Stratigraphy and sedimentology of Devensian (Dimlington Stadial) glacial deposits,east Yorkshire,England

The stratigraphy and sedimentology of the glacial deposits exposed along the coast of east Yorkshire are reviewed. Critical sections at Filey Brigg, Barmston and Skipsea are examined to reassess the stratigraphy of Devensian Dimlington Stadial glacial deposits in the light of recent developments in glacial sedimentology. Sedimentary and glaciotectonic structures studied in the field and by using scanning electron microscopy are emphasised. Two hypotheses are considered for the genesis of the interbedded diamictons and stratified sediments. The first involves the deposition of lodgement till and/or deformation till followed by meltout till, which was overridden to produce more deformation till, reflecting periods of ice stagnation punctuated by glacier thickening. The second hypothesis, which is favoured on the basis of field evidence and micromorphology, involves the vertical accretion of a deforming till layer associated with cavity/channel or tunnel valley fills, beneath active ice. At Barmston the upper part of the diamicton contains elongate pendant structures containing gravels, indicating that the diamicton was saturated and able to flow. The diamictons, therefore, represent a complex sequence of tills deposited and deformed by active ice during the Dimlington Stadial. Previously published stratigraphical schemes involving classifications of multiple tills in east Yorkshire should be simplified and it is more appropriate to assign these to a single formation, the Skipsea Till Formation. Rhythmic glaciolacustrine and proglacial glaciofluvial sediments overlie the tills at Barmston and Skipsea. These were deposited in sag basins during deglaciation as the tills settled and deformed under thickening sediment and as buried ice melted out. Extensive sands and gravels cap the succession and were deposited on a sandur during the later stages of deglaciation.     

Maralinga,a metamorphosed carbonaceous chondrite found in Australia

Abstract— The Maralinga meteorite was found near the village of Maralinga, South Australia (30°18′S, 131°16′E) in 1974, but was not recognized as a meteorite until 1989. One weathered individual was recovered with a total mass of 3.38 kg. The bulk composition and petrography of Maralinga indicate that it is a metamorphosed (petrographic type 4) carbonaceous chondrite with major similarities to the Vigarano-subtype. However, recent trace element data from the literature suggest that Maralinga should be included with the CK (Karoonda-type) carbonaceous chondrites. We classify Maralinga as an anomalous CK4 chondrite because of its abundant chondrules and refractory inclusions relative to other known members of the CK group. Maralinga contains homogeneous silicates, including Ni-bearing olivines (Fa₃₄), high-Ca clinopyroxene, and rare orthopyroxene. Plagioclase is chemically heterogeneous and falls into two distinct compositional groups one of ～ An₂₀ and an ～ An₈₀ group. Highly oxidizing conditions during metamorphism of Maralinga are indicated by the abundance of magnetite and the paucity of Fe-Ni metal.     

Study of the contact binary AK Herculis: Light-curve analysis and orbital period investigation

AK Her is a very interesting contact binary exhibiting variable lightcurves and an obvious O'Connell effect, with max I greater than max II. Inthe present work an extensive study of this system is made covering notonly its light curve analysis, but also its orbital period changes in anattempt to give a definite answer regarding the apsidal motion of AK Her.Photoelectric observations of AK Her, obtained between 1985–1987 at theNational Observatory of Athens Greece, are presented, analysed anddiscussed. The light curve analysis was made with the W-D code and thegeometric and photometric elements of the system were derived. TheO'Connell effect was faced with a two dark spot model. Moreover, theorbital period of the system was examined and two periodicities weredetected. Since the first one corresponds to the time interval for whichobservational data exist and the second was found to be half of the first,it turns out that none of them is true. Two other significant results thatcame from the present analysis are that the orbital period of AK Her doesnot follow a sinusoidal variation and that, from the times of minimumlight at primary and secondary eclipses, it seems that there is no apsidalmotion.     

Modulation of near-inertial motions on the Mississippi-Alabama Shelf

Ocean Dynamics - In this study, we diagnose the time variability and vertical structure of the high- and low-frequency motions on the Mississippi-Alabama Shelf as observed with a bottom-mounted...     

Resistance of salt marsh substrates to near-instantaneous hydrodynamic forcing

Salt marshes deliver vital ecosystem services by providing habitats, storing pollutants and atmospheric carbon, and reducing flood and erosion risk in the coastal hinterland. Net losses in salt marsh areas, both modelled globally and measured regionally, are therefore of concern. Amongst other controls, the persistence of salt marshes in any one location depends on the ability of their substrates to resist hydrodynamic forcing at the marsh front, along creek margins and on the vegetated surface. Where relative sea level is rising, marsh elevation must keep pace with sea-level rise and landward expansion may be required to compensate for areal loss at exposed margins. This paper reviews current understanding of marsh substrate resistance to the near-instantaneous (seconds to hours) forcing induced by hydrodynamic processes. It outlines how variability in substrate properties may affect marsh substrate stability, explores current understanding of the interactions between substrate properties and erosion processes, and how the cumulative impact of these interactions may affect marsh stability over annual to decadal timescales. Whilst important advances have been made in understanding how specific soil properties affect near-instantaneous marsh substrate stability, less is known about how these properties interact and alter bulk substrate resistance to hydrodynamic forcing. Future research requires a more systematic approach to quantifying biological and sedimentological marsh substrate properties. These properties must then be linked to specific observable erosion processes, particularly at the marsh front and along creek banks. A better understanding of the intrinsic dynamics and processes acting on, and within, salt marsh substrates will facilitate improved prediction of marsh evolution under future hydrodynamic forcing scenarios. Notwithstanding the additional complications that arise from morphodynamic feedbacks, this would allow us to more accurately model the future potential protection from flooding and erosion afforded by marshes, while also increasing the effectiveness of salt marsh restoration and recreation schemes. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd     

A regional coupled approach to water cycle prediction during winter 2013/14 in the United Kingdom

A regional coupled approach to water cycle prediction is demonstrated for the 4-month period from November 2013 to February 2014. This provides the first multi-component analysis of precipitation, soil moisture, river flow and coastal ocean simulations produced by an atmosphere-land-ocean coupled system focussed on the United Kingdom (UK), running with horizontal grid spacing of around 1.5 km across all components. The Unified Model atmosphere component, in which convection is explicitly simulated, reproduces the observed UK rainfall accumulation (r² of 0.95 for water day accumulation), but there is a notable bias in its spatial distribution—too dry over western upland areas and too wet further east. The JULES land surface model soil moisture state is shown to be in broad agreement with a limited number of cosmic-ray neutron probe observations. A comparison of observed and simulated river flow shows the coupled system is useful for predicting broad scale features, such as distinguishing high and low flow regions and times during the period of interest but are less accurate than optimized hydrological models. The impact of simulated river discharge on NEMO model simulations of coastal ocean state is explored in the coupled modelling framework, with comparisons provided relative to experiments using climatological river input and no river input around the UK coasts. Results show that the freshwater flux around the UK contributes of order 0.2 psu to the mean surface salinity, and comparisons to profile observations give evidence of an improved vertical structure when applying simulated flows. This study represents the first assessment of the coupled system performance from a hydrological perspective, with priorities for future model developments and challenges for evaluation of such systems discussed.     

Impacts of a fuel oil spill on seagrass meadows in a subtropical port, Gladstone, Australia--the value of long-term marine habitat monitoring in high risk areas

We used an established seagrass monitoring programme to examine the short and longer-term impacts of an oil spill event on intertidal seagrass meadows. Results for potentially impacted seagrass areas were compared with existing monitoring data and with control seagrass meadows located outside of the oil spill area. Seagrass meadows were not significantly affected by the oil spill. Declines in seagrass biomass and area 1month post-spill were consistent between control and impact meadows. Eight months post-spill, seagrass density and area increased to be within historical ranges. The declines in seagrass meadows were likely attributable to natural seasonal variation and a combination of climatic and anthropogenic impacts. The lack of impact from the oil spill was due to several mitigating factors rather than a lack of toxic effects to seagrasses. The study demonstrates the value of long-term monitoring of critical habitats in high risk areas to effectively assess impacts.     

Evolution of the Thames estuary during MIS 9: insights from the Shoeburyness area, Essex

Multidisciplinary, litho-, bio- and amino-stratigraphical investigations of the infills of buried channels on the coast of eastern Essex have a direct bearing on the differentiation of MIS 11 and MIS 9 in continental records. New data are presented from Shoeburyness, where a deeply incised channel filled with interglacial sediment can be directly related to the terrace stratigraphy of the River Thames. Fossil assemblages confirm that the interglacial beds began accumulating in a freshwater environment, which became transformed into a dynamic estuary as relative sea-levels rose. Pollen data confirm that this occurred early in the interglacial when mixed oak forest was becoming established.The geological context of the sediments indicates that they post-date the Anglian glaciation, yet pre-date the Barling Gravel terrace aggradation, which has been ascribed to MIS 8. Amino acid racemisation data based on Bithynia opercula further constrain the age to the Hoxnian (=MIS 11) or to MIS 9. An MIS 9 attribution is favoured because (i) AAR data suggest that the sequence post-dates the interglacial channel-fill at Clacton, which is widely ascribed to the Hoxnian; (ii) the bivalve Corbicula occurred early within the interglacial (unlike its late appearance during the Hoxnian); and (iii) the sequence includes evidence for a marine transgression that occurred earlier in the interglacial cycle than it did at local Hoxnian sites.Plant macrofossil remains suggest that the early part of the Shoeburyness interglacial was associated with warmer-than-present summer temperatures. This is in keeping with inferences from sites at Barling, Cudmore Grove and Purfleet, which are also attributed to MIS 9. All three sites are similar in terms of their palaeo-vegetation and inferred relative sea-level histories and provide an emerging picture of this temperate episode in southern Britain.     

Antifouling strategies: history and regulation, ecological impacts and mitigation

Biofouling increases drag on marine vessels resulting in higher fuel consumption and can also facilitate the transport of harmful non-indigenous species (NIS). Antifouling technologies incorporating biocides (e.g., copper and tributyltin) have been developed to prevent settlement of organisms on vessels, but their widespread use has introduced high levels of contamination into the environment and raised concerns about their toxic effects on marine communities. The recent global ban on tributyltin (1 January 2008) and increasing regulation of copper have prompted research and development of non-toxic paints. This review synthesises existing information regarding the ecological impact of biocides in a wide range of organisms and highlights directions for the management of antifouling paints. We focus particularly on representatives of the recent past (copper and tributyltin) and present (copper and ‘booster’) biocides. We identify knowledge gaps in antifouling research and provide recommendations relating to the regulation and phasing-out of copper.