bluuebunny/crossref_metadata_2025 huggingface dataset:
The spectrum of twisted Dirac operators on compact flat manifolds
Authors: Miatello Roberto , Podestá Ricardo
Published: June 2006

Let

M
M

be an orientable compact flat Riemannian manifold endowed with a spin structure. In this paper we determine the spectrum of Dirac operators acting on smooth sections of twisted spinor bundles of

M
M

, and we derive a formula for the corresponding eta series. In the case of manifolds with holonomy group

Z

2
k

\mathbb {Z}_2^k

, we give a very simple expression for the multiplicities of eigenvalues that allows us to compute explicitly the

η
\eta

-series, in terms of values of Hurwitz zeta functions, and the

η
\eta

-invariant. We give the dimension of the space of harmonic spinors and characterize all

Z

2
k

\mathbb {Z}_2^k

-manifolds having asymmetric Dirac spectrum. Furthermore, we exhibit many examples of Dirac isospectral pairs of

Z

2
k

\mathbb {Z}_2^k

-manifolds which do not satisfy other types of isospectrality. In one of the main examples, we construct a large family of Dirac isospectral compact flat

n
n

-manifolds, pairwise nonhomeomorphic to each other of the order of

a
n

a^n

.
Vanishing and non-vanishing of traces of Hecke operators
Authors: Rouse Jeremy
Published: June 2006

Using a reformulation of the Eichler-Selberg trace formula, due to Frechette, Ono and Papanikolas, we consider the problem of the vanishing (resp. non-vanishing) of traces of Hecke operators on spaces of even weight cusp forms with trivial Nebentypus character. For example, we show that for a fixed operator and weight, the set of levels for which the trace vanishes is effectively computable. Also, for a fixed operator the set of weights for which the trace vanishes (for any level) is finite. These results motivate the “generalized Lehmer conjecture”, that the trace does not vanish for even weights

2
k
≥
16

2k \geq 16

or

2
k
=
12

2k = 12

.
Finite edge-transitive Cayley graphs and rotary Cayley maps
Authors: Li Cai
Published: June 2006

This paper aims to develop a theory for studying Cayley graphs, especially for those with a high degree of symmetry. The theory consists of analysing several types of basic Cayley graphs (normal, bi-normal, and core-free), and analysing several operations of Cayley graphs (core quotient, normal quotient, and imprimitive quotient). It provides methods for constructing and characterising various combinatorial objects, such as half-transitive graphs, (orientable and non-orientable) regular Cayley maps, vertex-transitive non-Cayley graphs, and permutation groups containing certain regular subgroups. In particular, a characterisation is given of locally primitive holomorph Cayley graphs, and a classification is given of rotary Cayley maps of simple groups. Also a complete classification is given of primitive permutation groups that contain a regular dihedral subgroup.
Paley–Wiener theorems for the Dunkl transform
Authors: de Jeu Marcel
Published: June 2006

We conjecture a geometrical form of the Paley–Wiener theorem for the Dunkl transform and prove three instances thereof, by using a reduction to the one-dimensional even case, shift operators, and a limit transition from Opdam’s results for the graded Hecke algebra, respectively. These Paley–Wiener theorems are used to extend Dunkl’s intertwining operator to arbitrary smooth functions. Furthermore, the connection between Dunkl operators and the Cartan motion group is established. It is shown how the algebra of radial parts of invariant differential operators can be described explicitly in terms of Dunkl operators. This description implies that the generalized Bessel functions coincide with the spherical functions. In this context of the Cartan motion group, the restriction of Dunkl’s intertwining operator to the invariants can be interpreted in terms of the Abel transform. We also show that, for certain values of the multiplicities of the restricted roots, the Abel transform is essentially inverted by a differential operator.
Generic systems of co-rank one vector distributions
Authors: Jacobowitz Howard
Published: June 2006

This paper studies a generic class of sub-bundles of the complexified tangent bundle. Involutive, generic structures always exist and have Levi forms with only simple zeroes. For a compact, orientable three-manifold the Chern class of the sub-bundle is mod

2
2

equivalent to the Poincaré dual of the characteristic set of the associated system of linear partial differential equations.
Biological aspects of Chew Valley and Blagdon Lakes, England
Authors: WILSON R. S. , MAXWELL T. R. A. , MANCE G. , SLEIGH M. A. , MILNE R. A.
Published: June 2006

This paper forms a sequel to that describing the physical and chemical aspects of Chew Valley and Blagdon Lakes (Wilson et al., 1975).

General accounts of the phytoplankton, zooplankton, macrophytes, littoral and benthic faunas, and fish are presented, based on surveys undertaken between 1966 and 1973.

The spring diatom blooms (principally Asterionella) are correlated with silica and phosphate depletion in both lakes, while growths of blue‐green (principally Microcystis) in the summer and autumn are correlated with low values of nitrate and saline ammonia.

The principal zooplankter in both lakes is Daphnia hyalina. Daphnia pulex was found very commonly in Blagdon in 1970/71, but has not been recorded since. The Daphnia in Chew are smaller in size than those in Blagdon.

Blagdon is richer in abundance and number of species of littoral animals, and in macrophyte development, than is Chew. The benthos of both lakes is very similar, except that Blagdon has a well‐established population of Anodonta cygnaea, while in Chew the species has apparently only recently become established.

Both lakes are maintained artificially as trout fisheries. Other fish present include eels, sticklebacks, and gudgeon. Roach and Perch are found in Chew only. An outline account of their food is given based on stomach content analysis, and shows that trout feed principally on chironomid pupae in spring, and on small fish in autumn.
Alterations of p53, BCL‐2, and hMSH2 protein expression in the normal brain tissues, gliosis, and gliomas
Authors: Hussein Mahmoud R. , El‐Ghorori Rabab M. H. , El‐Rahman Yasser G. Abd
Published: June 2006

Tumorigenesis involves alterations in the tumor suppressor genes (p53), protooncogenes (BCL‐2), and housekeeping genes (human MutS homologue‐2 (hMSH2). We hypothesized that development of gliomas is associated with alterations of p53, BCL‐2, and hMSH2 protein expression. To test our hypothesis and to examine these issues, we immunostained 60 specimens entailing normal brain tissues, gliosis, and gliomas (Grade I, II, III, IV) for p53, BCL‐2, and hMSH2 protein expression. As compared with the normal brain and gliosis, examination of the average weighted scores in gliomas (Grade I, II, III, IV, respectively) showed significant up‐regulation of: (i) p53 protein (0.0 ± 0.0; 0.0 ± 0.0; 0.9 ± 0.5; 1.6 ± 0.8; 1.7 ± 0.5; and 4.1 ± 0.8, P < 0.0001) (ii) hMSH2 (1.3 ± 0.3; 1.5 ± 0.7; 1.9 ± 1.1; 2.2 ± 0.5; 4.1 ± 1.5; and 4.7 ± 1.1, P < 0.0006), and (iii) BCL‐2 (0.8 ± 0.5; 1.9 ± 0.5; 1.9 ± 0.6; 2.0 ± 0.6; 4.4 ± 1.2; and 4.6 ± 0.8, P < 0.001). The expression values (p53, BCL‐2, and hMSH2) were statistically significantly higher (P < 0.05) in astrocytomas (Grade III) than in other gliomas. There was an insignificant negative correlation between p53 and BCL‐2 (r = −0.07, P > 0.05) and between p53 and hMSH2 (r = −0.08, P > 0.05) protein expression. Alterations of the p53, BCL‐2, and hMSH2 proteins occur during the development of these tumors.
Pathotypic variation in turnip mosaic virus with special reference to European isolates
Authors: JENNER C. E. , WALSH J. A.
Published: June 2006

A collection of 124 isolates of turnip mosaic virus was gathered from around the world, principally from European countries, and characterized by inoculation to four differential lines of Brassica napus (oilseed rape and swede). Three symptom phenotypes were induced—apparent immunity, local infection only, or systemic infection. Twelve distinct patterns, i.e. pathotypes, were observed. Three pathotypes were predominant in the collection; pathotype 1 isolates, which were the most common, did not overcome any of the most extreme sources of resistance in the differential lines. Of the other two, pathotype 3 isolates overcame one of the major sources of resistance and pathotype 4 isolates overcame all sources of resistance. The distribution of pathotypes within Europe was examined. No pathotype was confined to any geographical area, although pathotype 4 isolates were not found in southern Europe or Asia. Most isolates (90) originated from Brassica hosts, while others were from other cruciferae genera (19) or non‐crucifers (5). The species of plant that the isolates originated from was not clearly related to the pathotype of the isolates. Resistance to pathotype 1 isolates is controlled by a dominant allele in one of the differential lines, and resistance sources are being examined in the other lines. Isolates belonging to pathotype 1 appeared to be able to mutate readily to overcome the resistance in one of the rape differential lines, but no isolates appeared to mutate to overcome the other major source of resistance in the differentials. The implications of the results for disease control strategies are discussed.
Association of phytoplasmas with the decline of European hazel in southern Italy
Authors: MARCONE C. , RAGOZZINO A. , EMÜLLER E. SE
Published: June 2006

In the Campania region of southern ltaly. commercial orchards of European hazel (Corylus avellana) are severely affected by yellowing and decline. To determine whether phytoplasmas are associated with the disorder, stem samples from diseased trees were examined using polymerase chain reaction assays. No visible products were obtained by amplification of sample DNA with universal and group‐specific phytoplasma primers. However, when the products obtained with universal primers were re‐amplified with nested primers that were specific for the fruit tree phytoplasmas of the apple proliferation group, most samples tested positively. Restriction site analysis revealed that the trees were infected with the apple proliferation, pear decline, and European stone fruit yellows phytoplasmas in about the same proportion. Some of the trees were doubly infected with one of the fruit tree phytoplasmas and the aster yellows agent. Most of the infected trees were also identified by hybridization of the products obtained in the initial amplification with suitable oligonucleotide probes.
Colletotrichum gloeosporioides as the cause of stem tip dieback of cassava
Authors: MOSES E. , NASH C. , STRANGE R. N. , BAILEY J. A.
Published: June 2006

A fungus with morphological features corresponding to the group species Colletorichum gloeosporioides was consistently isolated from cassava with shoots showing dieback symptoms in Ghana. When four locally‐grown cultivars were inoculated with isolates of the fungus, they developed disease symptoms, which consisted of discrete dark brown lesions on the stems followed by defoliation. Koch's postulates were completed by re‐isolating the fungus from the inoculated plants. The relatedness of the isolates lo other members of the genus Calletotrichum, whose identities were well established, was investigated by comparison of the nucleotide sequence of domain 2 of their ribosomal DNA. The cassava isolates differed from authentic isolates of C. gloeosporioides by only one nucleotide among the 193 analysed. The causal agent of cassava stem tip dieback (STDB) is thus identified as a form of C. gloeosporioides.
Development and use of a PCR assay to detect Rhizoctonia cerealis, the cause of sharp eyespot in wheat
Authors: NICHOLSON P. , PARRY D. W.
Published: June 2006

Random amplified polymorphic DNA assays were carried out on a range of isolates of Rhizoctonia cerealis to identify markers common to all isolates. Two fragments were isolated, cloned and used to probe Southern blots of DNA from R. cerealis and isolates from a range of anastomosis groups of Rhizoctonia solani. The two fragments hybridized specifically to DNA of R. cerealis and not to DNA of any of the isolates of R. solani. Both fragments were partially sequenced and two pairs of primers were generated for use in the polymerase chain reaction (PCR). Amplification of a fragment of the anticipated size occurred following PCR of all isolates of R. cerealis and not from any of a range of fungal species associated with disease of the stem base of cereals. The primer pairs for R. cerealis were also used, along with those for Microdochium nivale and W and R‐type of Pseudocercosporell herpotrichoides, to deled these pathogens in extracts from field‐grown wheat plants exhibiting symptoms of sharp eyespot, eyespot, foot rot or a combination of the diseases. No relationship was found between visual disease assessment of sharp eyespot at growth stage 37 and the results of PCR However, the results of PCR and visual disease assessment at growth stage 75 were similar, indicating that visual disease assessment may not be reliable until later growth stages. This system offers the potential to detect the presence of R. cerealis in cereals and avoid problems commonly associated with conventional diagnosis of this disease and isolation of the pathogen.
Investigation of the epidemiology of green mould of mushroom (Agaricus bisporus) compost caused by Trichoderma harzianum
Authors: SEABY D. A.
Published: June 2006

In 9 years of advisory experience in the British Isles and in virulence tests in the laboratory and field, only one of three distinct taxa of T. harzianum, namely Th2, consistently colonized mushroom compost either in vitro or in mushroom houses, A single particle of contaminated spawn initiated colonies up to 30 cm in diameter. Four other Trichoderma species common in the mushroom environment rarely caused problems. Circumstantial evidence suggested airborne dust to be a main source of contamination of compost or its packing machinery, along with transmission on workers’clothing, pallets, load covers, trailers and by vectors such as mites, mushroom flies and mice. The Th2 isolate of T. harzianum was recovered from all of these sources but, in two tests, it did not survive peak heating. The control measures described here, based on strict hygiene, proved effective. Timing of colonization was important, also temperature of spawn run. Type of compost, as judged by analysis, appeared not to be important. In the field, spawning with peat based 'spawn’instead of grain spawn failed to prevent colonization, whereas in vitro, it reduced it. In the absence of any spawn, Th2 only grew strongly in microwaved or autoclaved compost. Reasons for this are discussed.
Water relations and ethylene production as related to symptom expression in cocoa seedlings infected with defoliating and non‐defoliating isolates of Verticillium dahliae
Authors: RESENDE M. L. V. , MEPSTED R. , FLOOD J. , COOPER R. M.
Published: June 2006

Some isolates of Verticillium dahliae can induce severe defoliation on cocoa plants and others lead to wilting then desiccation of the leaves, without defoliation. The underlying mechanisms that precede the occurrence of these two distinct responses were studied in root inoculated seedlings under glasshouse conditions.

Rapid decreases in total transpiration, stomatal conductance and midday leaf water potential were closely associated with the onset of foliar symptoms, indicating that water stress is a major cause of symptom development. Water stress was most pronounced when plants were inoculated with a‘non‐defoliating’isolate. In contrast, a‘defoliating’isolate induced accumulation of ethylene in newly developed leaves, where the first symptoms generally appeared. This hormone appeared to be responsible for the accelerated senescence and defoliation, as demonstrated by reversal with the application of the ethylene inhibitor silver thiosulphate.

Increased symptoms, water stress and ethylene production occurred in upper leaves and coincided with more intensive colonization of this part of the plant by the pathogen. This unusual pattern reflects the vascular anatomy of the host.
Homothallism in Peronospora viciae f.sp. pisi and the effect of temperature on oospore production
Authors: VAN DER GAAG D. J. , FRINKING H. D.
Published: June 2006

Monoconidial cultures derived from seven P. viciae f.sp. pisi isolates, obtained from different countries, were able lo produce oospores, Apparently, these isolates were homothallic. Oospore production of one isolate was studied at 5, 10, 15 and 20°C in systematically colonized shoots, and in local lesions on leaflets, stem parts and pods of the pisum sativum cv. Kelvedon Wonder. The number of oospores produced per gram systemically colonized tissue increased with temperature. In lesions of leaflets and of stem parts, including tendrils, petioles and main stem, most oospores were produced at 20°C. At 10°C, a few oospores were found in stem parts but none in leaflet lesions. At 5° C, no oospores were formed at all. In pods, moe oospores were produced at 15 and 20°C than at 10°C, but the numbers of oospores was smaller than in the other plant parts. Oospores formed at lower temperatures were larger than those formed at higher temperatures. At 20°C, similar oospore densities were found in leaflet lesions of three cultivars widely differing in resistance to downy mildew.
THE RELEVANCE OF MAGNETIC MEASUREMENTS ON SOME FINE GRAINED SILTS TO THE STUDY OF THEIR DEPOSITIONAL PROCESS
Authors: GRIFFITHS D. H. , KING R. F. , REES A. I.
Published: June 2006

In order to explain why the magnetic directions of naturally and artificially deposited fine silts show deviations from the direction of the ambient field a theoretical model has been postulated of the process of deposition.

The deviations have been explained satisfactorily on the assumption that the sediment consists of quasi‐spherical, non‐cohesive particles which roll into hollows in the existing bed. A model of this kind provides a theoretical basis for the quantitative study of certain sedimentological questions which may be applied to the study of such problems as the apparent anomalous resistance to erosion of very fine grained sediments, their mechanism of compaction and the determination of current direction and velocity.

Since it does not depend on direct observation either visual or mechanical the magnetic method may be particularly fruitful for sediments of fine silt grade where such observation is very difficult.
THE STRUCTURE OF SEDIMENTARY DEPOSITS OF BRAIDED RIVERS
Authors: DOEGLAS D. J.
Published: June 2006

A description is given of the sedimentary structures and pebble orientations of two braided rivers, the Durance and Ardkhe, whose origin, hydrology, mineralogy, and mechanical composition are already well known.

Microtopographic measurements indicate uneven bedding planes. Macrostructures of the deposits show many channel or festoon laminations alternating with bar deposits, showing parallel bedding or oblique, foreset laminations.

Oblique laminations (foreset lamination) occur mainly at the downstream ends of the bars along the upstream side of steep concave banks of channels running obliquely to the general valley trend.

Pebbles, gravel, and coarse sand dominate over silty deposits which occur as the top layer of the flood plain and occasionally as channel fill. These silty deposits (loams) are very sandy and contain many irregular current ripple marks, distinguishing them from the heavy clay deposits of the flood plain of meandering rivers.

Graded bedding is rare. Structures resembling the flute casts and load casts of turbidity currents have been observed but are uncommon. Irregular current ripple marks of horseshoe shape and erosion flow marks parallel to the current direction are common.

The average orientation of the long axis of cobbles, pebbles, and coarse sand grains is normal to the current direction. The inclination of flat pebbles is upstream. Points aiding in discrimination between deposits of braided rivers and of turbidity currents are given in Table II.
SOME MIDDLE SILURIAN REEFS OF GOTLAND
Authors: MANTEN A. A.
Published: June 2006

A number of illustrations are presented, which show some characteristics of the reefs occurring in the Upper Visby and Hogklint Beds of Gotland. These series should probably be correlated with the uppermost Llandoverian and Lower Wenlockian. Reef growth took place as the water became progressively shallower. There are no reefs in the lower part of the Upper Visby Beds, which consist of marl with limestone Ienses, and was formed in relatively deep water. No reefs occur in the uppermost Hogklint, which consists of an algal limestone formed in very shallow water.
ETUDE DU COMPORTEMENT HYDRAULIQUE DU MICA
Authors: BERTHOIS LÉOPOLD
Published: June 2006

The study of the hydraulic behaviour of mica and particularly the study of the modalities of the fall of particles in a motionless liquid presents a great variety of types and a vast series of falling speeds. The observations made by Mc Nown (1953), concerning grains, show that there are various modalities.

The falling speed differs greatly from that indicated by the usual sedimentation speed curves, because the calculation of the nominal diameter in which the grain is compared to a sphere differs considerably from reality.

The calculation of the drag coefficient (Cn) with regard to the Reynolds number (Re) again accentuates this disparity.
STATISTICAL BASIS FOR CYCLOTHEMS: A QUANTITATIVE STUDY OF THE SEDIMENTARY SUCCESSION IN THE EAST PENNINE COALFIELD
Authors: DUFF P. MCL. D. , WALTON E. K.
Published: June 2006

Study of cyclic sedimentation in the Coal Measures is impeded by confused terminology and ideas. It is suggested that the first steps in the investigation of an area or sequence where cyclic sedimentation is suspected should be:

(1) to determine statistically if a modal cycle is present and to define that cycle,

(2) to erect a composite sequence representative of the succession.

The Coal Measures of the East Pennine (Yorkshire‐Derbyshire‐Nottinghamshire) Coalfield. England, are examined to illustrate the application of this idea. The succession shows amodal cycleof non‐marine shale followed upwards by seat‐earth with secondary modes (also non‐marine sediments) made up of shale—siltstone—shale—seat‐earth and shale—siltstone and sandstone—shale—seat‐earth. Thecomposite sequencefor the whole succession is marine shale—non‐marine shale—siltstone and sandstone—non‐marine shale—seat‐earth.

Consideration of cycle types, horizontal and vertical variation and thickness, lead to the suggestion that sedimentational controls played the major part in the development of the cyclic succession in the Coal Measures of the East Pennine Coalfield. Only three horizons are exceptional and suggest the possibility of regional diastrophic controls or world‐wide changes of sea level.
FACIES DELINEATION BY ACOUSTIC‐REFLECTION: NORTHERN GULF OF MEXICO1
Authors: CURRAY JOSEPH R. , MOORE DAVID G.
Published: June 2006

This study in Breton, Chandeleur, and Mississippi Sounds combines the use of bottom‐penetrating acoustic‐reflection records with lithologic descriptions of piston and gravity cores for construction of sections showing boundaries of depositional facies units. Continuous acoustic records delineate morphology of buried horizons (lithologic breaks, changes in density, water content, or degree of lithification). Lithologic descriptions give internal structure and variations of particle size, color, components such as shells and wood fragments, and consistency. With these criteria, deposits were divided into the major broad facies units of sound deposits, delta deposits, basal and barrier island sands and Pleistocene clays. Delta deposits are recognized as being of two distinct periods of the St. Bernard subdelta, which has subsided beneath Breton and Chandeleur Sounds.

Probable buried distributaries of these delta phases are recognized in the records. Sand bodies connecting islands in Mississippi Sound are suggested as remnants of an extensive barrier island which fronted the area previous to the subdelta growth and had its beginnings about 7,000 B. P.
TECHNIQUES FOR REMOVING INTERSTITIAL WATER FROM COARSEGRAINED SEDIMENTS FOR CHEMICAL ANALYSES
Authors: SCHOLL DAVID W.
Published: June 2006

Three methods, (a)dessication, (b)gas extraction and (c)immiscible‐liquid extraction, are described and evaluated for removing interstitial water from coarse‐grained sedi‐ ments for semi‐quantitative and quantitative chemical analyses. The dessication method is useful for chlorinity or chlorosity determinations and (with a correction of 5%) gives results probably accurate to within about ± 2O% Extraction of interstitial water with gas of high relative humidity gives results which are correct to within an error of ± l.O% The chlorosity of interstitial water extracted by forcing a high‐ viscosity epoxy plasticizer (immiscible with water) through the sediment falls within about ± 0.1% of the correct value. The immiscible‐extraction method is therefore recommended for work requiring quantitative knowledge of interstitial water chemistry.
DISTINCTIVE TYPES OF RIPPLE‐DRIFT CROSS‐LAMINATION
Authors: WALKER ROGER G.
Published: June 2006

From work on two Upper Carboniferous formations in southwest England, three morphologically distinct types of ripple‐drift cross‐lamination have been recognised. Type 1 is characterised by strong erosion of laminae on the stoss (or up‐current) side of the ripples, and absence of grading. Type 3 is characterised by an absence of erosion on the stoss sides, concentration of mud in the ripple troughs and an upward gradual decrease in grain size and amplitude of rippling. Type 2 is an intermediate form with some characteristics in common with types 1 and 3. An examination of the illustrated literature has shown that types 1 and 3 occur frequently, and that type 2 has not pre‐ viously been recorded.

It is suggested that type 1 is formed in fluvial and shallow water environments at times of net deposition of sediment, and that type 3 is formed by deposition from a tur‐ bidity current. Type 2 suggests hydrodynamic conditions intermediate between fluvial or shallow water traction currents, and turbidity currents.

Since all current ripples move forwards, or “drift”, it is suggested that the term “ripple‐drift” should be used to describe ripple cross‐lamination where the ripples can be seen to climb onto the stoss slope of the ripple immediately downstream, there having been a net deposition, and not merely a forward drift of sediment.
PETROLOGY OF UPPER DEVONIAN PELLETOIDAL LIMESTONES, ARROW CANYON RANGE, CLARK COUNTY, NEVADA
Authors: CARSS BRIAN W. , CAROZZI ALBERT V.
Published: June 2006

Approximately 1,200 ft. of Devonian limestone, 900 ft. belonging to the Arrow Canyon Formation and 280 ft. to the Crystal Pass Limestone, were sampled at 2 ft. intervals.

A thin‐section was prepared for each sample and examined petrographically. Polished specimens were examined also and a selected group of these slabs were investigated by X‐ray diffraction analysis to determine their gross mineralogy.

The petrographic examination involved the measurement of the particle size and determination of the frequency of occurrence of all the inorganic particles such as pellets and quartz grains. The organic elements such as Amphipora, stroniatopo‐ roids, calcispheres, bryozoans, ostracods and crinoids were also counted. On the basis of these measurements the samples were divided into ten microfacies, which are calcilutite, fossiliferous calcilutite, calcilutite with pocket‐like structures, breccia‐ conglomerate, poorly sorted calcarenite, arenaceous poorly sorted calcarenite, well sorted calcarenite, arenaceous well sorted calcarenite, sandstone and bioconstructed Amphipora‐stromatoporoid limestone.

The raw data were subjected to a multiple correlation analysis in order to determine the inter‐relationships of the microfacies. This information also made it possible to order the microfacies in such a way that the microfacies from the highest environmental energy was one end‐member, and the microfacies formed in the lowest environmental energy was the other end‐member.

These two end‐members were deposited in the deepest and the shallowest parts respectively, of the carbonate environment.

The variation in relative depth was plotted against the lithological column to give the bathymetric curve. Tangents drawn to the maxima and minima of this curve defined the degree of Juctunfion of the environmental energy. The mean of these maxima and minima values was defined as the energy index. This was also plotted against the lithological column in order to trace the evolution of the environmental energy.

Near the base of the measured section the degree of fluctuation is large and the energy index also has a great range in intensity. As sedimentation progressed, the degree of fluctuation lessened and the environmental energy attained a uniformly high value. The periodicity, that is apparent in the lower portion of the section for both the degree of fluctuation and the energy index, becomes less pronounced and then disappears completely in the Crystal Pass Limestone. The increasing environ‐ mental energy and the decreasing fluctuation in the bathymetry have been interpreted as being due to the carbonate basin being slowly infilled with sediments. The deposits were subjected to prolonged periods of reworking and occasional violent disturbances such as severe storms.
THE SEDIMENTARY HISTORY OF SOME TRIASSIC CONGLOMERATES IN THE VALE OF GLAMORGAN, SOUTH WALES
Authors: BLUCK BRIAN J.
Published: June 2006

From a study of maximum particle size distribution and sedimentary structures it is concluded that the Triassic conglomerates of the Vale of Glamorgan are alluvial fan deposits. A number of alluvial fans are sufficiently well preserved to be mapped, differences in the shapes of the maximum particle size isopleths, lithology and sedimentary structures leading to the interpretation that both stream flood and stream deposits are present. From details of succession an alternation of stream flood and stream deposits is demonstrated, and this is probably the result of the alternation of wet and dry periods.

Variations in sphericity and in particle shape through the parameters of size and distance show that an original population of roughly 50% round, 30% disc, 15% rod and 5% blade shaped particles in the size range 5‐125 mm median diameter was subjected to stream and stream flood transport which carried disc shaped particles futher (or more swiftly) than others of the same sizes. The postulated means of trans‐ port was suspension for discs of 5‐95 mm in diameter and traction for round and rod shaped particles of equal and larger sizes.
GRAVEL FABRIC IN WOLF RUN
Authors: SEMINAR SEDIMENTARY PETROLOGY
Published: June 2006

Size, flatness, and orientation of both maximum projection plane and longest axis were measured on 298 particles larger than 32 mm on two gravel bars in a modern stream in southeastern Indiana. Maximum projection planes dip into the current and long axes are transverse to it. Size and flatness have little effect on orientation.
CRYSTAL CASTS IN UPPER TRIASSIC LOCKATONG AND BRUNSWICK FORMATIONS
Authors: VAN HOUTEN FRANKLYN B.
Published: June 2006

Upper Triassic Lockatong argillite (lacustrine facies) and reddish‐brown Brunswick mudstone (mudflat facies) contain numerous pseudomorphs after glauberite. Those in the Brunswick Formation are large calcite casts of complete crystals both isolated and in bunches in beds a few inches thick, or are slender skeletal crystal casts forming open‐work rosettes in massive mudstone. Those in analcime‐rich dolomitic Lockatong argillite are smaller, more slender, skeletal crystal‐casts filled with dolomite and analcime; most of them are scattered through the rock but locally arranged in vague geometric patterns; less commonly they form conspicuous rosettes and downward‐ diverging conical sprays.

Many glauberite crystals (and rarely halite in the Brunswick mudstone) grew in soft mud during Late Triassic time, thus emphasizing dryness and the role of saline water in the later history of the closed carbonate‐sulphate Lockatong lake. Early extraction of calcium and magnesium carbonates and later of sodium and silica during each chemical cycle left the lake enriched in calcium, sodium, and sulphate. These crystallized as glauberite and possibly anhydrite in lake‐bottom mud and in surface mudcracks during the waning of a chemical cycle.

Crystals of the soluble salts in the Lockatong mud were then replaced by dolomite and analcime from solutions released during dewatering of the mud.
A REVIEW OF THE ORIGIN AND CHARACTERISTICS OF RECENT ALLUVIAL SEDIMENTS
Authors: ALLEN J. R. L.
Published: June 2006

Recent alluvial sediments are reviewed with respect to their geometrical, textural, structural and biological characteristics. These properties are related to the physiographic occurrence and hydraulic geometry of streams and to the dynamics of flowing water as controlling sediment transport‐deposition and stream morphological activities. Based on this data, three‐dimensional facies models are presented as an aid to the identification of ancient alluvial sediments, which are briefly reviewed also.
SUBMARINE FLOOD TUFFS (IGNIMBRITES) ASSOCIATED WITH TURBIDITES IN OLIGOCENE DEPOSITS OF RHODES ISLAND (GREECE)
Authors: MUTTI E.
Published: June 2006

Two pyroclastic sheet‐like deposits were found by the author between the stratigraphic sequence of marine Oligocene sediments of the Vati Group (Rhodes Island, Greece). The lower one is described in this paper.

Its uniform thickness over a large area suggests an origin from submarine ash flow. This assumption is also supported by some welding phenomena observed in several thin sections. Submarine eruption of ignimbritic type is advocated to account for these properties. This type of volcanism agrees well with tectonic and paleogeo‐graphic evolution of the Vati Group basin.

Strong analogies and relationship between submarine ash flows (gaseous suspension) and turbidity currents (watery suspension) are pointed out. The new term of “igniturbidites” is proposed to characterize some pyroclastic turbidity current deposits genetically related to submarine ash flows.

The paleogeographic reconstruction of the Vati Group basin gives some information about the location of the volcanic eruption area and about the submarine travelling of the ash flows.
RECHERCHES SUR LE COMPORTEMENT HYDRAULIQUE DES DEBRIS ORGANOGENES
Authors: BERTHOIS L.
Published: June 2006

Presentation of investigations on the hydraulic content of fragments of lamelli‐branches dredged on the continental shelf (diameters between 12 and 0.51 mm).

These lamellar fragments have fall velocities greatly different from those of quartz grains with which they are able to coexist in a sediment. The data of G. Rittinger (in TRASK, 1939) and R. W. Budryk (in TRASK, 1939) are not applicable to these fragments.

The author points out the interest of a basic documentation for the dynamic study of sedimentation.
RELATIONSHIP BETWEEN LONGITUDINAL AND TRANSVERSAL CURRENTS IN THE PALEOGENE OF THE TARCAU VALLEY (EASTERN CARPATHIANS)
Authors: JIPA DAN
Published: June 2006

In the Paleogene of the Tarcä Valley (Rumania) the largest part of the thick‐bedded and coarse‐grained material was supplied by longitudinal paleocurrents from a distant source. The longitudinal supplies were independent of the lateral ones.
THE INTERNAL PALEOGENE FLYSCH OF THE EASTERN CARPATHIANS: PALEOCURRENTS, SOURCE AREAS AND FACIES SIGNIFICANCE
Authors: CONTESCU L. , JIPA D. , MIHAILESCU N. , PANIN N.
Published: June 2006

After a brief review of the structure, the stratigraphy and the facies of the Rumanian eastern Carpathians flysch zone, the authors analyse the main paleocurrent directions on the internal facies of the paleogene flysch. The most important and numerous currents were longitudinal and came into the flysch trough from an outlet area situated in the Carpathian arc region. For this reason it is inferred that the principal source of detrital material was represented by the Pannonian–Transylvanian internal massif.

The crystalline core of the eastern Carpathians furnished only a small quantity of clastics, which were transported into the trench by means of transversal, relatively weak currents. The role of different structural elements (platforms, cordilleras, internal massifs) in providing detrital material is briefly discussed. Finally, an attempt is made to outline the paleogeographic evolution of the eastern Carpathians during the Paleogene.
CROSS‐BEDDING IN THE SALEM LIMESTONE OF CENTRAL INDIANA
Authors: SEMINAR SEDIMENTATION
Published: June 2006

In the middle Mississippian Salem Limestone of central Indiana 693 measurements showed that sediment transport during Salem deposition was to the southwest, as during deposition of most of the late Paleozoic sands of the Illinois Basin. Crossl bedding direction is variable, however, and noticeably bimodal. Oscillating tida‐currents on a shallow marine shelf are believed to have caused pronounced bimodality in the Salem Limestone and in the associated Ste. Geneviève and Harrodsburg Limestones.
SOME APPLICATIONS OF THEORY AND EXPERIMENT TO THE STUDY OF BEDDING GENESIS
Authors: JOPLING ALAN V.
Published: June 2006

The origin of many sedimentation units deposited in granular cohesionless materials can be rationally explained by utilizing the concept of the profile of equilibrium. This basic concept can be formally expressed in terms of the variables, or groups of variables, that characterize a sediment transport system. A change in one or more variables or a shift in local base level will generally cause a shift in the spatial position of the profile, resulting in either aggradation or degradation. As shown by flume experiments, the rate of shift of the profile is a critical factor in bedding genesis.

A relatively large and rapid upward shift of the profile results in the deposition of a tabular or wedge‐shaped unit of cross‐bedding, i.e., a laboratory delta. On the other hand, a gradual upward shift of the profile results in the deposition of a sequence of horizontal bedding that is commonly associated with intercalations of ripple or dune cross‐bedding. For the intermediate case of a moderately rapid shift of the profile, the depositional sequence includes trough units and poorly‐defined tabular units of cross‐bedding with numerous intercalations of horizontal bedding. The concept of the profile of equilibrium therefore provides a rationale for considering the depositional framework for sedimentary structures produced by current flow.
SCOUR RIPPLES IN THE LUDLOVIAN OF SOUTH RADNORSHIRE, WALES
Authors: BAILEY R. J.
Published: June 2006

Calcareous siltstone beds in the sub‐littoral marine sedimentary rocks of the highest Ludlovian (Upper Whitcliffian) in south Radnorshire display symmetrical ripples with wave lengths around 30 cm. These structures are interpreted as having been formed by the deposition of calcareous silt layers in conformity with bottom surfaces previously scoured into a pattern of symmetrical, gently‐rounded, crests and troughs; hence, they are termed scour ripples. There is some evidence of a longitudinal relationship between the scour ripples and the scouring and depositing currents involved in their formation.
THE DETERMINATION OF THE DIRECTION OF TRANSPORT OF FLUVIATILE ARENITES BY ORIENTATION ANALYSES OF THE DETRITAL MICA
Authors: DIESSEL C. F. K.
Published: June 2006

A simple method of determining the strike and dip of the AB planes of mica flakes in etched slides of arenaceous sediments by means of a universal stage mounted on a stereomicroscope is described.

The polar stereograms constructed from such measurements in fluviatile sandstones show monoclinic symmetry due to up‐current imbrication which compares well with the orientation of plant fossils, current bedding structures and the general current pattern. An angular discordance exists between these features and the direction of sole marks.

An example is given of how analyses of the orientation and imbrication of mica flakes can assist in the solution of sedimentation problems of coalfield geology.
THE SURF “BREAK”: KEY TO PALEOGEOGRAPHY?
Authors: TANNER WILLIAM F.
Published: June 2006

Ancient geosynclinal coastal deposits, preserved and exposed for present‐day examination, probably represent interior—and hence protected—shores, and were therefore characterized by low‐to‐moderate breaker energy levels, as is the modern Gulf of Mexico. Modern low‐energy beach sand size distributions are distinguished by an inflection, here called the surf “break”, formed by a winnowing or statistical filtering process, by the breakers, in the finer sizes. The result is a two‐segment curve having an intersection in many cases not far from 1.5 phi. If the energy level is very low, a tail of fines may be added, producing a three‐segment curve having two inflection points. Along high energy beaches, the surf “break” occurs at such large grain sizes that it cannot be preserved in sand; whether or not it can be recognized in gravel is not known.

Ancient sandstones which represent the breaker zone, along a low‐to‐moderate energy coast, should also exhibit the surf “break”. The Lyons Sandstone, a known Permian beach deposit, provides an example. Other examples are cited.

Any useful indicator of the shoreline position, in lithified rocks, should have three characteristics: ease of recognition, high reliability, and strong probability of preservation. The surf “break” scores reasonably well on all three points. Hence it may be an important key to paleogeography. Nevertheless, there still remains a question inasmuch as certain river sands have similar inflections. Whether these kinks were inherited from near‐by, but older, beach deposits, or were formed by stream action, is not known. The reliability of the surf “break” is estimated at 80% or better, except for the case where near‐shore sands, of whatever age, are reworked briefly by running water.
THIN‐SECTION ANALYSIS OF SANDSTONES ON WEIGHT‐FREQUENCY BASIS
Authors: SAHU BASANTA K.
Published: June 2006

The weight‐frequency size distribution is generally accepted to be log‐normal (phi‐normal) for sandstones, but the nature of number‐frequency distribution of particles in sandstones is largely unknown. This paper develops the theory of correction procedure for the observed weight‐frequency moments obtained by thin‐section analysis of sandstones (and clastic sediments in general) which was not available so far.
MORPHOLOGY, INTERNAL STRUCTURE, AND ORIGIN OF GLAUCONITE PELLETS
Authors: TRIPLEHORN D. M.
Published: June 2006

Glauconite pellets exhibit considerable variety in morphology and internal structure. Recognized morphological types are: (1) ovoidal or spheroidal; (2) tabular or discoidal; (3) mammillated; (4) ellipsoidal; (5) vermicular; (6) composite; and (7) fossil casts, internal molds, or replacements. Types of internal structures include: (1) random microcrystalline, (2) oriented microcrystalline, (3) micaceous, (4) organic (?) replacements, (5) coatings on detrital grains, and (6) fibroradiated rims.

These characteristics can be used to interpret the origin and/or subsequent history of pellet types. Suggested origins include: (1) chemical precipitation, (2) expansion and alteration of detrital mica, (3) alteration of fecal pellets, (4) alteration of clay fillings of fossil tests, (5) mechanical aggregation, and (6) chemical replacement.

Not all glauconite pellets exhibit diagnostic characteristics with regard to their genesis. Original morphologies may be obscured by abrasion (reworking) prior to final burial. Internal structures may be changed by recrystallization or other diagenetic processes.

It is concluded that glauconite pellets have multiple origins. They can form from several different parent materials and by several different processes. Frequently, however, characteristics which might reveal the original nature of the pellets have been lost during reworking and diagenesis.

Inasmuch as glauconite occurrences differ in kind and variety of pellets, recognition of pellet types and their distribution is potentially useful for stratigraphic correlation or environmental determinations.
BORON IN CLAYS AND ESTIMATION OF PALEOSALINITIES
Authors: LERMAN A.
Published: June 2006

Experiments on the uptake of boron by some clays from artificial sea‐water solutions at room temperatures show that the uptake is proportional to the concentration in solution, and takes place in relatively short time. The uptake process can be described by the Freundlich adsorption equation, with the constants in the equation, k and b, varying from one clay to another. Additional factor which apparently promotes the boron adsorption by clays is the occurrence of a sodium‐borate complex in saline waters. The boron concentrations in a sequence of marine Cretaceous sediments derived from a fairly localized source area show variation much greater than can be accounted for by a model which assumes (1) nearly constant boron concentration in illitic‐montmorillonitic clays prior to their deposition in the sea, and (2) changes in the boron concentration in solution as may be expected under slight variations in sea water of near “normal” salinity. Differences in the properties of clay‐mineral polymorphs, in predepositional histories of the clays, and possible adsorption from interstitial waters, render inconsequential the estimates of the boron concentrations in the waters at the time of deposition.
SEDIMENTARY CHARACTERISTICS AND CLIMATIC ANALYSIS OF EASTERLY DUST STORMS IN THE NEGEV (ISRAEL)
Authors: YAALON DAN H. , GINZBOURG D.
Published: June 2006

Sedimentary and meteorological characteristics of easterly dust storms causing severe damage in the Negev in November 1958 are analysed. Though the heavy storm originated in weather conditions outside of the affected area, the intense dustiness was of a more local nature. The sedimentological character of the dust indicates that the largest portion was of local origin, picked up by the turbulent current in the loess area of the northern Negev on its passage westward. Total quantity of sediment transported in the Beersheba Basin is estimated to be 10–20 million tons.

The analysis of climatic data and of sedimentary characteristics of several other dust samples indicates that though severe dust storms can produce dramatic effects in transporting and deposition of aeolian dust, the rare occurrence of easterly dust storms does not make it likely that they were responsible for the import of aeolian sediments found in the northern Negev.
A COMPUTER PROGRAM FOR GRAIN‐SIZE DATA1
Authors: SCHLEE JOHN , WEBSTER JACQUELINE
Published: June 2006

The computer program presented here seeks to improve estimation of statistical parameters for grain‐size data by use of interpolated values. Interpolation is made by fitting a series of overlapping parabolas to the data, and follows the method of Snyder (1961). The values are used in moment formulas to compute standard statistical measures. Skewness and kurtosis are reduced by the interpolation data, and extreme positive values of kurtosis tend to be greatly reduced. The program also picks major modes, the median, and sediment type.
SELECTIVE RECRYSTALLIZATION IN LIMESTONES
Authors: CHANDA S. K.
Published: June 2006

Structurally initiated recrystallization is of two types: in the first type, the common one, the effect is internal and self‐destructive, and in the second type the effect is external and leads to retention of pre‐existing structures.