Sea Cliffs Research Articles

Survey of Fragile Geologic Features and Their Quasi-Static Earthquake Ground-Motion Constraints, Southern Oregon

ABSTRACTFragile geologic features (FGFs), which are extant on the landscape but vulnerable to earthquake ground shaking, may provide geological constraints on the intensity of prior shaking. These empirical constraints are particularly important in regions such as the Pacific Northwest that have not experienced a megathrust earthquake in written history. Here, we describe our field survey of FGFs in southern Oregon. We documented 58 features with fragile geometric characteristics, as determined from field measurements of size and strength, historical photographs, and light detection and ranging point clouds. Among the surveyed FGFs, sea stacks have particular advantages for use as ground-motion constraints: (1) they are frequently tall and thin; (2) they are widely distributed parallel to the coast, proximal to the trench and the likely megathrust rupture surface; and (3) they are formed by sea cliff retreat, meaning that their ages may be coarsely estimated as a function of distance from the coast. About 40% of the surveyed sea stacks appear to have survived multiple Cascadia megathrust earthquakes. Using a quasi-static analysis, we estimate the minimum horizontal ground accelerations that could fracture the rock pillars. We provide context for the quasi-static results by comparing them with predictions from kinematic simulations and ground-motion prediction equations. Among the sea stacks old enough to have survived multiple megathrust earthquakes (n = 16), eight yield breaking accelerations lower than the predictions, although they generally overlap within uncertainty. FGFs with the lowest breaking accelerations are distributed uniformly over 130 km of coastline. Results for inland features, such as speleothems, are in close agreement with the predictions. We conclude that FGFs show promise for investigating both past earthquake shaking and its spatial variability along the coasts of Oregon and Washington, where sea stacks are often prevalent. Future work can refine our understanding of FGF age and evolution.

The effects of storms and a transient sandy veneer on the interannual planform evolution of a low-relief coastal cliff and shore platform at Sargent Beach, Texas, USA

Abstract. Coastal cliff erosion is alongshore-variable and episodic, with retreat rates that depend upon sediment as either tools of abrasion or protective cover. However, the feedbacks between coastal cliff planform morphology, retreat rate, and sediment cover are poorly quantified. This study investigates Sargent Beach, Texas, USA, at the annual to interannual scale to explore (1) the relationship between temporal and spatial variability in cliff retreat rate, roughness, and sinuosity and (2) the response of retreat rate and roughness to changes in sand and shell hash cover of the underlying mud substrate as well as the impact of major storms using field measurements of sediment cover, erosion, and aerial images to measure shore platform morphology and retreat. A storm event in 2009 increased the planform roughness and sinuosity of the coastal cliff at Sargent Beach. Following the storm, aerial-image-derived shorelines with annual resolution show a decrease in average alongshore erosion rates from 12 to 4 m yr−1, coincident with a decrease in shoreline roughness and sinuosity (smoothing). Like the previous storm, a storm event in 2017 increased the planform roughness and sinuosity of the cliff. Over shorter timescales, monthly retreat of the sea cliff occurred only when the platform was sparsely covered with sediment cover on the shore platform, indicating that the tools and cover effects can significantly affect short-term erosion rates. The timescale to return to a smooth shoreline following a storm or roughening event, given a steady-state erosion rate, is approximately 24 years, with the long-term rate suggesting a maximum of ∼107 years until Sargent Beach breaches, compromising the Gulf Intracoastal Waterway (GIWW) under current conditions and assuming no future storms or intervention. The observed retreat rate varies, both spatially and temporally, with cliff face morphology, demonstrating the importance of multi-scale measurements and analysis for interpretation of coastal processes and patterns of cliff retreat.

Conceptual model of fracture‐limited sea cliff erosion: Erosion of the seaward tilted flyschs of Socoa, Basque Country, France

AbstractSea cliff morphology and erosion rates are modulated by several factors, including rock control that reflects both lithology and rock structure. Erosion is anticipated to preferentially exploit ‘fractures’, broadly meant as any discontinuity in an otherwise continuous medium, where the rock mass is weakest. Unpicking the direct control of such fractures on the spatial and temporal pattern of erosion remains, however, challenging. To analyse how such fractures control erosion, we monitored the evolution of a 400 m‐long stretch of highly structured sedimentary cliffs in Socoa, Basque Country, France. The rock is known as the Socoa flysch formation. This formation combines decimetre‐thick turbidites composed of repeat triplets of medium to strong calcareous sandstone, laminated siltstones and argillaceous marls. The sequence plunges at 45° into the sea with a shore‐parallel strike. The cliffs are cross‐cut by two normal and reverse fault families, with 10–100 m alongshore spacing, with primary and secondary strata‐bound fractures perpendicular to the bedding, which combined delimit the cliff rock mass into discrete blocks that are exploited by the erosion process. Erosion, and sometimes plucking, of such beds and blocks on the cliff face was monitored using ground‐based structure‐from‐motion (SfM) photogrammetry, over the course of 5.7 years between 2011 and 2017. To compare with longer time change, cliff‐top retreat rate was assessed using SfM‐orthorectified archive aerial photographs spanning 1954–2008. We show that the 13,250 m2 cliff face released 4500 blocks exceeding 1.45 × 10−3 m3, removing a total volume of 170 m3. This equates to an average cliff erosion rate of 3.4 mm/year, which is slightly slower than the 54‐year‐long local cliff‐top retreat (10.8 ± 1.8 mm/year). The vertical distribution of erosion reflects the height of sea water inundation, where the maximum erosion intensity occurs ca. 2 m above high spring‐tide water level. Alongshore, the distribution of rockfall scars is concentrated along bed edges bounding cross‐cutting faults; the extent of block detachment is controlled by secondary tectonic joints, which may extend through several beds locally sharing similar mechanical strength; and rockfall depth is always a multiple of bed thickness. Over the longer term, we explain block detachment and resultant cliff collapse as a cycle. Erosion nucleates on readily exploitable fractures but elsewhere, the sea only meets defect‐free medium‐strong to strong rock slabs offering few morphological features for exploitation. Structurally delimited blocks are quarried, and with sufficient time, carve semi‐elliptic scars reaching progressively deeper strata to be eroded. Lateral propagation of erosion is directed along mechanical weaknesses in the bedding, and large episodic collapses affect the overhanging slabs via sliding on the weak marl beds. Collapse geometry is confined to one or several triplets of turbidite beds, but never reaches deeper into the cliff than the eroded depth at the foot. We contend that this fracture‐limited model of sea‐cliff erosion, inferred from the Socoa site dynamics and its peculiar sets of fractures, applies more broadly to other fractured cliff contexts, albeit with site‐specific geometries. The initiation of erosion, the propagation of incremental block release and the ultimate full failure of the cliff, have each been shown to be fundamentally directly controlled by structure, which remains a vital control in understanding how cliffed coasts have changed in the past and will change in the future.

Geomorphometric analysis of the natural and anthropogenic seascape of Naples (Italy): A high‐resolution morpho‐bathymetric survey

AbstractThis research aims to reconstruct the submerged morphologies of the high‐coast sectors of Naples discriminating between landforms and anthropogenic structures, by analysing the high‐resolution data of a multibeam survey in a GIS environment. In the case of natural landforms, a signal analysis was performed to characterize the seabed and discern between sandy and rocky bottom, together with a slope analysis pointing to the detection and mapping of different orders of palaeo‐shore platforms at different bathymetric ranges and interpreted as erosional traces of the Holocene sea cliff retreat affecting the study area, mainly caused by a subsiding trend that exacerbated the glacio‐hydro‐isostatic sea‐level rise. Then, the detected palaeo‐shore platforms were further analysed to quantify their roughness degree and, consequently, the differential erosion affecting the rocky platforms. On the other hand, regarding the submerged anthropogenic structures, the multibeam survey allowed several underwater archaeological remains of Roman Age to be mapped, demonstrating the high cultural relevance of the study area.

From Patagonia to Río de la Plata: Multistep long‐distance littoral transport of Andean volcaniclastic sand along the Argentine passive margin

AbstractLarge sediment masses are transferred over many hundreds of kilometres along the coast of passive continental margins worldwide. The relevance of such a phenomenon for source‐to‐sink studies, environmental issues, and coastal management remains largely unperceived. This study traces the paths of volcaniclastic sand along ca 2170 km of the Argentine coast and documents a 760 km long cell of littoral transport extending from the formerly larger Río Colorado delta to the edge of the Río de la Plata mouth. During deglaciation stages and humid periods of the Pleistocene, a much greater sediment volume than today was transferred by the Desaguadero and Colorado rivers from the highest‐relief tract of the Andean Cordillera to the Atlantic Ocean. Amphibole‐rich sand originally supplied by the Río Desaguadero is being recycled today from Pampean lowlands to feed the beaches along Río de la Plata southern shores, whereas pure quartzose sand of Río Paraná is found only adjacent to its prograding delta. Augite‐rich sand supplied by the Río Colorado is dominant along the coast of the Buenos Aires Province, where it mixes locally with coarser‐grained quartz‐rich detritus recycled in the urbanized Mar del Plata area. Hypersthene‐rich sand of the Río Negro is dispersed both north and south of the mouth, where heavy‐mineral‐rich lag deposits are formed in areas of accelerated erosion and retreating sea cliffs. Changes of mineralogical signatures during long‐distance littoral transport are largely ascribed to local supply from coastal erosion or hydrodynamic effects rather than to selective breakdown of labile grains. Whereas the relative abundance of amphibole and pyroxene is largely independent of transport distance, olivine is depleted both in the northern part of the Colorado littoral cell and south of the Río Negro mouth, which is chiefly ascribed to dilution by recycling of Neogene sediments that have undergone early intrastratal dissolution rather than to mechanical loss.

Geomorphological Approach to Cliff Instability in Volcanic Slopes: A Case Study from the Gulf of Naples (Southern Italy)

This paper deals with the problem of cliff stability and proposes a geomorphological zonation of a cliff using a sector of the Posillipo promontory (named the Coroglio-Trentaremi sea cliff, Italy), in the Campi Flegrei coastal area, as a case study. A detailed geological and geomorphological analysis was carried out, by combining field work with analysis of detailed scale topographic maps, orthophoto, and stratigraphical data from deep boreholes. Field and borehole data, together with structural data collected in seven different stations along the cliff, allowed us to derive six geological cross-sections and to reconstruct the complex stratigraphical and structural setting of the cliff. Geomorphological analysis focused on the detection of the main geomorphological factors predisposing to cliff instability. We selected the most significant factors and divided them into two groups: factors influencing landslide intensity and factors influencing cliff instability. Then, by means of a heuristic approach, we constructed a matrix that was used to derive a map showing the geomorphological zonation of the sea cliff. This map may enable to development of a reliable scenario of cliff instability and consequent retreat, which may be useful either to plan intervention works in the most critical areas or to organize prevention plans aimed at risk mitigation.

The Role of Fungal Microbiome Components on the Adaptation to Salinity of Festuca rubra subsp. pruinosa.

Festuca rubra subsp. pruinosa is a perennial grass that inhabits sea cliffs, a habitat where salinity and low nutrient availability occur. These plants have a rich fungal microbiome, and particularly common are their associations with Epichloë festucae in aboveground tissues and with Fusarium oxysporum and Periconia macrospinosa in roots. In this study, we hypothesized that these fungi could affect the performance of F. rubra plants under salinity, being important complements for plant habitat adaptation. Two lines of F. rubra, each one consisting of Epichloë-infected and Epichloë-free clones, were inoculated with the root endophytes (F. oxysporum and P. macrospinosa) and subjected to a salinity treatment. Under salinity, plants symbiotic with Epichloë had lower Na+ content than non-symbiotic plants, but this effect was not translated into plant growth. P. macrospinosa promoted leaf and root growth in the presence and absence of salinity, and F. oxysporum promoted leaf and root growth in the presence and absence of salinity, plus a decrease in leaf Na+ content under salinity. The growth responses could be due to functions related to improved nutrient acquisition, while the reduction of Na+ content might be associated with salinity tolerance and plant survival in the long term. Each of these three components of the F. rubra core mycobiome contributed with different functions, which are beneficial and complementary for plant adaptation to its habitat in sea cliffs. Although our results do not support an obvious role of Epichloë itself in FRP salt tolerance, there is evidence that Epichloë can interact with root endophytes, affecting host plant performance.

Genetic characteristics of a small breeding population of ancient murrelets from Teuri Island, Japan, based on mitochondrial DNA sequences and newly‐developed microsatellite markers

AbstractA small population of ancient murrelets (Synthliboramphus antiquus) nests and breeds on vertical sea cliffs in Teuri Island, Japan. Although this small population is at high risk of extinction, practical conservation plans were not established owing to the lack of basic data, for example, ecological and genetic information. Here, mitochondrial DNA and microsatellite analyses were performed on ancient murrelets collected in the Teuri and Aleutian breeding populations, as well as on wintering individuals in Japan and museum specimens. Mitochondrial DNA analysis revealed that the Teuri population shared haplotypes with the Aleutian population, but not with the British Columbian and the Kamchatka populations from a previous study. Microsatellite analysis revealed high gene flow between the Teuri and Aleutian breeding populations. There was no evidence of loss of genetic diversity in the Teuri population. Museum specimens possessed some unique alleles not found in the more recent samples. Our results suggest that strategies for the conservation of Teuri and Aleutian populations should be managed separately from those designed for breeding populations in the eastern Pacific region, at the very least. For conservation of the Teuri population, we do not recommend captive breeding because of gene flow between Teuri and Aleutian populations, but protection of nesting habitats and monitoring of demographic indexes would be more effective for maintaining their genetic diversity and population size.

Large-scale margin collapses along a partly drowned, isolated carbonate platform (Lansdowne Bank, SW Pacific Ocean)

The Lansdowne Bank is a partly drowned, isolated carbonate platform of around 4000 km2 located 300 km west of New Caledonia, in the SW Pacific Ocean, in water depths of 20 to 100 m. New multibeam bathymetric data, high resolution seismic reflection profiles and sediment gravity cores have been acquired on the bank top and adjacent slopes. This dataset reveals an almost continuous 4 km wide outer reef rim located in ca. 50 m water depth, surrounding a gently deepening inner platform, reaching up to 100 m water depth. The bank is bordered by very steep slopes showing numerous erosional morphologies such as canyons, channels and gullies. Along with these bypass features, spectacular bank margin collapses and slope failures are evidenced by up to 20 km-wide bank edge and intraslope failure scars, respectively, resulting in a typical “scalloped” geometry of the bank margin. These failure scars can lead to a complete collapse of the outer reef rim and impact subsequent reef development. Bank margin collapses are evidenced by hectometer to kilometer-scale blocks and debris shed on the slope, likely emplaced by rock fall/avalanching processes originating from the brittle failure of early cemented bank edge and upper slope sediments. In turn, failures triggered on the un-cemented mud-prone middle to lower slopes likely generate more cohesive, submarine debris flows that could be at the origin of erosive morphologies within the debris fields. Estimated individual failure volumes can reach up to 3 km3. Quaternary sea-level lowstands, that would have led to platform exposure, fracturing and karstification, and the development of an erosional sea cliff, as well as subsequent rising sea-level are believed to play a significant role in mass wasting event emplacement, yet “bottom up” submarine processes such as the upslope propagation of bypass morphologies by retrogressive headward erosion cannot be ruled out. In terms of geomorphic and stratigraphic constraints, the documented bank margin collapses affect a terrace located in 70 m water depth around the bank, which, depending on its age and origin, could provide a minimum age for collapse events. Finally, considering the shallow water depth of failure headscarps, the volumes of material involved in the slides as well as their vicinity to the nearby main island of New Caledonia, numerical simulations of the tsunamigenic potential of submarine slides have been performed. They showed that these slides would have been able to produce a meter-scale wave that would reach the northern coast of the island in less than an hour.

Evolution of a complex early Permian coarse-grained shoreline along a rift basin margin

ABSTRACT Tectonic activity in extensional basins has a profound control on accommodation and sediment supply through the interplay between footwall uplift and hanging-wall subsidence, and thus largely influences the three-dimensional architecture of syn-rift sequences. This is emphasized in areas close to major rift-border faults, where steep coastal reliefs and fluvial gradients produce compound facies zonation and stratigraphic styles with strong lateral variability. The lower Permian High Cliff Sandstone was deposited in an array of shallow marine environments along the margin of the northern Perth Basin during a protracted late Paleozoic rifting episode in Western Australian basins. The formation is composed of fluvio-deltaic and nearshore strata sharply overlying a thick succession of offshore mudstone that was deposited during a phase of tectonic quiescence. This basal contact likely reflects submarine erosion and is, therefore, interpreted as a regressive surface of marine erosion generated in response to forced regression. The facies arrangement consisting of interbedded sandstone, conglomerate, and heterolithic facies chiefly records the evolution of a low- to high-gradient paleoshoreline punctuated by coastal streams, steep sea cliffs, and back-barrier lagoons. Extraformational outsized clasts were probably emplaced by the erosion of exhumed basement and older sedimentary rocks through fluvial incision, wave sapping, or landsliding. The along-strike variability between low- and high-gradient shoreline deposits indicates a dynamic depositional setting with a complex tectonic influence. The basal regressive surface of marine erosion is attributed to footwall uplift during the early reactivation stage of basin-bounding normal faults and, therefore, records the initiation of a new syn-rift phase in the northern Perth Basin.

Intermittent but Rapid Changes to Coastal Landscapes: The Tsunami and El Niño Wave-Formed Sea Arch at Laie Point, Oahu, Hawaii, U.S.A.

Kukuiho’olua Island is an islet that lies 164 m due north of Laie Point, a peninsula of cemented, coastal, Pleistocene and Holocene sand dunes. Kukuiho’olua Island consists of the same dune deposits as Laie Point and is cut by a sea arch, which, documented here for first time, may have formed during the 1 April 1946 “April Fools’s Day Tsunami.” The tsunami-source of formation is supported by previous modeling by other authors, which indicated that the geometry of overhanging sea cliffs can greatly strengthen and focus the force of tsunami waves. Additional changes occurred to the island and arch during the 2015–2016 El Niño event, which was one of the strongest on record. During the event, anomalous wave heights and reversed wind directions occurred across the Pacific. On the night of 24–25 February 2016, large storm waves, resulting from the unique El Niño conditions washed out a large boulder that had lain within the arch since its initial formation, significantly increasing the open area beneath the arch. Large waves also rose high enough for seawater to flow over the peninsula at Laie Point, causing significant erosion of its upper surface. These changes at Laie Point and Kukuio’olua Island serve as examples of long-term, intermittent change to a coastline—changes that, although infrequent, can occur quickly and dramatically, potentially making them geologic hazards.

Late Pleistocene Boulder Slumps Eroded from a Basalt Shoreline at El Confital Beach on Gran Canaria (Canary Islands, Spain)

This study examines the role of North Atlantic storms degrading a Late Pleistocene rocky shoreline formed by basaltic rocks overlying hyaloclastite rocks on a small volcanic peninsula connected to Gran Canaria in the central region of the Canary Archipelago. A conglomerate dominated by large, ellipsoidal to angular boulders eroded from an adjacent basalt flow was canvassed at six stations distributed along 800 m of the modern shore at El Confital, on the outskirts of Las Palmas de Gran Canaria. A total of 166 individual basalt cobbles and boulders were systematically measured in three dimensions, providing the database for analyses of variations in clast shape and size. The goal of this study was to apply mathematical equations elaborated after Nott (2003) and subsequent refinements in order to estimate individual wave heights necessary to lift basalt blocks from the layered and joint-bound sea cliffs at El Confital. On average, wave heights in the order of 4.2 to 4.5 m are calculated as having impacted the Late Pleistocene rocky coastline at El Confital, although the largest boulders in excess of 2 m in diameter would have required larger waves for extraction. A review of the fossil marine biota associated with the boulder beds confirms a littoral to very shallow water setting correlated in time with Marine Isotope Stage 5e (Eemian Stage) approximately 125,000 years ago. The historical record of major storms in the regions of the Canary and Azorean islands indicates that events of hurricane strength were likely to have struck El Confital in earlier times. Due to its high scientific value, the outcrop area featured in this study is included in the Spanish Inventory of Geosites and must be properly protected and managed to ensure conservation against the impact of climate change foreseen in coming years.

Automated Registration of SfM‐MVS Multitemporal Datasets Using Terrestrial and Oblique Aerial Images

AbstractAccurate alignment of 3D models is critical for valid change‐detection analysis from multitemporal photogrammetric datasets. This paper assesses an automated registration strategy which uses the scale‐invariant feature transform (SIFT) algorithm implemented in modern photogrammetric software. This registration solution, also known as “Time‐SIFT”, was tested at two study sites featuring vertical surfaces, including a sea cliff (~500 m2) and a quarry face (~50 000 m2). Tests demonstrated that the investigated registration strategy can achieve accurate alignments between multitemporal point clouds even when using multisource and multi‐perspective data, captured across widely varying spatial and temporal scales and under a range of weather and illumination conditions. The combination of the Time‐SIFT approach with an ICP algorithm produced moderate improvements in the alignment. Furthermore, the use of an innovative direct georeferencing technique, which used the tracking feature of a robotic total station, allowed for accurate georectification of 3D models.

Holocene relative sea-level changes and coastal evolution along the coastlines of Kamaran Island and As-Salif Peninsula, Yemen, southern Red Sea

Geomorphic features (fossil terraces, notches and sea cliffs) from the southern Red Sea coasts provide valuable indicators of past sea-level change that enable the quantification of both the timing and magnitude of the mid-Holocene sea-level highstand. We demonstrate the utility of wave-cut notches in the southern Red Sea, and present U-series dated sea-level indicators from two locations on the As-Salif Peninsula that suggest a mid-Holocene highstand of ∼0.5–1 m above present mean sea level (apmsl) at about 5–5.4 ka BP. In addition, the similarity of the elevations of the different sea-level indicators at the two locations in As-Salif Peninsula and Kamran Island suggest relative tectonic stability, with limited influence of salt diapirism. Comparison of our data to other estimates of the Red Sea mid-Holocene highstand, and glacio-isostatic predictions suggest that water loading (and deformational response) is the primary factor in the spatial and temporal variability the mid-Holocene highstand, with some possible localized tectonic and neotectonic overprinting.

Mapping of large-scale diapir structures at the paleo-ice tongue bed in western Latvia from geophysical investigations and borehole data

This study comprises the investigation of the complex and deformed Late Pleistocene sedimentary sequence in western Latvia composed of sandy sediments that are protruded by large-scale clayey silt diapirs and covered by glaciotectonically disturbed discontinuous patches of the Late Weichselian till. We use detailed measurements by ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) combined with borehole data and sedimentological investigations at the Baltic Sea cliffs to map and characterize the large-scale deformation structures and discontinuous till patches. We distinguish the intriguing and previously not detected characteristics of the spatial distribution pattern of discontinuous till layer represented as elongated, up to 150 m long and up to 50 m wide patches, parallel to the seacoast and perpendicular to the latest ice flow direction. The upper surface of till patches is flat and not inclined in any direction that is partially explainable by the postglacial erosion of the Baltic Ice Lake. The possible locations of diapirs inland are drawn from GPR data. We relate the formation of observed large-scale deformations to subglacial diapirism induced by the ice loading of the advancing Apriķi Ice Tongue: clayey silt sediments become loaded and overpressurized, and flowed upwards intruding into the overlying sandy sediments. The initial deposition and deformation of till layer could have been affected by the diapirism process and preferred accretion of till in inter diapir spaces. We demonstrate that the geophysical methods can greatly supplement traditional geological investigations in the field revealing characteristics of deformed sediment sequences that are not recognizable from the outcrop data only and thus can have significant implications on the interpretation of deformation processes.

Forward geochemical modeling as a guiding tool during exploration of Sea Cliff hydrothermal field, Gorda Ridge

Maximizing scientific return is critical to the success of space exploration. During the SUBSEA project, which explored the Sea Cliff vent site aboard the E/V Nautilus as an analog for hydrothermal systems on Ocean Worlds, we used forward geochemical modeling to guide decision-making during the process of exploration. Before the expedition, we performed 1670 reaction-path calculations to simulate water-rock interactions during hydrothermal circulation covering wide ranges of reaction conditions to predict the diversity of possible chemical compositions and energy available for chemosynthetic microorganisms at the Sea Cliff vents. Calculation of the information entropy of predicted concentrations of major solutes and pH allowed us to identify dissolved silica as the chemical species capable of yielding the most information about reaction conditions; as such, the measurement of this parameter was implemented aboard ship for our field program. Using telepresence, results of onboard chemical analyses of fluid samples collected during seafloor Dive n were sent to our shore-based scientific team, who processed the data and used the outcomes to inform the design of Dive n ​+ ​2. Combining data processing with forward modeling revealed, within just two dives, that all the observed fluids venting from 10 °C to 300 ​°C most likely resulted from simple conservative mixing between seawater and a common hydrothermal fluid end-member: the result of reaction of seawater with basalt at ≥350 ​°C. Identification of these reaction conditions early within the cruise allowed additional calculations to be performed to quantify the energy available from redox disequilibria as a function of vent-fluid temperatures as they exited the seafloor. These calculations can help inform and optimize real-time microbiological sampling and culture experiments onboard the ship during field expeditions. The success of our approach coupling forward modeling and onboard ship analyses allowed improved efficiency in completing process studies at the Sea Cliff vent site, providing time for further exploration and sampling of a newly discovered vent site: Apollo. This study demonstrates a novel application of forward and real-time modeling for scientific exploration that allows the time required for result-informed decision making to be reduced from years to hours – an essential breakthrough for future space exploration missions.

The ABT BioMystery

This final BioMystery for 2020 is accompanied by multiple questions and can teach us a number of lessons about the history and science of biology. Certainly, this is some sort of fossil and must be important since it is framed as if it were a valued work of art. It was found in the sea cliffs below the village of Charmouth on the Dorset coast of England in 1828. But, what it this? What is the taxonomic class of this creature? What evolutionary principle does this animal represent? Finally—and for extra credit—who found this specimen and what nursey rhyme did this famous collector inspire? The answers can be found on page 656.Photos by W.F. McComas taken in the Oxford University Museum of Natural History and at Charmouth beach in England’s Dorset County

Science, poetry, and music for landscapes of the Marche region, Italy: communicating the conservation of natural heritage

Abstract. We present a method to educate the public about landscapes that uses artistic works to broaden the audience, entice people to learn about landscapes in a personal and human context, and thus encourage them to preserve the natural heritage. To this end, we use narratives about a place, in plain language, accompanied by visual presentations, original poetry, and ancient music. Several studies encourage the use of art since it can help to synthesize and convey complex scientific information and create a celebratory and positive atmosphere. Evidence suggests that the arts can deeply engage people by focusing on emotions rather than relying only on comprehension, which is often emphasized in science communication. The multidisciplinary approach arouses an emotional and intellectual experience that enables a personal connection to the place. The work is part of a larger multidisciplinary project covering 20 sites in the Marche region (central Italy), which includes scientific information on geological–geomorphological genesis, trekking itineraries, poetry, ancient music, video, and cultural offerings. The project resulted in live multidisciplinary performances, a book, a DVD, and a website. To give a taste of how we work among the many amazing landscapes of the Marche region, we focus here on three sites from the north, the centre, and the south of the region, namely the sea cliff of San Bartolo, the flatiron of Mount Petrano, and the fault of Mount Vettore, chosen as examples for their different processes of genesis and evolution. In the long run, our goal is to promote a deeper understanding of landscapes by integrating their origin and physical aesthetic with their cultural and artistic heritage. In doing so, we intend to inspire people to have a new perception of geosites, starting from their physical beauty, building on scientific study and cultural history, and arriving at the knowledge of their social importance. So far, our direct experience with the public has been highly encouraging. The participation at our live shows demonstrated a great interest in geological history, a result that is relevant for the development of geotourism. The method demonstrates the potential to develop a strong personal involvement of visitors with the places, stimulating their curiosity to know how and why that place was formed, and, finally, the desire to visit and protect it.

Geomorphology of the Coastal Plain of the Asir Region, Using Remote Sensing and GIS Techniques, Saudi Arabia

Coastal Plain in Asir Region under investigation stretches in the southwest of Saudi Arabia. The geo-morphologic features, shoreline configuration, sediment characteristics and dynamics have been established for understanding the processes that influence the coastal environments. The shoreline of the studied area is not linear and smooth; instead, it is complicated by arcuate beaches, sharms, inlets, lagoons, barriers and rocky hills. The width of the coastal plain varies widely; it is wide and featureless towards the south of the study area while being narrow and bounded by resistant sea cliffs towards the north of the study area. Asir coastal landforms include a marsh system, inlet and swamps, wave swash, dunes, shoreline processes, beach bars, a spit system, wadi systems and sabkha systems. Conditions on such beaches change rapidly. It is a unique environment, being characterized by some of the major geological environments (e.g. coastal reefs, mangrove stands, marshes, sabkhas, alluvial fans, sea cliffs, recent sediments, sand dunes, sabkhas, sand beaches, lagoons, nebkas, wadis, coral reefs, organic matter, and vegetation areas). The aim of this paper is to follow and assess the environment and characteristics of landforms. The previous procedures happen through measuring biodiversity, landforms and geo-morphological processes on the coastline. The study uses several methods such as field study, collection of samples from different geo-morphic environments of the coastal area,comparing the geo-morphological and environmental changes from maps and also using remote sensing and GIS techniques.

Application of Multiple Geomatic Techniques for Coastline Retreat Analysis: The Case of Gerra Beach (Cantabrian Coast, Spain)

The beaches of the Cantabrian coast (northern Spain) are exposed to strong winter storms that cause the coastline to recede. In this article, the coastal retreat of the Gerra beach (Cantabria) is analyzed through a diachronic study using the following different geomatic techniques: orthophotography of the year 1956; photogrammetric flights from 2001, 2005, 2010, 2014, 2017; Light Detection and Ranging (LiDAR) survey from August 2012; Unmanned Aerial Vehicle (UAV) survey from November 2018; and terrestrial laser scanner (TLS) through two dates per year (spring and fall) from April 2012 to April 2020. With the 17 observations of TLS, differences in volume of the beach and the sea cliff are determined during the winter (November–April) and summer (May–October) periods, searching their relationship with the storms in this eight-year period (2012–2020). From the results of this investigation it can be concluded that the retreat of the base of the cliff is insignificant, but this is not the case for the top of the cliff and for the existing beaches in the Cantabrian Sea where the retreat is evident. The retreat of the cliff top line in Gerra beach, between 1956 and 2020 has shown values greater than 40 m. The retreat in other beaches of the Cantabrian Sea, in the same period, has been more than 200 m. With our measurements, investigations carried out on the retreat of the cliffs on the Atlantic coast have been reinforced, where the diversity of the cliff lithology and the aggressive action of the sea (storms) have been responsible for the active erosion on the face cliff. In addition, this research applied geomatic techniques that have appeared commercially during the period (1956–2020), such as aerial photogrammetry, TLS, LiDAR, and UAV and analyzed the results to determine the precision that could be obtained with each method for its application to similar geomorphological structures.