bluuebunny/crossref_metadata_2025 huggingface dataset:
Developments in monitoring and modelling small‐scale river bed topography
Authors: Lane S. N. , Richards K. S. , Chandler J. H.
Published: February 2007

Recent research in fluvial geomorphology has emphasized the spatially distributed feedbacks amongst river channel topography, flow hydraulics and sediment transport. Although understanding of the behaviour of dynamic river channels has been increased markedly through detailed within‐channel process studies, less attention has been given to the accurate monitoring and terrain modelling of river channel form using three‐dimensional measurements. However, such information is useful in two distinct senses. Firstly, it is one of the necessary boundary conditions for a physically based, deterministic modelling approach in which three‐dimensional topography and river discharge drive within‐channel flow hydraulics and ultimately spatial patterns of erosion and deposition and therefore channel change. Secondly, research has shown that an alternative means of estimating the medium‐term bedload transport rate can be based upon monitoring spatial patterns of erosion and deposition within the river channel. This paper presents a detailed assessment of the distributed monitoring and terrain modelling of river bed topography using a technique that combines rigorous analytical photogrammetry with rapid ground survey. The availability of increasingly sophisticated terrain modelling packages developed for civil engineering application allows the representation of topographic information as a landform surface. Intercomparison of landform surfaces allows visualization and quantification of spatial patterns of erosion and deposition. A detailed assessment is undertaken of the quality of the morphological information acquired. This allow some general comments to be made concerning the use of more traditional methods to monitor and represent small‐scale river channel morphology.
Diurnal freeze–thaw depth in rockwalls: Field measurements and theoretical considerations
Authors: Matsuoka Norikazu
Published: February 2007

Rock temperatures were monitored for a year at two alpine rockwalls in the Akaishi Range, Japan, where permafrost is absent. Diurnal frost and thaw penetration depths were evaluated from subsurface isotherms drawn on the basis of the temperature records at 0, 10 and 40 cm depths. The surface of the rockwalls experienced more than 100 diurnal freeze‐thaw cycles, most of which accompanied a frost or thaw penetration shallower than 50 cm, and several long duration cycles with deeper frost or thaw penetration. Theoretical frost and thaw depths were also calculated by incorporating the surface freezing indices into the modified Berggren equation, the results from which were then compared with the actual values. The modified Berggren equation provided values that showed a strong correlation with observed depths, despite somewhat underestimating the actual values. Using the modified Berggren equation, the seasonal frost depth in the observed winter was estimated to be about 4·5 m. The frost and thaw depths are considered to give the maximum estimation of the depth to which frost‐induced cracking can propagate in the bedrock.
Holocene valley aggradation and gully erosion in headwater catchments, south‐eastern highlands of Australia
Authors: Prosser Ian P. , Chappell John , Gillespie Richard
Published: February 2007

Late Quaternary stratigraphy of a 50 km2 catchment on the south‐eastern highlands of Australia reveals processes and history of denudation, and helps resolve a long‐standing debate about factors controlling episodic valley aggradation and degradation during Holocene times. Valley sedimentation occurred when swampy vegetation fully colonized valley floors and obliterated all channels, promoting aggradation for periods of several thousand years, with most incoming sediment being trapped in swampy meadows. Much of the sediment was reworked from late Pleistocene alluvial fan and valley fill deposits, and primary hillslope erosion was minor during the Holocene. Differing sedimentation patterns between the Late Pleistocene, Holocene and Post‐European settlement periods reflect regional changes in sediment supply and transport capacity as a result of major environmental change. Within the Holocene, however, valley fill stratigraphy is controlled by massive, episodic gully erosion terminating aggradation. Gully initiation appears to be controlled more by thresholds of incision into vegetated valley floors than by changes to sediment supply. Whether the thresholds are exceeded because of climatic change, autonomous change or extreme events cannot yet be determined. Overall, the Holocene history represents continuing complex response to events of the Late Pleistocene, and does not support the K‐cycle concept, which has strongly influenced late Quaternary geomorphology in Australia.
Estimate of long‐term sediment discharge at tidal inlets using water level data from a tide gauge
Authors: Gao Shu , Collins Michael
Published: February 2007

A simple approach to the estimate of long‐term sediment discharge through an entrance to a tidal basin is described. Using the method, cross‐sectional mean current speeds are derived, on the basis of the definition of an ‘apparent tidal basin area’, from records of water level data from a single tide gauge. The obtained time‐series of current speeds are then used to define ‘local’ current speeds, through the use of a sectional distribution function for the currents. Sediment transport formulae are then applied, using the obtained speed data and other relevant parameters contained within the formulae and frequency distribution functions with regard to wave and tidal current characteristics, to estimate sediment discharge through the entrance. Analytical procedures of the method are described in detail, in an example from Christchurch Harbour (southern England).
Explorations into the formal structure of drainage basins
Authors: Werner Christian
Published: February 2007

Every basin of higher than first order is drained by a channel network composed of two subnetworks. Their basins are separated by a drainage divide line, called the basin divider, which is the primary organizing feature of the main basin. Each basin of magnitude n contains n – 1 subnetworks of higher order, and is therefore organized by a set of n – 1 dividers. The dividers and the basin boundary are interconnected in a graph called the divider network of the basin; in graph‐theoretic terms this network forms a tree and has the same magnitude and link numbers as the channel network draining the basin. While the subbasins and subnetworks of a drainage basin form a nesting hierarchy, the corresponding dividers do not; indeed, any two dividers share at most one node in common, and whether they do so is independent of whether the corresponding subbasins are nesting or disjoint. However, the dividers of nesting basins are linked by recursive relationships which permit the derivation of a set of algebraic equations; these equations relate the dividers of a basin to other basin components; for example, their combined length is equal to half the length of all first‐order basin boundaries minus the length of the main basin boundary.

The second part of the paper explores the dependence of the divider length on other basin parameters. The expected length, as predicted by the assumption of topological randomness, is clearly rejected by the data. An alternative approach (regression) is based on the observed magnitudes of the subbasins separated by each divider, and is reasonably successful in estimating divider length. The last section introduces the concept of the standardized basin defined by a boundary length of unity; the estimated lengths of the basin divider and the basin boundary permit an approximate reconstruction of the idealized basin shape and the location of the divider in it.
Measurement of bedload gravel transport: The calibration of a self‐generated noise system
Authors: Rouse H. L.
Published: February 2007

Self‐generated noise (SGN) is a passive acoustic technique for the measurement of bedload transport through the acoustic detection of intergranular collisions using a submerged hydrophone system. SGN is of interest because of the possibilities it offers to the measurement of transport parameters at the frequencies of turbulent or oscillating current scales. This paper describes the background of the technique, and reports the results from laboratory experiments on the relationship between SGN and the absolute transport rate.
Processes and timescales by which a coastal gravel‐dominated barrier responds geomorphologically to sea‐level rise: Story head barrier, Nova Scotia
Authors: Orford J. D. , Carter R. W. G. , Jennings S. C. , Hinton A. C.
Published: February 2007

Sea‐level rise (SLR) is considered to be important for barrier behaviour when barriers are swash‐aligned and single‐crested, which is typical of only one part of a barrier's lifeterm. Under such conditions gravel‐barrier retreat rate correlates with mesoscale (sub‐decadal: <101 a) SLR rate. Barrier crest overwashing, depending on surge frequency/magnitude, is recognized as the dynamic element that controls barrier retreat rate. Surge characterization of the Halifax tide gauge (using an annual forcing coefficient derived from tide gauge surge residuals) is shown to have high correlation with Story Head (Nova Scotia) barrier retreat rate between 1945 and 1987. Barrier response appears to vary as a function of mesoscale (sub‐decadal) SLR and antecedent barrier conditions in combination with the forcing coefficient. Mesoscale (100 a–102 a) rather than macroscale (> 102 a) SLR rate is the critical control on barrier retreat, as mesoscale SLR variation in combination with surge potential is able to raise water level to the elevation threshold sufficient for barrier overwash and hence drive barrier retreat.
Coastal slope terracing and relative sea‐level changes: Deductions based on computer simulations
Authors: Cinque A. , De Pippo T. , Romano P.
Published: February 2007

Although a traditional geological survey of terraced coastal slopes is an essential part of studies aimed to reconstruct relative sea‐level changes, the stratigraphic and chronological data so obtained frequently prove inadequate to completely unravel the sometimes very complex history of sea‐level fluctuation, especially where erosion has prevailed over deposition and/or deposits are difficult to date.

On the basis of our experience we think that much additional information can be gained through geomorphological interpretation of the profiles of those slopes. In order to facilitate such interpretation, a computer simulation model is developed that is able to predict the morphogenic response to a variety of possible relative‐sea‐level histories. The results can be used to envisage some new interpretation keys for the analysis of real situations and, hopefully, as bases for the conception of general models of coastal slope evolution under the action of a variable sea level.

Though preliminary, the results so far obtained permit identification of the geomorphological consequences (in terms of resulting slope profile) of ordered successions of transgressions and regressions of different amplitude, rate, order and style. Moreover they provide interesting insights into the role that different styles of tectonic uplift may play in the phenomenon of multiple terracing of coastal slopes.
Salt ramps: Wind‐induced depositional features on Tunisian playas
Authors: Millington Andrew C. , Drake Nicholas A. , White Kevin , Bryant Robert G.
Published: February 2007

Semicircular and crescent‐shaped accumulations of salt crystals developed on salt crusts were measured on three Tunisian playas in September 1990. These features have been termed salt ramps. Their morphology and chemistry suggest that they are formed in the late stages of shallow ephemeral lake desiccation in playa basins. They form by salt precipitation from shallow brine lakes that are blown across salt‐encrusted playa surfaces by the wind. Moreover, they appear to be short‐lived features and their degradation is related to the flooding of playas with less saline water, and possibly rainfall and deflation.
The multivariate controls of hydraulic geometry: A causal investigation in terms of boundary shear distribution
Authors: Huang He Qing , Warner Robin F.
Published: February 2007

Most downstream hydraulic geometry exponents have been found to be very close to the classic values reported by Leopold and Maddock (1953). These have been viewed as the simplified cases to general trends because the hydraulic geometry of alluvial channels is actually the product of ‘multivariate controls’ (Richards, 1982). This paper is an attempt to develop a soundly based foundation for the explanation of the physical mechanisms of these controls. A quantitative relationship between channel shape and boundary shear distribution developed from experimental flume results is found to be applicable in some instances to alluvial channels, particularly to stable canals. On the basis of this relationship, it is shown that downstream hydraulic geometry is determined not only by flow discharge, but also by channel slope, channel average roughness and sediment composition of the channel boundary. This is strongly supported by our analysis of 529 observations from both stable canals and natural rivers in the U.S.A. and the U.K. The difference between regime relations in canals and the hydraulic geometry of rivers appears to be caused mainly by channel slope and average roughness, which can be regarded as constants only in stable canals. The close relationship between discharge and channel average roughness observed in canals is not repeated in natural channels, partly because of the variety of flow values used to define the channel‐forming discharge. Furthermore, it is indicated that the effects of the sediment composition of the channel boundary on hydraulic geometry are significant and need further investigation.
The shoreline preservation index as a relative‐age dating tool for late pleistocene shorelines: An example from the bonneville basin, U.S.A.
Authors: Sack Dorothy
Published: February 2007

This paper evaluates the utility of the shoreline preservation index (s.p.i.) for estimating the age of late Pleistocene palaeolake shorelines, the relative influence of various factors on shoreline preservation, and whether shoreline preservation varies significantly with shoreline aspect. Sampled shorelines from the 3300 km2 study area, which includes the Skull, Tule and Puddle Valley portions of the Lake Bonneville basin, range in age from approximately 26 to 12 ka. Their total s.p.i. values range from 23 to 69 per cent, average 46 per cent, and do not vary significantly with shoreline aspect. The data from Skull and Tule Valleys, where studied shorelines are of known age, are analysed first in order to determine if there are statistically significant associations between variables representing shoreline preservation, age, degree of geomorphic development and duration of subaerial exposure. Pairwise correlation is then repeated using observations from all three valleys in order to determine how data from the Puddle Valley shorelines, whose hypothesized ages are not supported by radiocarbon analyses, affect the results. Results show that s.p.i. is useful as a relative‐age dating tool, that the postulated ages of the Puddle Valley shorelines are ordinally correct, and that geomorphic development is not an important influence on the preservation of these late Pleistocene shorelines. The relative importance of shoreline age and the relative unimportance of duration of subaerial exposure with respect to shoreline preservation suggest that subaqueous processes play a more substantial role in shoreline obliteration than is generally suggested.
Channel form and processes of the flood‐dominated Narmada River, India
Authors: Rajaguru S. N. , Gupta Avijit , Kale V. S. , Mishra Sheila , Ganjoo R. K. , Ely L. L. , Enzel Yahouda , Baker V. R.
Published: February 2007

The 1300 km long Narmada River flows along a structural lineament, alternating between constricting rocky gorges and rapids, and meandering wide alluvial reaches. Channel forms and processes were studied in a 120 km long section of an alluvial reach. Channel size, shape and bedforms in the Narmada River are related to very large floods which have occurred three times in this century. During such floods the entire 400 m wide channel is utilized and 10–15 m high cliffs on both sides operate as riverbanks. Normally, even the high flows of the south‐western monsoon are insufficient to fill the whole channel, and hence their effects are limited to building of discontinuous floodplains between the cliffs and modifying bedforms and bars. A channel‐in‐channel topography is thus created. The very large floods are also responsible for erosion of the rocky stretches and building of point bars. The river meanders, but its movement is restricted because of (1) rocky gorges and scablands operating as anchor points at intervals, and (2) the presence of high alluvial cliffs which are topped on extremely rare occasions. In spite of being located in a tectonically active zone in a monsoon setting, it is the exceptional high‐magnitude floods at irregular intervals which control the form and behaviour of the Narmada River.
Limestone weathering in Eastern Australia. Part 1: Erosion rates
Authors: Smith D. I. , Greenaway M. A. , Moses C. , Spate A. P.
Published: February 2007

A traversing microerosion meter (MEM) was used to measure the rates of surface weathering of limestones in southeastern Australia. There were two groups of MEM sites installed in 1978/9. The aim of the experimental design for the first type, the 13 sites at Cooleman Plain and Yarrangobilly Caves, was to obtain erosion rates for limestones of similar lithology exposed under comparable climate conditions. The sites were positioned to measure erosion over a range of microsolutional forms and with exposure to differing forms of erosion, i.e. subaerial, subsoil and instream. The second set, at Ginninderra close to Canberra, consists of nine limestone slabs of differing lithology, collected from different locations but exposed under identical climatic conditions. The number of individual measurement points at each MEM site varied from 24 to 68.

There were major differences in erosion rates between subaerial bedrock and instream sites at Yarrangobilly and Cooleman Plain, but no evidence of differential erosion across the micro‐forms. There were differences in the weathering rate for bedrock sites, due to climatic differences, and between the limestone lithologies exposed at Ginninderra. The average rate of erosion for the subaerial bedrock sites at Cooleman Plain and Yarrangobilly over the 13 years was 0·013 mm a−1and at Ginninderra 0·006 mm a−1. At some of the sites microflora (lichens and mosses) caused problems for field measurement. The weathering processes that contribute to the surface lowering are discussed in the accompanying paper by Moseset al.
Challenges and objectives for geomorphology in U.K. river management
Authors: Brookes Andrew
Published: February 2007

This paper reviews some of the challenges and objectives in the application of fluvial geomorphology to improved river management in the U.K. It describes the mechanisms by which geomorphology can be applied to solve problems, including the development of design guidance, policy, management approaches, procedures and training. While it is true that geomorphology is being used increasingly, there remain a number of challenges, such as the need to promote a more professional image and to develop appropriate standards. The scientific basis on which decisions relating to the water environment are made needs to be developed further. Perhaps some of the most significant challenges for fluvial geomorphology in U.K. river management during the next decade will concern river and floodplain restoration.
Sediment‐related river maintenance: The role of fluvial geomorphology
Authors: Sear D. A. , Newson M. D. , Brookes A.
Published: February 2007

This paper addresses the role that fluvial geomorphology might play in the management of sediment‐related river maintenance in the U.K. Sediment‐related river maintenance refers to the operational requirement of river management authorities to remove deposits of sediment or protect river boundaries from erosion, where these compromise the flood defence levels of service. Using data collected as part of a National Rivers Authority (NRA) Research and Development Project it is possible to identify the geomorphic causes of problems, and engineering responses to sediment‐related river maintenance (SRRM) in England and Wales. The Project identified the management problem as widespread and often treated in isolation from the causative processes. Geomorphological guidance is shown to be both relevant and complementary to conventional engineering practice through its ability to identify the cause of a SRRM problem. A methodology for conducting a geomorphological survey, or ‘fluvial audit’, is presented, which synthesizes historical data on the catchment land‐use and channel network, with contemporary morphological maps to present a statement of the location and type of sediment supply, transport and storage within the river basin under scrutiny. The application of geomorphology to two contrasting SRRM problems is explored using case studies from two catchments: the River Sence, a fine sediment system, and the Shelf Brook, a coarse sediment system.
The humber observatory: Concepts, instrumentation and software systems
Authors: Hardisty J. , Rouse H. L. , Middleton R. , Hirst R. S. , Scott T.
Published: February 2007

The role of geomorphological research into sediment flux within modern dynamical systems and the consequent role of geomorphological research in the development of practical environmental management tools are seldom reconciled. Sediment fluxes can be estimated using instruments and numerical models, but problems arise when these results are to be interpreted to inform the environmental management debate. This paper presents one set of solutions in which we describe the work of the Humber Observatory and detail the concepts, instrumentation and software systems which have been developed to address such issues. The design and deployment of a new, automated meteorological station, new multiple sensor, radio‐linked outstations and the collection of associated tidal and bathymetric data are described, together with discussion of the operational problems and data archiving and output issues. We also describe the numerical models based upon the dynamical equations which have been used to estimate water and sediment fluxes through the Humber Estuary, and we describe the design criteria for new semi‐empirical models. Results from the various systems and models are presented as the basis for a regional research capability and in terms of operational delivery for environmental management.
Dynamic COI‐tracking concept for the control of generators in multi‐machine power systems
Authors: Lan Zhou , Gan Deqiang , Shi Libao , Ni Yixin , Bi Tianshu
Published: February 2007

In the conventional excitation control concept, the power angle and frequency of a generator are driven to a pre‐designed operation point after the fault occurs. It is named as Constant Point Stabilization (CPS) concept in this paper. A novel concept, called dynamic Center of Inertia (COI)‐tracking concept is proposed in this paper. In the concept, the power angle and frequency of each generator track the dynamic COI of the power system. Compared to CPS concept, a salient feature the suggested dynamic COI‐tracking concept has is that the generators are not restricted to constant angle point or frequency any longer but track the dynamic COI trajectory of the system to keep synchronous in rotor angle and frequency. Wide area measurement system (WAMS) will be used to transform COI signals to each generator. The time delay within a certain limit of WAMS signals is permitted. To make comparison between the two concepts, the control system models based on the two concepts are first established. Then, using the back‐stepping method, two robust controllers are designed to achieve the control objectives of the two concepts. At last, dynamic simulations are carried out based on a 2‐area‐4‐machine test power system, and the control effects of the two controllers, together with that of the conventional AVR + PSS excitation system, are compared. Copyright © 2007 John Wiley & Sons, Ltd.
Evidence for association between multiple complement pathway genes and AMD
Authors: Dinu Valentin , Miller Perry L. , Zhao Hongyu
Published: February 2007

In this paper we explore the use of biological knowledge to supplement statistical analysis in identifying genes associated with disease. It has been previously found that the 402H variant in complement factor H (CFH) is associated with risk for developing age related macular degeneration (AMD). By focusing on the single nucleotide polymorphisms (SNPs) in the complement pathway, we were able to use the genotype data from a recently published AMD genome wide association study to identify two additional genes, C7 and MBL2, as potentially associated with subtypes of AMD. Two SNPs situated in introns of C7 and MBL2 could help differentiate between two forms of AMD: wet (more severe form of AMD) and dry (milder form of AMD). We identified a C7 haplotype associated with protection against developing wet AMD among individuals with homozygous CFH risk allele 402H (p‐value 0.001 for wet AMD versus dry AMD, odds ratio (OR) 0.16, OR 95% CI 0.05–0.49) as well as among individuals with at least one CFH risk allele (p‐value 0.007 for wet AMD versus dry AMD, OR 0.35, OR 95% CI 0.16–0.77). The fact that the statistical scores for the C7 and MBL2 SNPs were significant (low false discovery rate) at the pathway level, but not significant at the genome level suggests that focusing at the pathway level can be beneficial for identifying SNP signals that would be lost at the genome‐wide level. Genet. Epidemiol. 2007. © 2007 Wiley‐Liss, Inc.
A boring in the millstone grit near darwen, lancashire
Authors: Lacey William S.
Published: February 2007

The geological section exposed in a deep boring for water in the Millstone Grit near Darwen, Lancashire, is described. Details are given of the lithology and palaeontology throughout a thickness of 700 ft. of rock, extending from the Holcombe Brook Grit well into the Fletcher Bank Grit. In discussion, the rhythmic character of sedimentation is emphasised, and attention is also particularly drawn to the importance of marine bands (with Gastrioceras aff. sigma, Reticuloceras reticulatum early mut. γ and late mut. β) and a Lingula band in determining the Grits.
The natural moisture‐content, voids (porosity) and compaction of unconsolidated clayey rocks
Authors: Boswell P. G. H.
Published: February 2007

Data relating to the natural moisture‐content of samples of saturated fine‐grained sediments, ranging from Devonian to Recent, are assembled and discussed. They indicate that the voids occupy volumes proportionally much greater than those shown by published figures for porosity obtained by standard displacement methods. Void‐ratio/pressure (depth) relationships and formulae devised to facilitate prediction are thus likely to need revision.

The natural moisture‐content varies with the predominance of particular clay‐minerals, as well as with grading. The special cases of calcareous muds, organic muds, varves and boulder clays (tills), are discussed, together with geological implications of the further study of moisture‐contents.
Some aspects of the new red desert in britain
Authors: Shotton F. W.
Published: February 2007

A number of points of interest and controversy in British Permo‐Trias stratigraphy are discussed. Evidence is put forward to suggest that the location of the British area in relation to the poles was very different from that of the present day. The origin of the red colouration in the dune sands is discussed. An attempt is made to reconstruct the outcrop geology of northern England in New Red times, and from this deductions are drawn about the extent of the Zechstein sea. The nature of the false‐bedding in the dune sands is analysed and conclusions are drawn about the extent of the sand sea and the regional pattern of prevailing winds. The relation between false‐bedding and true dip is discussed in an appendix.
Some sedimentary structures from the lower Keuper Sandstones
Authors: Cummins W. A.
Published: February 2007

Some sedimentary structures from the Lower Keuper Sandstones, recorded by H. C. Beasley mainly from the area round Liverpool, are redescribed. Two of these, flute casts and groove casts, are well‐known in the marine greywacke facies. Attention is drawn to records of their occurrence in other facies. The origin of these structures is briefly discussed.
The black marble of Ashford‐in‐the‐water, Derbyshire
Authors: Ford Trevor D.
Published: February 2007

The paper records the little‐known and now extinct marble industry of Ashford‐in‐the‐Water, Derbyshire. An account of the distribution of the dark‐grey limestone used as Black Marble, and the other limestones and materials used for inlaying is included. Methods of mining and processing the Marble and the history of the industry are described.
On a fossil tree found in an opencast coal site near Wigan, Lancashire
Authors: Broadhurst F. M. , Magraw D.
Published: February 2007

The cast of a Coal Measures tree seen in position of growth is described. The cast is about 13 feet long, and evidence is given that the original tree trunk was probably at least 38 feet long before it became completely buried in sediment. The precise history of the tree is unknown but the rate of sedimentation round about it must have been very high.
Geophysical investigations in the Vale of Clwyd
Authors: Wilson C. D. V.
Published: February 2007

A seismic refraction survey has shown three layers below the drift, correlated with Trias, Upper Carboniferous and Carboniferous Limestone, respectively. The thicknesses of the first two have been estimated. A detailed gravity survey has been co‐ordinated with three of the four seismic lines. One of the faults on the west of the Vale has been traced by the gravity survey for 11/2 miles and identified on a seismic line. It is shown to be either a single fault of 700 feet throw and approximately 45° hade, or else two or more step‐faults. The first arrival times at this line can all be explained on the simple ray theory with the assumption of wave diffraction. The significance of the later arrivals is discussed.

The Vale is shown to be divided into basins of Trias by the faults on the west side, but the Vale of Clwyd fault on the east side is continuous.
Some recent advances in the study of deltaic sedimentation
Authors: Van Straaten L. M. J. U.
Published: February 2007

Recent advances in delta sedimentology are briefly summarized. Most of the review is based on data that have been published elsewhere. Some new information is presented concerning the Rhǒne delta, e.g., the distribution of its marine environments (Fig. 2) and the regional variations in differentiation of the mollusc shell assemblages (Fig. 3). The bulk of the sediments in deltas of the Rhǒne type are formed in marine environments. The volumetric proportions between deposits of different facies, as found in many recent deltas, may be very dissimilar to those in fossil (pre‐Quaternary) deltas, formed under “non‐glacial” conditions (cf. Fig. 7).
Recent advances in the palæontology of fishes
Authors: Westoll T. S.
Published: February 2007

Recent advances in our knowledge of the lower vertebrates are extremely striking, and result from more widespread and active geological exploration, from greatly improved possibilities of collecting, from very great advances in methods of clearing the rock from the fossils, and from increasingly deep studies on comparative anatomy and histology. Earlier classifications have had to be revised, and in some respects more may be known of details of anatomy of fossil fishes than can be found in the literature on recent forms. This review of progress is also a pointer to further desirable work.
A pebble bed in the Carboniferous limestone at Llysfaen, N. Wales
Authors: Simpson Brian
Published: February 2007

The pebble bed described is located in the Carboniferous Limestone at Llysfaen and, on the basis of the foraminifera, a middle S2 age is suggested for it. The lithological character of the bed is described, a probable source for the pebbles is suggested and a shallow water environment is postulated for its locus of accumulation.
The origin of the Mersey anD Dee Estuaries
Authors: Gresswell R. Kay
Published: February 2007

The present coastal configurations of these estuaries are contrasted with known fluvial drowned estuaries and attention is drawn to their non‐fluvial characteristics. Two other sub‐parallel depressions in Wirral and southwest Lancashire are described, together with the sub‐glacial surfaces of all four. Their floors are found to contain irregular rock‐bound hollows, and other features reminiscent of glaciated areas. It is suggested that they are escape routes taken by Irish Sea ice hemmed in by the mountains of Wales and the outliers of the Pennines. The term “iceways” is suggested for such ice‐gouged features. A rock shelf in the University area of Liverpool is also tentatively attributed to the same ice erosion.
Kimberlites of Northeastern USSR and allied problems
Authors: Lebedev A. P.
Published: February 2007

Kimberlites are discussed in the light of knowledge obtained from their occurrence in the Siberian platform. Their relation to tectonic pattern, the basement and its cover are considered together with their petrographic and chemical composition and their association with basaltic rocks. It is concluded that kimberlites originated from a deep‐seated kimberlite magma which was injected periodically. The chemical resemblance to peridotes is noted and the peculiarities of kimberlite are put down to periodic enrichment of peridotitic magma with volatiles. It is suggested that diamonds owe their origin to both primary and assimilated carbon.
The carboniferous limestone of the blore‐with‐Swinscoe district, Northeast Staffordshire, with revisions to the stratigraphy of neighbouring areas
Authors: Parkinson D. , Ludford A.
Published: February 2007

This investigation of previously undescribed country along the Staffordshire‐Derbyshire border indicated the need for re‐examination of adjoining areas described in 1950 and 1951. The main revisions concern the ages of certain beds and the nature of the unconformities. Evidence is adduced of vertical earth‐movements in pre‐S2 and in middle D1 time.
Fining‐upwards cycles in alluvial successions
Authors: Allen J. R. L.
Published: February 2007

Fining‐upwards cycles on a scale of thickness from a few metres to a few tens of metres, and consisting of a coarse grade member (erosive base) overlain by a fine grade member, are the hall‐mark of a distinct non‐marine sedimentary facies widely distributed in space and time. Using data on modern alluvial sediments, it is shown that the interpretation of the cycles in terms of an alluvial environment is probably correct. The cyclicity itself cannot yet be accounted for, although three principal factors are likely to have been involved.
Intrusive quartz latites in the Blaenau Ffestiniog area, Merioneth
Authors: Bromley Alan V.
Published: February 2007

Certain flow‐banded and fragmental rocks amongst the Moelwyn Volcanic Series are shown to be of intrusive origin, although at one time they were believed to be extrusive lavas, ashes and agglomerates. Thus the thickness and extent of the volcanic rocks are greatly reduced. New palaeontological evidence shows that part of the Moelwyn Volcanic Series is Caradocian.
Reversed coiling trend in Gryphaea arcuata
Authors: Burnaby T. P.
Published: February 2007

The law of growth of the left valve in Gryphaea arcuata is investigated, and it is shown that it is possible to define a growth‐invariant measure of tightness of coiling.

Recent papers by A. Hallam and G. M. Philip are discussed. The latter author's conclusions are shown to be based upon premises which are untenable. It is here concluded that there is a change in tightness of coiling from the angulata to the gmuendense‐bucklandi horizons at the Glamorgan, Yorkshire, and S. England localities from which Hallam collected his samples of Gryphaea shells. The trend is towards less tightly coiled shells in the higher beds, amounting to an average reduction of a few millimetres in peripheral length at an arbitrary constant radius of 20 mm. There are differences between localities of the same order of magnitude, and it is therefore proper to adopt a cautious attitude towards this result. It is however clear that the pronounced apparent increase in shell coiling originally reported by Trueman in 1922 is simply the direct concomitant of increased size.
The stratigraphy and origin of the portaskaig boulder bed series (Dalradian)
Authors: Kilburn C. , Shackleton R. M. , Pitcher W. S.
Published: February 2007

The late Pre‐Cambrian Portaskaig Boulder Bed Series shows a very uniform sequence for some 600 km along the Caledonian strike, from Connemara on the west coast of Ireland to Aberdeenshire in Scotland. The Series, which is divided into four groups of beds, comprises numerous individual boulder beds separated by stratified sediments. The lower boulder beds are carbonate‐bearing and contain abundant intrabasinal fragments of dolomite and few extrabasinal crystalline rocks while the higher beds are psammitic and contain mainly extrabasinal crystalline rocks. Varve‐like banding, involutions and sandstone polygons suggest periglacial conditions. It is concluded that the boulder beds represent subaqueous tills deposited on unconsolidated sediments. Contemporaneous deformation of some of these sediments is attributed to the movement of ice, although the possibility that sliding of the unconsolidated sediments occurred locally is considered.
The deformation of quartz in a granite
Authors: Phillips W. J.
Published: February 2007

The deformation structures in a quartz porphyroclast are described in detail and the sequence of their formation is established. During the final stages of plastic deformation, the crystal structure was distorted by undulatory bending resulting in undulose extinction, and by the development of oblique surfaces of optical discontinuity lying parallel to the axix of undulatory bending and about 40° to the optic axis. The optic axis of the crystal has been rotated into parallelism with the oblique surfaces of optical discontinuity along a recrystallised zone, and the axis of rotation approximately coincides with the axis of undulatory bending. It is postulated that the reorientation of the crystal structure was accomplished by the intragranular rotation within needle‐like units elongated parallel to the axis of undulatory bending, and that this was initiated by movements along the oblique surfaces of discontinuity in response to external stresses. Similar structures with signs of reorientation of the optic axis have been observed in many pophryroclasts with very different orientations and it is suggested that the postulated mechanism of reorientation might also explain the commonly observed (ac) girdle in the quartz orientation patterns of polycrystalline tectonites.

Subsequent recrystallisation in place and later primary recrystallisation from nuclei released local strain in the most distorted parts of the porphyroclast and resulted in the formation of numerous minor grains. The minor grains formed by primary recrystallisation have a pronounced preferred orientation which is unrelated to the orientation of the parent crystals and it appears that this developed without any appreciable movement of the fabric.
Spatial and seasonal pebble beach profile characteristics
Authors: Caldwell N. E. , Williams A. T.
Published: February 2007

Beach profiles along eight sections of two fringing pebble beaches located in the Glamorgan Heritage Coast, Wales were regularly surveyed for over one year. The data were used to examine spatial and seasonal beach profile variations by utilizing them in several graphical procedures. Results showed seasonal variations in terms of beach profile configuration, beach face slope and the rate of profile change, although these variations were not necessarily concurrent. This highlights the special case of fringing pebble beaches on which accretional profiles are probably compensated for by erosional profiles alongshore at any one time. This makes it difficult to generalize spatially the profile response of an entire beach system. For this reason, the rate of profile change may more realistically reflect periodic variations in wave regime, which in European latitudes can be approximated with the summer and winter seasons.
Pyrite formation and the drowning of a palaeosol
Authors: Wright V. Paul
Published: February 2007

Palaeosols may be modified in a variety of ways during burial diagenesis but significant alteration can take place during the earliest phases of burial caused by rising groundwaters. A calcrete palaeosol, the Heatherslade Geosol, from the Lower Carboniferous of South Wales, contains abundant pyrite which overprinted the original soil fabrics. The pyrite is interpreted as the product of anaerobic conditions caused by drowning during the early stages of a marine transgression. Unusual diamond‐shaped forms of pyrite occur which possibly represent pseudomorphs after gypsum.
Comparative Tertiary petroleum geology of the Gulf Coast, Niger, and Beaufort‐Mackenzie delta areas
Authors: Curtis Doris M.
Published: February 2007

Oil and gas are produced from Tertiary sandstone reservoirs in deltaic and related depositional systems in the Gulf Coast (U.S.), Niger (Africa), and Beaufort‐Mackenzie (Canada‐Alaska) basins. In each area there is an orderly, predictable interrelationship of sedimentation, stratigraphy, depositional environment, and structure, with the characteristics, ages, and distribution of producing trends.

In comparing and contrasting the three areas, it is apparent that they have many essential aspects in common, resulting from the fact that they are relatively young, subsiding paralic basins on 'Atlantic type' or passive margins. They contain thick accumulations of deltaic terrigenous sediments that have prograded in regressive basin‐filling sequences as the basins subsided. Therefore each has a vertical gross lithologic sequence with shale at the base, overlain by interbedded sandstones and shales, overlain by massive sandstones. The vertical sequence is repeated laterally from the basin landward. In each basin the stratigraphic units of the sequences thicken basinward across a series of normal, listric, down‐to‐the‐basin syndepositional faults, with which are associated 'rollover' anticlines which form traps. Trapping associated with diapiric structures is also characteristic of all three areas.

Although similarities among these areas is striking, significant differences are related to their different geologic settings and geologic histories. For example, the presence of salt in the Gulf Coast basin has resulted in a wide variety of salt dome‐related trapping mechanisms in addition to the shale diapirs and roll‐over anticlines common to all three areas. Pre‐Tertiary tectonic settings, different in each case, control basin configurations and affect structural trends. Vertical and lateral differences in depositional systems and sequences, as well as variations in delta morphology and sandstone geometries, result from variations in ratios of rates of deposition to rates of subsidence.

The framework for the occurrence of oil and gas is well understood in the maturely‐explored and intensively‐studied Gulf Coast Tertiary basin. Concepts developed there can be applied to developing the less‐explored Niger basin and to exploring the frontier Beaufort‐Mackenzie basin. An extensive bibliography is included.
Experiments in long‐range climate control
Authors: Donn William L.
Published: February 2007

Extrapolation of the palaeoclimate chronology of the past million years or so seems to leave little doubt that another glacial stage can be expected in the near geologic future. On a shorter time scale it appears that the increasing greenhouse effect from the use of fossil fuel will raise atmospheric temperature by 2 to 3 °K within a hundred years. The possibility of man's reversing or at least weakening these portentous climate changes is investigated here with the use of a thermodynamic climate model. Preliminary results indicate that the climate effects referred to may be reversible if caught early and certainly suggest that further and more sophisticated attention be given the subject.
Dimlington Stadial (Late Devensian) ice‐wedge casts and involutions in the Severn Estuary, southwest Britain
Authors: Allen J. R. L.
Published: February 2007

The largely concealed sub‐Flandrian bedrock surface in the Severn Estuary, chiefly known from borings and chart soundings, has the form of a valley within a valley. In the aftermath of an unusual storm in March 1986, which removed from many places the obscuring modern sediments normally present, periglacial structures were recognized on the floor and upper margins of the upper valley at ten widely scattered localities. The structures occur only where the valley is formed on relatively soft Triassic and Jurassic mudrocks; they involve gravels and/or red‐brown sands belonging to the Main Terrace sequence, but in some places incorporate local gravels. There are no completely convincing indications of cold conditions where the relatively strong Silurian and Old Red Sandstone rocks and the Carboniferous Limestone form the valley floor. The altitudinal relationships of the involutions and wedges, together with the scale of the outer valley, suggest that this sub‐Flandrian rock bench was merely re‐excavated during the Late Devensian. Then permafrost developed while the river lay confined within the much narrower inner gorge.
Cryptic exposure horizons in the Carboniferous Limestone of Portishead, Avon
Authors: Faulkner T. J. , Wright V. P. , Peeters C. , Garvie L.
Published: February 2007

Two unusual subaerial exposure horizons containing fibrous columnar calcite crystals are described from the (early Chadian) Lower Carboniferous of Portishead, near Bristol in southwest Britain. The lower horizon overlies the Courceyan Black Rock Limestone (mid‐ramp facies) and is separated from the upper horizon by the Sub‐Oolite Bed and is overlain by the Chadian Gully Oolite (both are inner ramp deposits).

Regionally the Portishead Palaeosol Beds are interpreted as forming part of extensive emergent surfaces which developed along the southern margin of the Welsh–Brabant Massif. They correlate with similar subaerial exposure horizons in Belgium and southern Germany, and may be the product of a proposed major eustatic sea level fall at the end of the Courceyan.
Tide versus storm in Epeiric coastal deposition: Two Proterozoic sequences, India
Authors: Bose Pradip K. , Chaudhuri Amit K.
Published: February 2007

The relative importance of tides and storms in coastal sedimentation in ancient epeiric seas is frequently problematical. Here we appraise the depositional regimes in two Proterozoic Vindhyan formations in India with the aim of elucidating the records of each of these processes. The respective products of the two processes are not easily distinguished as both of them entail repeated fluctuations in water level and depositional energy. Two orders of fluctuation are recognized in both formations. The nature and scale of these two orders of fluctuation along with high‐resolution facies analysis make the distinction between the respective products of the two processes possible. Many of the features so long counted as characteristics of tidal rhythms, in the studied formations, exclusively or frequently manifest waxing and waning of storms or fairweather–storm cyclicity. This study highlights the need for reevaluation of ancient coastal sequences in epeiric setting.