Long-Term Evolution and Monitoring at High Temporal Resolution of a Rapidly Retreating Cliff in a Cold Temperate Climate Affected by Cryogenic Processes, North Shore of the St. Lawrence Gulf, Quebec (Canada)

This article focuses on the quantification of retreat rates, geomorphological processes, and hydroclimatic and environmental drivers responsible for the erosion of an unconsolidated fine-sediment cliff along the north shore of the Gulf of St. Lawrence (Quebec, Canada). Annual monitoring using field markers over a period of twenty years, coupled with photo interpretation and historical archive analysis, indicates an average annual erosion rate of 2.2 m per year between 1948 and 2017. An acceleration in retreat occurred during the last 70 years, leading to a maximum between 1997 and 2017 (3.4 m per year) and 2000–2020 (3.3 m per year). Daily observations based on six monitoring cameras installed along the cliff between 2008 and 2012 allowed the identification of mechanisms and geomorphological processes responsible for cliff retreat. Data analysis reveals seasonal activity peaks during winter and spring, which account for 75% of total erosional events. On an annual basis, cryogenic processes represent 68% of the erosion events observed and subaerial and hydrogeological processes account for 73%. Small-scale processes, such as gelifraction, solifluction, suffosion, debris collapse, and thermoabrasion, as well as mass movement events, such as slides and mudflows, induced rapid cliff retreat. Lithostratigraphy and cliff height exert an important control on erosion rates and retreat modes, which are described by three main drivers (hydrogeologic, cryogenic, and hydrodynamic processes). Critical conditions promoting high erosion rates include the absence of an ice-foot in winter, the absence of snow cover on the cliff face allowing unrestricted solar radiation, the repetition of winter warm spells, snow melting and sediment thawing, and high rainfall conditions (>30 mm or SPI > 2). The relationships between hydroclimatic forcing and retreat rates are difficult to establish without taking into account the quantification of the geomorphological processes involved. The absence of quantitative data on the relative contribution of geomorphological processes can constitute a major obstacle in modeling the retreat of cliffs with regard to climate change.

Assessing the ecological value of dynamic mountain geomorphosites

Geoheritage is a component of geodiversity constituted by all the elements of geodiversity recognized by society for their particular values. The definition of these values, including the importance of geoheritage for biodiversity, plays a key role in the process of heritage recognition and geoconservation policymaking. In mountain environments, dynamic geomorphosites have a strong influence on plant diversity because the active geomorphological processes responsible for their formation act as renovators for habitats of pioneer species. In this paper, we propose criteria to assess the ecological value of dynamic mountain geomorphosites. We show that the interest of plant communities (species richness and presence of rare or protected species) and the influence of geomorphological processes on plant communities (disturbances, surface movement and soil) are fundamental criteria for assessing the ecological value in an exhaustive and objective way and that the question of the scale (local and national scales) is also a crucial parameter. We then illustrate this methodological proposal by evaluating the ecological value of three dynamic geomorphosites and a talus slope in the western Swiss Alps.

THE GEOLOGICAL AND GEOMORPHOLOGICAL MONUMENTS OF UKRAINE AND THEY SIGNIFICANCE FOR THE DEVELOPMENT OF NATURAL-COGNITIVE TOURISM

The article reviews publications devoted to geological and geomorphological monuments of Ukraine highlights specific features of their formation in different regions and reveals their importance for the development of nature-cognitive tourism as a basis for the formation of the tourism industry. The methodological unity of the concepts "geological monuments" and "geomorphological monuments", which characterize the original course of natural processes and their results and therefore have great scientific and cognitive value are considered. Emphasis is placed on the important participation of geomorphological processes in the formation of natural monuments, which show different geological monuments on the earth's surface and reflect not only the features of geological factors but also the diversity of relief processes, their dynamics, which determines the status of most monuments as "geological and geomorphological". Important for establishing the protection status of geological and geomorphological monuments are the developed criteria for assessing the aesthetics of the relief of Ukraine, its uniqueness, the presence of features "architecture-composition", combination with other elements of the landscape, stability or mobility, imagery – photogenicity, visual effect, emotional perception, attractiveness, etc. It is noted that the category of natural phenomena "geological and geomorphological monuments" is characterized by significant conservatism compared to other components of the natural environment. Such monuments are carriers of paleogeographic and ethnocultural content, which, in addition to scientific significance, gives them the status of interesting tourist attractions. This creates an opportunity for the development of nature-cognitive tourism, which can be both independent and successfully complements all other known types of tourism. Geological and geomorphological monuments influence the nature of recreational activities. The specificity and sequence of recreational functions of the relief of Ukraine according to the special properties of endogenous, exogenous, and anthropogenic genetic varieties of recreational geological and geomorphological monuments have been established. Key words: geotourism; nature-cognitive tourism; geological-geomorphological monuments; geoheritage of Ukraine.

Geomorphology and InSAR-Tracked Surface Displacements in an Ice-Rich Yedoma Landscape

Ice-ridge Yedoma terrain is susceptible to vertical surface displacements by thaw and refreeze of ground ice, and geomorphological processes of mass wasting, erosion and sedimentation. Here we explore the relation between a 3 year data set of InSAR measurements of vertical surface displacements during the thaw season, and geomorphological features in an area in the Indigirka Lowlands, Northeast Siberia. The geomorphology is presented in a geomorphological map, based on interpretation of high resolution visible spectrum satellite imagery, field surveys and available data from paleo-environmental research. The main landforms comprise overlapping drained thaw lake basins and lakes, erosion remnants of Late Pleistocene Yedoma deposits, and a floodplain of a high-sinuosity anastomosing river with ancient river terrace remnants. The spatial distribution of drained thaw lake basins and Yedoma erosion remnants in the study area and its surroundings is influenced by neotectonic movements. The 3 years of InSAR measurement include 2 years of high snowfall and extreme river flooding (2017–2018) and 1 year of modest snowfall, early spring and warm summer (2019). The magnitude of surface displacements varies among the years, and show considerable spatial variation. Distinct spatial clusters of displacement trajectories can be discerned, which relate to geomorphological processes and ground ice conditions. Strong subsidence occurred in particular in 2019. In the wet year of 2017, marked heave occurred at Yedoma plateau surfaces, likely by ice accumulation at the top of the permafrost driven by excess precipitation. The spatial variability of surface displacements is high. This is explored by statistical analysis, and is attributed to the interaction of various processes. Next to ground ice volume change, also sedimentation (peat, colluvial deposition) and shrinkage or swelling of soils with changing water content may have contributed. Tussock tundra areas covered by the extreme 2017 and 2018 spring floods show high subsidence rates and an increase of midsummer thaw depths. We hypothesize that increased flood heights along Siberian lowland rivers potentially induce deeper thaw and subsidence on floodplain margins, and also lowers the drainage thresholds of thaw lakes. Both mechanisms tend to increase floodplain area. This may increase CH4 emission from floodplains, but also may enhance carbon storage in floodplain sedimentary environments.

The morphological variability of Maltese ‘cart ruts’ and its implications

Hundreds of ‘cart ruts’ – pairs of incised parallel grooves in the bedrock – are found across the Maltese archipelago in the central Mediterranean. The age, functional association, formation processes, and taphonomic alteration of these ruts, which occur here with a globally unrivalled frequency, has been much debated. Generally seen as being created by erosion from vehicles such as wheeled carts, or alternatively being cut into the rock to facilitate movement of such vehicles, specific models range from the use of carts to move soil in the Neolithic to them reflecting classical era stone quarrying, and many other possibilities. One interesting aspect concerns the morphological variability of the cart ruts, such as the notion that they have a standard gauge (width between ruts), and that this gauge is very similar to that of modern railway tracks. Evaluating the morphological variability of the cart ruts contributes to an understanding of the phenomenon, as, for instance, we might expect that if they date to different periods, with different functions, and/or were extensively modified by geomorphological processes this will be reflected in the character of their morphological variability. The analysis suggests that cart ruts are fairly standardised in terms of basic measurements such as widths and depth, perhaps suggesting that they are of a consistent age and function. This study identified a need for definitional clarity as the commonly cited gauge measurements are not taken in the same way as gauge is defined for railway tracks. There are hints of rut shape changes reflecting extensive use and or processes such as limestone dissolution, which give insights into their formation histories.

Pendekatan Hidrogeomorfologi Dan Pendugaan Geolistrik Untuk Identifikasi Potensi Airtanah Di Jedong Malang

This study aims to identify the potential groundwater in Jedong, Malang, East Java. The hydrogeomorphological approach is a suitable approach to describe the relationship between hydrological and geomorphological processes on and below the earth's surface. The survey of geoelectricity complements the hydrogeomorphological approach. It will give a better description of the groundwater conditions below the earth's surface. Based on the research, there are 2 hydrogeomorphological units in the study area, which are: Volcanic Foot Valley Unit and Volcanic Foot Ridge Unit. The best groundwater potential is in Volcanic Foot Valley Hydrogeomorphological unit, namely Awar-awar Valley and Cokro Valley. The valleys are dominated by gully erosion and landslides. They have surface deposits up to a depth of 7 meters, and lots of outcrops of breccia, pumice, and andesite boulders. The valley’s springs discharge between 56 - 198 m3/day. The average infiltration rate in the valley is 1776 mm / hour, with sandy soil material. The best aquifer consisting of sandy material is more than 10 meters in depth, based on the geoelectrical survey. Water in the aquiclude layer, cannot be exploited because it is breccia and tuff material. The Sawah valley cannot be exploited further because the groundwater potential is very low. This can be identified by the thick water outflow seepage. In the Volcanic Foot Ridge Hydrogeomorphological unit, the groundwater potential is also very small. Hydrogeomorphically, water will flow down the slope to the valley. It will reduce the infiltration rate. In general, the ridge area is only used for settlement, while the slopes are used for dryland agriculture. The geoelectric analysis results show that the groundwater potential is at a depth of more than 45 meters. This research’s results show that the combination of the hydrogeomorphological approach and the geoelectric use will provide a better description of the potential groundwater.

Physical experiments in geomorphology

An experiment is a program of observations specially constructed to provide a critical test of theory or generalization about nature. It is designed to acquire firm evidence for or against the effect in question. Accordingly, it must be arranged to control all sources of variability contributing to the phenomena under examination save those it is intended to study. In the natural environment this is difficult to achieve. Consequently, classical geomorphology had no established tradition of experimentation. However, in the latter third of the 20th century, geomorphologists began to explore experimentation as a means to resolve questions that arise in the study of geomorphological processes. In the period 1976-84 an IGU commission on field experiments in geomorphology formally established an interest in the approach. Although few field studies before the turn of the century achieved experimental status, valuable experience was gained in laboratory experiments, scaled and unscaled, leading to present wide acceptance of experimentation as a means to approach questions about geomorphological processes.

Dynamics of hydrological and geomorphological processes in evaporite karst at the eastern Dead Sea – a multidisciplinary study

Karst groundwater systems are characterized by the presence of multiple porosity types. Of these, subsurface conduits that facilitate concentrated, heterogeneous flow are challenging to resolve geologically and geophysically. This is especially the case in evaporite karst systems, such as those present on the shores of the Dead Sea, where rapid geomorphological changes are linked to a fall in base level by over 35 m since 1967. Here we combine field observations, remote-sensing analysis, and multiple geophysical surveying methods (shear wave reflection seismics, electrical resistivity tomography, ERT, self-potential, SP, and ground-penetrating radar, GPR) to investigate the nature of subsurface groundwater flow and its interaction with hypersaline Dead Sea water on the rapidly retreating eastern shoreline, near Ghor Al-Haditha in Jordan. Remote-sensing data highlight links between the evolution of surface stream channels fed by groundwater springs and the development of surface subsidence patterns over a 25-year period. ERT and SP data from the head of one groundwater-fed channel adjacent to the former lakeshore show anomalies that point to concentrated, multidirectional water flow in conduits located in the shallow subsurface (< 25 m depth). ERT surveys further inland show anomalies that are coincident with the axis of a major depression and that we interpret as representing subsurface water flow. Low-frequency GPR surveys reveal the limit between unsaturated and saturated zones (< 30 m depth) surrounding the main depression area. Shear wave seismic reflection data nearly 1 km further inland reveal buried paleochannels within alluvial fan deposits, which we interpret as pathways for groundwater flow from the main wadi in the area towards the springs feeding the surface streams. Finally, simulations of density-driven flow of hypersaline and undersaturated groundwaters in response to base-level fall perform realistically if they include the generation of karst conduits near the shoreline. The combined approaches lead to a refined conceptual model of the hydrological and geomorphological processes developed at this part of the Dead Sea, whereby matrix flow through the superficial aquifer inland transitions to conduit flow nearer the shore where evaporite deposits are encountered. These conduits play a key role in the development of springs, stream channels and subsidence across the study area.