrecked the region, occurred in the Mishmi Hills. The study area lacks tectonics research, therefore understanding the region's undulations requires a thorough understanding of terraces. Using ArcGIS 10.4, a digital elevation model (DEM) with a 30m resolution and satellite images form Google Earth Pro was superimposed on the Survey of India's topographic map for this investigation. The goal of the study is to use terrace analysis to comprehend the regional tectonic activity of the entire frontal and foothills of the Mishmi Hills. The Lohit, Dibang and Noa Dihing River are the most notable rivers in the research area. The rivers possess incised valleys and tributaries where different level of terraces may be identified. The terraces of the said rivers and tributaries are the subject of this study. Since the terrace levels vary from valley to valley, it is impossible to correlate adjacent valleys. The terraces are typically found where one of these rivers and one of its tributaries converge. The tectonic influence on various features in the studied area is typically defined through the study of terraces.

The Role of Past Climatic Variability in Fluvial Terrace Formation, a Case Study from River Mureş (Maros), Romania

Fluvial terrace formation is a complex process governed by the interplay of climatic and tectonic forcings. From a climatic perspective, an incision is usually related to climatic transitions, while valley aggradation is attributed to glacial periods. We have reconstructed the formation of Late Pleistocene fluvial terraces along the middle, mountainous section of a temperate zone river (Mureş/Maros) in order to identify the roles of different climatic periods and potential vertical displacement in terrace development. Investigations were based on two profiles representing two different terrace levels. The profiles were subjected to sedimentological and detailed geochronological analyses using optically stimulated luminescence (OSL). The results indicated that the investigated terraces represent different incision events coinciding with climatic transition periods. However, a joint MIS 3 valley aggradation period can be identified at both of them. Thus, the relatively mild but highly variable climate of the MIS 3 facilitated sediment mobilization from upland catchments. On the other hand, there is no evidence of aggradation under the cold and stable climate of MIS 2. However, the tectonic setting favours incision at the site. Based on our results, we concluded that the timing of the main events was controlled primarily by climatic forcing. The terrace formation model recognised might also be applied at other rivers in the region.

GEOMORPHOLOGY, TERRACES OF VARIOUS DOMINE OF ALAKNANDA ITS TRIBUTARIES AND NEOTECTONISAM, GARHWAL HIMALAYA PARTS OF CHAMOLI TEHRI UTTAKASHI &amp; PAURI UTTAR PRADESH (UTTRARKHAND) INDIA

The Geological and Geomorphological study in Upper Ganga basin has been attempted in parts of de Uttarkashi,Chamoli, Pauri and Tehri districts, an area of 10000 Sq.kms in parts of QA sheet 53J and 53 N on 1:50000 scale of Garhwal Himalaya U.P has been covered presently known as Uttrakhand State of Union of India. Out of total area of study, an area about 3500 sq.Kms (1:50000 scale) has been selected for detailed Geological, Geomorphological and Sedimentological study. The area of Upper Ganga basin consisting of Alaknanda, Bhagirathi, Bhilangna, Nandakini, Mandakini, Pindar, Dhauli- Ganga Bal- Ganga, Madhmeshwar Ganga and Berhi Ganga. The Alaknanda is chracterised by six terraces followed by Bhagirathi with five terraces, Bhilangna Nandakini four terraces, Mandakini /Pindar/Dhauli-Ganga /Balganga three terraces, Madhmshwar Ganga two terraces and Berhi Ganga one terrace, amidst these Alaknanda is trunk stream and others are tributaries. Geomorphologically, the area is divided in to seven geomorphic units viz High relief formerly glaciated area, Structural hills, Denudational hills, Area of mass wasting, High level dissected fans River Terraces and Present day flood plain of Alaknanda and its tributaries. These units area developed in response to lithology to erosional land depositional activities and tectonic in which they are embedded. Each unit is characterized by distinct drainage, diagnostic geomorphic landform elements and features, photo charcters and morphogenetic expression. The other geomorphic features and elements identified in the area are point bar, channel bar, alluvial fans ,talus cone , rock cut terraces fan cut terraces , abandoned and fossil channel courses,epigenetic gorges, strant lines landslides, rock fall scree and scree slope, retreating scarp, abandoned cirque, cirque morines, arêtes, threshold, horn peak and glacial lake. The area genetically comprised of terraces of three domains, viz. glacial, fluvio-glacia and fluvial which represent distinct environment of sedimentation of Pleistocene, late Pleistocene and Holocene time during Quaternary period. The glacial terraces are identified at an average elevation of 1150 m above m.s.l. the fluvio-glacial terraces at an average elevation of 975 m above m.s.l. and fluvial terraces at an average elevation between 650 to 900 m above m.s.l. The Badrinath temple is situated in glaciated trough valley of Alaknanda, which comprise of, four levels of the glacial terraces (lateral moraine), cirque moraine on mountain flanks and the terminal moraine at the base of valley. whereas Kedarnath in the upstream of Mandakini, where number of well developed cirques were identified on high mountain, they are mostly arm chair shaped hollows with a steep to vertical head walls, concave floor and a threshold, these cirques are noticed at an average height of about 4500 m. The Kedarnath temple is situated in glaciated trough valley on quaternary platform formed by coalescing of cirque, lateral moraine and terminal moraine. The-Himalayan thrust like Central thrust Srinagar thrust, Alaknanda fault, Tons thrust show flattening dip suggesting that they lie at comparatively at shallow depth at short distance, down dip from their out crops, recent movements along the trace of these thrust/ faults are not of high and longer magnitude but have considerably affected Quaternary terraces of glacial, fluvio-glacial and fluvial domain of Alaknanda and its tributaries. Beside drainage, river bed profile, landscape architect and over all morphogenetic expression of the area, this bears the adverse impact of tectonic activity. The imprints of neotectonisam associated in the area indicate that these thrust /faults are active and have, signatures of sinking of landscape, mass wasting activities and posed neosiemic hazards and tectano-ecological problems, bears signatures of sinking of the area, mass wasting activities and neosiemic hazards. The geomophological study of the area, overall morphogenetic illustration, imprints of neotectonisam, disposition of terrces of different domains, mass wasting activities, drainage net, channel morphology, landform elements of glacial, fluvioglacial and fluvial domain of Alaknanda and its tributaries indicate that tectonically the area is active and slow movements are taking plae along thrust, faults and lineament. In the area North of Wazri in Jamuna valley, North of Uttarkashi around Sainj in Bhagirathi valley, around Tugnath and Chamoli and South of Joshimuth in Alaknanda valley revealed that there is sharp persistent curvilinear break in topography, which has geothermal manifestation at Wazri Gagnani anda Tugnath in the form of emitation of hot springs. This curvilinear line has further reconfigurated the neo stream net works system and affected morphogenetic expression it appears to be due to horizontal movement of sub - tectonic plate towards south, which, is sole collective and cumulative causative factor in dislocation of tectonic ecology of the area and has resulted micro earthquake shocksand and segmental sinkiking of area. The overall study revealed that the the area is sensitive active and is vulnerable to any techtono- seismic event it is matter of serious concerned and needs further attention.

Late Quaternary fluvial and aeolian depositional environments for the western Red River, Southern Great Plains, USA

AbstractUbiquitous Holocene dune systems are associated with major west-to-east flowing rivers across the Southern Great Plains (SGP), USA. Critical questions remain as to whether aeolian activity reflects multiple environmental signatures, including increased sand supply from riverine sources. This research focused on the western Red River where geomorphic mapping revealed three terrace levels up to 16 m, buried partially by up to 10 m of aeolian sediments. Pedosedimentary facies analyses of sections and Geoprobe cores extracted from terraces and close-interval optically stimulated luminescence dating of quartz grains revealed two periods of fluvial aggradation at ca. 80 ka to ~5 to 8 m above the Red River forming the Vernon terrace, and at 30 to 13 ka to ~20–15 m, the highest identified Childress terrace. Net degradation of 20 m also occurred between 13 and 7 ka to 4 m below the current channel, reflecting regional fall in the groundwater level. The latest aggradation event, which built the lowest Luna terrace at ~2 m, ended 1.5 to 0.7 ka and was partially buried by fluvial-sourced dunes in the sixteenth and seventeenth centuries. This recent phase of aeolian deposition coincides with a comparatively wet period in the central United States during the Little Ice Age, rather than with regional drying.