bluuebunny/crossref_metadata_2025 huggingface dataset:
Human response to Etna volcano during the classical period
Authors: Chester D. K. , Duncan A. M. , Guest J. E. , Johnston P. A. , Smolenaars J. J. L.
Published: April 2008

Volcanoes and eruptive activity played a part in the lives of many people in southern Italy during the classical era, no more so than on the flanks of Mount Etna (Sicily), a volcano that has been continually active throughout the historical period. Both the Romans and Greeks settled at the foot and on the lower flanks of the volcano and it seems likely that they were attracted to the region by its considerable agricultural potential, in particular its plentiful supplies of water. In this paper, literary sources are used to explore three aspects of human response to the activity of Etna during the classical period. First, the role of Etna as a stimulus to the development of myth and legend is considered, and is followed by a discussion of more ‘scientific’ explanations of the volcano’s activity. To a large extent Etna’s volcanic activity was ascribed by early writers to mythological figures, but other authors, such as Empedocles and Lucretius, stand apart from this tradition by seeking more rational explanations. The paper concludes with a discussion of what can and cannot be gleaned about the eruptive behaviour of Etna during the classical period by using literature-based and geological sources of information in combination. Records suggest that the city of Catania was partly destroyed by lava in
c.
693
BC
and in 425
BC
. The eruption of 122
BC
was unusual for Etna in being explosive, and significant amounts of ash and lapilli were deposited on the southeastern flanks of the volcano, causing great distress in Catania, which required the provision of state aid.
Endemic stress, farming communities and the influence of Icelandic volcanic eruptions in the Scottish Highlands
Authors: Dodgshon R. A. , Gilbertson D. D. , Grattan J. P.
Published: April 2008

This paper explores present understanding of the possible impacts that volcanic eruptions in Iceland might have had upon the environments and traditional farming systems of the Highlands and Islands of Scotland, before ‘the Clearances’ of the late 18th and 19th centuries
AD
. It reconstructs both the nature of the impacts and the character of the risks that might have been faced by subsistence communities within the historical period from such Icelandic volcanic eruptions, and as such serves to redirect a research emphasis that has previously been principally focused upon the European Bronze Age. The study also emphasizes that it is inadequate to envisage the impacts from volcanic aerosols as threats to the community to be understood solely along a continuum of environmental hazards. For example, in the historical period before the Clearances, the wider social, political and economic contexts of subsistence economies affected can be shown to have raised or lowered the thresholds at which environmental risks became real or were turned into subsistence crises. In times past, as now, the capacity of people to cope with such environmental vicissitudes would have varied according to a complex of pre-disposing factors, their recent experiences, attitudes and perceptions, political and social relationships, health and well-being (especially their susceptibility to respiratory problems), economy, education and memory, and general inventiveness and resilience. Unlike much earlier research, which focused upon the European Late Bronze Age and emphasized global climatic change and its regional-scale consequences, this account of more recent times emphasizes the small scale, the importance of local pre-disposition and contingency, and hence the likely patchiness and indeterminacy of consequences on the ground of distant volcanic eruptions. The paper concludes that in the historical past, for a variety of environmental, agricultural, social and political reasons, some communities in the Highlands and Islands would have already been typically at risk of a subsistence crisis one year in every four or five. Hence a particular group of people could have been at notable further risk if a significant quantity of volcanically derived noxious and toxic materials had fallen upon them. As a result, for both habitats and human populations in historical times, the consequences of an Icelandic volcanic eruption are likely to have varied from place to place and from time to time. This analysis also suggests that it is difficult to envisage that any postulated region-wide abandonment of settlement in the British Isles might be attributable, directly or indirectly, to the distal impacts of volcanic eruptions in Iceland.
Volcanic soils: their nature and significance for archaeology
Authors: James Peter , Chester David , Duncan Angus
Published: April 2008

Whereas previous reviews of volcanic soils are biased in favour of those in tephra, the present paper examines the nature of weathering and pedogenesis in both tephra and lava. The classification of volcanic soils is discussed and examples are described of the response of pedogenesis to variations in climate, drainage, topography, vegetation and type and age of parent material. Archaeological implications considered include the distinctive properties of soils in tephra and the problems these may pose for laboratory analysis, evidence from buried soils, the ages of soils and their rates of development, and the fertility and erosion of volcanic soils.
The use of volcaniclastic material in Roman hydraulic concretes: a brief review
Authors: Siddall Ruth
Published: April 2008

The realization that the addition of volcaniclastic material to hydrated lime cements produced a concrete that was not only waterproof but would also set under water revolutionized the building programmes of the Roman Empire. The material became known as
pulvis Puteolis
(dust of Puteoli) from the Latin name for modern Pozzuoli on the Bay of Naples. Pozzuoli itself is the root of ‘pozzolana’, meaning any material (in most natural cases, volcanic in origin) that is capable of producing a hydraulic (waterproof) set when combined with lime cement. A reaction between quicklime (CaO) and volcanic ash promotes the growth of phases that, rather than reverting to calcium carbonate on curing, as in non-hydraulic cements, produce a hard, watertight material. Although volcanic materials were the aggregates of choice in the building projects of Imperial Rome, being locally derived, abundant and relatively easily quarried, their hydraulic properties were soon fully realized, perhaps as a result of observations of naturally calcite-cemented scoria and ash flows in sea water or from experimental building. Away from the Imperial centre, terrestrial architecture involving waterproofing (baths and cisterns) effectively used waste ceramic sherds as a substitute for volcanic ash. However, for marine and riparian architecture, volcanically derived pozzolanic cements were the preferred material of use.
Fault pattern of Nisyros Island volcano (Aegean Sea, Greece): structural, coastal and archaeological evidence
Authors: Stiros Stathis C.
Published: April 2008

There has been much debate about the fault pattern of Nisyros Island at the southeastern edge of the Aegean volcanic arc. The small active volcanic island, less than 200–100 ka old, is dominated by a well-developed caldera and by post-caldera domes that are less than 25 ka old and up to 600 m high. Detailed mapping of the tectono-volcanic features of Nisyros have revealed that faults have a clear radial pattern, and they are more abundant in the northwest of the island, where volcanic domes are also concentrated. In contrast to previous speculations that certain major faults control the tectono-volcanic development of Nisyros, this paper argues that the radial fracture pattern is expected where faulting is a secondary effect of volcanic doming. Structural, coastal and archaeological evidence supports this contention. Most faults have a short fault length and a ‘scissors-type’ geometry typical of magma or salt ascent dynamics, and variable throws that are too high to reflect simply tectonic effects. Elevated coastal marine fossils (vermetids) in the northwest of the island indicate rates of uplift too high to be explained solely by differential fault movements. In the same area, a fault that borders the fortifications of a fourth-century BC castle is inferred to be the source of seismic damage effects observed in its ramparts and responsible for the near-total destruction of its westernmost fortifications. Together, the evidence suggests that localized high rates of uplift, faulting and tilting reflect tectonvolcanic deformation effects, and remind us that associated fault activity is likely to have constituted a major threat for the island since antiquity.
Along-strike variability of forced regressive deposits: late Quaternary, northern Peloponnesos, Greece
Authors: McMurray Lesley S. , Gawthorpe Robert L.
Published: April 2008

Late Quaternary depositional sequences in northern Peloponnesos, central Greece, occur as a number of offlapping and downstepping forced regressive wedges. Major along-strike variability is evident, with three environmental responses to forced regression: (i) attached shoreface deposits; (ii) detached shoreface deposits; (iii) fan-deltas. All three depositional systems are cut by incised valleys. Relative sea-level change was responsible for similarities in key stratal surfaces and stacking patterns; regional uplift drove the overall forced regression, whereas individual sequences relate to fourth- and fifth order glacioeustatic cycles. Variations in basin physiography and the amount and type of sediment led to along-strike variability of depositional sequences. Fan-deltas developed at the mouths of incised valleys in the west of the area, where supply of coarse-grained sediment was high and slope gradients were steep. In contrast, limited supply of coarse-grained sediment and low slope gradients over most of the study area promoted the development of shoreface systems. Forced regressive wedges in the shoreface systems attach and detach along strike. Detached wedges developed where both slope gradients and coarse-grained sediment supply were low, away from the axes of major incised valleys.
Early Stages of Evolution of the Black Sea
Authors: Kazmin V. G. , Schreider A. A. , Bulychev A. A.
Published: April 2008

Comparison of two sets of structural and thickness maps of the Black Sea Basin produced by Russian and Italian workers revealed important differences in the interpretation of thickness and structure of the lower sedimentary unit, referred to in both works as ‘Palaeocene-Eocene’. The map based on the Italian data shows two depocentres with τ 5 km of sediment in the westernmost part of the Western Black Sea Basin (WBSB), while in the rest of the WBSB and in the Eastern Black Sea Basin (EBSB) the thickness is 2–3 km. Analysis of the land and submarine geology suggests that depocentres correspond to two segments of this system is represented by the Karkinit Graben on the northern shelf of the Black Sea. Submarine studies reveal that the graben originated behind and Early Cretaceous volcanic arc situated on the present day continental slope and rise.

Most of the WBSB and the EBSB opened in the Eocene. For the EBSB this age is supported by data on its landward extension — the Adjaro—Trialet Basin. The EBSB could not open due to anticlockwise rotation of the Shatsky Rise because there was no corresponding subduction or shortening in the Greater Caucasus Basin. An alternative hypothesis is that of simultaneous opening of the EBSB and the WBSB as a result of southward drift of the Pontides and clockwise rotation of the Andrusov Rise.
Patterns of flow and suspended sediment concentration in a macrotidal saltmarsh creek, Bay of Fundy, Canada.
Authors: Schostak Laura E. , Davidson-Arnott Robin G. D. , Ollerhead Jeff , Kostaschuk Ray A.
Published: April 2008

Measurements of velocity and suspended sediment concentration were carried out in a saltmarsh tidal creek network in the Cumberland Basin, Bay of Fundy, Canada. The study area was located on the NW shore of the basin in part of an undyked marsh that is about 200 m wide with a simple reticulate creek network. The area is macrotidal with spring tides greater than 12 m and suspended sediment concentrations in the basin characteristically range from 150–300 mg l
−1
. The purpose of the study was to determine vertical and along channel variations in these two parameters over individual tidal cycles and to use these data to assess the role of the tidal creeks in the import and export of water and sediment from the marsh surface.

Measurements using a vertical array of co-located electromagnetic current meters and OBS probes for measuring suspended sediment concentration were carried out over four spring tides at a cross section in the lower part of Middle Creek. Six sets of measurements were carried out at four locations along the length of the creek, a distance of about 200 m over six tides ranging from spring to neap. Maximum mean velocities measured over sampling times of eight minutes did not exceed 0.1 m sec
−1
in Middle Creek and 0.15 m sec
−1
in Main Creek. Transient high velocities associated with the overbank flows were weakly developed as a result of the absence of significant levees or embankments on the marsh surface. Suspended sediment concentrations in the creek generally decreased steadily over the period of inundation. Flow across the marsh margin occurred simultaneously with the achievement of bankful conditions and the creeks themselves appear to play a relatively minor role in the movement of water and sediment onto and out of the marsh. Despite the fact that the marsh surface is still low in the tidal frame and active sedimentation is still occurring, the low flow velocities and observations in the field suggest that the tidal creek network is unable to flush itself and that it is contracting.
Lake gravel beach sedimentological variability, Milarrochy Bay, Loch Lomond, Scotland
Authors: Pierce Lydia R.
Published: April 2008

The nature and environmental significance of variations in sedimentological parameters of a restricted-fetch lake coastal system (Milarrochy, Loch Lomond) are described in the context of climate change. Grain size characteristics of the beach, streams, cliffs and nearshore/offshore sedimentary environments are distinct, with variability being related to sediment supply, beach altitude and process conditions. Beach grain sizes range from silt to cobble, and are predominantly rounded discs and blades. There is an overall trend of offshore fining with increasing depth, beyond the mixed surf zone and clear limit of coarse sediment (coarser than -1 phi), resulting from dominant shore-normal process trends. Seasonal trends of water level fluctuation, sediment discharge and transfer from river to beach are important controls on local scale variability. The broader significance is that local physiography, sediment characteristics and supply strongly influence beach sedimentology and morphological response, even in the context of larger scale climate change. The record of sedimentological variability detailed here is significant for beach management projects and a better understanding of lake sedimentary facies within the Quaternary.
Post-reclamation changes in estuarine mudflat sediments at Bothkennar, Grangemouth, Scotland
Authors: Barras Beverley F. , Paul Michael A.
Published: April 2008

The Engineering & Physical Sciences Research Council research site at Bothkennar is located on former intertidal mudflats adjacent to the Forth estuary, which were reclaimed for agricultural use around the year 1784. A desiccated surface crust has developed in the 200 years following the reclamation, largely in response to the introduction of artificial drainage. Its formation has involved both compaction and material translocation, due to effective stress changes and to infiltration and geochemical alteration respectively. At first, new deposits accumulated in an artificial tidal lagoon and underwent autocompaction under saturated conditions. The subsequent introduction of field drains and cultivation then induced suction stresses due to evapotranspiration, leading to overconsolidation by around 150–200 kPa. These processes have also been associated with the development of an immature soil profile to a depth of around 0.7 m. The infiltration of fresh water has caused both desalination and the eluviation of clay particles. There is also a general rise in pH and fall in Eh with depth, which is associated with leaching and the downward translocation of DCB (dithionate-citrate-bicarbonate) soluble iron compounds. We conclude that the physical development of the crust was rapid and is now largely completed, whereas the chemical development is not yet completed and thus the soil profile remains immature.
Sedimentological controls on the erosion and morphology of saltmarshes: implications for flood defence and habitat recreation
Authors: Crooks Stephen , Pye Kenneth
Published: April 2008

The factors which influence the morphology, drainage characteristics and erosion resistance of saltmarshes are of major interest from the standpoint of flood defence and habitat recreation. Sedimentological characteristics, including grain size distribution, mineral composition and pore fluid chemistry are all highly important. Of particular importance in muddy marshes is the nature of the clay mineral assemblage and dissolved cations present in the pore fluids. In marshes which are deficient in detrital calcium carbonate, such as those in Essex, UK, sodium ions dominate the exchange sites on clays, leading to the formation of thick water films around the clay particles and slow rates of sediment consolidation. This, in turn, causes low erosion resistance and a tendency for the development of highly dissected marsh morphology. Calcium and magnesium-rich marsh sediments, on the other hand, allow these ions to replace sodium in exchange sites, leading to more rapid dewatering and consolidation. Erosion resistance is thereby enhanced and such marshes tend to be characterized by low drainage densities and a low ratio of bare mud to vegetated surface area. The possibilty of engineering the erosion resistance and morphology of marshes through chemical treatments requires further investigation.
Recent geological evolution and human impact: Fraser Delta, Canada
Authors: Barrie J. Vaughn
Published: April 2008

Throughout the Holocene, the river dominated Fraser Delta on the Pacific coast of Canada has prograded by continuous channel switching and avulsion into a deep (>300 m) basin. However, at the beginning of the 20th century the delta was modified to provide a navigable channel and port facilities for the city of Vancouver. Now most of the sand brought down by the river (35% of the sediment load) is removed from the system by dredging. The remaining fine-grained sediment is transported in a plume past the intertidal estuary within the distributary channels then deflected northwards by the dominant flood tidal flow into the basin. Two causeways to the south of the main channel and one to the north that cross the intertidal zone to the delta foreslope act as barriers to the dominant northward sediment transport causing estuarine and localized seabed erosion. An eroded distributary channel failure complex has been exposed on the delta foreslope, off the southern causeways, by flood tidal flows that scour the seabed and form northward migrating subaqueous dunes, further increasing the delta slope. This, combined with slow sea-level rise and seismicity, intensifies the risk of further erosion and instability of the delta, particularly along the subaqueous delta front and the intertidal estuaries.
How anthropogenic factors in the back-barrier area influence tidal inlet stability: examples from the Gulf Coast of Florida, USA
Authors: Davis Richard A. , Barnard Patrick L.
Published: April 2008

Human development along the coast of the world has caused important changes to coastal morphodynamics. The barrier-inlet system of Florida, especially the tidal inlets, has been severely impacted by this development. Beginning in the 1920s and continuing through the 1960s there was: (1) extensive construction of fill-type causeways connecting the mainland to the barrier islands, (2) widespread dredge-and-fill construction along the backbarrier and mainland, and (3) dredging of the Intracoastal Waterway (ICW) in the back-barrier area.

The primary effect of these various types of construction and development was to cause instability of many inlets by diminishing the tidal flux through them. In some cases there was a combination of human and natural causes that resulted in the inlet degradation or closure such as at Dunedin Pass and Blind Pass, whereas at others this instability was almost exclusively the result of human activity such as at Midnight Pass. Although these detrimental development practices have been stopped, a large amount of irreparable damage has been done.
Holocene development of the east bank of the Gironde Estuary: geoarchaeological investigation of the Saint Ciers-sur-Gironde marsh
Authors: Mellalieu Simeon J. , Massé Laurent , Coquillas Didier , Alfonso Stéphanie , Tastet Jean-Pierre
Published: April 2008

The nature of postglacial sea-level change and sediment infilling of the Gironde Estuary, SW France, has previously been reconstructed using a sequence stratigraphic model. This paper examines specifically the development of the St Ciers-sur-Gironde marsh during the late Holocene. The study area forms the largest expanse of coastal wetlands on the east bank of the Gironde. A geoarchaeological approach is used incorporating borehole survey, sedimentological and diatom analysis, radiocarbon dating, archaeological, documentary and cartographic evidence, which aims to test and refine the previous model of estuarine development.

The later Holocene sequence is characterized by alternating clay-silt and peat facies. Diatom evidence indicates that clay-silt units represent sedimentation under marine-brackish estuarine conditions in intertidal mudflat, and potentially saltmarsh, environments. The palaeoenvironmental conditions represented by the main upper peat unit, dated to 5600-2600
bp
, are currently unknown due to the absence of diatom evidence from these levels. Within an overlying trend of rising relative sea-level over the past 6000 years, 3 negative sea-level tendencies appear to have occurred. There is insufficient resolution in the present data set to determine the exact nature of each or their duration.
Holocene coastal change in the north of the Isle of Man: stratigraphy, palaeoenvironment and archaeological evidence
Authors: Gonzalez Silvia , Innes Jim , Huddart David , Davey Peter , Plater Andrew
Published: April 2008

New multidisciplinary work at Phurt in the north of the Isle of Man using stratigraphy, radiocarbon dating, pollen, diatoms, foraminifera and archaeology has reevaluated the sedimentological and archaeological sequence located in a series of basins containing organic peats, silts and sands at the south end of the Flandrian Ayres raised beach succession. From this work it is clear that all the Mesolithic finds from the beach have been reworked and are not significant in terms of human occupation in this area and there is no evidence for human modification of the Mesolithic vegetation from Phurt. The radiocarbon dates for the middle peat fit into the Neolithic phase and although all the
in situ
artifacts are from layers above the peat from a sandy palaeosol, these layers are likely to have been deposited rapidly after the peat formation. Although the artifacts are Middle Neolithic in typology it is considered that the dates from the peat are not inconsistent with the archaeological dating framework.

The pollen indicates an early woodland phase but there are indicators of the close proximity of the sea from coastal pollen taxa, foram test linings in the upper peat layer and diatoms. In the middle peat tree pollen was much less frequent, there was a wide range of open ground herb taxa, mainly of freshwater type but again there were salt marsh taxa present, indicating the close proximity of the sea. In the upper organic horizon and the burnt mound profiles the lack of coastal pollen must indicate a relative sea-level drop. The depositional environment envisaged to account for the litho- and pollen stratigraphy in these small basins is predominantly a freshwater lake behind shingle bars, with the close proximity to seaward of a saltmarsh. On occasions there must have been brackish water in these lagoons and a marine connection through the shingle barrier based on the diatom evidence, which is similar to the interpretation at nearby Lough Cranstal. This is in contrast with the Liverpool Bay sequences where there is evidence for several marine transgressions, but in both areas the coastal or near coastal environments indicate much well preserved evidence for Neolithic and Bronze Age occupation and vegetational alteration by these populations.
Doggerland: the cultural dynamics of a shifting coastline
Authors: Coles Bryony J.
Published: April 2008

The landmass now covered by the North Sea, here referred to as Doggerland, has had an important but neglected influence on the course of prehistory in northwestern Europe. The physical character of Doggerland in the Late Glacial and earlier Holocene is assessed, together with its re-colonization by humans after the Last Glacial Maximum. The development of a maritime-based society along the northern coast of Doggerland is postulated, and it is argued that the coastal inhabitants, with their specialized adaptation to this zone, will have moved with the coast as relative sea-levels changed. The interactions of coastal and inland populations are considered, including the probable influence of the coastal groups in delaying the spread of farming into the region.
Development-led archaeology in coastal environments: investigations at Queenborough, Motney Hill and Gravesend in Kent, UK
Authors: Firth Antony
Published: April 2008

This paper reviews a series of investigations undertaken by Wessex Archaeology in North Kent in advance of major construction projects. Three sites have been investigated on areas of former saltmarsh at Queenborough, Motney Hill and Gravesend. All three sites currently contain wastewater treatment works (WTW) which are being enhanced in order to meet new water quality standards, involving the construction of new buildings on dense grids of piles driven through the alluvium to more solid strata up to 15 m below ground surface. The paper discusses each investigation in terms of the archaeological and geotechnical background, the evaluation and mitigation strategy adopted, and the contribution that the results may make to our understanding of human activity on the North Kent coast over the past 10 000 years. The paper also looks ahead to development-led investigations at other coastal locations, to show how such work can make a direct contribution to geoarchaeological research while reconciling the objectives of construction and conservation.
Folding in the Johnsons Glacier, Livingston Island, Antarctica
Authors: Ximenis L. , Calvet J. , Garcia D. , Casas J. M. , Sàbat F.
Published: April 2008

An active fold system revealed by interbedded tephra layers is visible on the ablation surface of Johnsons Glacier (Livingston Island, South Shetland Islands, Antarctica). Johnsons Glacier is a cirque-shaped glacier of 5 km
2
area located in a temperate ice cap. Converging flow-lines as a consequence of the reducing channel section extend from ice divides and terminate in a calving ice-cliff. Recent tephra layers from the volcano on Deception Island constitute excellent markers of the internal structure of the glacier and, when dated, provide valuable information about deformation kinematics.

Detailed field mapping of the clearly visible tephra markers revealed several folded layers that define a set of folds with sub-horizontal and fan-distributed axes being sub-parallel to the converging flow-lines. Folds become tighter towards the centre of the channel, where a cylindrical anticline is clearly exposed. Related deformational structures, comprising minor folds, foliations, thrust faults and crevasses, are observed in the ablation area. Strain-rates reflect extensional flow and higher deformation values where maximum confluence occurs.

We examine how the occurrence of this structure results from the transverse shortening in response to the reducing channel section and the consequent confluence of ice masses, increase in differential flow-rates between the centre of the glacier and the margins, and the development of passive folding processes.
The Pasterze glacier, Austria: an analogue of an extensional allochthon
Authors: Herbst Paul , Neubauer Franz
Published: April 2008

Structures of the Pasterze glacier (Austria) have been studied in detail and interpreted as representing a natural model of an extensional allochthon formed on top of an orogenic wedge, and also a model for raft tectonics at passive continental margins. Structures of the lower, ablation-controlled portion of the glacier, including ductile structures at the base, are forming close to the melting point of ice, with predominantly brittle structures close to the surface of the glacier. Formation of these structures results from self-weight, gravity-driven spreading, similar to extensional allochthons.

S-planes are common and clearly related to three individual flow units. They show a typical, spoon-like arrangement. These three flow units are bordered by centimetre- to decimetre-wide shear zones which also include shear folds. Brittle structures include ice-mineralized tension gashes, thrust and normal faults, and hybrid, shear-extensional fractures. Together, these structures show that glacial flow is more rapid in middle to upper sectors of the glacier than along the lateral, and lower margins. The coherent upper sheet is behaving in a brittle manner and is elongating slightly along the flow direction by tensional deformation.

The distribution of structures allows three structural domains within the lower, ablation-controlled sector of the glacier to be distinguished: (1) an upper sector with predominant extensional structures due to rapid flow; (2) a lower sector with ductile and brittle thrust faults, penetrating from the ground and dipping strictly opposite to the local flow direction; (3) a few normal faults at the terminus that developed by rapid melting along the steep lower frontal margin of the glacier. These three structural domains are also found within extensional allochthons as exemplified by the Neogene Alpine-Carpathian system where a huge allochthon, partly driven by gravity, extruded from the Eastern Alps towards the Carpathian arc. Three similar structural domains are also found in recent analogue models and field examples of passive continental margins.
Behaviour of subglacial sediment and basal ice in a cold glacier
Authors: Fitzsimons Sean J. , Lorrain Regi D. , Vandergoes Marcus J.
Published: April 2008

Tunnels in glaciers offer unique opportunities for examining basal processes. At Suess Glacier in the Taylor Valley, Antarctica, a 25 m tunnel excavated into the bed of the glacier provides access to a 3.2m thick basal zone and the ice-substrate contact. Measurements of ice velocity over two years together with glaciotectonic structures show that there are distinct strain concentrations, a sliding interface and thin shear zones or shear planes within the basal ice. Comparison of ice composition, debris concentrations and the shear strength of basal ice samples suggest that strength is controlled by ice chemistry and debris concentration. The highest strain rates occur in fine-grained amber ice with solute concentrations higher than adjacent ice. Sliding occurs at the base of the ice that experiences the highest strain rates. The substrate and blocks of the substrate within basal ice are characterized by brittle and slow ductile deformation whereas ice with low debris concentrations behaves in a ductile manner. The range of structures observed in the basal ice suggests that deformation occurs in a self-enhancing system. As debris begins to deform, debris and ice are mixed resulting in decreased debris concentrations. Subsequent deformation becomes more rapid and increasingly ductile as the debris and sedimentary structures within the debris are attenuated by glacier flow. The structural complexity and thickness of the resulting basal ice are considerably greater than previous descriptions of cold glaciers and demonstrate that the glacier is or was closely coupled to its bed.
Molecular phylogeny of the Bivalvia inferred from 18S rDNA sequences with particular reference to the Pteriomorphia
Authors: Steiner Gerhard , Hammer Sabine
Published: April 2008

The classification of the Pteriomorphia, a major division of the Bivalvia with Ordovician origins, is controversial both among palaeontologists and neontologists. To elucidate phylogenetic relationships new near-complete 18S rDNA sequences of 26 Pteriomorphia, three Protobranchia, three Heterodonta, one Anomalodesmata and three Scaphopoda were obtained, aligned with 71 other published molluscan sequences, and analysed with parsimony, maximum likelihood and spectral analysis. Although Bivalvia appear diphyletic due to heterogeneity of substitution rates among lineages, monophyly of Protobranchia, Heteroconchia and Pteriomorphia is supported. The heteroconch Lucinida, Myoida and Venerida are not monophyletic, and Anomalodesmata arise from within Heteroconchia. The basal nodes of Pteriomorphia have little support but two major clades, [Pinnoidea (Ostreoidea + Pterioidea)] and [(Anomioidea + Plicatuloidea) + (Limoidea + Pectinoidea)], are resolved with more confidence. The strongly supported clade of Anomioidea + Plicatuloidea, the separation of Pinnoidea from Pterioidea and most of the intrafamiliar relationships are not in accordance with morphological classifications. Combining these results with selected morphological characters, a phylogenetic hypothesis is proposed showing Mytiloidea and Arcoidea as the basal pteriomorph groups, the latter giving rise to the clade uniting the pinnoid-ostreoid-pterioid and the anomioid-limoid-pectinoid lines.
Prodigious polyphyly in imperilled freshwater pearly-mussels (Bivalvia: Unionidae): a phylogenetic test of species and generic designations
Authors: Lydeard Charles , Minton Russell L. , Williams James D.
Published: April 2008

Unionid bivalves or freshwater pearly-mussels (Unionoidea: Unionidae) serve as an exemplary system for examining many of the problems facing systematists and conservation biologists today. Most of the species and genera were described in the late 1800s and early 1900s, but few phylogenetic studies have been conducted to test conventional views of species and classification. Pearly-mussels of Gulf Coastal drainages of the southeastern United States from the Escambia (southern Alabama to Florida) to the Suwannee Rivers (Florida) are a unique fauna comprised of approximately 100 species, with about 30 endemic to the region. In this study, mitochondrial cytochrome c oxidase subunit I and 16S rRNA gene sequences were used to test the monophyly and to estimate evolutionary relationships of five unionid species representing three different genera. The molecular phylogenies depict all three genera as polyphyletic. The prodigious polyphyly exhibited within unionids is due to incorrect notions of homology and false assumptions about missing anatomical data. In contrast, the molecular phylogeny provides evidence to support the recognition of all five unionid species as distinct evolutionary entities. Furthermore, molecular genealogical evidence supports the elevation of
Quincuncina infucata
(Conrad) of the Suwannee River to species level, for which
Q. kleiniana
(Lea) is available.
Early Cretaceous giant bivalves from seep-related limestone mounds, Wollaston Forland, Northeast Greenland
Authors: Kelly Simon R. A. , Blanc Eric , Price Simon P. , Whitham Andrew G.
Published: April 2008

Anomalous mound-forming limestones, here termed the Kuhnpasset Beds, occur within Late Barremian (Early Cretaceous) mudstones on Wollaston Forland, Northeast Greenland. The normal mudstones contain a sparse fauna of small nuculoids, arcoids and inoceramids; by contrast, the mounds contain an unusual faunal assembage, dominated by large bivalves. These include an abundant lucinid,
Cryptolucina kuhnpassetensis
sp. nov., and, less commonly,
Solemya
, both known seep-associated genera. Locally, a large modiomorphid,
Caspiconcha whithami
gen. et sp. nov., is common and reaches > 300 mm in length and has a shell up to 28 mm thick. Also, the wood-boring bivalve
Turnus
is abundant in driftwood. Gastropods are rare, but the associated cephalopod fauna includes ammonites, belemnites, nautiloids and a remarkable large orthoconic phragmocone. The form of the mounds with calcite-cemented tube systems, associated laminated calcite crusts and void fills, together with the fauna, is analogous to those of methane-based cold-seep complexes. However, preliminary studies indicate that much of the original aragonitic shell is now replaced by silica. This precluded conclusive geochemical studies based on the shells themselves. It is believed that the mounds formed on the seafloor in a mid- to outer shelf situation at the end of a period of extensional rifting on the eastern Greenland passive Atlantic margin. The vents occur near the footwall crest of a tilted fault block. The underlying faults may have provided routes or influenced direction of movement for nutrient migration. Source rocks were probably the Late Jurassic black shales from depths of < 600–1200 m. If methane was being generated, it was probably forming by shallow-depth organic breakdown rather than by thermogenic processes, which require greater burial.
The function of pallial eyes within the Pectinidae, with a description of those present in
Patinopecten yessoensis
Authors: Morton Brian
Published: April 2008

The structure of the pallial, ectopic eye of
Patinopecten yessoensis
is described and shown to be of the typical pectinid form, located on the middle mantle fold. The cornea is, however, a tall epithelium and, with the lens, forms a Cartesian oval, unlike the lens alone in other pectinids which functions to counter spherical aberration. The basal cell layer beneath the retina and argentea is poorly pigmented, although this may be countered by the fact that the optic tentacle epithelium itself is apically heavily pigmented.

It is generally assumed that pectinid pallial eyes, being able to perceive a moving image, are used to warn of vicinal predators, resulting in swimming. However, this does not seem to be the case; although crabs and starfish, in particular, are known predators of scallops, which respond by swimming to the latter, they do so (usually) on receipt of mechanical and chemical stimuli, not visual. Some scallop species live in seagrass beds and there is evidence that these may afford protection. Scallops are visually attracted to the waving fronds.

Scallops may also make relocation movements and, in more specialized taxa, e.g. species of
Amusium
, can swim for several metres. The visual sense of scallops is poorly understood and although pallial eyes may have developed early in the ancestry of the Pectinidae, as an antipredation sense organ, they may, in the descendants, now have a different, but perhaps related, function, although what this is, is unknown. Pectinid pallial eyes may improve the efficiency of photon capture in low light intensity subtidal habitats but for what purpose is unclear, since even if they are functioning as optical ‘burglar alarms’, what could they see in such a situation, especially as there is no brain to formulate an image?
Functional anatomy of the digestive system of
Neoteredo reynei
(Bartsch, 1920) and
Psiloteredo healdi
(Bartsch, 1931) (Bivalvia: Teredinidae)
Authors: Lopes Sônia G. B. C. , Domaneschi Osmar , De Moraes Daniela T. , Morita Marisa , Meserani Georgeana De L. C.
Published: April 2008

Studies on the digestive system of the Teredinidae are useful for a better understanding of the evolution of these bivalves in relation to the xylophagous habit.
Neoteredo reynei
and
Psiloteredo healdi
, two common species in Brazilian mangroves, have evolved differently in their methods to use wood as food, despite the similarities in the anatomy and functioning of their globular type II stomachs.
N. reynei
is predominantly xylophagous throughout its life, while
P. healdi
, despite its predominant suspension-feeding habit, uses wood more efficiently as the animal grows older. The outstanding differences that allow these conclusions are the large size of the appendix and anal canal in
N. reynei
, always conspicuous and packed with wood, and the small appendix of
P. healdi
, which increases in size with age. Based on anatomical data and revision of the literature, it is suggested that in both species the appendix, and also the anal canal in
N. reynei
, is of primary importance in the digestion of wood and absorption of nutrients, counterbalancing the reduced specialized digestive diverticula.
Evolutionary trajectories of a redundant feature: lessons from bivalve gill abfrontal cilia and mucocyte distributions
Authors: Beninger Peter G. , Dufour Suzanne C.
Published: April 2008

Recent data on the distributions of cilia and mucocytes on the bivalve gill abfrontal surface are analysed with respect to evolutionary relationships of the principal autobranch gill types. From the primitive function as a mucociliary cleaning surface in the protobranchs, two evolutionary trajectories are evident: (1) progressive reduction of both cilia and mucocytes with resultant loss of surface function, seen in the homorhabdic filibranchs studied; (2) reduction of cilia but retention or increase in acid mucopolysaccharide-secreting (AMPS) mucocyte density in the eulamellibranchs, corresponding to the assumption of a new function, probably in the reduction of frictional resistance to flow in the water canals. Heterorhabdic gill abfrontal surfaces present a mixture of these characteristics: reduction of cilia and mucocytes on the ordinary filaments, and retention of both on the principal filaments. The retention of AMPS mucocytes on the abfrontal surface of the pseudolamellibranchs may be related to the degree of interlamellar fusion, reducing frictional resistance to water flow as in the eulamellibranchs. The gill abfrontal surface thus constitutes an excellent candidate for the study of the different evolutionary options and trajectories of a redundant feature.
Morphodynamics of
Bryopa
and the evolution of clavagellids
Authors: Savazzi Enrico
Published: April 2008

Typical clavagellids are either tube dwellers in soft sediments or facultative semiendolithic borers.
Bryopa
deviates from this pattern by being fully and obligatorily endolithic. The left valve in
Bryopa
is permanently attached to the wall of the borehole. In spite of this, the bivalve migrates forwards within the substrate throughout growth. These seemingly incompatible feats are achieved by continuously elongating the shell in the anterior direction and sliding forwards the soft parts, hinge and right valve within the shell. While the left valve becomes elongated, the posterior region of the right valve is continuously destroyed by resorption. The resulting strongly inequivalve condition is unique among clavagellids, as well as endolithic bivalves.

In the lack of direct evidence, the evolution of clavagellids from less specialized stocks remains open to alternative hypotheses. Probable parallel evolution within the clavagellid stock further complicates the problem. Evolution of tube-dwelling clavagellids directly from burrowing ancestors is as likely as their evolution from a hypothetical, endolithic protoclavagellid. In the latter case, however,
B. lata
is probably too specialized to reflect the adaptations of such an ancestor.
Calcium concretions in the interstitial tissues of the Australian freshwater mussel
Hyridella depressa
(Hyriidae)
Authors: Byrne Maria
Published: April 2008

The Australian freshwater mussel
Hyridella depressa
(Lamarck, 1819) has extensive deposits of calcium phosphate granules in its interstitial connective tissues. The structure, distribution and elemental profile of these granules were documented by light and electron microscopy. For the elemental study, granules in cryo-prepared mantle tissue were examined by X-ray microanalysis. The granules were bright orange and formed a conspicuous cover over the mantle and palps, and were also abundant in the visceral mass. By contrast, they were not common in the gills and foot. The granules were typically distributed in discrete clusters and, in places, dominated the tissue space. Iron was a particularly important component of the granules and may account for their colour. The granules also contained other common elements, including Mg, Mn and Al, and trace elements, including Cu, Zn and Pb. Considering the important position of the Hyriidae in understanding the evolution and phylogeny of the Unionoida, emphasis was placed on comparison of the calcium granules of
H. depressa
to those in the Margaritiferidae and Unionidae. Granule distribution in
H. depressa
was most similar to that described for margaratiferids and contrasted with that described for unionids. The impressive capacity to accumulate extensive calcium deposits in their tissues is a unique feature of the Unionoida, but the rationale underlying production of these excess calcium stores is not understood. It is suggested that the granules may be a by-product of biomineralization processes in the Unionoida associated with the highly efficient calcium uptake system these bivalves evolved in conjunction with colonization of freshwater environments.
Teranota
and its implications on anomalodesmatan phylogeny
Authors: Rogalla Nicole S. , Amler Michael R. W.
Published: April 2008

Bedded carbonaceous siltstones from the Buechel Subformation of the Bergisch-Gladbach-Paffrath Syncline, Germany, of Middle Devonian (Middle Givetian) age have yielded a remarkable sample of extremely elongated, articulated bivalves preserved in life orientation. The specimens are associated with a single left valve embedded horizontally in the bedding plane and further isolated but articulated shells. Combining the information given by the specimens and the palaeobiological interpretations allows the reconstruction of the complete morphology and probable life habits. The very distinct morphological features led to the erection of a new taxon,
Teranota ebbighauseni
Rogalla & Amler, 2000, provoking discussion on habitats, life habits and evolutionary trends in anomalodesmatan bivalves. A combination of characters typical of the orthonotids and the modiomorphids, as well as the preserved life position at an angle of some 60–70° relative to the bedding plane, suggests that these specimens were part of a minor branch off the main evolutionary lineages within the Anomalodesmata. It is proposed that these animals represent a convergent line of endobenthic bivalves distantly related to true siphonate forms.