The Contribution of UNESCO Global Geoparks in the Promotion of Sustainable Tourism

The Estrela UNESCO Global Geopark, which encompasses the highest mountain in mainland Portugal, is a geographically defined territory with resources of notorious geological interest, with precious ecosystems, identity, and ways of life. Its geodiversity, associated with traces of glacial origin, the richness of its natural and cultural heritage, make this a unique territory, whose structured approach will strengthen its knowledge, the importance of its functions, and its tourist, heritage, and cultural potential. The Estrela UGGp has the mission of contributing to the protection, valorisation, and dynamics of the natural and cultural heritage, with special emphasis on geological heritage, with a view of disseminating scientific knowledge, promoting tourism and the sustainable development of serra da Estrela. Overall, the Estrela UGGp fosters the development of an integrated development strategy, combined with geoconservation, education, and tourism, supporting the construction of development strategies for the well-being of the community.

Lithofacies Analysis of the Tista River Deposits, Rangpur, Bangladesh

Eight (8) distinct lithofacies within the fluviatile reach of the Tista River have been recognized by the detailed study of the sediments as exposed along the river bank and river bars. Genetically, the matrix-supported conglomerate (Gms), massive sand (Sm), Trough cross stratified sand (St), planar cross stratified sand (Sp), ripple laminated sand (Sr) comprise the channel deposits whereas, the ripple laminated sand (Sr), parallel laminated sand (Sh), clay with silt (Fl) and massive Clay (Fm) represent overbank fine deposits. The channel deposits were laid down under relatively high energy conditions compared to the sediments of overbank fines. The stratigraphic succession is indicative of fining upward sequence. The dominance of coarser-grained sediments at the base of the lithostratigraphic unit, especially the matrix supported conglomerate (Gms) suggests that the deposition took place in the proximal part of the Tista Fan, which might be of glacial origin. Massive clay (Fm) is the final stage of vertical aggradations in the overbanks, possibly in the floodplains, flood basins, and back swamps when the velocity of the transporting medium was virtually lean that promotes the deposition of clay materials from suspension. The growth of cracks in the sedimentary succession is resulting from the compaction of the sediments and/or instant change in the paleoslope direction. The unimodal distribution of paleocurrent data with high mode value indicates mainly unidirectional sediment transport. The study of the lithofacies manifests that the deposits are produced by the braided river and debris flows. The modification of the depositional pattern from debris flow to overbank fines discloses the change of climatic condition in the Quaternary period.

Groundwater Lowering for Construction of the Kilsby Tunnel – Geological and Geotechnical Interpretation

The Kilsby Tunnel, constructed in the 1830s, faced severe problems when a section of the tunnel, almost 400 m long, encountered unstable ‘quicksand’ conditions. The engineer for the project, Robert Stephenson, developed an extensive groundwater lowering scheme, unique for the time, using steam engines pumping from multiple shafts, to overcome the quicksand. Modern geological information indicates most of the tunnel was in Middle Lias bedrock, but the ‘quicksand’ section passed through a buried channel of water-bearing sand of glacial origin. In the early 19th century the impact of glacial processes on British geology was not widely accepted and, based on contemporary geological knowledge, Stephenson’s problems appear to be genuine unforeseen ground conditions, not predicted by his experienced advisers. It seems just random chance that trial borings missed the buried channel of sand. The work at Kilsby was two decades before Darcy’s law established the theoretical understanding for groundwater flow, and 90 years before Terzaghi’s effective stress theory described how reducing pore water pressures changed ‘quicksand’ into a stable and workable material. Despite the lack of existing theories, Stephenson used careful observations and interpretation of groundwater flow in the ‘quicksand’ to navigate the tunnel project to a successful conclusion.

Characteristics of Striae and Clast Shape in Glacial and Non-Glacial Environments

<p>Linear abrasion features on rock surfaces are produced by interacting rock particles in relative motion. The most common examples are striae produced by temperate glaciers, and as a consequence, striae have long been used as a means of identifying the passage of past glaciers. However, there are many non-glacial processes that can produce striae. These have been sporadically documented in the geological literature but have failed to make a lasting impression on the wider Earth Sciences community. These non-glacial processes include tectonic deformation, meltwater flow, non-glacial ice, wind action, volcanic blasting, mass movements of rock debris, among many others. Many produce coarse-grained deposits similar in character to glacial tills and there are several instances where non-glacial deposits and striae have been misinterpreted as glacial in origin. This thesis examines linear abrasion features (mostly striae) from five different environments, three glacial (temperate, polythermal and cold) and two non-glacial environments (mass movement and tectonic) to characterise the striae from different origins. The aim was to assess if there are readily observable and measurable differences in striae character between environments and to develop field-based criteria that allow a sound judgement of their origin in the geological record. Over 760 measurements of individual striae were made (orientation and size) on around 20 representative clasts and characteristic features of about 50 striated clasts from the various environments are illustrated in an "Atlas of linear abrasion features". In addition clast shape and striae occurrence were measured on 1260 clasts from deposits and about 100 bedrock linear abrasions from a cold-based glacier were recorded. The results show that some striae are diagnostic of certain environments but a combination of clast shape and striae characteristics is the most reliable method of correctly interpreting coarse-grained deposits with striated clasts. Results also highlight the wide range of striae characteristics within each environment and the importance of lithology in striae generation. This is evident even within the well-known temperate glacial environment where there is a marked contrast between striae formed within a thick debris layer and those formed in thin debris-rich basal ice. There appears to be little difference in striae formed by temperate and polyhermal glaciers, but glacial striae are readily distinguishable from striae found in various mass movement deposits or tectonically deformed conglomerates. Glacial striae tend to be sub-parallel to the clast long axes and show a high density on individual surfaces, whereas those in non-glacial origin typically show a lower density of slightly shorter, wider striae and show either no preferred orientation or weak grouping. The survivability of glacial abrasion features of clasts once they have entered a fluvial system has been assessed in a small South Island glacier fed river. This has provided a basis for estimating the proximity of a glaciofluvial deposit to the glacier front. Striae are found to survive only 1 to 2 km and glacial facets are mostly removed within 6 km. The study has also documented previously undescribed linear abrasion features from a cold-based glacier in Antarctica. This discovery is a significant advance in understanding cold glacial processes, and has provided new criteria for recognising the passage of cold-based glaciers in polar areas or regions where cold-based ice may have existed in the past.</p>

Characteristics of Striae and Clast Shape in Glacial and Non-Glacial Environments

<p>Linear abrasion features on rock surfaces are produced by interacting rock particles in relative motion. The most common examples are striae produced by temperate glaciers, and as a consequence, striae have long been used as a means of identifying the passage of past glaciers. However, there are many non-glacial processes that can produce striae. These have been sporadically documented in the geological literature but have failed to make a lasting impression on the wider Earth Sciences community. These non-glacial processes include tectonic deformation, meltwater flow, non-glacial ice, wind action, volcanic blasting, mass movements of rock debris, among many others. Many produce coarse-grained deposits similar in character to glacial tills and there are several instances where non-glacial deposits and striae have been misinterpreted as glacial in origin. This thesis examines linear abrasion features (mostly striae) from five different environments, three glacial (temperate, polythermal and cold) and two non-glacial environments (mass movement and tectonic) to characterise the striae from different origins. The aim was to assess if there are readily observable and measurable differences in striae character between environments and to develop field-based criteria that allow a sound judgement of their origin in the geological record. Over 760 measurements of individual striae were made (orientation and size) on around 20 representative clasts and characteristic features of about 50 striated clasts from the various environments are illustrated in an "Atlas of linear abrasion features". In addition clast shape and striae occurrence were measured on 1260 clasts from deposits and about 100 bedrock linear abrasions from a cold-based glacier were recorded. The results show that some striae are diagnostic of certain environments but a combination of clast shape and striae characteristics is the most reliable method of correctly interpreting coarse-grained deposits with striated clasts. Results also highlight the wide range of striae characteristics within each environment and the importance of lithology in striae generation. This is evident even within the well-known temperate glacial environment where there is a marked contrast between striae formed within a thick debris layer and those formed in thin debris-rich basal ice. There appears to be little difference in striae formed by temperate and polyhermal glaciers, but glacial striae are readily distinguishable from striae found in various mass movement deposits or tectonically deformed conglomerates. Glacial striae tend to be sub-parallel to the clast long axes and show a high density on individual surfaces, whereas those in non-glacial origin typically show a lower density of slightly shorter, wider striae and show either no preferred orientation or weak grouping. The survivability of glacial abrasion features of clasts once they have entered a fluvial system has been assessed in a small South Island glacier fed river. This has provided a basis for estimating the proximity of a glaciofluvial deposit to the glacier front. Striae are found to survive only 1 to 2 km and glacial facets are mostly removed within 6 km. The study has also documented previously undescribed linear abrasion features from a cold-based glacier in Antarctica. This discovery is a significant advance in understanding cold glacial processes, and has provided new criteria for recognising the passage of cold-based glaciers in polar areas or regions where cold-based ice may have existed in the past.</p>

Red Sea tectonics unveil the largest known terrestrial ice stream: New constraints on Late Ordovician ice sheet dynamics

Mega-streamlined landforms on Earth and Mars have been attributed to aeolian, glaciogenic, fluvial, and tectonic processes. Identifying the forces that shaped these landforms is paramount for understanding landscape evolution and constraining paleo-climate models and ice sheet reconstructions. In Arabia, east-northeast, kilometer-scale streamlined landforms were interpreted to have been formed by Quaternary aeolian erosion. We provide field and satellite-based evidence for a Late Ordovician glacial origin for these streamlined landforms, which were exhumed during the Red Sea–related uplift. Then we use Late Ordovician paleo-topographic data to reconstruct the Late Ordovician ice sheet using identified and previously reported glacial deposits and landforms. Our reconstruction suggests these glacial features are part of a major, topographically controlled, marine-terminating ice stream, twice the length of the largest known terrestrial ice streams. Our results support models that advocate for a single, major, and highly dynamic ice sheet and provide new morphological-based constraints for Late Ordovician climate models.

Sea level response to Quartenary erosion and deposition in Scandinavia

&lt;div&gt; &lt;p&gt;The landscape in western Scandinavia has undergone dramatic changes through numerous glaciations during the Quaternary. These changes in topography and in the volumes of offshore sediment deposits, have caused significant isostatic adjustments and local sea level changes, owing to erosional unloading and depositional loading of the lithosphere. Mass redistribution from erosion and deposition also has the potential to cause significant pertubations of the geoid, resulting in additional sea-level changes. The combined sea-level response from these processes, is yet to be investigated in detail for Scandinavia.&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;In this study we estimate the total sea level change from late-Pliocene- Quaternary glacial erosion and deposition in the Scandinavian region, using a gravitationally self-consistent global sea level model that includes the full viscoelastic response of the solid Earth to surface loading and unloading. In addition to the total late Pliocene-Quaternary mass redistribution, we &lt;span&gt;also &lt;/span&gt;estimate transient sea level changes related specifically to the two latest glacial cycles.&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;We utilize existing observations of offshore sediment thicknesses of glacial origin, and combine these with estimates of onshore glacial erosion and estimates of erosion on the inner shelf. Based on these estimates, we can define mass redistribution and construct a preglacial landscape setting.&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;Our preliminary results show &lt;span&gt;perturbations of&lt;/span&gt; the local sea level up to &amp;#8764; 200 m since&lt;span&gt; the&lt;/span&gt; late-Pliocene in the Norwegian Sea, suggesting that erosion and deposition ha&lt;span&gt;ve&lt;/span&gt; influenced the local paleo sea level history in Scandinavia significantly.&lt;/p&gt; &lt;/div&gt;