Weathering, Soils and Landforms 

Weathering and soil formation are decisive factors to understand and interpretate the actual landscape physiognomy, constitution, and its evolution. The aim of this thematic section is to contribute to go deeper into the questions that still deserve investigation, as well as to consolidate the relationships between time and space related to weathering, soils, and landforms. These relationships are the main research objective in several disciplines where the geoforms and related regoliths/soils are studied in different temporal and spatial scales. The submitted works can present different focus seeking to illustrate the characteristics of the different approaches, as well as to identify their strengths and limitations, or can be related to the understanding of the indicators of the process concerned, such as: conceptual, methodological, or operational, being to confirm or to create new paradigms and theories in this theme.

Conveners: selma Castro, Silvio Rodrigues, Chiaki Oguchi
| Tue, 13 Sep, 14:30–16:30, 17:00–19:00|Room Sala Sofia-C2B
| Attendance Tue, 13 Sep, 16:45–17:00 | Display Mon, 12 Sep, 09:00–Tue, 13 Sep, 19:00|Poster area

Orals: Tue, 13 Sep | Room Sala Sofia-C2B

Chairpersons: Silvio Rodrigues, Chiaki Oguchi
Masahiro Chigira, Yasuto Hirata, and Hironori Katou

Tors or rock columns and corestones are well known as characteristic topography of granitoids; most of them are made in the ground and subsequently exposed by the exhumation of the materials of weathering, which proceeds along joint sets. The primary joint sets of granitoids have long been believed to be orthogonal since the pioneer work of Cloos (1921, 1922). However, such studies are based on the observations from limited angles mainly from the ground surface, so 3-D morphology of joint sets has been poorly characterized. On the other hand, recently developed analytical technique using unmanned air vehicle and photogrammetric software, give us completely different configurations and find that columnar joints are common in granitoids as well as volcanic rocks like basalt. We found granitoid bodies that have columnar joints near its roof because of rapid cooling down. Exposure of rock columns separated by columnar joints form high unstable rock towers or tors, which are susceptible to rockfalls. Rock columns separated by columnar joints tend to be spheroidally weathered to form corestones surrounded by saprolite under the ground. When they are eroded to form hills, they frequently fail during rainstorms and transform to debris avalanche or debris flow with high destructive potential because of large mass of boulders. Granite without columnar joints is not suitable for spheroidal weathering but is sheeted by unloading; sheeting forms dip slopes, on which rock slides occur. Some granite is micro-sheeted by unloading and micro-sheeted granite is weathered to form a loose soil layer beneath slope surfaces. Such soil layers are very prone to heavy rainfalls and frequently slide, transforming debris avalanches and debris flows.

How to cite: Chigira, M., Hirata, Y., and Katou, H.: Origins of rock columns and corestones of granitoids and their contributions to landslides, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-27, https://doi.org/10.5194/icg2022-27, 2022.

Lukasz Pawlik, Piotr Gruba, Dawid Kupka, Pavel Samonil, and Brian Buma

Within the current project, we focus on the problem of rock weathering processes and soil evolution under tree root impact. Our working hypothesis says that tree roots significantly contribute to weathering processes and alter soil properties. Through this, they change the course of geomorphic processes on hillslopes: for instance, erosion, mass movements, and soil creep. Soil samples were taken from two localities in Poland: 1) Sącz Beskidy Mountains, Outer Western Carpathians, SE Poland, and 2) the Stołowe Mountains, the Middle Sudety Mountains, SW Poland. We analyzed 145 soil samples: 111 samples from the Sącz Beskidy Mountains (one study plot) and 34 samples from the Stołowe Mountains (two study plots). The samples were taken from different parts of the tree root zone (rhizosphere, rock cracks) and control positions not occupied by trees and having no evidence of the past tree growth in the place. The following analyses have been conducted: the content of Fe and Al (amorphous and labile forms), the content of N, C, and soil pH. The results were analyzed statistically using ANOVA and ordination methods (PCA, RDA). In the Żegiestów plot, reference soil samples differ significantly from other microsites of the root zone except for rhizospheric soils samples. It applies to all chemical compounds and soil pH. In the Stołowe Mountains plots, reference soil plots differ significantly from all other microsite soils of the root zone. There is a strong correlation between Fe and Al forms and N and C in both study plots, whereas soil pH is negatively correlated with other chemical compounds. Our results suggest an essential role of trees and tree root systems in modifying weathering processes and soil properties in temperate forests.

The study has been financed by the Polish National Science Centre (project no: NCN2019/33/B/ST10/01009).

How to cite: Pawlik, L., Gruba, P., Kupka, D., Samonil, P., and Buma, B.: Weathering processes and soil evolution under trees, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-246, https://doi.org/10.5194/icg2022-246, 2022.

Daniela S. de Campos, Hevelyn S. Monteiro, Paulo M. Vasconcelos, Kenneth A. Farley, and Pablo Vidal-Torrado

Bauxites associated with quartzite karsts have not been previously reported.  In the Southern Espinhaço Range, Southeastern Brazil, bauxitic duricrusts reveal a unique geological-geomorphological setting. The spatial relationship between hematite-phyllites and quartzites and their different strengths play a key role in the development of thick bauxite profiles. The quartzites, resistant to physical and chemical denudation, scaffold the more easily eroded phyllites, protecting the later from physical erosion and allowing long-term – tens of millions of years – chemical weathering to transform phyllites into bauxites. We investigate the geochemical, mineralogical, geochronological and micromorphological signatures of bauxites in order to reconstruct their evolutionary history. Our data reveal periods of intense aluminum and iron dissolution-precipitation triggered by the strong bioturbation, revealing a crucial role for vegetation in bauxite evolution. (U–Th)/He geochronology of Al-goethite reveals bauxitization peaks in the Upper Miocene and Lower Pleistocene, during periods of higher rainfall. We identify a ferruginous duricrust that preceded bauxitization, suggesting perhaps an even more protracted history of weathering, now partially erased by the later-stage bauxitization. Our findings show that the elevated landscape positions and effective drainage into the exposed bedrock were crucial for ferruginous duricrusts to be chemically dismantled, leaving essentially a bauxitic duricrust residue. The chemically and mechanically resilient quartzites of the Southern Espinhaço Range were the main scaffolds that permitted bauxitization of the hematitic phyllites. A new model of bauxitization scaffolded by quartzites is revealed by this study.

How to cite: S. de Campos, D., S. Monteiro, H., M. Vasconcelos, P., A. Farley, K., and Vidal-Torrado, P.: Bauxitization scaffolded by quartzites , 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-706, https://doi.org/10.5194/icg2022-706, 2022.

János Kovács, Gábor Újvári, and György Varga

In the continental stratigraphic record, paleosols are unique archives allowing for the reconstruction of ancient surface processes, paleo-ecosystems, and local- to global-scale paleoclimate conditions. Geochemical proxies derived from paleosol chemistry are powerful indicators of chemical weathering and various environmental parameters (rainfall, temperature, acidity) and provide a wealth of information to understand Earth's climatic history, but these paleosol archives also have their own limitations. Many paleosol-based proxies are applied to a limited number of paleosol profiles, as determined by outcrop exposure and quality, and most of them are not well-constrained on landscape or basin-scales, which are often the scales of interest for paleoclimate and paleoenvironmental reconstruction. Paleosol proxies including e.g., traditional stable and clumped isotopes in soil carbonates or organic matter, phytoliths, mineralogical indicators such as the goethite/hematite ratio have great potential to improve our understanding of how different terrestrial biogeochemical processes are linked in landscape scales, and how their different preservation biases could impact the interpretation of the paleosol proxy records. Here, we present geochemical data from pedogenic goethite pisoliths and nodules from Plio-Pleistocene red paleosols of the Carpathian Basin, East-Central Europe. Pisoliths and nodules are generally dominated by Fe oxides and oxihydroxides. Inorganic geochemistry and mineralogical data of these goethite pisoliths can provide a context for the depositional environment, climate, age, and origin of the red clays. Size, morphology, abundance, and location of goethite (hematite) nodules within a paleosol profile can yield valuable information on pedogenic processes and environmental conditions during soil development. Goethite is the main mineral in pisoliths and nodules beside quartz, hematite muscovite, and kaolinite. The Fe-hydroxides and Fe-oxides dominate in the samples, which is typical of aerobic environments. The goethite content varies from 55% to 82%, and the hematite from 5% to 12%. The hematite/goethite ratio is very low (0.062–0.160) in the samples showing highly weathered source sediment (paleosol). Clay minerals, such as kaolinite, indicate subtropical weathering of the parent material. The major element composition demonstrates that the soluble constituents (CaO, MgO, Na2O, and K2O) are leached, while the insoluble constituents (SiO2, Al2O3, and Fe2O3) are accumulated as oxides/hydroxides during surface and sub-surface weathering processes. A concentric laminae fabric was not observed in any of the examined samples, which indicates the development of pisoliths above the water table in the unsaturated zone. The analyzed pisoliths and nodules have no protolith relics and contain less than 10–15% detrital grains, showing homogeneous structures with mottled and syneresis fabrics. According to our previous research on these paleosols, the mean annual paleoprecipitation was 1100–1400 mm and the mean annual paleotemperature was 13–15°C. The studied red paleosols are weathered in a tropical/subtropical climate. In such conditions, fersiallisation and ferruginisation are the most important processes during the diagenesis of the pisoliths and nodules.

This research was funded by National Research, Development and Innovation Office, grant number NKFI K120213.

How to cite: Kovács, J., Újvári, G., and Varga, G.: A paleosol-based proxy: pedogenic goethite pisoliths, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-521, https://doi.org/10.5194/icg2022-521, 2022.

Anna Masseroli, Guido S. Mariani, and Luca Trombino

Because of the close relationship among soils features and their forming factors, soils and paleosols are a useful archive both to reconstruct past environmental conditions and to gather information on the morphodynamic processes affecting landscape evolution through time. The formation of complex paleosols sequences is deeply affected by the combined effect of different soil forming factors that, shaping pedogenesis, leave marks that can be interpreted and used to reconstruct the climatic and environmental history of the landscape.

By integrating geopedological, geomorphological and geoarchaeological data gathered in over 20 years of research, we aimed to reconstruct the environmental Holocene history of the Mt. Cusna area (Northern Italian Apennines). We collected chemical, physical and micromorphological data of about 70 soil profiles into a georeferenced database, which maps different soil characteristics from both modern soils and paleosols. The integration of soil data with other types of available data, as geomorphological map, previous paleoenvironmental and geoarcheological reconstructions, allowed to highlight natural and anthropogenic trends and model the dynamics of past climate history, past environmental conditions, and the reciprocal distribution of landforms and paleosurfaces.

We have defined the occurrence of different phases of biostasy, characterized by the absence of erosion and/or deposition on the slope, the presence of vegetation cover, and the soil development, alternated with phases of rhexistasy, characterized by slope instability and soil erosion and burial. The soil and paleosols variability across the study area mirrors the different impact of soil forming factors on pedogenesis (e.g., vegetation cover, human impact, slope dynamics), supporting a detailed characterization of the succession of different environments conditions through space and time.

These results highlight how soils can represent an important archive for paleoenvironmental information as well as geomorphological dynamics and demonstrate that a multi-disciplinary approach is necessary to properly characterize soils and retrace environmental changes.

How to cite: Masseroli, A., Mariani, G. S., and Trombino, L.: Environmental significance of (paleo)soils surveyed throughout 20 years of research in the Mt. Cusna area (Northern Apennines), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-286, https://doi.org/10.5194/icg2022-286, 2022.

Nurit Shtober-Zisu and Lea Wittenberg

Rock fragments in soil and on the soil surface affect key soil hydrological processes, including water repellency, thermal properties physical degradation, erosion, and productivity. The severe wildfire at Mt. Carmel, Israel, in 2010, caused massive destruction of carbonate rocks. The thermal shock caused extreme exfoliation, producing large and flat clasts, affecting rocks to a depth of up to 20 cm. A decade after the fire, most flakes and spalls disappeared from the rock outcrops and adjacent soils. From these observations, this study pursued two objectives: (a) to monitor and analyze the spatio-temporal distribution of the disintegrated flakes 10 years after the fire and (b) to test the hypothesis that fires contribute to increased soil stoniness via physical and chemical flake erosion. This research showed that after a decade, most of the spalled surface on the burned outcrops was lost, broken down and pulverized, exposing new rock surfaces to atmospheric and weathering processes. The most prominent effects were changes in surface stoniness on the rendzina soils over the chalks, while there was less impact on the dolomite and limestone samples. The stoniness of the non-burned chalk was 23-39% and increased significantly to 69-86% in the burned area. Chalk erosion produced large (>16 mm, median 8-16 mm) and abundant gravel, suggesting fragmentation of large spalls, and particles that lost their bladed shapes becoming oblate and equant. While earlier works suggested that increasing rock fragment cover is often associated with the removal of fine particles, our results showed a substantial increase in rock fragments due to fire-induced exfoliation of rock surfaces, leading to long-term changes in soil properties. We therefore propose that the size, shape, and spatial distribution of rock fragments should be considered when examining the effects of rock fragments on hydrological and geomorphological processes or on post-fire soil rehabilitation.

How to cite: Shtober-Zisu, N. and Wittenberg, L.: Long-term effects of wildfire on rock weathering and soil stoniness in the Mediterranean landscapes , 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-169, https://doi.org/10.5194/icg2022-169, 2022.

Chiaki Oguchi, Konomi Nakamura, and Tsuyoshi Wakatsuki

Granitic rocks tend to turn into sandy sediment, grus, through weathering, which makes them prone to collapse even on relatively gentle slopes. Such weathering of rocks is broadly classified into chemical weathering and physical weathering, with chemical weathering dominant in warmer regions and physical weathering dominant in colder regions. Many weathering indices have already been proposed for chemical weathering, and it is possible to estimate the chemical weathering process by using these indices. However, it has not been clearly stated how the weathering process affects the properties of the weathering product, the sediment. Therefore, in this study, we examined the characteristics and regional characteristics of weathering of the soil layer, the collapse reserve material, by examining the relationship between grain size composition, the simplest physical property of the soil, and chemical weathering index values. The samples studied were weathered granite and granodiorite collected near the slip surfaces of slopes where slope failures have occurred in the past in several areas with different climates in Japan. First, each weathering index of CIA (Chemical Index of Alteration, Nesbitt and Young, 1982) and the Si/Al ratio (Marbut, 1935) were calculated based on chemical composition values. The percentage of clay and silt is analyzed and calculated by using Wentworth's (1922) scale. The relationship between CIA values and the clay-silt ratio is positive and proportional. A negative proportional relationship was obtained between Si/Al ratio and the clay-silt ratio. The relatively cold region is more affected by physical weathering than other regions, due to the smaller difference in chemical weathering index values between the surface soil and base rock and the higher percentage of coarse-grained weathering products.


How to cite: Oguchi, C., Nakamura, K., and Wakatsuki, T.: Climatic Influence of chemical weathering on the particle size distribution of the slope soil layers in granitic bedrock areas, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-427, https://doi.org/10.5194/icg2022-427, 2022.

Adolfo Quesada-Román, Manuel Camacho, and Leonardo Quesada-Román

The Torres River is one of the most urbanized catchments in Costa Rica, with only 46.67 km2 and approximately 50% of its area is covered by urban land uses, comprising nearly 13% of the national population. The quick rural-urban transition during the last century has had intense environmental impacts along the Greater Metropolitan Area (GAM) of Costa Rica. We performed a geomorphology map of the Torres River catchment using photointerpretation and digitization processes. Moreover, we generated three catenas of the upper, middle, and low sections of the catchment in order to describe and characterize soil profiles, where we also included clay mineralogy analysis using X-ray diffraction techniques. Our results are key to understand the landforms and soils interactions with the surrounding environmental dynamics and anthropic pressures.

How to cite: Quesada-Román, A., Camacho, M., and Quesada-Román, L.: Soil-geomorphology characterization in urban tropical contexts, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-54, https://doi.org/10.5194/icg2022-54, 2022.

Coffee break and poster session
Chairpersons: Silvio Rodrigues, selma Castro
Contrasting soil dynamics in the Serra da Estrela mountain plateau –  Portugal
Gerald Raab, Wasja Dollenmeier, Dmitry Tikhomirov, Gonçalo Vieira, Piotr Migoń, Michael E. Ketterer, Marcus Christl, Jamey Stutz, and Markus Egli
Arindam Sarkar

The study of soil geomorphology is linked to a scientific experiment involving the variation of its properties. Soil and landform parameters are intertwined. Nature's endogenetic and exogenetic forces interplay among these factors. The LULC attribute is influenced by the soil and geomorphological characteristics of the location. The objectives are to discover the many characteristics of soil and geomorphology, as well as their interrelationships. Another goal is to determine the link between soil geomorphology and land use and land cover attributes. To create an accurate DEM for the investigation of the morphology and topography of this region, SRTM and ALOS data were employed. The LULC map is created using remote sensing software and Landsat 8 satellite images. To create an accurate DEM for the investigation of the morphology and topography of this region, SRTM and ALOS data were employed. The LULC map is created using remote sensing software and Landsat 8 satellite images. The Archaean and Gondwana geological formations make up this region. Granitic (grey bedded biotite, granite, genesis, etc.) as well as sedimentary (conglomerate) and schistose rocks are found in the Archean formation (phyllite, quartzite, schist, etc.).

The highest points in the Purulia district are Ajodhya and Garpanchakot. The highest points in the Bankura district are Biharinath and Susunia. The major geomorphic processes that occur here throughout the year are weathering and overland flow. There are a handful of solitary remnant hills on the Ajodhya hill. Garpanchakot is a residual hill with an undulating slope. Biharinath Hill is a lingering hill with an almost conical shape. Susunia is the final major topographic elevation of the Chhotanagpur plateau in the direction of the Bengal basin. The hills have a modest to the high slope (2°-49°) on all sides. The predominant soil texture in this area is sandy loam. This area's surface soil developed on the hard, massive crystalline rock. The soil at the top of the hill and along the escarpment is quite thin. The foothills of these four hills are known for bare soil, cultivated land, fallow land, and poor vegetation due to the relatively deep soil profile. Soils have the characteristic of being dry. Because of the slow rate of soil organic matter breakdown, soil organic matter ranges from.03 to 65 percent. Seasonal grassland in the forest and escarpment has the highest percentage of soil organic matter. The pH of the soil remains neutral. In the soil, there is a high level of nitrogen (N). Phosphorus (P) and potassium (K) levels in the soil are extremely low. The percentage of sand rises as the slope increases. Among all the soil geomorphological factors, elevation and slope explain the most. The main independent aspect of this location is its elevation. Sand is one of the most important components of soil. The texture's most prominent component is sand. Residents engage in somewhat extensive agriculture operations in the foothills. Rice, wheat, maize, sugarcane, legumes, chilies, and vegetables are the principal crops grown in this area using the plowing and terrace farming methods.

How to cite: Sarkar, A.: Assessment of soil geomorphological character and its impact on land use of the hills of Purulia and Bankura districts of West Bengal, India, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-331, https://doi.org/10.5194/icg2022-331, 2022.

Anais Zimmer and Timothy Beach

The formation of new soils after glacier retreat due to climate change can provide insights into the rates of soil formation during the Anthropocene. Recently deglaciated terrains (<150 years) are subject to weathering and pedogenesis because freshly exposed sediments are prone to react readily with the environment. During the first decades of soil genesis, the variability observed relies on the typical CLORPT factors, but geomorphic activity and climate change are rapid and biotic migrations are highly variable. This paper studies the soil properties, composition, geomorphic dynamics, and environmental characteristics of nine chronosequences of deglaciation in the Alps and the Peruvian Andes. Between 2019 and 2020 we collected 189 soil samples within the nine proglacial landscapes and buried 113 temperature sensors. We measured soil organic matter (LOI), nitrogen and carbon content (Dumas combustion), pH, and bulk density. We also identify the elemental composition by XRF and ICP-AES and mineralogy by XRD of our samples. Our preliminary results show faster SOM accumulation in the Andean proglacial soils than within the Alps. Similarly, higher N and C accumulation are detected in the Andean soils at a similar age. In most sites, we also observe different tendencies over short (35 years) and longer chronosequences (80 or 150 years) and between soil properties. The age factor also affects soil properties differently. Our results suggest that proglacial soil formation is mainly driven by climate and parent material characteristics and we can associate faster soil formation with subtropical climates.

How to cite: Zimmer, A. and Beach, T.: Proglacial Soil Formation in the Anthropocene: soil chronosequences in the Sub tropical Andes and Alps, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-466, https://doi.org/10.5194/icg2022-466, 2022.

Grace Alves, Matheus Figueiredo, Ilo Andrade, João Henrique Sousa, and Alisson Diniz

Soil and landform coevolution seem to develop a significant influence on the Coastal Tablelands landscape of Bahia. This area presents Neogene sediments covering a cratonic region after intense dissection of the inland, forming Coastal Tablelands. Our goal was to understand the contribution of soil evolution to landform development using a multiscalar approach and investigating soil toposequences on both sides of a hillslope. Our results showed a drainage network controlled by regional lineaments. Tablelands are more dissected on litoral (convex tops) than in the inner (flat tops) due to the higher humite that comes from the ocean. Iron crusts sustain flat tops, but they are being transformed into other materials due to pedogenesis, forming a soil sequence of Argissolo (Lixisol) and Espodossolo (Podzol) in closed depressions found on flat tops with a higher water table. Hillslopes are dissymmetrically in deeper valleys with a lower water table, presenting more erosion of sand materials. In these hillslopes, the iron crusts appear in outcrops or deep into the soil with a toposequence of Latossolo (Ferralsol) and Argissolo (Lixisol). Soil transformation observed on the hillslopes shows a relationship between pedologic cover and landforms whose triggers for the changes are the lineaments and the height of the water table. To conclude, soil and landforms characteristics of Coastal Tablelands are influenced by the current processes, also working as a record of preterits times owing to pedogeomorphological evolution.

How to cite: Alves, G., Figueiredo, M., Andrade, I., Sousa, J. H., and Diniz, A.: Soil evolution on Coastal Tablelands in northeastern Bahia, Brazil, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-501, https://doi.org/10.5194/icg2022-501, 2022.

Gregory Pope and Jennifer Callanan

In previous research, we noted the presence of major, minor, and trace elements in soils following forest fires.  In case studies from wildfires and experimental burns from the Rocky Mountain conifer forest (Colorado, USA), Appalachian mixed hardwood forests (Pennsylvania and New Jersey, USA), and sandy pine barrens (New Jersey, USA), we identified increases in most of the major elements and some minor elements in soils following forest fires, identified with ICP-MS analysis. Elements such as Mn, Mg, Na, Ca, Na, K, Cu, and Ba derived from an infusion of biomass ash. Some elements present were distinctly different from any mineral parent material contribution to the soil, and were therefore unique signatures of fire contribution. Signature post-fire elements persisted in some cases more than one year following the fire, and were found in both topsoil horizons and into illuvial soil horizons.

Beyond detecting the presence of post-fire signature elements, we investigate here a quantification of the soil chemical impact by means of widely use weathering indices. Fires do contribute to mechanical weathering of rock, though the impact on chemical weathering is less studied. Chemical weathering is usually assumed to be a long-term process, weathering indices summarize these processes. In contrast, the application of weathering indices to fire impacts reflect instantaneous events in pedogenic time spans, with abrupt geochemical changes due to additions of biomass ash. Nevertheless, there is benefit in the ability to compare values, so that fire imposed geochemical changes can be assessed in context.

In general, our data show that fire-impacted soils exhibit weathering indices trending toward “less weathered”. The weathering ratios correlate closely with elements that are abundant in biomass ash; many of these elements would normally be preferentially depleted by weathering over time. Weathering ratio values may correlate with burn temperature, based on results from laboratory simulations. The fire-impacted soil chemistry has bearing on modern and paleoenvironmental biogeochemical assessments. First, the calculated weathering index values have potential as indicators of the degree of impact from modern fires. Second, where weathering indices are used as paleoenvironmental proxies in sedimentary records, there exists a potential to misinterpret values for times where fires might have been prevalent (such as during drought periods), if the fire chemical signature persists. Ongoing research comparing modern soils and paleosols will further explore these potential discrepancies.

How to cite: Pope, G. and Callanan, J.: Chemical Weathering Indices for Fire-Impacted Soils, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-520, https://doi.org/10.5194/icg2022-520, 2022.

Fran Domazetović, Ante Šiljeg, Ivan Marić, Neven Cukrov, and Lovre Panđa

In this study we focus on the assessment of impacts of lithology on short-term gully evolution, with special emphasis on detection and quantification of one-year gully erosion induced spatio-temporal changes (STCs) within different lithological units. Study was implemented within the lithologically versatile wider area of gully Santiš (13 881.613 m2), located within the karst relief of the Pag Island (Croatia).

Repeat UAV photogrammetry was used for creation of very-high resolution (VHR) digital surface models (DSMs) of study area, where identical aerial surveys were carried on December 17th, 2019 and December 17th, 2020. Detection of gully erosion induced STCs was based on creation of digital elevation model of difference (DoD) from two created multi-temporal DSMs, using the Geomorphic change detection 7 software. Detailed lithological map (1:50) of whole study area was created through the comprehensive field lithological mapping, that was carried on September 16th, 2020.

In total nine different lithological units were mapped within the chosen karstic study area and VHR DoD with spatial resolution of 1 cm was created, allowing the detection of sub-decimeter STCs. Short-term gully evolution (2019-2020) resulted with the 13.46 m3 of eroded material, with very high variability of erosion intensity between certain lithological units. Highest erosion rates (6.80 m3) were detected within carbonate sandstones and sands, where gradual selective erosion has caused collapse of larger part of the more resistant sandstone. Significant erosion rates (4.84 m3) were also detected within Calcocambisol soil sediments, which were mainly caused by the mass wasting and gradual uphill retreat of the main gully headcut. Other seven mapped lithological units (e.g. limestone, quaternary breccia, talus, etc.) accounted for only 13% of all detected erosion (average erosion rate = 0.22 m3), thus confirming the lower erodibility to gully erosion of these more resistant units.

Carried study has confirmed that short-term gully evolution within specific karstic relief is highly affected by lithology, which directly controlls the intensity and distribution of erosion processes. Combined use of repeat UAV photogrammetry derived VHR DoD and detailed field lithological mapping has shown great potential for detection and monitoring of complex STCs and interpretation of short-term gully evolution. Due to that this methodology can be applied for monitoring of short-term geomorphic evolution in other lithologically complex areas.

How to cite: Domazetović, F., Šiljeg, A., Marić, I., Cukrov, N., and Panđa, L.: Assessing the Impacts of Lithology on Short-term Gully Evolution using the Very-high Resolution UAV Photogrammetry, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-261, https://doi.org/10.5194/icg2022-261, 2022.

Marissa Swart

Soil erosion is one of the most critical problems in the environment. Gullies, as a result of soil erosion are visible in large parts of South Africa. There are various elements that enhance gully formation like land use, climate, and anthropogenic elements. Armoured roads as an anthropogenic aspect change surface water flow because they are impermeable and thus lead to accelerated soil erosion and gully formation on their road shoulders.

Due to a shortage of studies addressing the linkage between aspects that enhance gully formation and armoured road drainage, the aim of this project is to determine how different factors impact gully development along major armoured roads. The objective is to determine if hillslope gradients and rainfall can be correlated to gully formation next to major armoured roads in the Mpumalanga province of South Africa.

This study will be conducted along national and regional roads in the Emakhazeni Local Municipality in South Africa’s Mpumalanga province. GPS locations will be physically collected of approximately 440 potential gullies next to the roads.

Possible gully locations next to the roads will be identified on Google Earth. These locations will be compared to the collected GPS locations in ArcGIS Pro. ILWIS software will be used to process the obtained 30 m ASTER GDEM data. Using spatial analyst tools, the locations of the gullies will be analysed in relation to elevation. Data on the change in amount of rainfall over the past 30 years will be obtained from rainfall stations closest to the measured gullies.

Dimensions of every 20th gully will be taken with a surveyor’s tape to calculate gully volumes. These dimensions will include gully length, width, and depth. Measurements of the width and depth of each of these gullies will be averaged. The actual direction and direction of gullies in relation to the roads will also be noted.

The gully volumes, locations, rainfall data, and hillslope gradient will be stacked in ArcGIS Pro and extracted as a table, grouping the factors into gully extent categories. Simple linear regression and R2 values will be used to assess the relationship between the factors. To determine if there was multicollinearity, the variance inflation factor will be calculated. The combined effect will be determined with multi-linear stepwise linear regression. ANOVA will be used to determine if significant differences are present. All the statistical analyses will be done with R in R studio.

By increasing the understanding of how hillslope gradient and amount of rainfall impact gully development, can add to previous knowledge about how gullies develop and extend. This will contribute to determining whether gullies that occur adjacent to armoured roads are created due to changes in these factors or due to the concentration of water at culverts. Furthermore, the use of GIS and remote sensing can also help to increasingly establish its use to assess gully development next to major armoured roads. Ultimately, it can aid in determining how suitable and sustainable land use and management practices are and where to effectively focus rehabilitation efforts.

How to cite: Swart, M.: Assessment of gully erosion along major armoured roads in Mpumalanga, South Africa, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-578, https://doi.org/10.5194/icg2022-578, 2022.

Maciej Swed, Anna Potysz, Agata Duczmal-Czernikiewicz, Marcin Siepak, and Wojciech Bartz

Study area is located in the Olkusz ore district, in the south Poland where Zn and Pb were recovered from sulfide and calamine ore bodies. The primary ore is composed mainly of sphalerite, galena, and marcasite/pyrite and was excavated from the so-called ore bearing dolomite of the Middle Triassic age. Studied rocks are mainly composed of smithsonite, cerussite, goethite, hemimorphite, anglesite and are considered as supergene ore derived from alterations of sulfides mainly during Miocene. The chemically-mediated weathering of sulfides has extensively been studied, whereas microbially-mediated weathering of calamines requires experimental research to be undertaken to improve our understanding on dissolution of such rocks. This study aimed: (i) to determine the bioleaching potential of Zn, Pb, Cd, and As from Zn-bearing supergene ores exposed to A. thiooxidans, native soil microorganisms, and root exudates; (ii) to assess the impact of mineral composition (goethite-bearing vs. hemimorphite-bearing samples) of the rocks on leaching of elements; (iii) to determine mineral dissolution under bioweathering conditions. Two supergene samples were investigated: first collected from the mining heap next to the abandoned “Bolesław” calamine open-pit in the Bolesław village (B), and second from the weathering site of the abandoned “Olkusz-Pomorzany” Zn-Pb underground mine (OP). Trace elements in solutions were measured using by ICP-QQQ whereas mineral composition of the fresh and weathered samples was determined using by XRD, SEM-EDS, EPMA, and DSC-TG methods. Results of the experiments revealed the highest leaching efficiency for Zn was found for both samples treated by A. thiooxidans  (up to 125 000 and 14 000 mg·kg-1 for OP and B, respectively) and Cd (up to 817 and 46.8 mg·kg-1 for OP and B, respectively). The highest amounts of Pb (3840 mg·kg-1  and 660 mg·kg-1) were liberated from sample OP by root exudates and soil bacteria, respectively. As compared to other elements studied, arsenic revealed the lowest leaching efficiency under bioweathering conditions. In sample OP, dissolution of hemimorphite and cerussite caused the release of Zn and Pb, respectively. In sample B, goethite was found to weather intensively.

How to cite: Swed, M., Potysz, A., Duczmal-Czernikiewicz, A., Siepak, M., and Bartz, W.: Laboratory simulations of weathering of Zn-Pb-bearing rocks: leachability of metal(loid)s and dissolution of minerals – the case of the Olkusz area, South Poland, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-691, https://doi.org/10.5194/icg2022-691, 2022.

Display time: Mon, 12 Sep 09:00–Tue, 13 Sep 19:00

Poster: Tue, 13 Sep, 16:45–17:00 | Poster area

Chairpersons: selma Castro, Silvio Rodrigues, Chiaki Oguchi
Thallita Nazar, Silvio Rodrigues, Fabiana Santos, and Gelze Rodrigues

Geocovers contribute to the analysis of geomorphological processes that occur/occurred on the surface, serving as witnesses of these processes. Quartzitic regions tend to present incipient unconsolidated geocovers and are often characterized by rocky outcrops, even under humid tropical climates. The degree of weathering of geocovers and its relationship with the topography in these environments are still poorly understood. In this sense, the objective of this work is to analyze the relationship between topography and mineralogy of the clay fraction found in geocoverings developed on quartzitic relief, in a case study in Serra da Canastra, Chapadão do Diamante (ChD). We carried out a previous compartmentalization of the landscape into three main patterns, from which we selected three representative slopes for the survey of transects, from the interfluve to the valley floor. Thus, we selected nine geocoverage samples to perform the X-Ray Diffractometry (XRD) analysis, and analyzed the results using the exploratory multivariate technique of Principal Component Analysis (PCA). The results suggest a correlation between the identified minerals, their position on the slope and the characteristics of concavity and the presence of natural barriers. In the first transect, in very incipient geocoverings, minerals were found indicative of highly weathered environments and with poor drainage, such as Kaolinite and Illite, indicating greater permanence of water in the environment, due to small structural traps that allow the storage of products of quartzite weathering. In the second transect, the samples showed oxides and hydroxides of Fe and Al, which demonstrate the advanced degree of weathering in the area, which can constitute lateritic geocoverings, when in large quantities. The last transect, with deeper geocovers, in high slope, presented Goethite and Siderite, indicating a poorly drained environment, with water remaining longer in the system. This study revealed that mineralogical analyzes of materials from quartzite sample areas in a humid tropical environment may indicate that these areas refer to the management of the balance between the resistance of the quartzitic parent material and the intensity of weathering on the one hand, and the position and topographic shape of the slope can influence the weathering degrees of another.

How to cite: Nazar, T., Rodrigues, S., Santos, F., and Rodrigues, G.: Correlation between geochemical parameters and topography of geocovers of quartzitic relief at tropical area: study case in Serra da Canastra, Brazil, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-101, https://doi.org/10.5194/icg2022-101, 2022.

Micromorphological features and weathering in soils and soil-like bodies of ice-free areas of Eastern Antarctica
Ivan Alekseev, Ksenia Romashova, and Antonina Chetverova
Johan Liebens and Chelsea Randall

Delineation of relict marine terraces along the Northwest Florida coast facilitated investigation of soil development within the Gulf of Mexico (GOM) coastal plain. Previous research in the region that defined coastal terraces primarily relied on topographic studies with little consensus on the number and extent of terraces. Research investigating soil development within the GOM coastal plain is also limited. Our study utilized GIS and a LiDAR-derived Digital Elevation Model (DEM) to apply a Surface Classification Model (SCM) for selection of terrace surfaces based on slope and surface roughness. Hypsographic analyses of the SCM output identified potential terrace surfaces but visual interpretation along transects across the surfaces was necessary to refine the bounding terrace elevations. Five terraces were defined. Soil properties known to exhibit time related trends were analyzed across the delineated terraces. At increasing elevations, and presumably increasing ages, soils exhibited a thickening of both the solum and Bt horizon, an increase in clay content, and a decrease in organic matter content. The lowest terrace had the greatest solum thickness due to the presence of thick Histic epipedons and thick Spodic horizons. Bt horizons were observed at increasingly greater depths, with the exception of the highest terrace, where it was at a shallower depth. This is likely due to advanced erosion associated with the older age of the terrace and the higher elevation and greater exposure of the surface. This study demonstrates that GIS and LiDAR-derived DEMs are valuable tools to systematically and semi-automatically map marine terraces on a regional scale.

How to cite: Liebens, J. and Randall, C.: Identification and soil characteristics of coastal terraces along the northern coast of the Gulf of Mexico., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-53, https://doi.org/10.5194/icg2022-53, 2022.

Rose Paque, Ilia Alomia Herrera, Jean Dixon, Marcus Christl, and Veerle Vanacker

Understanding the spatial variation of rock-derived weathering products across heterogeneous landscapes is important to constrain ecosystem processes. Few quantitative data exist on soil-landscape development in pristine volcanic ecosystems, as most of these ecosystems are prone to intensive land use and management. By working in the Galapagos Islands, a UNESCO World Heritage Site, we aim to constrain physical erosion and weathering over millennial timescales from empirical data in pristine ecosystems. Our monitoring sites on the island of Santa Cruz cover a ~10 km long NW-SE stretch with a 10-fold increase in precipitation rates and associated changes in vegetation cover. In five ecosystems, we monitor two sites: one that is developed on basaltic lava flows and a second one on basaltic scoriae. By controlling for the age and composition of the basaltic parent material, we focused on the unique natural soil landscapes that developed along the sharp hydroclimatic gradient. We determined weathering extent, and rates of physical erosion based on geochemical proxies and meteoric 10Be isotopes (10Bem). These data were then related to time-series of precipitation, air, and soil temperature to explore the relationship between soil development, climate, and parent material. Along the hydroclimatic gradient, the empirical data on chemical weathering and physical erosion show a nonlinear relationship with the precipitation rate.

How to cite: Paque, R., Alomia Herrera, I., Dixon, J., Christl, M., and Vanacker, V.: Combined effect of climate and vegetation on soil-landscape development in volcanic ecosystems (Galapagos, Ecuador), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-180, https://doi.org/10.5194/icg2022-180, 2022.

Diego Machado, Thaís Fioravanti, and Francisco Ladeira

Buried soils and paleosols may be important paleoenvironmental indicators, providing information about the processes that act in the relief elaboration. The Bastos archaeological site is currently considered the oldest in the State of São Paulo. Archaeological records were preserved due to erosive/depositional events that led to the burial of the site. The present work aims to identify the depositional events associated with the burial. The methodological procedures consisted of a morphological description of a vertical section, physical-chemical analysis, in addition to the collection of undisturbed samples for micromorphological description. The area is located in a low-slope terrace condition, close to the Silvestre stream with small irregular levels, lowered by an average of 2.9 m in relation to the colluvium ramps. Its contact occurs through ruptures of concave-converging slopes. The vertical section investigated presents 229 cm depth, in which 10 horizons were identified, composing 7 distinct soil profiles. The highest values ​​of silt and clay occur in the A, Bi, 5Bt, 7Cg1 and 7Cg2 horizons, with mean values ​​of 25.3% and 34.4% respectively. The 2C, 3C1, 3C2, 4Cg and 6C horizons present high levels of sand, between 53.2% and 84.8%, with predominance of the coarse fraction. The terraces show evidence of alternations in erosion and local deposition cycles, where a sequence of truncated and buried soil profiles occur. Two types of events may be described, the colluvial processes, interspersed by fluvial depositions. On the colluvium ramps and slopes, fine materials (silt and clay) predominate, due to basalt alteration. Along the valley, we see conical shapes modeled by the action of concentrated surface runoff through narrow channels. When unconfined, the detrital flows are dispersed, forming fan-shaped deposits. The deposits truncate soils and deposit poorly selected materials, especially basalt fragments, in the midst of a clayey matrix. The process supplies material to form the profiles with clayey texture in the studied section, evidenced by the similar textural and chemical characteristics. However, in cases such as the discontinuity that marks the abrupt transition between the 7Cg1 and 6C profiles, the presence of silcrete clasts and the relative proportion of sand in the fine land fraction (+87%) highlight the existence of an alluvial deposit. In the higher areas, close to the channel's drainage head, the slopes are built on the sandstones of the Vale do Rio do Peixe Formation. Thus, the materials that make up the archaeological site present both alluvial and colluvial origin, indicating the complex geomorphological dynamics of the valley. Currently, the channel continues to rework the slope deposits that fill the valley and are distributed throughout the study area. The channel thalweg is approximately 115 cm below its most recent depositional event (2C), and 15 cm above the oldest (6C), evidencing the dynamics of the deposition and erosion processes in the valley.

How to cite: Machado, D., Fioravanti, T., and Ladeira, F.: Dynamics of the slope at Bastos Archaeological Site - Dourado/SP/Brazil, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-300, https://doi.org/10.5194/icg2022-300, 2022.

Fábio Oliveira, William Rodrigues, Carlos Ernesto Scahefer, and Maringela Leite

This research was conducted to evaluate the contribution of landforms in establishing Giant petrels (G. petrels) and Brown skuas (B. skuas) nesting and the formation of ornithogenic soils by the phosphatization process in Harmony Point, Maritime Antarctic. Ten nests from the coastal domain (marine terrace) and the cryoplanated platform were selected to collect topsoil samples (0-20 cm). The samples were collected from 0 m up to 20 m in each nest, with regular spacing of 2 m. The analysis of the samples included the physical, chemical, mineralogical, and geochemical analyses. The pH acidity found in the topsoils is similar to the phosphatized soils in penguins. Phosphate minerals such as apatite, leucophosphite, and vivianite were identified. The high content of some trace elements, such as Zn, Cu and Sr is associated with the bird’s excrements.  Total-P recorded higher levels in the cryoplanated platform, while higher levels of bioavailable-P were observed in the marine terrace. This result demonstrates the importance of the landforms in the bird’s nesting, as well as in the development of the soil in these soil-forming environment. Phosphatization in these areas is not restricted to the specific location of the nest since high values of P have been identified at distances between 8 and 12m, from de nest’s top. This suggests the transport of P-rich solutions and phosphatized material along with fractures by the freeze-thaw cycles, depositing these materials 20 m away, contributing to increasing the geographical expression of this phenomenon in this ice-free area, consequently the development of soils and the establishment of vegetation.

How to cite: Oliveira, F., Rodrigues, W., Scahefer, C. E., and Leite, M.: Ornithogenic soil genesis by flying birds in Maritime Antarctica: the role of landforms in the nests establishment, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-443, https://doi.org/10.5194/icg2022-443, 2022.

Adriana Costa, Eduardo Pagliaroni, and Fabio Oliveira

One of the most important issues in soil-landscape studies is the understanding of how pedological transformations in the slopes occur from the modification of the base level. Local and regional geomorphological processes, such as scarp retraction, drainage captures, modification of fluvial activity in water courses, etc., can lead to important fronts of pedological transformation. In this context, the pedological covers on the edges of plateaus are inserted, with emphasis on the cuestas. This study aimed to investigate the organization of soil cover on the edge of a basaltic-sandstone plateau, in the extreme northeast of the São Paulo state, between 1050 and 850m altitude, in the municipality of Pedregulho. Morphological descriptions and physical, chemical and mineralogical analyzes were performed on the five soil profiles, arranged in toposequence, from the top of the slope to the bottom of the valley. Two pedological compartments were identified. The most common is the latosollic compartment, which occurs from the top to the mid-slope, with the transition from the typical Dystrophic RED LATOSOL to the cambisolic Eutrophic RED LATOSOL. The other compartment is the neo-cambisollic, which occurs towards the base of the slope, with typical Eutrophic Cambisol and a small portion of typical Dystrophic Tb FLUVIC NEOSOL. This transition reveals that scarp retraction has accelerated erosive processes on the immediately affected slopes, and that morphogenetic processes has more intensy with soil genesis in the studied plateau. Thus, the pedological transformation from latosols to cambisols has been caused by erosion in the study area.

How to cite: Costa, A., Pagliaroni, E., and Oliveira, F.: Soil transformations at the edge of the Pedregulho plateau, São Paulo, Brazil, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-447, https://doi.org/10.5194/icg2022-447, 2022.

Teresa Cristina Tarle Pissarra, Adriana Monteiro da Costa, Fábio Soares de Oliveira, and Renata Cristina Araújo Costa

The weathering of rocks and minerals of the córrego Rico Watershed processes was studied to understand the internal forces to determine the distribution of soil and relief in space. The objective of this paper is to analyze the relation present in rock formation, soil, relief and water courses in a watershed landscape. Remote sensing orbital image and geographic information system techniques were used in research to data analysis. The multispectral and hyperspectral imagers were available for mapping the land cover, water courses and to process the relief. The physical soil and mineralogy data was collected in field and the samplings were analyzed in the soil and mineralogy laboratories. The exogenic system then transforms rock-forming minerals and their constituent elements into soil showed the differences between relief and soil formation in the area. The landforms composed the watershed landscape was verified. The results showed the influence of relief on soil types and their distribution in the landscape. The areas with higher drainage density present a dissected relief. Ultisols are present in areas of higher drainage density and Latosols are present in areas of lower drainage density, showing a close relationship between relief forms and soil distribution in the landscape. The areas more susceptible to natural erosive processes – Ultisols requires sustainable management in the watershed.

How to cite: Pissarra, T. C. T., Costa, A. M. D., Oliveira, F. S. D., and Costa, R. C. A.: Soil-landscape relationship in the watershed of the Rico stream, São Paulo State, Brazil., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-640, https://doi.org/10.5194/icg2022-640, 2022.

Jose Osmar Silva Neto, Larisse Freitas Soares, Vládia Pinto Vidal de Oliveira, and Anna Sabrina Vidal de Souza

The Baturité Massif is located in northern Ceará state (Northeast Brazil) and is the most humid mountain range of the state, with an average annual rainfall of 1500mm. The predominant lithostratigraphic unities are composed of gneisses, schists, quartzites, amphibolites, and other calcium-silicate rocks. The mountainous relief reaches 800-900 m a.s.l on the central region of the massif, which stands out by steep and winding slopes in contrast with vast flattened surfaces of 100 - 200 meters a.s.l. Based on previous studies in the area, this research aimed to analyze the correlation between the coloration of the Lixisols - the most common type of soil in the region, and the changes in size and density of the vegetation, featuring a tropical evergreen forest at the highest altitudes and a tropical semideciduous forest at low altitudes. In order to identify variations in soil color, a morphopedological analysis was carried out through toposequence in the municipality of Pacoti, located at the windward slope of the Baturité massif. Samples were collected in 6 soil profiles, with altitudes ranging from 300 to 950 meters. The determination of coloration was executed with the wet samples, using the Munsell chart and from the collected values, the soil redness index (RI) was calculated using the following equation: RI= ((10- M) × C)/V; M = hue (7.5R = 0; 10R = 1; 2.5YR = 2; 5YR = 3; 7.5YR = 4; 10YR = 5; 2.5YR = 6); V = value; C = chroma. Profile 1 (960 meters) presented low-density vegetation of arboreous size, with low RI on both superficial and sub superficial soil horizons. At intermediate altitudes (>400m and <600m), the soil profiles 2, 5 and M, presented vegetation in a climax state with low RI values on superficial horizons but high RI values on sub superficial horizons. On the other hand, at the lower altitude region (<400m), soil profiles 3 and 4 presented quite the opposite, with high RI values on the superficial horizons and low RI values at the sub superficial ones, the vegetation in this area was shrubby and with a high density of individuals. Thus, it is assumed that there is a direct correlation between reddening indexes, topography, and state of vegetational development of the landscape

How to cite: Silva Neto, J. O., Freitas Soares, L., Pinto Vidal de Oliveira, V., and Sabrina Vidal de Souza, A.: Landscape analysis based on soil color in the windward slope of the Baturité Massif, northeastern Brazil, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-707, https://doi.org/10.5194/icg2022-707, 2022.