ICG2022-1

Structural and lithological control has a key role in the shape of the rocky coast and its dynamics. Therefore, deepening the knowledge about these zones is one of the main aims for the future. In this sense, a granitic-gneissic sector was analyzed in the Galician coast (NW Iberian Peninsula) to understand their past and future evolution. For the characterization, we were used remote techniques based on data from UAVs (orthoimages and DEMs), just as hardness testers (Equotip and Schmidt-Hammer). The study was carried out at two scales, one general to analyze the main characteristics and select the interest sectors, and the other in detail applying the fieldwork survey techniques to explain the coastal landforms. This methodology allowed us to verify the correlation between remote and field data and improve our knowledge about the rocky coast dynamics by detecting and quantifying the topographical difference between closest sectors.

How to cite: Gomez-Pazo, A., Perez-Alberti, A., Freitas, L., and Chaminé, H. I.: Geostructural control in the rocky coast evolution: combination between UAVs and field survey techniques, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-257, https://doi.org/10.5194/icg2022-257, 2022.

The morphology of the emergent and submerged landscape reflects the processes and times that are involved in the shaping of the respective environments. The border between these landscapes is represented by the sea surface. It is highly variable insomuch that the current sea level is far from being an average level in relation to the Earth’s surface and to the geological history of Earth. The continuous change in altitude of the sea surface produces a transitional zone, roughly between a few meters above the current sea level and 150 meters deep. Below the transitional zone, that corresponds to the uppermost part of the continental shelf, the processes are almost totally marine, while above it they are almost totally continental. In the middle, it is possible to find landforms of mixed origins.

Until less than a century ago, the emergent landscape was already well-known with respect to the submerged one that was almost totally unknown . Therefore, the sea surface clearly distinguishes two separate worlds, the emerged one and the submerged one, the former being easily accessible, the latter much less. For this reason, geomorphology, like geology, was basically born as an Earth-driven discipline, and only later it also focussed below the sea surface. Geomorphological theories have been deeply affected by this border because until one century ago, little information was available on the sea bottom. Geomorphologists could not produce really data-based global theories until few decades ago. The base-level represented generally the lower limit of geomorphological theories. Even today the submerged lands continue to be much less accessible and certainly not directly available to the classic geological field surveys, apart from limited shallow areas where it is possible to use snorkel or scuba equipment.

How to cite: Furlani, S. and Musumeci, D.: Did The Physical and Metaphorical Border of the Sea Surface force Geomorphology as a Land-Driven Discipline?, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-346, https://doi.org/10.5194/icg2022-346, 2022.

The Shark Bay Marine Park in Australia is a UNESCO World Heritage Property in a region of marginal tropical cyclone influence and its sustainability requires a deep consideration of cyclone hazards. Here, we analyse historical records of a large storm surge from a Tropical Cyclone in 1921 that generated remarkable overland flow leaving fish and sharks stranded over 9 km inland. We weight information from the historical archives in a new framework and model event scenarios to reconstruct its magnitude. The plausible event scenarios imply that the cyclone was a marginal Category 4 or 5 storm with a return interval equivalent or slightly greater than the regional planning level. The outcome underscores the importance of examining the pre-instrumental events in areas of marginal cyclone influence as they are commonly of key economic importance.  Our work also implies that TC risk affects marine conservation in the Shark Bay World Heritage Property and requires attention.

How to cite: Switzer, A. D., Christensen, J., Aldridge, J., Taylor, D., Watson, H., Churchill, J., Fraser, M. W., and Shaw, J.: A 1921 Western Australian tropical cyclone underscores the utility of historical records for hazard analysis in areas of marginal cyclone influence., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-348, https://doi.org/10.5194/icg2022-348, 2022.

According to the recent and inspiring global review performed by Migoń (2020), one of the major gaps in conglomerate geomorphology research is the global geographical coverage of such terrains and corresponding landforms. Aiming at contributing with this global distribution, this communication presents the Serra do Segredo area, located in subtropical, southernmost Brazil (30^o32’S; 53^o33’W), in the territory of the Caçapava UNESCO Aspiring Geopark. That relatively small (some 30 km²) cuesta escarpment was developed upon a 300-meter-thick coarsening-up succession comprising the uppermost section of the Ediacaran-Cambrian, alluvial/fluvial Santa Bárbara Group of the Camaquã Basin. That rock package, within the cuesta domain, begins with tabular sandstones, grading towards a thick pile of lens- and scoop-shaped, cross-bedded, poorly sorted, polymictic conglomeratic sandstones and true conglomerates, and ending with more frequent interlayering of disorganized conglomerates/breccias with very angular clasts of granite and greenschist. The Serra do Segredo area exhibits: (a) tilting of strata to ESE, as well as an ESE-WNW pattern of lineaments limiting blocks; (b) a very smooth folding of the entire succession, with open fold crests oriented E-SE; and (c) a slight difference of tilting, with 20^o in the northern part, and 30^o in the southern portion. This last characteristic results in the appearance, in map view, of a more solid, consistent, uniform massif in the south, and more spaced “sub-ranges” in the north, giving rise to a more substantial accumulation of colluvial material, and to the installation of a fluvial valley (of the Lanceiros creek). The Serra do Segredo is a stepped cuesta, with three clearly distinguishable steps. The first and western step was built dominantly upon sandstones. That westernmost, external cuesta rim is relatively continuous, straight to smoothly curved, denticulated (according to ESE-WNW fractures), and only disrupted in zones with higher fracture density or volcanic dykes, hence zones of preferential weathering, soil development, and denser vegetation cover. The second step, though also dominated by sandstones, has an overall coarser grain size, with substantial interlayering with conglomerates. That inner step rim, despite being also continuous, is much more curved, with more abundant embayments, and also denticulated. The third and final step, fully developed upon conglomerates and breccias, can barely be recognizable as a step. That uppermost massif (which extends through some 8 km²) can be regarded as a true conglomerate dome cluster: steep-sided domes with strikingly rounded summits (covered by aprons of detached pebbles/cobbles), separated by ESE-WNW lineaments. That portion shows more significant emergence in the south, and a series of isolated domes (regionally known as ‘pedras’) in the northern portion. In the conglomerate domes, smaller scale features include: wavy walls, bedding caves, arcades, tafoni, stepped cliffs, honeycombs (in permanently shadowed, inner walls of caves) and speleothems. Also noteworthy is the large amount of metric to decametric collapsed blocks at the base of the conglomerate domes, even forming talus voids and caves, attesting for the frequent and recent (in geological timescales) occurrence of important rock slope failures.

How to cite: Borba, A., Guadagnin, F., and Corrêa, A. P.: Sandstone and conglomerate geomorphology in the Serra do Segredo area of southernmost Brazil: contribution for a global distribution of features and processes, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-454, https://doi.org/10.5194/icg2022-454, 2022.

It is common in international literature that deals with the history of geographical thought, to locate in Germany the conceptual foundations that allowed the institutionalization of geography as a modern science to occur. However, little attention has been given by researchers on the formation of Physical Geography and Geomorphology in particular, and most of the time there is a rapid affiliation of this to the Davisian corollary that has been reworked and disseminated by French physical geographers. However, the German geographical-geological reflection of the 18th-19th centuries (until at least the 1890s) was based on a geomorphology that, before being climatic or structural, understood the relief as an environment and at the same time an epistemological medium capable of connecting society and nature, from which they generate spatialities and their thresholds, an epistemological foundation so important for the present day. Thus, the objective of this work is to establish some relationships between the epistemological foundations of Geomorphology and the context of Natural Sciences, Philosophy and Geography in the 18th-19th century. Timothy Lenoir (2003) in the book "Instituting science: the cultural production of scientific disciplines" offers us light and paths to walk on the institution of science as a discipline. His trajectory by establishing a reading on the "cultural production of scientific disciplines"; its starting point is several historical episodes from the history of sciences, seeking to elucidate the internal and external factors in science, an understanding of authors, institutions, in order to trace institute an epistemology of science. In fact, for the author, the practice in the systematization and organization of sciences as cultural products is permeated in the very trajectory of writing, of producing science. The relationship of ideas, images about the history of nature and, also, how chronological time contributes to the consolidation of Earth Sciences and Society were, emerging forms of knowledge between the seventeenth and eighteenth centuries that influenced the sciences in the nineteenth century. The investigation of nature, in this context, traces a scientific methodology, "since the form was a momentary product of a space-time dynamic, involving a complex web given by the relationship between the history of nature and environmental conditions (VITTE, 2014, p. 4). Finally, it is fundamental to understand that scientific fields (geomorphology) are a cultural production, which offers us trails to relate the historical-epistemological aspects of geomorphology in the context of philosophical and scientific development of sciences of the eighteenth-nineteenth century; adding the role of authors, ideas, the circulation of ideas, but also political, economic and cultural institutions in the context of the industrial revolution and European imperialist expansion.

How to cite: Cardoso Ferreira, D. and Carlos Vitte, A.: GEOMORPHOLOGY IN THE CONTEXT OF NATURAL SCIENCES IN 18th-19th CENTURY GERMANY, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-576, https://doi.org/10.5194/icg2022-576, 2022.

The glacial history of the Iberian Peninsula, both glacial landforms and associated deposits, as well as the geochronology framework of the successive glacial stages within the Last Glaciation (LG), is now better understood. In turn, there is a growing body of evidence on glacial stages prior to LG. The increased use of absolute dating techniques has made these advances possible. However, some issues should be addressed to fully understand the extent and significance of past glacial processes in the Iberian Mountains. Those areas that were marginally affected by the ice during the LG (that is, located in low or moderate altitude sectors) remain unexamined in depth, with few geochronological contributions. These are more distant areas and often far from the main research focus. Moreover, the finding of glacial evidence (generally scarcer) is hindered by a dense vegetation cover. This is the case of A Seara Valley (Courel Mountains), located in the NW edge of the Iberian Peninsula, where several boulders and erosion surfaces of glacial origin were sampled for ³⁶Cl Cosmic-Ray Exposure (CRE) dating. Nine samples were collected during the spring2019 fieldwork campaign. Additionally, the paleoglacier was reconstructed and the associated landforms were mapped. Sampling strategy was challenging because only few moraines are well-preserved, and suitable boulders for CRE dating are scarce due to the predominant outcropping of slates. Only one moraine ridge was located at the bottom of A Seara Valley (1113 m a.s.l.), in which seven samples were collected. It is a polygenic moraine, dismantled by postglacial processes. Besides, the discrepant ages obtained in some boulders show that they were probably covered by sediments. The oldest geochronological data indicates that, at least, the glacier connected with this moraine at 21 ka (MIS-2). Additionally, two samples were collected on a glacial polished threshold located in an intermediate sector of the valley, at 1243 m a.s.l. Here, the result of 19 ka points to an accelerated retreat of this glacier to its headwater (as in other glaciated areas of NW Spain), i.e., a very quick deglaciation process.

Acknowledgments:

Benjamín González Díaz appreciates the support of the Spanish FPU program (reference: FPU19/06583). This contribution studies the research topics addressed in the project FUO-19-112 (Courel Mountains UNESCO Global Geopark; Ribeira Sacra-Courel Local Action Group, LEADER Program of the European Union).

How to cite: González Díaz, B., Pérez-Alberti, A., Ruiz-Fernández, J., Rinterknecht, V., Rodríguez-Rodríguez, L., García-Hernández, C., and Team, A.: Glacial evolution of La Seara Valley (Courel Mountains, NW Spain) based on 36Cl Cosmic-Ray Exposure dating, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-724, https://doi.org/10.5194/icg2022-724, 2022.

Scientific knowledge of the glacial evolution of the Cantabrian Mountains (NW Spain) has experienced important advances in the last four decades. There are numerous works focused on the description and mapping of glacial landforms, as well as on the application of age models based on relative chronologies and correlations with other Iberian mountain areas. However, the application of dating techniques to obtain absolute ages is very recent here, and has focused mainly on the highest altitude mountain ranges. In contrast, areas such as the Central-Western Asturian Mountains, with lower altitudes and less evident glacial footprints, have received scarce scientific attention. With the aim of establishing a solid geochronological framework of the deglaciation pattern, this study is focused on the northern slope of Puerto de Ventana. It is a paradigmatic example of the glacial evolution that occurred during the Last Glacial Cycle in the Central-Western Asturian Mountains due to its altimetric and lithostatigraphic characteristics: moderate altitudes (Ferreirúa Peak, 1977 m a.s.l.) and predominance of quartzites, sandstones and slates of Paleozoic age. During the summer of 2021 we carried out an exhaustive fieldwork campaign, from which a detailed geomorphological mapping was carried out, and a total of 17 samples for ¹⁰Be Cosmic-Ray Exposure dating purposes were collected. Sampling strategy has been based on the in situ evaluation of each of the glacial landforms identified, and the search for the most suitable glacial boulders and surfaces. Specifically, two moraines belonging to the outermost moraine complex have been dated, obtaining age ranges from 64 to 34 ky (MIS 4-3). This shows that there is an asynchrony between the Maximum Ice Extend (MIE) of the Ventana Glacier and the global Last Glacial Maximum (gLGM), as has been confirmed in other Cantabrian and Iberian Mountain areas. In the internal moraine complexes, eight samples have been obtained, which provide ages of 25-18 ky, indicating their correlation with the gLGM (MIS 2). Therefore, it would be the second glacial stage in the evolution of the Ventana Glacier. Regarding the moraine complexes located at the foot of glacial cirques, two blocks belonging to a frontal moraine arch were dated, as well as three belonging to a rock glacier. Both the chronologies of the above-mentioned moraine complex and the rock glacier, seem to indicate that they are contemporary to the interstadial warm period known as Bølling-Allerød, in which the last stages of glacial retreat would take place, as well as the stabilization of the rock glacier.

Acknowledgment:

Benjamín González Díaz appreciates the support of the Spanish FPU program (reference: FPU19/06583). This contribution studies the research topics addressed in the project PID2020-115269GB-I00 (MICINN, Government of Spain).

How to cite: González Díaz, B., Ruiz-Fernández, J., Rinterknecht, V., González Díaz, J. A., García-Hernández, C., and Team, A.: Glacial evolution in the Asturian area of the Puerto de Ventana (Cantabrian Mountains, NW Spain) based on 10Be Cosmic-Ray Exposure dating, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-726, https://doi.org/10.5194/icg2022-726, 2022.