Geomorphology

Journal: Geomorphology

Publisher

Elsevier

ISSN

0169-555x
1872-695X

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Publications 1 - 10 of 110

Emergence of the Shackleton Range from beneath the Antarctic Ice Sheet due to glacial erosion
Sugden, D.E.; Fogwill, C.J.; Hein, A.S.; et al. (2014)
Geomorphology
Geology and radiometric 14C-, 36Cl- and Th-/U-dating of the Fernpass rockslide (Tyrol, Austria)
Prager, C.; Ivy-Ochs, Susan; Ostermann, M.; et al. (2009)
Geomorphology
Rapid post-glacial bedrock weathering in coastal Norway
Andersen, Jane Lund; Margreth, Annina; Fredin, Ola; et al. (2022)
Geomorphology
Quantifying bedrock weathering rates under diverse climate conditions is essential to understanding timescales of landscape evolution. Yet, weathering rates are often difficult to constrain, and associating a weathered landform to a specific formative environment can be complicated by overprinting of successive processes and temporally varying climate. In this study, we investigate three sites between 59 degrees N and 69 degrees N along the Norwegian coast that display grussic saprolite, tafoni, and linear weathering grooves on diverse lithologies. These weathering phenomena have been invoked as examples of geomorphic archives predating Quaternary glaciations and consequently as indicators of minimal glacial erosion. Here we apply cosmogenic nuclide chronometry to assess the recent erosional history. Our results demonstrate that all three sites experienced sufficient erosion to remove most cosmogenic nuclides formed prior to the Last Glacial Maximum. This finding is inconsistent with preservation of surficial (<1-2 m) weathered landforms under non-erosive ice during the last glacial period, while simultaneously demonstrating that post-glacial weathering and erosion rates can be locally rapid (4-10 cm kyr(-1)) in cold temperate to subarctic coastal locations. (C) 2021 The Authors. Published by Elsevier B.V.
Complex patterns of schist tor exposure and surface uplift, Otago (New Zealand)
Raab, Gerald; Martin, Adam P.; Norton, Kevin P.; et al. (2021)
Geomorphology
Landscapes are subjected to surface denudation during their complex and non-linear evolution. In order to quantify the in situ surface lowering and, thus, denudation or soil erosion rates, new, multi-millennia archives are needed and must be rigorously tested. Large residual rocks, tors, are the basis for the Tor Exhumation Approach. Here we present novel results on meta-sedimentary (schist) rock tors using this approach, which previously has only been applied in granitic terrains. The exhumation patterns of eight schist tors in three landscape locations (valley, ridge, distal) of Otago, New Zealand, were studied using cosmogenic dating. The in situ 10Be ages have high variability along individual vertical tor profiles. Average surface age is 122 ± 12 ka and ranges from 836 ± 89 ka to 19 ± 2 ka. The majority of investigated tors have surfaced during the MIS 5 which was one of the wettest and warmest climate periods. The resulting surface denudation trend of the three locations differs. The valley commenced denudation no earlier than ~200 ka with rates of ~0.22 [m kyr−1] to ~0.02 [m kyr−1]. In contrast, exposure started at the ridge position around 230 ka at ~0.03 [m kyr−1]. An age inversion found in the valley is considered to be the result of mushroom-like exposure by undercutting and repeated rock breakoffs. The distal site tor has been exhumed continuously for ~120 ka at a rate of ~0.2 to ~0.05 [m kyr−1]. We identified a mix of surface emergence patterns of the tors such as continuous-, mushroom-, tafoni- and structural-like. The comparison to modern erosion rates indicates that surface erosion has increased up to a factor of ten during the last few decades. To determine the actual surface uplift, we linked the tor derived surface denudation rates with rock uplift data. The data indicates that the surface uplift rates started to decrease during the Middle Pleistocene (0.04–0.09 [m kyr−1]), remained relatively low during the Late Pleistocene (~0.01 [m kyr−1]) and started to increase again during the Holocene (c. 0.21–0.64 [m kyr−1]). In summary, the emergence pattern of local tors enabled reconstruction of the evolution of Pleistocene-Holocene surfaces in East Otago.
Genesis of folia in a non-thermal epigenic cave (Matanzas, Cuba)
D'Angeli, Ilenia M.; De Waele, Jo; Melendres, Osmany C.; et al. (2015)
Geomorphology
A giant Early Holocene tsunamigenic rock-ice avalanche in South Greenland preconditioned by glacial debuttressing
Pedersen , Lisbeth L.; Svennevig , Kristian; Morino , Costanza; et al. (2026)
Geomorphology
Deposits of a giant (more than 1 km³) rock-ice avalanche with a runout of 15.8 km and an associated failure scar have been discovered in Tupaasat Valley, South Greenland (Kalaallit Nunaat). To study its formation, a geomorphological map of the area has been produced using mainly remote sensing, while the age of the landforms has been constrained based on ¹⁰Be cosmogenic nuclide exposure dating. The rock-ice avalanche landforms include a 1100 m wide mound of displaced material located approximately 6.4 km from the scar, at a change in slope from around 4° to 1.5°. A boulder field containing boulders up to 45 m across lies 0.5 km farther down the valley. Beyond the boulder field are kettle holes up to 45 m in diameter and debris cones interpreted as molards reaching heights up to 36 m and diameters up to 140 m. The source area of the rock-ice avalanche is on a mountain crest above a present-day glacier. The rock-ice avalanche landforms yielded ¹⁰Be ages ranging from c. 12.3 to 9.5 ka with a weighted mean of 10.9 ± 0.5 ka, which coincides with the generally known deglaciation age of the valley. Based on our results, we suggest that the rock-ice avalanche was preconditioned by glacial debuttressing during the deglaciation of the valley and created a tsunami when it impacted a nearby fjord. Such events are expected to be more frequent due to climate change and future ice loss and pose a hazard for populations located near glaciated valleys. A better understanding of past events can help mitigate future large rock-slope failures.
Reconstructing extreme Late Pleistocene floods in Morocco's Inaouène Valley reveals larger discharges during terrace aggradation than both incision and modern floods
Lghamour , Mohammed; Karrat , Lhoucine; Picotti , Vincenzo; et al. (2026)
Geomorphology
Understanding how Quaternary climate shifts shaped fluvial systems through cycles of aggradation and incision is a central theme in fluvial geomorphology. A widely observed pattern is that wetter climatic phases enhance flood discharge and transport capacity, driving valley incision. Whether this relationship is reversed in sediment-rich, semi-arid environments, however, has remained poorly constrained by direct quantitative evidence. Here we present the first quantitative reconstructions of peak flood paleodischarges from the Late Pleistocene Inaouène valley, northern Morocco. Our results show that minimum peak flood discharges during Last Glacial Maximum aggradation were at least 8487 ± 1128 m³/s, exceeding those of the subsequent incisional phase (≥1950 ± 181 m³/s) by more than four times and the maximum modern recorded flood by over 6.5 times. These findings demonstrate a sediment-supply-dominated regime, where abundant clast production from hillslopes overwhelmed even extreme floods and drove valley-wide aggradation. Incision, in turn, occurred under conditions of much lower discharge and reduced sediment input. This study provides direct, quantitative evidence linking abrupt Lateglacial climate transitions to flood-driven landscape evolution in a semi-arid Mediterranean environment.
New data on tributary terraces and a reappraisal of the incision history of the Jinshan Gorge, middle Yellow River
Zhong, Yuezhi; Picotti, Vincenzo; Xiong, Jianguo; et al. (2024)
Geomorphology
River channel profiles and river terraces are two typical landscape features to investigate river incision history. However, incision history inferred from the two markers can be inconsistent. For example, along the Jinshan Gorge in the middle Yellow River, pseudo-terraces (a virtual metric derived from channel profile modelling) suggest a recent acceleration in incision rates only in the southern gorge, and the northern keeps steady, while river terraces in the trunk channel indicate recently increased incision rates all along the gorge. To mitigate these discrepancies, we investigate six tributaries along the Jinshan Gorge by mapping and dating several strath terraces at various distances from the confluence to the trunk channel. By comparing tributary terraces of similar age, we find generally increasing incision rates towards the confluence with the trunk river in the southern Jinshan Gorge. North to south increasing incision rates along the gorge are also observed from coeval tributary terraces. In addition, two different landscapes between the southern and northern tributaries near the confluence are recognized, one with a deeply incised gorge and another one with floodplains, suggesting incision rate in the northern gorge is steady through time. Integrating the new infrared stimulated luminescence (IRSL) and Accelerator Mass Spectrometry (AMS) 14C data from tributaries with the abundant literature data of terrace samples mostly in the Jinshan Gorge dated with various methods, we suggest published ages from optically stimulated luminescence (OSL) might be too young. The methodological limitation associated to the dating method can explain the observed mismatch of incision history in the northern gorge inferred from pseudo-terraces and from river terraces in the trunk channel, and reconcile some contradicting patterns in published trunk terrace data.
Interplay between tectonics and surface processes in the evolution of mountain ranges: Insights from landscape dynamics, uplift, and active deformation of Talesh Mountains (NW Iranian Plateau margin)
Moumeni, Mohammad; Delchiaro, Michele; Seta, Marta Della; et al. (2024)
Geomorphology
Drainage divides are dynamic features of a landscape that migrate over time during the development of river networks. In this study, we focused on the geomorphic response of a landscape to the interaction among tectonics, climate, and lithology in the Talesh Mts. along the northwest of the Iranian Plateau. The footprints of these competing forces have been analyzed by divide stability analysis and applying χ, χQ, and Gilbert metrics. Additionally, we examined the effects of bedrock erodibility on landscape evolution processes by measuring the mechanical rock strength of the lithological units in different sectors of the mountain range. The distribution of the χ values suggests a disequilibrium of the drainage networks across the whole main divide and its tendency to migrate towards the interior of the plateau. In contrast, Gilbert metrics, which focuses on a narrow topographic zone across the divide, suggest that the uppermost divide in the northern and southern Talesh Mts. is stable. Moreover, asymmetry in Gilbert metrics across the central part of the range suggests that the divide might be migrating towards the plateau interior. The possible scenario for the whole divide's behavior is associated with the contrasting erosion rates across the divide. In the northern and southern sectors of the Talesh Mts. range, the erosional wave related to the most recent uplift pulses has not reached the divide yet. Mechanism of topographic rejuvenation is controlled by heterogeneous uplift of strong bedrock units in the northern and southern sectors, and weak bedrock units outcropping in the central sector, initiated topographic rejuvenation largely in the central Talesh Mts. Parallelly, the precipitation has a limited effect in assisting and magnifying the divide mobility, reorganization, and landscape transience. In general, we can infer that divide is in a transient state due to the spatially varying rock uplift and bedrock erodibility.
Quantifying denudation rates and sediment storage on the eastern Altiplano, Bolivia, using cosmogenic Be-10, Al-26, and in situ C-14
Hippe, Kristina; Kober, Florian; Zeilinger, Gerold; et al. (2012)
Geomorphology

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Journal: Geomorphology

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