Glacial Landforms Research Articles

Reconstructing the Holocene glacial history of northern Troms and western Finnmark, Arctic Norway

Here we present the first Lateglacial and Holocene glacial history from Rotsunddalen, northern Troms and western Finnmark county, northern Norway, based on both relative and numerical moraine dating using Schmidt hammer, soil chronosequencing and terrestrial cosmogenic nuclide dating. We combine these chronological data with a regional map of the glacial geomorphology to hypothesize key events in the glacial history from around 14 ka to present. Our reconstruction shows that, following deglaciation of the main ice sheet across central Troms and Finnmark, mountain glaciers were terminating on land, close to the coast, between around 12.1 and 10.6 ka. Continued recession of the main Fennoscandian Ice Sheet margin towards the SE led to the isolation of several large plateau icefields and outlet glaciers that generated moraines at around 10.2–9.2 ka, which we ascribe to the Erdalen Event, and 8.4–8.2 ka, which is broadly contemporaneous with the 8.2 ka cold event. Although the latter corresponds with the Scandinavian Finse Event, very few moraines have been dated to this time and we therefore view it as a tentative hypothesis for future work to test. During the Holocene Thermal Maximum (~6.6 to 6.3 ka) most (if not all) glaciers in the region disappeared, but then regrew during the Neoglaciation and produced large moraines dated to around 4.7 ka that lie a few hundred metres distal to the prominent Little Ice Age moraines (previously dated to AD 1810s–1870s). Given the limitations of our dating approach, the preservation of moraines dated to this period in northern Norway also warrants further investigation. We also highlight that terrestrial cosmogenic nuclide dating of the moraines is not consistent with other dating approaches and the widely established deglaciation history of the region, probably owing to cosmogenic inheritance and insufficient glacial erosion.

A machine learning approach to the geomorphometric detection of ribbed moraines in Norway

Abstract. Machine learning is a powerful yet underutilised tool in geomorphology, commonly used for image-based pattern recognition. Analysing new high-resolution (1–10 m) elevation datasets, we investigate its usefulness for detecting discrete geomorphological features. This study develops a machine-learning-based method for identifying ribbed moraines in digital elevation data and progresses to test its performance versus time-consuming, manual methods. Ribbed moraines share geomorphometric characteristics with other glacial landforms, hence representing a valuable test of our new methodology in terms of differentiating between similar features, and for detecting landforms with similar characteristics. Furthermore, mapping ribbed moraines may provide valuable indications of their origin, a topic of debate within glacial geomorphology. To automatically detect ribbed moraines, we extract simple morphometrics from high-resolution digital elevation model data and mask regions where ribbed moraines are unlikely to form. We then test several machine learning algorithms before examining the best performer (K-means clustering) for three study areas of 15 km2 in Norway. Our results demonstrate a balanced accuracy of 65 %–75 % when validating versus ground-truthing. The performance depends on the availability of high-resolution elevation data in Norway that are needed to resolve the spatial scale of the target (10–100 m). We find the method effective at detecting both fields of ribbed moraines, as well as individual ribbed moraines. We propose pathways for the future implementation of this method on a large scale and for increasing the detail of information gained about detected landforms. In conclusion, we demonstrate K-means clustering as a promising method for detecting ribbed moraines, with great potential to reduce the time needed to produce landform maps.

Observing changes in the present and paleo-glacial extents of major glaciers in the Alaknanda Basin of Central Himalaya

The erosional and depositional landforms modified by the glaciers can be used effectively to reconstruct the palaeo-glacial events along with dating techniques. In this study, a detailed reconstruction of the Satopanth Glacier (SPG), Bhagirath Kharak Glacier (BKG), and Bhagnyu Glacier (BG) in the Alaknanda Basin of Central Himalaya is carried out using glacier morphological features identified from a comprehensive dataset that includes historic toposheets (1882–1962), satellite images (1968–2020), and field observations (2019 & 2020). We also compute paleo, contemporary ice thickness, and glacier volumes using the Glacier Reconstructio (GlaRe) and the Himalayan Glacier Thickness Mapper (HIGTHIM) tools, respectively. Our results demonstrate that the region has witnessed three major glacial advances: Stage I (oldest), Stage II, and Stage III glaciations. The SPG, BKG, and BG were tributaries of a primary primitive glacier that existed during the Stage I glaciation that extended to the Mana village. The Stage I glacial moraines are at a distance of 8.4 ± 1.1 km, 7.8 ± 1 km, and 8.4 ± 1.1 km from the present-day snout of SPG, BKG, BG, while the Stage II moraines are 5.1 ± 0.71 km, 4.2 ± 0.58 km, and 5 ± 0.7 km away, and Stage III moraines are 1.9 ± 0.26 km, 1.3 ± 0.18 km, and 2.8 ± 0.39 km away, respectively. The area of the primitive glacier reduced (Stage I to the recent period) from 78 ± 4.6 km2 to 60 ± 3.6 km2 with a volume reduction from 4.7 ± 0.94 km3 to 3.5 ± 0.63 km3. Most importantly, the rate of recession of the glaciers in the Alaknanda Basin is more in the last 5 decades ∼(8.4 ± 1.1 m a−1 (SPG), 7.2 ± 1 m a−1 (BKG), 10 ± 1.4 m a−1 (BG)) than that reported over the last 12,000 years, which is ∼0.42 m a−1 (SPG), 0.35 m a−1 (BKG), 0.42 m a−1 (BG). The present study provides a detailed characterization of the long-term evolution of glaciers in the Alaknanda Basin for the first time.

HOTSED: A new integrated model for assessing potential hotspots of sediment sources and related sediment dynamics at watershed scale

In this paper we introduce HOTSED, a novel, innovative GIS-based model designed for assessing potential hotspots of sediment dynamics at watershed scale. HOTSED integrates geomorphic spatial information with both structural and functional properties of connectivity. HOTSED provides a single and intuitive output that depicts the location of sediment source hotspots. Moreover, it enables the identification of “relative hazard” classes for sediment production and related effects. The general methodological framework is based on the initial elaboration of an Inventory Map (IM) of sediment-related landforms and processes, along with the implementation of a corresponding database. Subsequently, we used data stored in the IM to estimate the geomorphic Potential of Sediment Sources (PSS) through a relative scoring system. Furthermore, we computed Structural Sediment Connectivity (STC) and the Potential for Sediment Transport (PST) by combining terrain and hydrological parameters, vegetation roughness, and rainfall erosivity. Afterwards, PSS, STC, and PST components are integrated through a raster-based calculation method yielding the HOTSED model. We tested the HOTSED procedure in the upper Val d’Arda-Mignano watershed, which is a representative geomorphologically highly active Mediterranean area of the Northern Apennines (Italy). Through photointerpretation, terrain analysis, and fieldwork, we mapped sediment-related geomorphic features for a total of 4640 ha including: badlands and gullies (0.26%), rill-interrill erosion (15.03%), fluvial erosion (0.03%), landslides (70.06%), litho-structural erosional systems (0.87%), slope deposits (12.56%), and alluvial deposits (1.19%). HOTSED revealed hotspots with a very high hazard potential located near main channels or upstream of the reservoir. These areas are often linked with active landslides highly connected to the drainage system and frequently associated with other processes like bank erosion or surficial soil erosion. The model also highlighted linear hotspots corresponding to drainages flowing alongside or intersecting complex geomorphic systems such as landslides. Furthermore, HOTSED identified areas where sediments are stored in depositional landforms, exhibiting a low hazard potential, considering both low geomorphic potential and sediment connectivity. Our conceptual model is generally applicable but proves to be particularly effective in areas characterized by complex and polygenetic geomorphic systems, such as the Northern Apennines. HOTSED offers a valuable tool for watershed authorities to support sustainable watershed and reservoir management.

The hidden glacial landscape of the Monti della Laga (central Apennines, Italy)

AbstractThe geological and geomorphological record of the Last Glaciation in the Apennines is extensively documented, except for the Monti della Laga sector, where limited indicators of glacier extension have been reported. This study presents field evidence of glacial deposits and landforms from two specific sites within the Monti della Laga Range: Monte Pelone and Tordino Valley head. Although limited, this evidence suggests glaciation within a structural and lithological setting that facilitated rapid slope evolution. The post-glaciation paraglacial processes in the area erased most glacial traces, but our geomorphological and stratigraphical investigations identified specific landforms of glacial origin. Notably, at Monte Pelone, a semi-circular depositional landform exhibiting a significant presence of coarse clasts and distinctive rotational features has been identified as a moraine. Additionally, a smaller moraine ridge with evidence of diamicton deposition was observed in the Tordino Valley head. These observations align with an Equilibrium Line Altitude estimated at 1750 m a.s.l. in the central Apennines in the Last Glacial Maximum and, considering the favourable topographic conditions of the area, significantly contribute to the understanding of glaciations within the central Apennines.

Geomorphological study of the debris flow events in the Harsovska River (Blagoevgradska Bistritsa catchment), observed within 2019-2023

Debris flow events in the Blagoevgradska Bistritsa catchment (SW Bulgaria) become more frequent in the past few years. To localize the debris source along the tributary system, the Harsovska River is chosen in this study. During the observation period a torrential event was registered in June 2023. The synoptic situation, which caused the flood, is re-analyzed and also geomorphological research is made for depositional landforms in the river channel for the period 2019-2023. In the study, the alluvial sediments are defined by grain size and also by morphoscopic study of pebble-sized grains. During the field research, two critical flood-risk sites are pointed, located in the Harsovo hamlet. The data about past debris flow events are collected from residents of Harsovo with interviews regarding their experience in this issue. In the period of the study, the main part of debris nourishment in Harsovska catchment is provided by the tributary Marulevska River, where active mass movement processes are registered. However, the alluvial profiles of both rivers – Marulevska and Harsovska, showed an alternation of coarser and finer materials, resulting of turbulent and calm discharge. Such periodical change in the sedimentary environment of the two compound rivers demonstrates their unsteady torrential character. Regarding the fortification activities in this area, at the moment some new forestation has been noticed. Still, the species, used to fortify the river banks are not suitable for the climate and hydrological regime of the region. The channel fortifications, built in the middle of the 20th century, currently are not maintained properly, which puts under threat of future debris flow events the settlements and infrastructure along this catchment.

Landscape and Landform Mapping in the Rongdo Basin, Eastern Karakoram, Ladakh, India

ABSTRACT Eastern Karakoram is one of the least studied areas with respect to glacial geomorphology due to its remoteness and inaccessibility and hostile climatic conditions, hence the use of remotely sensed data is indispensable in studying glaciers and related features of the region. In the present article, we present a comprehensive description of the glacial landforms and landscape evolution in the Rongdo basin Eastern Karakoram Ladakh, India. The region is dominated by well-preserved glacial features which offer an excellent opportunity to map and evaluate past glacial fluctuations. The mapping was carried out using high-resolution satellite data (Planet images), and Google Earth, along with ASTER GDEM scenes supplemented by field-based observations to delineate and map various glacial-geomorphological features in the region. The geomorphological landforms mapped include various types of erosional and depositional features. Based on the position of frontal and lateral moraines and glacial trimlines it is evident that the region has witnessed multiple episodes of glacial advances and experienced huge glacial thickness in the recent past. The study highlights role of a number of variables, including topography, climate, and geology, that have contributed to the formation and evolution of landscapes in study area. However detailed dating of the landforms in the region is vital in understanding the past glacial fluctuations and the impact of the climatic variations on the glaciers of the region.

Millennial-scale fluctuations of palaeo-ice margin at the southern fringe of the last Fennoscandian Ice Sheet

Abstract. The paper presents the first terrestrial record of millennial-scale palaeo-ice margin oscillations at the southern fringe of the last Fennoscandian Ice Sheet (FIS) during the last glacial cycle. The study area is located in northern Poland close to the last FIS maximum limit. The chronology and dynamics of palaeo-ice margin oscillations at the southern fringe of the FIS are based on combined luminescence and 10Be surface exposure dating. Optically stimulated luminescence (OSL) was used to date sandy deposits (fluvioglacial sediments and aeolian deposits filling fossil periglacial wedges) intercalating basal till layers. The most likely age of the tills was constrained by Bayesian modelling of the sequence of OSL ages and lithostratigraphy. 10Be surface exposure dating was used on erratic boulders left during the final retreat of the last FIS and resting on the surface of glacial landforms. Our results, which are mainly based on OSL chronology and Bayesian modelling, indicate millennial-scale oscillations of the last FIS in northern Poland between ∼19 and ∼17 ka. The last FIS retreated and re-advanced over a relatively short period of time (2–3 ka), leaving lithostratigraphic records (basal tills) of three ice re-advances over a millennial-scale cycle: 19.2±1.1, 17.8±0.5 and 16.9±0.5 ka. Despite 10Be surface exposure ages obtained for 14 erratic boulders being poorly clustered, the main mode of age distribution occurs at ∼18 ka and indicates a possible signal of the ice sheet retreat after one of the re-advances. We explore the dynamics of these oscillations and compare the proposed cycles of the southern FIS advances and retreats with existing patterns of the last deglaciation and millennial-scale fluctuations of the last FIS inferred from marine records.

Preliminary Investigation of the Remnants of Low-Latitude Glacial Activity on the Southeastern Margin of the Qinghai–Tibet Plateau

The formation of Quaternary glaciers represented a pivotal event in the climatic and geological history of the Tibetan Plateau. However, due to the scarcity of direct evidence for low-latitude glaciation, the timing and extent of late Quaternary glaciation on the Tibetan Plateau remain controversial. This study focuses on the Liangwang Mountains, which are located in the southeastern part of the Tibetan Plateau and has a maximum elevation of 2820 m, as the subject of investigation. Through a comprehensive application of glacial landform analysis, scanning electron microscopy (SEM)-based micromorphology analysis of quartz sand, and spore-pollen data analysis, we uncovered evident signs of glacial activity in this region during the Quaternary period. Our research identified typical glacial landforms such as cirques, U-shaped valleys, fluted moraines, and terminal moraines. Additionally, spore-pollen analysis revealed a high frequency of fir pollen, indicating cold climatic conditions during that time. Furthermore, the micromorphology analysis of quartz sand further corroborated the glacial origin of these deposits. Based on these combined findings, our study confirms that the Liangwang Mountains experienced glaciation during the Quaternary period, making them glacial relics at the lowest latitude currently known in mainland China. This discovery provides a valuable reference for understanding the paleoclimate and glacial history of the Tibetan Plateau and its surrounding regions.

Late Pleistocene to Holocene glacial, periglacial, and paraglacial geomorphology of the upper Río Limarí basin (30–31° S) in the Andes of central Chile

ABSTRACT We present a field-based reconstruction of the geomorphology in the Subtropical Andean mountains of the Limarí basin, semiarid central Chile (30–31° S). Fieldwork campaigns and remote-sensing analysis served for detailed geomorphological mapping at four formerly glaciated valleys in the heads of the Combarbalá and Río Hurtado sub-basins. We identify a mosaic of glacial, periglacial, and paraglacial landforms. Glacial landforms include a massive dead-ice moraine complex, with thermokarst and debris-filled fractures suggesting former ice-cored moraine degradation. This landform is superimposed by transversal and arcuate ridges suggesting active-ice processes. Periglacial landforms such as rock glaciers, gelifluction, and protalus lobes occur in cirques and U-shaped valleys, but also on moraine deposits. Paraglacial processes are indicated by talus accumulation in those formerly glaciated slopes. The geomorphological imprint is evidence for the interaction and succession between glacial, periglacial, and paraglacial dynamics from the Late Pleistocene to the present.

Glacial and volcanic landforms in the upper catchment of Claro River, Central Chile (35.5°S): A Late Quaternary geomorphological case study

AbstractThe upper catchment of the Claro river is located within the Transitional Southern Volcanic Zone in the Maule Region of Chile (35.5°S), at the foothills of Manantial Pelado volcano, a Pleistocene stratovolcano whose morphology suggests the occurrence of important glacial processes in the area. The observed glacial landforms can be sequenced and associated with episodes of volcanic activity. Different units of volcanic and glacial origin were identified based on field observations, detailed mapping, and digital elevation model and satellite image analysis. The contact relations between them made it possible to discern four events that can be linked to Marine Isotope Stages 8, 6, 4‐2, and to the Neoglacial. We propose seven stages in the geomorphological evolution from the late Pleistocene to the late Holocene, where there is coexistence between volcanic and glacial episodes, such as the emplacement of the Manantial Pelado volcano overlying the Abanico and Cola de Zorro formations; a subsequent debris avalanche; the enlargement of the Del Indio valley during the Penultimate Glaciation; the construction of Cerro Redondo (a minor eruptive center at the head of Del Indio valley); ongoing fluvial incision; and Neoglacial advances. The relative chronology proposed in this work contributes to clarifying the Pleistocene–Holocene geomorphological history in this catchment and to further understand the interplay between volcanic and glacial processes in the central Chilean Andes during the Quaternary.

Okanogan lobe tunnel channels and subglacial floods into Moses Coulee, Channeled Scabland, northwestern United States

Abstract Outburst floods from glacial Lake Missoula largely explain erosion of the Channeled Scabland, a system of overfit, basaltic channels in Washington, northwestern United States. However, it is challenging to explain Missoula flood routing into Moses Coulee due to its topographic isolation from flood routes. To clarify flood pathways into Moses Coulee, we mapped channels that delineate a radial-anastomosing network connecting to Moses Coulee. Channels consist of coulee-like features eroded mainly in basalt. Channels climb adverse slopes and cross divides, and the network is draped with eskers and recessional moraines. These channel geometries and glacial landform associations suggest a tunnel channel network. Large channel dimensions and network anastomosis indicate formation in subglacial floods. The network connects to Moses Coulee with sufficient cross-sectional area to convey megafloods, hinting that subglacial floods may have been a significant source of Moses Coulee meltwater, in addition to possible diverted Missoula floods.

Glacial geomorphology of the Vanch River basin, the western Pamirs, Tajikistan

ABSTRACT Geomorphological mapping of glaciers and glacial landforms helps describe the current environment and investigate past glacial changes. Here we present the first detailed 1:80,000 glacial geomorphological map of the Vanch River basin (about 2100 km2), the western Pamirs, Tajikistan [38.6667°N, 72.0000°E]. Mapping was performed using DEM (30 m), Landsat 8 imagery (15 m), and Google Earth images (∼1 m). The resultant map provides the spatial distribution of glaciers and associated erosional and depositional landforms such as cirques, glacial valleys, rock glaciers, and moraines. Morphology of the lower section of the main valley outlines the limits of Vanch Glacier in the Middle Pleistocene. Comparison with former glacier inventories indicates that the glaciers have generally been stable, but the proportion of debris-covered areas has increased since 2007. The identified 184 intact rock glaciers represent hidden water storage, providing a new basis for estimating water resources in the basin.

Post-little ice age glacial geomorphology of contrasting topographic settings at Skálafellsjökull, southeast Iceland

ABSTRACT Glacial geomorphological mapping from the southern margin of Skálafellsjökull, southeast Iceland, depicts a topographically diverse mountainside, influencing glacier dynamics, landform formation and glacier retreat since the Little Ice Age maximum in ∼1890. The glacial landforms present are typical of southeast Icelandic temperate glaciers, comprising recessional push moraines, including sawtooth moraines, and associated fluting. Study area A demonstrates an abandoned lobe confined by steep V-shaped topography, displaying moraines and minimal fluting, suggesting low preservation of landforms, and changes in glacier behaviour. At study area B, the sawtooth moraine morphology demonstrates changes in the glacier margin as the ice interacted with a series of topographic benches during active recession. The steep-sided valley at study area C illustrates densely spaced arcuate moraines, reflecting subtle changes in ice elevation. This mapping provides a framework for further investigations into glacier retreat rates and the influence of local topography and climate.

Mapping of morainic complexes and reconstruction of glacier dynamics north-east of Cook Ice Cap, Kerguelen Archipelago (49°S)

AbstractDue to the limited landmasses in the Southern Hemisphere, we must rely on data from sub-Antarctic islands within the Southern Ocean to record historical climate patterns. Over the past few decades, glaciers throughout the Southern Ocean region have experienced a noticeable retreat, especially in the Kerguelen Archipelago, whose glacial landforms offer valuable insights into long-term climate fluctuations. Our comprehensive glacial geomorphological study conducted in its remote north-western region meticulously examines morainic complexes from smaller cirque glaciers and larger outlet glaciers stemming from the Cook Ice Cap. We mapped these landforms to reconstruct historical glacier extents during the Holocene. The surface area of the three main glaciers had decreased in 1962–1964 by only 35% compared to their maximum extents, whereas surface area changes across 12 time intervals spanning from 1962 to 2019 from aerial and satellite imagery reveal a cumulative reduction of 43.5%. Additionally, we modelled changes in glacier thickness and equilibrium-line altitude for the key glaciers at three distinct stages: 1) their maximum extent before 1962, 2) the early 1960s and 3) 2019. This multifaceted analysis contributes valuable insights into the dynamics of Kerguelen's glaciers and the broader implications for understanding past and ongoing climate dynamics in the Southern Hemisphere.

The Pleistocene ice-sheet dynamics in north-central Poland based on magnetic fabrics of tills and landform analysis

Abstract This research was carried out in north-central Poland, which was occupied by the ice sheet of the Saalian (Marine Isotope Stage [MIS] 6) and Upper Stadial of the Weichselian (MIS 2) glaciation. The application of the anisotropy of magnetic susceptibility (AMS) method supported by a digital elevation model (DEM) analysis of the orientation of glacial landforms allowed for the reconstruction of ice-sheet extent and ice movement directions of these two Pleistocene glaciations. The research used an innovative method of collecting AMS till samples from the glacial plateau areas. Based on the research, it was found that during the general recession of the ice sheet of the Saalian glaciation, a previously undescribed glacial transgression occurred, characterized by a different direction of ice-sheet movement. On the basis of detailed geomorphological studies of the area of terminal moraines, previously described in fragments, the maximum extent of the ice sheet during the Weichselian glaciation was clarified. The recession of the ice sheet of the Weichselian glaciation from the area of north-central Poland took place in four regressive or transgressive–regressive stages with variable directions of ice-sheet movement. The results obtained indicate the great potential of the AMS method in paleoenvironmental studies of glaciated areas.

Rock and ice avalanche-generated catastrophic debris flow at Chamoli, 7 February 2021: New insights from the geomorphic perspective

Within mountainous landscapes neighboring glaciers, slope instabilities and consequent catastrophic mass flows are vital processes on Earth's surface, which have been of increasing interest for decades. These events commonly exhibit large volume, high velocity, and high mobility. Recently, a catastrophic debris flow occurred in India on 7 February 2021, which unfortunately claimed 70 lives and left 134 people missing. The failed mass comprises 80 % rock debris and 20 % glacier ice. Our remote sedimentological investigation of remnant deposition shows clear evidence of wet granular flow in upper Ronti Gad valley, which doesn't support the previous interpretation of immediate melting of the failed 20 % ice mass during the falling and impacting process. We further utilized the superelevation phenomenon to back-calculate the velocity downstream of the impact zone, and estimated the peak discharge, which is verified by field-documented data. Our results revealed an initial waning trend of rock and ice mass flow. As it entered the narrow valley of the lower Ronti Gad River, the extensive material erosion resulted in three-fold flow enlargement, which gave rise to a maximal peak discharge of up to 48–54 × 104 m3/s. The transition from granular flow to debris flow occurred in the 2-km-long channel downstream of the Ronti Gad-Rishigangga confluence. The sediment deposition of 4.8 × 104 m3 and the incorporation of stream water in this zone have dominated the rheologic transition. We inferred that the intense erosion of erodible sediment due to topographic constraint plays an essential role in maintaining the mobility of the flow. Therefore, the effect of glacier ice meltwater on high mobility may be overestimated. As long as the granular flow can access the stream water in major rivers, flow transformation can easily happen because of sufficient water supply in the channel. The valley morphology in the proglacial region is commonly featured by the shift from an upstream U-shaped valley carved by glacier erosion into a downstream fluvial-erosion-dominated V-shaped valley. This geomorphic setting of glaciated tributary favors the long-distance run-out of rock and ice avalanche.

Laurentide Ice Sheet configuration in southern Ontario, Canada during the last glaciation (MIS 4 to 2) from stratigraphic drilling and LIDAR-based surficial mapping

Regional subsurface mapping of glacial depositional systems preserved in buried bedrock paleovalleys, and quantitative analysis of new LiDAR imagery of surface glacial landforms using machine learning techniques, when combined, are powerful tools for assessing the dynamics of the Laurentide Ice Sheet (LIS) during the last (Wisconsinan) glaciation in southern Ontario. While age dating of deposits preserved below Last Glacial Maximum tills (LGM: marine isotope stage (MIS) 2 < c.24 000 years B.P. (ybp)) is still sparse, newly available sedimentological data derived by cored drilling, combined with legacy outcrop data, identify thick (100 m+) successions of glaciolacustrine sediments and a lack of till(s), indicating that the ice sheet margin did not extend beyond the Niagara Escarpment at the western end of Lake Ontario, during the earliest phases of the glaciation (MIS 4) or the ensuing mid-Wisconsinan (MIS 3). Ice was able to extend into New York State blocking the Rome outlet to the Hudson Valley ponding deep proglacial lakes in the glacio-isostatically depressed Huron–Ontario–Erie basins recorded by thick glaciolacustrine sediments in paleovalleys. These were cannibalized by an expanding Late Wisconsinan ice sheet after ∼24 000 ybp recorded by extensive till sheets resting on a marked erosional unconformity, with drumlinized surfaces. Analysis and visualization of LiDAR data identifies discrete statistically validated flow sets of highly elongated streamlined bedforms (mega-scale glacial lineations (MSGLs)). These provide key evidence of a major reorganization of the ice sheet margin during deglaciation into lobate paleo ice streams shortly after 17 400 ybp. MSGLs are cut across earlier LGM drumlinized tills creating widespread “palimpsest” surfaces. At least two principal phases of fast ice flow can be identified, marked by large fluxes of sediment and the rapid building of large gravel and sand-dominated moraine complexes within interlobate depocentres, the largest glacial landforms in southern Ontario. Analysis of LiDAR data further reveals the common presence of DeGeer moraines where ice margins retreated in water, and iceberg scours. Future work using LiDAR mapping has the objective of fully documenting the number, extent, and timing of ice streams to enhance glaciological modelling when the ice sheet rapidly lost mass.

Paleosol distribution and morphology along a late Cretaceous distributive fluvial system in the Bauru Basin, Brazil

Distributive Fluvial Systems (DFS) are fan-shaped landforms constituted by a radial system of channels that diverge downstream from an active apex, where the drainage emerges from the confinement valley. In such landforms, elevation, distance from fluvial channels, sedimentation rates, surface stability, and plant cover control weathering processes and soil development, but these features are obliterated within geological time. Thus, the micromorphological analysis of paleosols can be helpful for paleoenvironmental reconstruction of ancient DFS, improving the knowledge of soil genesis in these depositional landforms. Here, we describe macro and micromorphological features of twenty paleosols developed under arid to semiarid climates along the proximal to the medial zone of an Upper Cretaceous DFS in the Marília Formation, Bauru Basin, Brazil. Paleosols on the proximal zone typically showed features consistent with poor drainage, namely Bg, Btg and Bss horizons, and reddish Bt horizons in higher positions. Conversely, paleosols on the medial zone commonly showed reddish colours and pronounced secondary carbonate accumulation, consistent with a predominantly arid climate. Based on this distribution, we elaborated an evolution landscape model for the proximal and medial zone of the Bauru DFS, including allogenic and authigenic controls of soil development during the Campanian to the Maastrichtian epochs of southeastern Brazil.

Multi-source deep-learning approach for automatic geomorphological mapping: the case of glacial moraines

ABSTRACT Landform mapping is the initial step of many geomorphological analyses (e.g. assessment of natural hazards and natural resources) and requires vast resources to be applied to wide areas at high-resolution. Among geomorphological objects, we focus on glacial moraine mapping, since it is a task relevant to many fields (e.g. paleoclimate and glacial geomorphology). Here we proposed to exploit the potential of Deep Learning-based approaches to map moraine landforms by exploiting multi-source remote sensing imagery. To this end, we propose the first Deep Learning model to map glacial moraines, namely MorNet. As multi-source remote sensing information, we combine together three different sources: Topographic (Pleiades-derived DSM), Multispectral (Sentinel-2), and SAR (Sentinel-1) data. To cope with such heterogeneous information, the proposed model has a dedicated branch for each input source and, a late fusion mechanism is leveraged to combine them with the aim to provide the final mapping. The performance of the MorNet model is evaluated on several glacier valleys in China in the Himalayan range. This area contains minimally eroded moraines, so they are well-defined and of varied morphology. The behavior of the proposed method is compared to models using individual mono-source models in order to highlight the benefit to simultaneously leverage multi-source information. The use of multi-source data allows MorNet to exploit the complementarity of the three input sources and improve its performance from an f1-score of about 41.6 using a single source to 52.8 using three sources. MorNet provides a first-order moraine map through its ability to identify well-defined moraines. Consequently, MorNet can identify areas likely to contain moraines and intends to be used as a tool by experts to facilitate and support large-scale mapping.