bluuebunny/crossref_metadata_2025 huggingface dataset:
Geometrical simulation studies of coastal cliff failures in liassic strata, South Wales, U.K.
Authors: Williams A. T. , Davies P. , Bomboe P.
Published: February 2007

Three numerical models of cliff failure have been developed, based on analyses of rockfalls along the 22 km Liassic coastline of the Glamorgan Heritage Coast, U.K. Detailed field investigation of the bucklandi (limestone dominated) and angulata (mudstone dominated) Lias series at four locations confirm the veracity of the models. Translation failure was correctly predicted at the mainly limestone buttressed cliff sites in the bucklandi and at locations where the angulata series formed a high proportion of the cliff mass. Toppling was predicted for vertical and overhanging cliffs with basal undercutting. The factor of safety reduces as the ratio of undercutting depth (d) to tension fracture distance (D) from the cliff face increases. Instability can be triggered by thrust forces generated by wave/tide impact, freeze/thaw and expansion/contraction associated with clay infill. Thrust forces can be modest, ranging from 1·7 to 2·7 MN m2, but can exceed the cross‐joint strength as weathering proceeds.
Geomorphic effects of a large flood on fluvial fans
Authors: Scott Pamela F. , Erskine Wayne D.
Published: February 2007

The response of 12 fluvial fans near Sydney, Australia to a large storm between 2 and 4 February 1990 was determined by repeating previously surveyed longitudinal profiles and by undertaking detailed field observations of erosion and deposition. Peak rainfall intensities occurred on 3 and 4 February when between 173 and 193·8 mm were recorded. Return periods for 24 h duration peak rainfall ranged between 5·7 and 11·0 years on the annual maximum series at six stations within the study area and return periods for 48 h peak rainfall ranged between 13·5 and 29·4 years.

Of the 12 fans, seven were trenched and five untrenched. The most significant geomorphic effects of the storm were recorded on the proximal region of the fans. However, fan response was highly variable, with one fan exhibiting no detectable change, three fans localized deposition, two fans spatially disjunct erosion and deposition, two fans channel avulsions, and seven fans fanhead trench reworking. Some fans exhibited more than one type of response.

A four‐stage, tentative cyclical model of fanhead development was constructed from the field data. Stage 1 refers to the episodic aggradation of the fanhead by localized deposition, spatially disjunct erosion and deposition and/or channel avulsions. Stage 2 represents the initiation of a fanhead trench when progressive aggradation locally exceeds a threshold slope leading to localized erosion. This erosion initially creates one or more discontinuous flow‐aligned scour pools. Over time, the scour pools widen, deepen and extend both up‐ and downfan. Stage 3 refers to the coalescence of discontinuous scour pools into a continuous trench by the removal of intervening log and boulder steps. Stage 4 represents the backfilling phase of the trench once it has been overwidened and/or slope reduced. Aggradation then continues as for stage one.
A development of the lichenometric method applied to the dating of glacially influenced debris flows in southern chile
Authors: Winchester V. , Harrison S.
Published: February 2007

Lichenometry is a dating technique that has problems relating to questionable assumptions. The development of a size frequency approach, previously used in attempts to resolve some of the problems, is described and applied to the dating of four debris flows marginal to the San Rafael Glacier in Southern Chile. This study provides examples of the development's application, its problems and directions for further work. The size frequency approach, based on new assumptions, uses parameters derived from population size frequency distributions of the lichen species Placopsis patagonica to provide relative and absolute dating for rock surfaces. Changes in the shapes of distributions suggest the relative age of populations. Absolute dating is based on a curve (spanning a 24 year time period) derived from mean diameter size/age correlations. A stratified random sampling design permits the use of inferential statistics. Standard deviations and confidence intervals show error margins, the degree of relatedness between neighbouring populations, and populations that are anomalous. One‐way analysis of variance is used to indicate where populations may safely be grouped. The size frequency approach appears to be particularly suitable for use on unstable debris flows where secondary movements are common. The approach also demonstrates that lichen growth and colonization are sensitive to aspect differences and other variations in microhabitat.
Fire and ecosystem heterogeneity: A mediterranean case study
Authors: Kutiel Pua
Published: February 2007

The response of a Mediterranean ecosystem to fire is summarized in this paper. The results were obtained over a 3‐year period at sites with a known fire history on Mt Carmel, Israel. The results give some idea of the complexity and variability of the ecosystem response to fire, and about factors that could determine these responses. It also shows how fire increases species and landscape diversity.
Discussion: Bulk sampling of coarse clastic sediments for particle‐size analysis
Authors: Dunkerley D. L.
Published: February 2007

Gale and Hoare (1992) have provided a figure relating maximum particle diameter in a coarse clastic sediment to the size of sample required to generate a reproducible measure of the particle‐size distribution of that sediment. However, they fail adequately to justify the basis for the criterion of sample adequacy adopted in their proposal. Additionally, there is a range of separate issues neglected by Gale and Hoare (1992) which makes their conclusion inapplicable in many situations. A fundamental issue that they neglect is the purpose lying behind a grain‐size analysis: this issue determines what grain size measures are appropriate, rather than the empirical, seemingly purpose‐independent, approach of Gale and Hoare (1992).
‘real’ geomorphology revisited
Authors: Richards Keith
Published: February 2007

Some of the reasons are given for the editorial (Richards, 1990) now discussed by Rhoads (1994) and Bassett (1994). These include the lack of interest generally displayed by geomorphologists in matters of scientific philosophy and method, and the instrumentalist view of research often presented to postgraduate students given present funding imperatives. It is suggested that in a revision of views about the validity of a hypothesis‐testing, critical rationalist methodology might have considerable implications for the practice of environmental sciences, and that accordingly the debate initiated by Rhoads and Bassett is worthy of continuation.
A field test of tubino's (1991) model of alternate bar formation
Authors: Welford Mark R.
Published: February 2007

This study investigates the fluvial dynamics of straight natural stream channels. In particular, this experimental field study quantitatively assesses a physically based non‐linear mathematical theory of alternate bar formation under unsteady natural flow conditions within a straight alluvial stream. The study site is an artificially straightened section of the Embarras River located approximately 16 km south of Champaign, Illinois. Data were collected on channel form, gradient, alternate bar dimensions, bed sediment size and flow stage over a 2 year study period.

Both linear and non‐linear steady flow hydrodynamic theories suggest that alternate bars are critical to the process of meander development. But these theories do not predict bar development for unsteady flow conditions, which typically occur in natural alluvial channels. Tubino (1991) suggests that bar evolution for a flood hydrograph can be divided into three parts: (1) a period of limited bar growth during the rising stage of the flood; (2) a stage of modest bar decay near the peak of the flood; and (3) a stage of non‐linear bar growth during the prolonged falling stage of the flood.

Bars developed during the falling limb of a hydrograph, and exhibited sequential development rather than the uniform growth along the reach predicted by Tubino's model. As flow stage decreased, short, low, fine‐grained bars were superimposed on long, high and coarser‐grained bars that developed under preceding high flow stages. These results suggest that the process of bar formation in artificially straightened natural streams with heterogeneous bed material may occur under different flow conditions and in a different manner than predicted by theoretical models. Further work should focus on attempting to isolate the physical mechanisms responsible for alternate bar formation in straight natural streams with heterogeneous bed material and flashy hydrologic flow regimes.
Within‐storm variations in runoff and sediment export from a rapidly eroding coal‐refuse deposit
Authors: Smith Laurence C. , Olyphant Greg A.
Published: February 2007

Measurements of rainfall, runoff and sediment export from a barren deposit of coal mine refuse in south‐western Indiana were collected during three storms in the summer and autumn of 1990. Interfluve sheetwash, sediment mass flux, sediment concentration and, to a lesser extent, trunk gully discharge all responded quickly to changes in rainfall intensity. Grain‐size distributions varied considerably during storms, containing exclusively fine‐grained sediment at low sediment discharges but very large quantities of coarse (> 2mm) sediment at peak sediment discharges. Although data from a fairly long, multipulsed storm indicate that sediment production is limited by supply, the imbricated layer of flat chips that exists at the surface of the deposit is apparently mobilized during most high‐intensity pulses of rainfall, thereby producing large volumes of coarse sediment during summer thunderstorms.
Deterministic uncertainty in landscapes
Authors: Phillips Jonathan D.
Published: February 2007

Deterministic complexity (chaos) may be common in geomorphic systems, but traditional definitions may have limited practical utility for empirical geomorphology. These definitions are based on sensitivity to initial conditions, which in geomorphology are both unknown and unknowable. Further, chaos analysis depends on distinguishing deterministic complexity from stochastic complexity. This is problematic in geomorphology because some stochastic complexity is virtually always present in addition to any chaos that may be present. While it is important to recognize that some complex, apparently random patterns may derive from inherent non‐linear system dynamics, this is of limited use in explaining process–response relationships or mechanics of landscape evolution. A more general term, which subsumes chaos, is deterministic uncertainty, i.e. uncertainty associated with an identifiable but unknown or uncertain source. An analysis of landscape entropy shows that such underlying constraints produce spatial patterns which are apparently chaotic. For the case of geologic controls, the apparent contribution of deterministic chaos to the landscape entropy is a direct non‐linear function of the extent of geologic constraints. However, the underlying constraints and their contribution to observed spatial patterns can also be interpreted in non‐chaotic terms. Examples are given, involving geologic constraints on stream channel networks and parent material control of surface soil textures. Because both randomness and chaos may be more apparent than real, the concept of deterministic uncertainty is more useful in process geomorphology than that of chaos.
Variability of bedload transport and channel morphology in a braided river hydraulic model
Authors: Warburton Jeff , Davies Tim
Published: February 2007

This paper investigates variability in bedload transport and channel morphology for 11 replicate experimental runs in an approximately 1:50 braided river model. The experiments, each of 90 h duration, were carried out in a 20 × 3m tilting flume. All the experiments started with the same initial conditions. Bedload transport was measured at 5 min intervals in a collection drum at the exit from the flume. The model showed reasonable hydraulic similarity when compared to prototype rivers. Results show that mean bedload transport rates for the 11 runs vary in the range 0·98 to 1·49gs−1 (mean + 1·21, coefficient of variation 11 per cent). Within‐run transport rates commonly vary from close to zero, to two and occasionally three or four times the mean rate. Within the bedload series, several irregular phases of transport intensity can be observed, but time series analysis of the data show little underlying serial structure (an AR(2) autoregressive model is appropriate). Channel patterns are narrow/braided, are established quickly and remain relatively stable throughout the runs, although channel widths increase between 20 and 103 per cent over the 11 runs. Channel behaviour varies from aggradational to transitional between aggradation and degradation. Time‐averaged bedload transport rate is weakly correlated with braiding intensity. In general, these results demonstrate that for a given set of controlling variables, bedload transport and channel morphology can be approximately replicated.
Dynamics of fluvial and slope processes in the changing geomorphic environment of singapore
Authors: Chatterjea Kalyani
Published: February 2007

The nature and rates of fluvial and slope processes change over time and space as urbanized areas replace forested land in Singapore. Storm‐based and time‐based data, from undisturbed rainforests, heavily disturbed construction sites, urban grass‐covered slopes and an experimental plot, are collected to observe the impact of rainwater on the soil moisture conditions, surface microtopography, runoff generation, sediment movement, and ground lowering in the three different categories of land use.

The undisturbed forested environment is characterized by high throughfall (58% of total rainfall) and frequent negative soil moisture suctions. The slow and unconcentrated overland flow during heavy storms is restricted by the forest floor microtopography. No rills develop. Ground lowering is recorded as 3·2–3·4 mm a−1. But sediment movement is episodic and suspended sediment concentrations in overland flow are 172–222 mg l−1. During urban construction, gully development is rapid on the bare slopes, runoff generation, voluminous, and sediment‐laden discharges (5200–75498 mg l−1) lead to sediment plumes at channel mouths. Ground lowering rates are measured at 132·4 mm a−1. Once grass‐covered, runoff carries less suspended sediment (800 mg l−1) and ground lowering rates are reduced, but depend on the condition of the cover, ranging from 0·2 to 8·2 mm a−1.

As urban development continues, environments are altered both in time as well as spatially.
A one‐person, one‐instrument method for precision barometric altimetry
Authors: Goldrick Geoff
Published: February 2007

This paper describes an adaptation of the ‘leap‐frog’ method of barometric altimetry which enables altimetric surveys to be undertaken by a single operator using a single barometer with no requirement for base stations. The method involves two readings at each station, the first bracketed by readings at the previous station, and the second bracketed by readings at the subsequent station. Linear interpolation is used to estimate what the readings would have been at each station at the time that readings were taken at the adjacent stations. Under suitable meteorological conditions errors are generally less than ±1 m, which is sufficiently accurate for a wide variety of geomorphological applications. The method has significant advantages in terms of cost and/or time over more accurate methods such as electronic distance measurement surveys or survey quality global positioning systems. The paper is accompanied by a Microsoft Excel template spreadsheet, BAROSURV.XLT, which converts temperature and pressure readings to relative elevations, and graphs the results. Notes on the use of BAROSURV.XLT are included in the ASCII text file BAROSURV.NOT.
A digital surface roughness meter
Authors: Brian Whalley W. , Rea Brice R.
Published: February 2007

Geomorphological studies often require precise devices to measure surface roughness or variations with high precision and good repeatability. A digital measurement device is described, which provides these features and can be linked to a small, light and portable recorder and processor. Such an arrangement allows rapid, accurate data recording by a single operator and can be used in the laboratory or field. With interchangeable measurement rods the vertical range of the instrument is 150 mm, with an actual measured range of 30 mm per rod. The potential accuracy is 0·001 mm with an operating temperature range of+5 to +40°C. Its light weight, relatively low cost and precision make it a useful measuring device which can be adapted for many tasks simply by modification of the stand.
Sea‐level rise: A review of recent past and near‐future trends
Authors: Gornitz Vivien
Published: February 2007

Global mean sea level is a potentially sensitive indicator of climate change. Global warming will contribute to worldwide sea‐level rise (SLR) from thermal expansion of ocean water, melting of mountain glaciers and polar ice sheets. A number of studies, mostly using tide‐gauge data from the Permanent Service for Mean Sea Level, Bidston Observatory, England, have obtained rates of global SLR within the last 100 years that range between 0·3 and 3 mm yr−1, with most values concentrated between 1 and 2 mm yr−1. However, the reliability of these results has been questioned because of problems with data quality and physical processes that introduce a high level of spatial and temporal variability. Sources of uncertainty in the sea‐level data include variations in winds, ocean currents, river runoff, vertical earth movements, and geographically uneven distribution of long‐term records. Crustal motions introduce a major source of error. To a large extent, these can be filtered by employing palaeo‐sea‐level proxies, and geophysical modelling to remove glacio‐isostatic changes. Ultimately, satellite geodesy will help resolve the inherent ambiguity between the land and ocean level changes recorded by tide gauges.

Future sea level is expected to rise by ∼ 1 m, with a ‘best‐guess’ value of 48 cm by the year 2100. Such rates represent an acceleration of four to seven times over present rates. Local land subsidence could substantially increase the apparent SLR. For example, Louisiana is currently experiencing SLR trends nearly 10 times the global mean rate.

These recently reduced SLR estimates are based on climate models that predict a zero to negative contribution to SLR from Antarctica. Most global climate models (GCMs) indicate an ice accumulation over Antarctica, because in a warmer world, precipitation will exceed ablation/snow‐melt. However, the impacts of attritional processes, such as thinning of the ice shelves, have been downplayed according to some experts. Furthermore, not all climate models are in agreement. Opposite conclusions may be drawn from the results of other GCMs. In addition, the West Antarctic Ice Sheet is potentially subject to dynamic and volcanic instabilities that are difficult to predict. Because of the great uncertainty in SLR projections, careful monitoring of future sea‐level trends by upgraded tide‐gauge networks and satellite geodesy will become essential.

Finally, because of the high spatial variability in crustal subsidence rates, wave climates and tidal regimes, it will be the set of local conditions (especially the relative sea‐level rise), rather than a single global mean sea‐level trend, that will determine each locality's vulnerability to future SLR.
Dune mobility and vegetation cover in the Southwest Kalahari desert
Authors: Wiggs Giles F. S. , Thomas David S. G. , Bullard Joanna E. , Livingstone Ian
Published: February 2007

As part of a wider project investigating the palaeoenvironmental significance of partially vegetated linear dunes in the southwest Kalahari, data collected in the latter part of 1992 concerning dune movement and vegetation cover suggest that sediment transport is occurring on some dune surfaces, and that the majority of surface activity occurs on the crests and upper slopes of the dunes. The data suggest that the limiting variables on surface sediment movement vary on different parts of a dune. On interdunes and lower dune slopes the primary limiting variable is available wind energy, while on dune crests and upper slopes it is vegetation cover. Ground cover by litter has much greater importance in protecting the surface sediment from erosion than rooted vegetation. From individual data points, no evidence is found to support a threshold vegetation cover below which sediment movement occurs. Rather, a gradient of activity is suggested whereby a reduction in vegetation cover increases the potential for sediment movement and surface change. However, dunes with differing amounts of mean vegetation cover display differing degrees of surface activity, and at this scale, a vegetation cover threshold in the region of 14 per cent may be recognized.
The Spey Bay geomorphological study
Authors: Riddell Keith J. , Fuller Terence W.
Published: February 2007

The Spey Bay coastline and the estuary of the River Spey exhibit a rapidly evolving planform. They provide an opportunity to study geomorphological changes in a coupled coastal/estuarine system which can be measured over hours and days rather than the years and decades associated with more slowly evolving landscape features. Attempting to understand coastal and estuarine geomorphology provides engineers and earth scientists with an exciting intellectual challenge. This is not, however, simply an academic challenge because the successful management of coastal and estuarine environments depends on improving this understanding. The impetus behind our work in this area is the protection of land‐use interests. It is in this context that Babtie Dobbie Limited have been employed in studying the River Spey since 1962. This paper is based on a practical case study performed for coastal and river engineering purposes between 1990 and 1992. The case study was formulated using the results and conclusions of earlier geomorphological studies of the area undertaken over the past 32 years. Knowledge gained from previous studies was crucial in designing the detailed methods and techniques employed in the 1990–1992 geomorphological study. Methods used included historical analyses, photogrammetry, numerical modelling, geographic information systems (GIS) and interpretation of the complex processes which drive landform changes in the estuary and along the adjacent shoreline. The improved understanding of geomorphological processes that has been achieved has enabled engineers to formulate a new management strategy. Central to this strategy are engineering solutions to river and coastal stability and flooding problems which are in sympathy with the environment and which take maximum advantage of our understanding of geomorphological processes.
Turbulent flow structure in a gravel‐bed river: Markov chain analysis of the fluctuating velocity profile
Authors: Kirkbride Alistair D. , Ferguson Rob
Published: February 2007

Three electromagnetic current meter probes were deployed in a Canadian gravel‐bed river to obtain simultaneous records at 10 Hz of streamwise (u) and vertical (v) velocity components at three heights above the bed. By looking at the positive and negative signs of the instantaneous fluctuations from the time‐average values of each velocity component at each height, the fluctuating velocity profile of u or v can be treated as a Markov chain with eight states and its statistical properties can be tested against null hypotheses based on the absence of spatial structure. We report results of this novel approach.

The most common states of the u profile were those with either higher‐than‐average or lower‐than‐average velocities at all heights; these ‘high speed’ and ‘low speed’ states persisted for up to 3 s. The most common v profiles were all‐upwards or all‐downwards, but these persisted for shorter times than the high speed and low speed u profiles. Analysis of transition probabilities shows statistically significant tendencies for acceleration from the low speed u profile, and change from all‐upwards to all‐downwards v profile, to take place progressively from the uppermost probe downwards, in a sweep‐like way. Deceleration from the high speed to low speed u profile and change from all‐downwards to all‐upwards v profile (burst‐like behaviour) do not show such clear patterns.

The results are interpreted in terms of the advection of inverted wedges of relatively high‐momentum fluid, followed by more chaotic structures. A separate set of flow visualization experiments over a mixed gravel bed in a flume supports the presence of advected wedge structures, the decelerating part of the sequence corresponding to irregular ejections of near‐bed fluid.
Textural, geochemical and mineralogical evidence for the origin of peoria loess in Central and Southern Nebraska, USA
Authors: Winspear N. R. , Pye K.
Published: February 2007

Possible sources of Peoria loess in central Nebraska have been investigated through the fingerprinting of the textural, geochemical and mineralogical characteristics of the loess and possible source sediments, with statistical comparison of the textural and compositional fingerprints. The results of the investigation contrast with the ‘desert loess’ model proposed by Lugn (1960), and are instead consistent with the derivation of the Peoria loess in Nebraska primarily from fluvio‐glacial outwash sediments carried by the ancestral North and South Platte River systems from the Rocky Mountain Front Ranges during the late Pleistocene.
Galilean invariance and stabilized methods for compressible flows
Authors: Scovazzi G.
Published: February 2007

In a recent work (Comput. Methods Appl. Mech. Eng. 2007; 196(4–6):966–978), it was observed that lack of Galilean invariance led to catastrophic instabilities when stabilized methods were used in Lagrangian shock hydrodynamics computations. By means of an arbitrary Lagrangian–Eulerian (ALE) formulation, Galilean invariant SUPG operators were consistently derived in (Comput. Methods Appl. Mech. Eng. 2007; 196(4–6):1108–1132), and their Lagrangian and Eulerian limits were compared to the most commonly used stabilized formulations. In the particular case of Eulerian meshes, it was shown that most of the SUPG operators designed to date for compressible flow computations are not invariant. However, due to the significant overhead of algebraic manipulations, the use in (Comput. Methods Appl. Mech. Eng. 2007; 196(4–6):1108–1132) of the referential form of the ALE equations made the presentation of the main ideas quite involved. The present paper addresses this particular issue, since the invariance analysis is presented with the aid of the intuitive current configuration reference frame, more familiar to computational fluid dynamicists. Copyright © 2007 John Wiley & Sons, Ltd.
A Multi‐Scale Dynamic Mechanistic Model for the Transient Analysis of PEFCs
Authors: Franco A. A. , Schott P. , Jallut C. , Maschke B.
Published: February 2007

Electrochemical impedance spectroscopy is an experimental technique widely used for the transient analysis of PEFCs. Experimental results are usually analyzed using equivalent circuit models, which have to be fitted to each operation point and do not offer direct access to the internal physical parameters of the electrodes.

In this paper, a multiscale mechanistic Membrane‐Electrode Assembly model is proposed, based on irreversible thermodynamics and electrodynamics, and dependent on the internal physical parameters, such as the effective catalyst surface, the electrical permittivity of the materials, the reaction kinetics, and the diffusion coefficients of the reactant species.

This model results from the coupling of a microscale transport phenomena description through the electrode and the electrolyte thickness, a spatially distributed microscale model of the reactant diffusion through the Nafion® layer covering the Pt/C particles, and a spatially distributed nanoscale description of the Nafion®‐Pt/C interface. This interfacial model is based on an internal description of the double layer dynamics, coupling the transport phenomena in the diffuse layer with the electrochemical reactions and water adsorption in the inner layer.

The system dynamics can be simulated and are dependent on the current, the temperature, the reactant pressures, and the Pt/Nafion® loadings on the electrodes. The first simulations carried out are in good qualitative agreement with experimental results, giving access to the contributions of the different phenomena and to the sensitivity of the operating conditions.
The anatomy of a coal seam split, Durham coalfield, Northeast England
Authors: Fielding C. R.
Published: February 2007

A pronounced coal seam split, one of many within the Lower Westphalian B (Upper Carboniferous) sequence of the Durham coalfield, northeast England, occurs in the vicinity of the village of Burnhope. This feature involves the division of the combined Main/Fivequarter coal into its two component parts, which become separated by up to 8 m of clastic sedimentary rocks over a horizontal distance of 150 m.

Three‐dimensional outcrop data from an opencast (surface) coal mine straddling the split, supported by extensive subsurface information, have allowed detailed study of the seam split geometry, in addition to that of three overlying coal seams and intervening clastic facies.

The study suggests that deposition of the interval as a whole, including the split, was strongly influenced by compaction‐controlled subsidence, and not by either contemporary fault movements or channel sedimentation.

A substantially greater aggregate thickness of coal is preserved over the five seam interval where the Main/Fivequarter is unsplit than where split. This relationship is consistent with the coal depositional model proposed by Fielding (1984a), which proposed that thick coals in the Durham area are located adjacent to, but not within, coal seam splits. It further implies that attractive sites for future opencast development in the area may be predicted from a regional knowledge of coal seam splits.
Gulf of Mexico Basin: Newest coal province
Authors: Groat C. C.
Published: February 2007

Post World War II oil came to replace coal as the dominant energy source in the U.S.A. Recently, coal in the form of lignite has again become a significant energy resource in the Gulf Coast region, where it occurs in Eocene and Oligocene rocks. Efficient exploitation requires a proper understanding of the facies in which it occurs. Studies of surface outcrops are providing the basis for predicting the nature of the reserves at depth.
The Northern Charlotte belt North Carolina and South Carolina: A deformed composite batholith
Authors: Wilson Frederick A. , Jones William J.
Published: February 2007

The Charlotte belt in North Carolina and South Carolina, U.S.A. is characterized by numerous plutons with granitic to gabbroic composition that have intruded gneiss, schist, metavolcanic rocks, and metamorphosed mafic complexes (basalt, gabbro, and ultramafic rocks). The exposed rock constitutes a composite batholith which contains three superunits: (1) the Old Plutonic (metaquartz diorite, metagranodiorite, and metagabbro) approximately 550 my old; (2) the Concord‐Salisbury (gabbro and granodiorite) approximately 400 my old; (3) the Landis ('big feldspar') granite approximately 300 my old. Geophysical and geologic studies suggest small bodies of granodiorite and mafic complexes intruding metavolcanic rocks, schist, and gneiss form the upper level of the batholith; a thick metagabbro sill penetrated by gabbro stocks and underlain by poikilitic gabbro and small bodies of syenite form the middle level; and a complex of metaquartz diorite and metagranodiorite intruded by Landis granites form the lowest level. Outcrop patterns and structural profiles based on gravity suggest the batholith forms an east‐dipping monocline. The bimodal suite of gabbro and granodiorite plutons suggest a tensional tectonic environment ∼ 400 my ago, and negates subduction as the only mode of formation for the batholith.
The Quassaic Group, a Medial to Late Ordovician arenite sequence in the Marlboro Mountains Outlier, mid‐Hudson Valley, New York, U.S.A
Authors: Waines Russell H.
Published: February 2007

The Quassaic Group occurs as an outlier in the north‐south trending Marlboro Syncline which extends 40 km between Kingston and Newburgh in southeastern New York. The group is comprised primarily of 3050 m of late Medial to medial Late Ordovician marine arenites. It is subdivided (oldest to youngest) into five formations: Creek Locks, Rifton, Shaupeneak. Slab Sides, and Chodikee. On the western limb of the syncline the group overlies a minimum of 610 m of the early late Medial Ordovician Bushkill Shale and the bottom three formations grade north and south to Bushkill Shale.

Abundance of graded but occasionally conglomeratic beds, common tabular cross‐lamination, much less common trough cross‐lamination, comparative lack of channelling, general lack of shales, and scarcity of fossils indicate that the average depositional environment of the formations was near the base of the slope of a sedimentary apron or delta which lay to the southeast. The environment, however, probably extended from a basin plain, in the marginal Bushkill Shale, through the lower and middle slope and, rarely, to the upper slope. The occasional molasse‐like deposits in the Shaupeneak Formation may indicate local transport of molasse to an upper slope position.

The Quassaic Group thus records an initial, local extension of arenites of the lower slope of an apron or delta onto a downwarping basin plain in the Bushkill Trough. This was followed by progressive enlargement and extension of the delta slope with attendant shallowing, culminated by the appearance of molasse‐like sediments. Subsequent deposition involved greater slope extension followed by recession with gradual deepening. These activities were prelude to the Hudson Valley Phase of the Taconian Orogeny which downfolded the Quassaic Group into the Marlboro Syncline during latest Ordovician times.
A section in Linley Brook (Shropshire) showing a previously unrecorded junction between the Ludlow and Přídolí Series
Authors: Bradfield Kim E. S. , Tucker E. V.
Published: February 2007

A new contact between the Ludlow and Přídoli Series is described in Linley Brook (Shropshire) previously noted only for its exposure of the Downton Castle Sandstone Formation and the Temeside Shales Formation. The Ludlow Bone Bed and the Downton Bone Bed are recorded and the Upper Whitcliffe and the Downton beds are correlated with a section at Willey.
The age of the Lugar sill and a discussion of the Late‐Carboniferous/Early‐Permian sill complex of S.W. Scotland
Authors: Henderson C. M. B. , Foland K. A. , Gibb F. G. F.
Published: February 2007

The incremental heating 40Ar/39Ar method has been used to date a kaersutite separate from the main theralite‐picrite unit of the Lugar sill. Ar‐release spectra show discordance mainly due to the presence of excess Ar in alteration phases intimately associated with the primary kaersutite. Plateaus in the spectra allow an emplacement age of 288 ± 6 Ma (2γ) to be assigned to the sill. The results are used to discuss the age relations of the alkaline Permo‐Carboniferous sill complex of southwest Scotland. It is concluded that these sills could have been emplaced over a shorter period of time than implied by the available conventional K/Ar data. The classification of the alkaline sills into kylite and teschenite types has little petrogenetic significance.
The outflow of Windermere, Cumbria: A re‐appraisal
Authors: Wilson C. D. V.
Published: February 2007

Possible causes for the outflow of Windermere through the Leven valley instead of the Cartmel valley are discussed. An earlier seismic investigation of the problem by Coster and Gerrard (1947) is reviewed and shown to be inconclusive. Further geophysical surveying and mapping demonstrate a rock bar in the Cartmel valley, 3km southeast of Newby Bridge. This barrier is 21m above the present water level in Windermere. Blockage by glacial deposits is disproved and the probable history of the outflow discussed. It is concluded that the outflow from Windermere has used the Leven valley from an early stage.
Depositional environments in the Telychian Stage (Silurian) of the central Oslo region, Norway
Authors: Baarli B. G.
Published: February 2007

The Telychian succession in the central Oslo region was previously interpreted as deposited in a relatively deep, calm environment showing a continuous transgressive development. A new analysis of fossil assemblages shows that sediments in the central districts were deposited at varying water depths in an environment marked by intense infaunal activity in soft substrates. Two small‐scale fluctuations in sea level are attributed to eustasy. The maximum deepening events occurred during the Monograptus turriculatus and Monoclimacis crenulata graptolite zones.

Previous depositional models include development of a trough to the north of the Oslo region in early Telychian time, which formed due to isostatic loading caused by an advancing thrust front of the Caledonian Orogeny. Bathymetric analysis shows a deepening in the Ringerike district in the latest Aeronian, which here is interpreted as a distal effect of the loading to the north. The local deepening led to reversal of the epicontinental slope between the northern and western districts and the central districts and the development of an east–west elongate positive area further south. The thrust front acted as a source of siliciclastic material; and when the front halted in mid‐Telychian time the trough was filled in gradually by a prograding coast or delta. The diachronous Vik Formation is viewed as a distal development of this progradation. When the east–west oriented positive area subsided the Vik Formation was deposited in Skien to the south.
Late Ordovician stratigraphy northwest of the Sugarloaf, mid‐Wales — a discussion
Authors: James D. M. D.
Published: February 2007

Several modifications are proposed to the Ordovician stratigraphy recently proposed by Mackie and Smallwood (1987), based in particular on the recognition of a major Mynydd Trawsnant anticline on the northwest flank of the Tywi structure and on field relationships indicating the Foel Formation directly to overlay the Caradoc black shale succession and directly to underlay the Craig Las Formation. The Clyn Glas Formation is suggested to have accumulated at a slope base rather than a shelf–slope break.
Granitoid rocks and terrane characterization: An example from the northern Appalachian Orogen
Authors: Barr Sandra M.
Published: February 2007

Granitoid rocks in the Aspy, Bras d'Or, and Mira terranes of Cape Breton Island in the northern Appalachian Orogen display contrasts in age and petrological characteristics that reflect differences in source rocks and tectonic events in these three terranes. The Aspy Terrane is characterized by a protracted Silurian and Devonian plutonic history, during which granitoid rocks were generated sequentially in volcanic‐arc, post‐arc, collisional, and extensional tectonic settings. In contrast, the Bras d'or and Mira terranes are characterized by Late Precambrian calc‐alkalic I‐type granitoid suites, and only minor Devonian plutonism. Late Precambrian suites in the Bras d'Or Terrane (age ca. 565–555 Ma) are significantly younger than those in the Mira Terrane (age ca. 620 Ma), and the two suites are interpreted to have formed in separate volcanic arcs.
Anorogenic granite evolution in Namibia—a fluid contribution
Authors: Bowden Peter , Kinnaird Judith A. , Diehl Michael , Pirajno Franco
Published: February 2007

Field observations, petrological interpretations combined with cationic geochemical data and diagrams illustrate the magmatic and postmagmatic events in the Mesozoic anorogenic complexes of northern Namibia. The magmatic lineage of the Damaraland alkaline centres is cationically defined in a modified Q–P diagram (Debon and Le Fort 1988). Major element concentrations for Brandberg and Erongo supported by chemical data from other Damaraland complexes at Cape Cross, Otjihorongo, Messum, Spitzkoppies, and Paresis, have been converted to millications, to delineate a magmatic lineage which follows an alkaline oversaturated trend. Superimposed on this magmatic lineage is textural and geochemical evidence for hydrothermal metasomatic disequilibrium and partial re‐equilibration. Volcanic rocks and their granitic equivalents from the Erongo complex show petrological and geochemical criteria indicating substantial potash and boron metasomatism which has given the Erongo rocks a subalkaline potassic geochemical signature. Similar granite compositional trends are also recorded within the Brandberg massif. However, at Brandberg, there is a later‐stage hydrothermal overprint generating a texturally variable peralkaline granite, with spectacular examples of linear zones of aegirine and arfvedsonite apparently constrained to microfractures in marginal granite sheets. The zones of mineral ‘layering’ can be divided into three repetitive units and traced horizontally along the southwestern margin of the Brandberg massif for a distance of 3 km and vertically for 200–300m. These marginal rocks are cross‐cut by dykes and sheets of brandbergite, a mesocratic fine‐grained peralkaline rock. Fenite veins, described elsewhere from marginal zones of strongly alkaline massifs, are found near the inner brecciated contact zone with the main granitic mass of the Brandberg. These fenite veins are interpreted as fluid‐channel ways along which mass transfer of peralkaline components occurred during the final stages of cooling and consolidation.
A late ordovician/early silurian non‐depositional slope and perched roll‐over basin along the tywi anticline, mid wales
Authors: James D. M. D.
Published: February 2007

Ordovician stratigraphy between the Sugarloaf and the Wye valley is summarized with particular attention given to the area northeast of Abergwesyn. New data refine thickness estimates for the Cerriggwynion Formation, the Trembyd Formation (new), and the Cefn Cynllaith Formation (new). The major Bron Rhudd Fault is suggested to have been a synsedimentary down‐to‐basin fault which was later reactivated, folded, and suffered local reversal of throw. Roll‐over into this fault controlled deposition of mass‐flow conglomerates in a perched basin. During the late Ordovician‐early Silurian the axis of the Tywi Anticline underlay a non‐depositional slope which developed by northwest‐directed progradation of a shelf margin, possibly accentuated by flexure over a basement fault zone with contemporaneous basin‐down normal movement. The slope angle cannot be estimated from the geometry of the Ordovician because the contemporaneous throw on the Bron Rhudd Fault cannot be determined, but from the rate of Silurian onlap it was about 5 degrees.
Ice directions in western lleyn and the status of the gwynedd readvance of the last irish sea glacier
Authors: McCarroll Danny
Published: February 2007

A ‘Gwynedd readvance’ of the last Irish Sea glacier, terminating on the north coast of the Lleyn peninsula in northwest Wales, has been proposed on the basis of differences in ice flow direction and in drift landforms on either side of the proposed limit. However, detailed drift mapping of western Lleyn reveals erosional and depositional evidence of ice flow direction which are consistent with a single advance and retreat. Differences in drift landforms are explained by the influence of topography on glacier dynamics and sedimentation. There is, therefore, no reason to invoke a ‘Gwynedd readvance’ of the last Irish Sea glacier and the marked climatic deterioration which a substantial readvance of such a large glacier would imply.
A newly‐discovered coal measures marine band in billinge beacon quarry, lancashire, and its stratigraphical significance
Authors: Eagar R. M. C. , Chisholm J. I. , Varker W. J. , Williamson I. A.
Published: February 2007

A thin band yielding conodonts and Foraminifera and therefore demonstrably marine, has been found in mudstone lying immediately above the uppermost coal horizon in Billinge Beacon Quarry. The existence of this newly recognized horizon, which is very likely to be the Langley Marine Band at the top of the Lenisulcata Chronozone, much strengthens the correlation of the Billinge Beacon sandstones with the regionally developed Crutchman Sandstone. An alternative correlation of the Billinge Beacon sandstones with the Dyneley Knoll Flags of Burnley, which was recently proposed by F. M. Broadhurst, is not supported by the new evidence, nor by the evidence of boreholes, since it appears that the Dyneley Knoll Flags die out some distance to the north of Billinge.
A non‐glacial origin for the ordovician (middle caradocian) cosquer formation, veryarc'h, crozon peninsula, brittany, France
Authors: Long D. G. F.
Published: February 2007

The presence of a dispersed clast fraction in strata near the base of the Cosquer Formation in west Brittany, does not support a glacial origin for this unit. The upper 25 to 30 m of the underlying Kermeur Formation consists of a prograding sequence of very fine to fine sandstones deposited in a mid to distal current swept shelf setting. This sequence shows signs of slope instability, as do the supposed ‘glacial strata’ which overlie it. The upper two thirds of the Cosquer Formation contain spectacular slump‐breccias. Smaller clasts within the laminated mudrocks at the base of the formation are associated with thin graded and non‐graded sandstone laminae. They show no evidence of active penetration into underlying laminae other than can be explained by compaction. Larger clasts are confined to thicker massive beds, or disrupted units with marked internal contorted lamination. This, along with the abundance of slump features within the sequence suggests lateral emplacement by sediment gravity flows in a distal shelf‐slope setting. Surface textures of sand grains within the formation are related to rock disaggregation along fractures developed during post‐depositional deformation and are not related to glacial processes. Distinctive mineralogically immature, poorly‐sorted aggregate sediment pellets, which have been considered as positive proof of glaciation, are not present.
An endemic brachiopod fauna from the Middle Ordovician of North Wales
Authors: Harper D. A. T. , Brenchley P. J.
Published: February 2007

The brachiopod fauna from the base of the Bryn Siltstone Formation (middle Caradoc), Glyn Ceiriog, north Berwyn Hills, North Wales, consists of Platystrophia elevata sp. nov., Salopia abbreviata sp. nov., Kiaeromena ungula (M'Coy) and unnamed species of Hesperorthis?, Reuschella and Bicuspina. The dominant brachiopod species, Leptaena (Leptagonia) ungula M'Coy, 1851 is revised and its current assignment to the leptaenid genus Kiaeromena confirmed, based on the examination of type and topotype material from the Bryn Siltstone Formation. Kiaeromena spjeldnaesi nom. nov. is proposed to replace the junior homonym K. ungula Spjeldnæs, 1957 for that congeneric species from the upper Caradoc rocks of Ringerike, southern Norway. The fauna as a whole is unusual within the context of the Anglo‐Welsh province and may represent a rare preserved nearshore community.