Beach Formation Research Articles

Regional Difference in Distribution Pattern and Morphological Characteristics of Embayed Sandy Beaches in Zhejiang Province, Eastern China

The distribution pattern and the morphology of sandy beaches have been extensively studied, while those in turbid coastal environments near large river estuaries are still unclear. This study analyzes the distribution pattern, morphological characteristics, and influencing factors of Zhejiang sandy beaches using statistical analysis, based on field data and historical records. Results show that the mean grain size distribution of Zhejiang sandy beaches ranges from fine sand to very coarse sand, and the beach slope and sediment grain size correspond well with the wave heights in the three regions of Zhejiang. The extent of beach headlands in central Zhejiang appeared the largest, suggesting an increased susceptibility to wave erosion due to the less sheltered headlands. Most sandy beaches in Zhejiang formed on the islands and the areas far from the estuaries, showing quantity difference in beach distribution. The comparison of the regional difference in Zhejiang sandy beaches shows that embayment is the main factor affecting the beach distribution pattern and morphological characteristics. The different embayment characteristics provide the space for beach formation and the interaction with the coastal process, the sediment supply, the nearshore hydrodynamic environment, and human intervention also have influence on the morphological characteristics of Zhejiang beaches.

Formation of new beaches from lahar deposits, Ambae volcano, Vanuatu

Formation of new beaches from lahar deposits, Ambae volcano, Vanuatu

First report of Sansabaina acicula, an organic-cemented siliceous agglutinated foraminifera from the Early Permian glaciomarine Pebbley Beach Formation, Southern Sydney Basin, southeastern Australia

A ca 6 cm-thick microfossil coquina bed dominated by plastically deformed and siliceous tubular test fragments is described for the first time from the Lower Permian (Artinskian) Pebbley Beach Formation of coastal and glacial marine origin in the southern Sydney Basin, southeastern Australia. The test fragments are mostly very large, straight, smooth, nearly cylindrical in shape, and the test walls are composed mainly of homogenous microcrystalline quartz grains. This homogeneous siliceous test-wall microstructure is interpreted to have resulted from diagenetic alteration of what might have been originally organic-cemented, flexible (not rigid) and siliceous agglutinated walls. As such, this microscopic tubular test is identified as Sansabaina acicula, an organic-cemented siliceous-agglutinated foraminifera originally described from the Kungurian Quinnanie Shale in the Carnarvon Basin of Western Australia. The discovery of Sansabaina acicula supports the previous interpretation of the studied strata being deposited in a stressed marine shelf environment. G. R. Shi [guang@uow.edu.au], Sangmin Lee* [lsam@uow.edu.au], Paul F. Carr [pcarr@uow.edu.au] and Brian G. Jones [briangj@uow.edu.au], School of Earth, Atmospheric and Life Sciences, University of Wollongong, Northfields Avenue, NSW 2522 Australia David W. Haig [david.haig@uwa.edu.au], Oceans Institute, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia.

A first approach of beach sanding on the Black Sea Romanian’s coast

The Romanian coastline, which is subject to complex processes of geomorphological evolution due to beach sanding actions, as well as other natural and anthropogenic factors. Beach sanding is an important action in the maintenance and development of coastal areas, it provides protection against erosion, contributes to the formation and maintenance of beaches, as well as to the preservation of coastal ecosystems The main source of sand for Romanian beaches is coastal transport, i.e. the movement of sand along the coast under the action of values, current and wind. Naturally, there is some redistribution of sand along the coast, with an area where it accumulates and an area where it is lost. However, human intervention and other influences can disrupt this natural balance. In order to counteract the negative impact of insufficient sanding, various coastal management measures have been implemented in Romania. These include the artificial replenishment of beaches by bringing in additional sand from the seabed or other sources, as well as the construction of beach protection and stabilization works.

The Reason for the Rise in Critical Shear Stress on Sloping Beds

In sediment mechanics, the conditions for the onset of sediment movement are of particular importance. However, despite decades of research, questions remain unanswered. Thus, physical logic suggests that sediments move more easily on beds inclined in the direction of flow than on horizontal beds and that transport rates are correspondingly increased. However, numerous studies have shown that sediments require increased rather than decreased shear stress to move on sloping beds and that transport rates are lower instead of increased. Since an early publication on this issue by Ashida and Michiue in 1973, many possible effects have been suggested for this apparent contradiction. The literature almost consistently concludes that high relative roughness (d/h), i.e., low water cover (h/d), is mainly responsible for this contradictory effect. This is true for current-induced sediment transport and for the initiation of debris flow. In this paper, an analytical solution for the effect of small water coverage on the transport process is developed. Effects of low coverage also occur on beaches during wave runup and runoff and thus control the formation of steep or less steep beaches. The present paper shows that the effect of turbulence damping occurring under low water coverage plays a decisive role here.

Morphosedimentary characteristics and formation mechanisms of new beaches generated after the Tajogaite volcano eruption of 2021 (La Palma, Spain)

Only in very special circumstances can new beaches develop due to natural processes in areas where they did not exist before. One such circumstance is related to volcanic eruptions, when a lava flow reaches the ocean. The sudden formation of new beaches is examined in this paper. Following the Tajogaite volcano eruption in September 2021, two lava deltas formed after the arrival of several lava flows to the coast. Attached to the flanks and front of these lava deltas, thirteen gravel beaches formed in just a few months. Detailed topographic and sedimentologic information was collected both on the beaches and adjacent submarine areas. The volume of sediments accumulated on these beaches was obtained after comparison of the actual topography with a previous one, yielding a total net accumulation of about 79,000 m3 of volcanoclastic pebbles and cobbles. This material comes from two major source areas: extensive offshore deposits of volcanic clasts within the depth of closure which are moved onshore by low steepness swell waves, and rock fragments derived from erosion of the lava delta front by high energy waves. Two types of beaches were identified. Beaches that already existed prior to the eruption showed significant increases in cross-shore length and height, with a net accumulation of 67,000 m3. In contrast, the dismantling of the lava delta front led to the formation of totally new beaches in certain locations, accounting for about 12,000 m3 of sediments. Several features, such as a steep foreshore slope, a well-developed storm berm and the presence of wood debris in many of these beaches at several meters height and tens of meters inland, are examined conjointly with the sediment characteristics, showing how textural maturity can change in response to the forcing agents acting in the different parts of the beach profile. The future evolution of these beaches is also considered. This study can enrich the knowledge regarding how new gravel beaches can form in volcanic settings.

Early morphodynamics of the sudden formation of beaches during the 2021 volcanic eruption of La Palma

On 19 September 2021, a new Strombolian monogenetic volcano erupted on the island of La Palma (Canary Islands, Spain). During the 12-week eruption, a succession of lava flows progressed down the west-central slopes, descended down the coastal cliffs and advanced over a narrow island shelf, filling it in the form of lava deltas. After the stabilization of the lava deltas, the formation of beach-like sedimentary bodies could be observed. This works aims to document the rhythms and formation dynamics of these beaches in the first months after their emergence using orthophotographic materials obtained using unmanned aerial vehicles (UAVs). These technologies have allowed analysis of the subaerial coastal evolution of the lava deltas between October 2021 and May 2022 through high-resolution digital images of approximately weekly frequency. The study includes analyses of the dichotomous evolution (emergences, disappearances, disintegrations and coalescences), short-term surface and shoreline variability (by rates of variation, Shoreline Change Envelope and Net Shoreline Movement indicators) and medium-term surface and shoreline trends (by linear regressions and End Point Rate indicators). The observations show that the formation of shoreline sedimentary bodies was sudden, within 24–48 h after stabilization of the lava fronts, and that most were subsequently long-lasting. Despite their durability, the dynamics after their appearance show high morphological mutability. The analysis of the maritime regime has allowed us to interpret these early, abnormally changing dynamics as initial states of morphodynamic disequilibrium and adjustments towards morphological stability and equilibrium with the physical environmental conditions.

Wind–Wave Conditions and Change in Coastal Landforms at the Beach–Dune Barrier of Cesine Lagoon (South Italy)

Several coastal barriers experienced significant erosion and change in shape throughout the Mediterranean coasts over the past decades, and the issue has become of increasing concern for scientists and policymakers. With reference to a case study and by meteorological and geomorphological investigations, this note aims to define the wind–wave conditions, infer the net longshore transport, and detect the geomorphological processes that shape the landforms of the Cesine Lagoon barrier (South Italy). Despite the importance of the site in coastal defense and environmental conservation, there are still no specific studies. A challenge for this research was to obtain significant results from publicly available sources and simple and inexpensive methods. Geomorphological changes, such as the retreat of dune toes, accretion of washover fans, and formation of gravel beaches, are related to the analyzed wind–wave conditions. The net longshore transport is found in accordance with the direction of the more intense winds. The role of extreme events in the shaping of coastal landforms is yet to be established, even if they greatly increase the vulnerability to flooding of the study area. The results achieved so far are starting points for further data collection and analysis in the perspective of assessing the impact of climate changes and the threatening hazards on the lagoon barrier.

The organic geochemistry of Permian high latitude sediments in two boreholes in the southern Sydney Basin, New South Wales, Australia

Twenty six samples of Permian high latitude sedimentary rocks from the southern Sydney Basin were analysed using organic geochemical methods for their thermal maturity, organic matter inputs, and depositional environment. Fourteen samples are from the Elecom Clyde River (ECR) DDH01 borehole (inland; Southern Highlands), and 12 are from the ECR-DDH07 borehole (coastal; near Nowra). The analysed formations are the Berry Siltstone, the Nowra Sandstone, the Wandrawandian Siltstone, the Snapper Point Formation and the Pebbley Beach Formation. This study is the first organic geochemical study of samples from the Berry Siltstone and Nowra Sandstone. The formations mostly have total organic carbon varying from 1 to 2 wt%, but the Snapper Point Formation is leaner in TOC (0.2–0.7 wt%). The samples vary from low to very high thermal maturity. The samples from the ECR-DDH01 borehole are in the early to middle of the oil window (vitrinite reflectance equivalent = 0.60–0.80%), based on hopane, sterane, alkylnaphthalene, alkylphenanthrene, alkylbiphenyl, and alkyldibenzothiophene thermal maturity parameters. The samples from the ECR-DDH07 borehole are much more thermally mature, in the late part of the oil window to the early gas window (vitrinite reflectance equivalent = 1.2–1.7%). This high thermal maturity has led to the loss of nearly all polycyclic biomarkers, and the thermal rearrangement of many groups of compounds, including monomethylalkanes. The ECR-DDH01 borehole location and time-equivalent outcrop samples south-west of Ulladulla have similar thermal maturities and are close to the margins of the Sydney Basin, and it is estimated to have previously been covered by about 3 km of overburden. In contrast, the samples in the ECR-DDH07 borehole were buried much deeper, with about 4–5 km of overburden, which means that only limited information about their source inputs and depositional environment could be recovered. Aliphatic biomarker, n-alkane and aromatic data are consistent with an overall strong terrigenous organic matter input for the samples from the ECR-DDH01 borehole. Sterane/hopane ratios are mostly low, but only a few compounds diagnostic of specific source inputs were identified. There is a microbially-dominated sample near the base of the Snapper Point Formation (high C29 αβ hopane/C30 αβ hopane ratio and 2α-methylhopanes), and high amounts of parent polycyclic aromatic hydrocarbons in some samples from the Berry Siltstone, likely reflecting an occasional pyrogenic signature from palaeo-forest fires. Several parameters, including sterane carbon number distributions, terpane ratios and the relative abundance of dibenzofuran compared to phenanthrene show that the samples from the ECR-DDH01 borehole have a more strongly terrigenous signal than the previously analysed outcrop samples. This is inferred to be because the ECR-DDH01 location was closer to the palaeo-shoreline than the likely more distal outcrop samples. Based on the pristane/phytane ratio and hopane distributions, deposition of the sediments was under varying oxicity conditions, from highly oxic to suboxic. The inferred environments are marine shale/lacustrine and fluvial/deltaic, so the organic geochemical data agrees with the Permian depositional history of the southmost part of the Sydney Basin previously inferred from sedimentological and palaeogeographic studies.

Тенденции развития горнолыжного туризма в Карачаево-Черкесии

Introduction. T he sphere of ski tourism is one of the priorities of state policy, which is expressed in the following factors: comprehensive restructuring of the tourism sector; development of large infrastructure projects; introduction of a mandatory system of classification of tourist facilities by location; formation of new ski trails and beaches. The strategic direction of the development of the ski tourism sector within the framework of the development of internal and external travel is the growth of consolidation of all territories of the Russian Federation, based on the development of transport infrastructure, purposeful activity of the state, establishing the principles and amounts of fees for various services, transportation of passengers and cargo, export and import of goods, subsidizing interregional transportation. The purpose of the study is to determine the strategic priorities for the development of ski tourism in the world and Russia. Materials and methods of research. Theoretical foundations of the Russian school of strategizing, general logical research methods, system and situational approaches, modeling of economic processes. Research results and discussion. The study identified the main problems and ways to solve them within the framework of sustainable development of the mountainous territories of Russia. It is determined that with global transformation processes, the country has a wide range of opportunities for the development of tourist territories, while it is necessary to develop comprehensive programs for the development of the tourism industry, effective marketing solutions in the context of strengthening the interaction of the country's tourist facilities with international tourist markets. Conclusion. Comprehensive solutions to the key problems of mountain territories require the development of a unified system of classification and accessibility of tourist information, the creation of a modern regulatory framework for tourism development, the formation of large ski complexes and territories that operate all year round and are accessible to the average citizen, the development of environmental aspects in the tourism sector.

Reserves and Distribution of Sand Capacities on the Marine Underwater Coastal Slope of the Anapa Bay-Bar

The Anapa sandy bay-bar and the territories bordering it occupy one of the leading places in Russia as a recreational sanatorium-resort area, sea tourism and children’s recreation, the role of which as a resort of federal significance has now significantly increased. Unfortunately, in recent decades, areas with progressive erosion have been observed on the seashore of this bay-bar. To substantiate the forecast of further development of the coast and the choice of ways to stabilize it, a number of studies have been carried out, including the determination of sand reserves from which the bay-bar is composed, a number of measures for their conservation have been proposed and potential replenishment opportunities have been considered. The presented work considered and analyzed the results of geophysical studies on the marine underwater coastal slope of the Anapa bay-bar, first performed to assess the volume and distribution of wave field sand deposits within the coastal zone as a possible source of beach formation and, accordingly, an increase in the volume of sand in the bay-bar as a whole.

Evolution of the French Guiana coast from Late Pleistocene to Holocene based on chenier and beach sand dating

The 1500-km-long Guianas coast between the Amazon delta in Brazil and the Orinoco delta in Venezuela is characterized by alternations of muddy shoreline advance and retreat caused by large mud banks migrating alongshore from the mouths of the Amazon. In this dominantly muddy environment, wave reworking of sand and shells results in the formation of beaches, termed ‘cheniers’, that provide valuable information on coastal evolution, especially on past erosional phases. Twenty-eight depositional ages showing the long-term patterns of shoreline mobility in French Guiana were obtained from optically stimulated luminescence. Twenty-one ages younger than 7 ka define three clusters centred on 4.5 ka, 1.0–1.3 ka, and 0.30 ka. They indicate that chenier formation was relatively synchronous and significantly affected by alongshore diversions of river mouths and changes in river-mouth position over time under the influence of muddy shoreline advance. A prominent cluster at 1.0–1.3 ka reveals a clear hiatus after the 4.5 ka cluster, indicating that the present muddy coastal plain of French Guiana was largely formed and preserved after 1.0–1.3 ka. This cluster also implies either an episode of coastal retreat or no coastal advance around 1.0–1.3 ka. The remaining seven samples were derived from Late Pleistocene deposits of headland-bound beaches and probable cheniers capped by aeolian sand, suggesting similar conditions of coastal Amazon mud-dominated sedimentation. By informing on past patterns of shoreline mobility, these results have broader implications for coastal land-use planning and shoreline management between the mouths of the Amazon and Orinoco Rivers.

Determining the change in the bathymetry of Saldanha Bay due to the harbour construction in the seventies

Bathymetry is the science to study and measure the depths of the ocean floor. The differences in water depth, underwater slope and ocean floor structure were investigated using a geographic information system (GIS). This article investigates changes to the hydrodynamic sedimentation processes in Saldanha Bay as a result of the harbour constructions that took place in the early 1970s. The construction of the harbour included the massive dredging operations and resultant relocation of 30 million m3 of soil. Bathymetric data from Saldanha Bay before (1957) and after (1977) the construction of the harbour in the early seventies were analysed and compared in ArcGIS. It was found that the overall depth of the inner part of Saldanha Bay increased with about 1.4 m and that the bottom and slopes were smoothed. The physical structure that was constructed for the harbour had a serious impact on the hydrodynamic sedimentation processes. It was found that these interventions altered the depth profile of the Bay and the article finally draws conclusions on coastal and beach formation, based on the change in the hydrodynamic sedimentation processes of Saldanha Bay.

Assessment of coastal variations due to climate change using remote sensing and machine learning techniques: A case study from west coast of India

Climate change and other environmental disturbances are causing sea level rise all over the world. Due to sea-level rise and other unprecedented atmospheric phenomena caused by climate change, Indian coasts are vulnerable to coastal erosion. The Kerala coast, at the southern tip of India's west coast, has experienced a sea change in the last decade. To address coastal variations, we investigate coastal erosion, coastal accretion, and shoreline changes (from 2006 to 2020) along this coast between Pozhiyoor and Anchuthengu (58 km). To monitor the status and predict changes along the coast, remote sensing, GIS, field checks, and machine learning tools were used. The data analysis reveals that the shoreline configuration, rate of beach accretion, and erosion have all changed significantly. When the rate of erosion in the 58-km-long coastal stretch was examined, it was discovered that approximately 42 km face acute erosion, 13 km face accretion, and approximately 3 km face neither accretion nor erosion and remain in equilibrium. According to the estimates, approximately 2.62 km2 of land has been eroded away from the shore over a 14-year period, while 0.7 km2 of land has been accreted. At locations where the influence of river discharge or groynes is minimal, the normal rate of accretion in the stretch is around 1–2 m/y. Nonetheless, the rate of accretion increased to 5–8 m/y where groynes or river mouths, or both, have a significant influence on shoreline stability. The normal rate of erosion in the stretch under consideration, however, is around 5 m/y. With a rate of 10.59 m/y, Pozhiyoor had the highest erosion rate. According to the data, the rate of erosion is faster between Pozhikkara and Veli. The increase in shoreline changes is primarily may be due to increased cyclone occurrences in the Arabian Sea, the formation of swell waves, changes in wave energy, and sea level rise due to climate change. The slow rate of sediment discharge by rivers, groyne construction, groyne spacing, groyne length, long shore currents, and preferential northward sediment transport all play a role in the formation and destruction of beaches along India's west coast. Using machine learning techniques, a prediction model for the year 2027 was created using data from the previous 14 years (2006–2020). According to the model, almost the entire stretch will experience severe erosion, with the rate remaining consistently high between Shanghumugham and Anchuthengu. As a result, soft and appropriate engineering solutions are required for coastal stability all along the beach, particularly at these two locations after a feasibilty study.

Reassessing the chronostratigraphy and tempo of climate change in the Lower-Middle Permian of the southern Sydney Basin, Australia: Integrating evidence from U–Pb zircon geochronology and biostratigraphy

The Permian of the southern Sydney Basin (Australia) comprises both marine and non-marine sedimentary sequences with evidence of glacial deposition and syndepositional magmatism represented by tuffs, lava flows and hypabyssal intrusions. This succession has been well-studied in lithostratigraphy and sedimentology, but the Lower-Middle Permian chronostratigraphy remains poorly constrained due to a lack of radiometric isotope ages and strong faunal endemism. In this study, we report the first suite of reconnaissance U–Pb zircon ages from this succession, comprising two Wandrawandian Siltstone (WS) tuffs (Green Point tuff 272.6 ± 6.5 Ma population, Callala Bay tuff ≥290 Ma Permian populations) and magmatic zircon ages from three discrete syndepositional intrusions: the Termeil Complex intruding the Snapper Point Formation dated 278.9 ± 3.7 Ma (95% confidence), the Milton Complex intruding the Snapper Point Formation and likely the WS dated 275.5 ± 4.3 Ma, and a dyke/sill at Kinghorn Point intruding the WS dated 275.6 ± 4.3 Ma. In light of the new preliminary U–Pb ages, combined with stratigraphic and biostratigraphic evidence, the age of the Wasp Head Formation is reassessed to be late Asselian-Sakmarian, Pebbley Beach Formation Artinskian, Snapper Point Formation early Kungurian, Wandrawandian Siltstone late Kungurian-Roadian, Nowra Sandstone and Berry Siltstone both confined within early Wordian, and Broughton Formation from mid-Wordian to early Capitanian. The ages and duration of the Permian glacial events are also revised, with the first episode (P1) lasting from basal Permian to early Sakmarian (~299–293 Ma), P2 spanning Artinskian (~290–283 Ma), P3, possibly the longest of all Permian glacial intervals, extending from mid-Kungurian to early Capitanian (~278–263 Ma), and P4 from mid-Capitanian to late Wuchiapingian (~260–254.5 Ma). The ≥290 Ma Permian zircon populations in the Callala Bay tuff reflect either an early Permian volcanism or older zircons recycled from elsewhere.

MORFOMETRI GISIK KAWASAN PANTAI WISATA BAHARI SARIO KOTA MANADO

Beach formation has an important role in protecting land from the action of the sea and it is useful for recreation, conservation and other uses. In “Wisata Bahari Sario” Kota Manado coastal area there is still a particular area of beach that is used for various purposes, so it is important to study its morphology. This research was conducted with the aim of describing morphology and analyzing oceanographic factors that affected the dynamic process of beach morphology. The results showed that the beach had an area of 422.69 m2, with the criteria for short slopes in the Northeast and long slopes in the Southwest. The shapes of the beach surface were in the form of gutters and shoots, their appearance was more visible towards the Southwest. In general, the deposition process took place more intensively in the Southwestern part of the beach. Keywords: Beach, Morphology, Slope, Deposition

УЧЕБНОЕ ПРОЕКТИРОВАНИЕ ПЛЯЖНЫХ ЗОН ОТДЫХА В Г. СОЧИ

Beach recreation areas are one of the most favorable for walking and recreation of residents and guests of Sochi city. Therefore, the educational design of beach recreation areas in terms of environmental design aims to develop the image of the city of Sochi as a "resort city". The historical background of the use of natural balances of the coastal territory for mass use is considered. The beach areas of Sochi city are part of the coastal strip. The organization of natural beaches was associated with the removal of natural rocks into the sea from the mouths of rivers such as Sochi, Bytkha, Vereshchaginka, Khosta, Mzymta, and others. The creation of artificial natural beaches and the increase in their number is associated with the use of engineering structures in the Soviet period since the 1930s. The study of the formation of beaches on the Black Sea coast allowed the students of Sochi State University to competently organize methods for designing beach areas in such areas of the city as Dagomys, Central District, Khosta District. The projects were carried out by students and were focused on releasing the area of beach areas from unauthorized buildings; an arrangement of areas available for modernization by introducing new planning solutions. Reference objects in the form of buildings in the coastal zone are proposed. The forms of modernization of embankments with beach areas in student projects depend on the resolution of problematic issues for each site separately

Age and Paleoenvironmental Significance of the Frazer Beach Member—A New Lithostratigraphic Unit Overlying the End-Permian Extinction Horizon in the Sydney Basin, Australia

The newly defined Frazer Beach Member of the Moon Island Beach Formation is identified widely across the Sydney Basin in both outcrop and exploration wells. This thin unit was deposited immediately after extinction of the Glossopteris flora (defining the terrestrial end-Permian extinction event). The unit rests conformably on the uppermost Permian coal seam in most places. A distinctive granule-microbreccia bed is locally represented at the base of the member. The unit otherwise consists of dark gray to black siltstone, shale, mudstone and, locally, thin lenses of fine-grained sandstone and tuff. The member represents the topmost unit of the Newcastle Coal Measures and is overlain gradationally by the Dooralong Shale or with a scoured (disconformable) contact by coarse-grained sandstones to conglomerates of the Coal Cliff Sandstone, Munmorah Conglomerate and laterally equivalent units. The member is characterized by a palynological “dead zone” represented by a high proportion of degraded wood fragments, charcoal, amorphous organic matter and fungal spores. Abundant freshwater algal remains and the initial stages of a terrestrial vascular plant recovery flora are represented by low-diversity spore-pollen suites in the upper part of the unit in some areas. These assemblages are referable to the Playfordiaspora crenulata Palynozone interpreted as latest Permian in age on the basis of high precision Chemical Abrasion Isotope Dilution Thermal Ionization Mass Spectrometry (CA-IDTIMS) dating of thin volcanic ash beds within and stratigraphically bracketing the unit. Plant macrofossils recovered from the upper Frazer Beach Member and immediately succeeding strata are dominated by Lepidopteris (Peltaspermaceae) and Voltziopsis (Voltziales) with subsidiary pleuromeian lycopsids, sphenophytes, and ferns. Sparse vertebrate and invertebrate ichnofossils are also represented in the Frazer Beach Member or in beds immediately overlying this unit. The Frazer Beach Member is correlative, in part, with a thin interval of organic-rich mudrocks, commonly known as the “marker mudstone” capping the Permian succession further to the north in the Bowen, Galilee and Cooper basins. The broad geographic distribution of this generally <5-m-thick mudrock unit highlights the development in eastern Gondwana of extensive, short-lived, shallow lacustrine systems with impoverished biotas in alluvial plain settings in the immediate aftermath of the end-Permian biotic crisis.

Особенности литодинамики галечных пляжей южного берега Крыма

The results of the study of the peculiarities of lithodynamics of pebble beaches of the South Coast of Crimea based on the long-term monitoring of the state of beaches performed at the Black Sea Hydrophysical Subsatellite Proving Ground of the Marine Hydrophysical Institute of the Russian Academy of Sciences in the settlement of Katsiveli are presented. Long-term changes of the beach of Limensky Bay since 1950 and of beaches of the shore protection structures since 1988 are characterized. The volume of income and outcome of pebbles during the change of wind-wave regimes was estimated by the example of Limensky Bay beach and the artificial beaches of the coast protection structures in the coastline section from Katsiveli to Ponizovka settlement. The most influential factor in the formation of the pebble beaches of the Southern Coast of Crimea is the change in alongshore wind-wave regimes in the “days-months” time scale, which leads to significant fluctuations in sea level near the coast and a corresponding change in the directions of the bottom current velocity components perpendicular to the shoreline. The largest expense and income of beach-forming material (up to 1 m3/day per linear meter of beach) occurs during storms, respectively, with wind-wave regimes of the eastern and western directions. The largest irreversible removal of the mass of beach-forming materials during the change in wind-wave regimes occurs from the eastern and central sections of the bays and artificial beaches of coastal protection structures, and partial restoration of beaches—on their western sections. Natural underwater reefs in the coastal waters of bays and artificial beaches of shore protection structures contribute to the preservation of beaches in them. The reason for the gradual average long-term degradation of beaches may be the predominance of eastern storm winds over western ones in conditions of blocking the natural income of beach-forming materials from the coast by the coastal infrastructure objects.

First known trace fossil of a nesting iguana (Pleistocene), The Bahamas.

Most species of modern iguanas (Iguania, Iguanidae) dig burrows for dwelling and nesting, yet neither type of burrow has been interpreted as trace fossils in the geologic record. Here we describe and diagnose the first known fossil example of an iguana nesting burrow, preserved in the Grotto Beach Formation (Early Late Pleistocene, ~115 kya) on San Salvador Island, The Bahamas. The trace fossil, located directly below a protosol, is exposed in a vertical section of a cross-bedded oolitic eolianite. Abundant root traces, a probable land-crab burrow, and lack of ghost-crab burrows further indicate a vegetated inland dune as the paleoenvironmental setting. The trace fossil matches dimensions and overall forms of burrows made by modern iguanas, and internal structures indicate active backfilling consistent with modern iguana nesting burrows. The trace fossil is also located on an island with a modern native species of rock iguana (Cyclura riyeli riyeli), suggesting a presence of iguanas on San Salvador since the Late Pleistocene. This nesting burrow may provide a search image for more fossil iguana burrows in The Bahamas and other places with long-established iguana species and favorable geological conditions for preserving their burrows.