bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of photosynthetically raised pH and light on some ciliated Protozoa in a eutrophic pond
Authors: GOULDER R. 
Published: June 2006

SummarySome ciliated Protozoa (e.g. Loxodes magnus, L. striatus, Spirostomum teres, S. ambiguum and Frontonia leucas) are abundant during summer in the hypolimnion of a eutrophic pond in north‐west England but are absent from the epilimnion. The work described in this paper was begun with the aim of investigating the suggestion that high pH values caused by phytoplankton photosynthesis contributed to the exclusion of these ciliates from the epilimnion. In July 1973, phytoplankton photosynthesis and high pH were found only in the epilimnion, hence conditions were compatible with the above suggestion. Ciliates were, therefore, kept in the laboratory in hypolimnion water and were exposed to phytoplankton photosynthesis, both with and without pH increase. It was found that Loxodes died under both treatments hence there is no evidence that high pH is lethal to Loxodes. It seemed possible, therefore, that either light or toxins released by algae during photosynthesis are lethal to Loxodes. L. magnus was, therefore, exposed to light in the absence of phytoplankton (in filtered hypolimnion water) both in the laboratory and in the pond and it was found that light was lethal. High light intensities might, therefore, contribute to the exclusion of at least Loxodes species from the surface water of the pond, although other adverse factors are probably operative since Loxodes species do not migrate into the epilimnion at night.
Physical and chemical aspects of Chew Valley and Blagdon Lakes, two eutrophic reservoirs in North Somerset, England
Authors: WILSON R. S. , SLEIGH M. A. , MAXWELL T. R. A. , MANCE G. , MILNE R. A. 
Published: June 2006

SummaryChew Valley and Blagdon Lakes are two shallow, hard‐water, lowland eutrophic reservoirs, situated near Bristol in the south‐west of England.Chew Lake is more turbid and richer in plankton but poorer in macrophytes than Blagdon, and is more exposed to wind action. Both lakes show evidence of transient stratification in the summer coupled to deoxygenation of the bottom water, which has led to release of nutrients from the sediments.Severe algal blooms in Chew Lake in 1968 and the consequent filtration difficulties led to the establishment of a collaborative research programme between the University of Bristol and the Bristol Waterworks Company, to define the present biological status of the lakes, and to predict their possible future development. The work covers a wide range of measurements and observations on the limnological conditions of the lakes, which form an elegantly contrasted pair, and this paper describes their general physical and chemical features.
Isolation and identification of hypovirulent Rhizoctonia spp. from soil
Authors: JUAN‐ABGONA R. VILLA , KATSUNO N. , KAGEYAMA K. , HYAKUMACHI M. 
Published: June 2006

Two‐hundred and forty‐eight isolates of Rhizoctonia spp, were obtained from 13 locations in Gifu Prefecture in Japan using the plant debris particles isolation, colonization of bait tissue, and soil‐clump plating methods. Of the isolates, 143 were binucleate Rhizoctonia spp., 60 were R. solani and 45 were R. zeae. Three isolates of R. solani and 54 of binucleate Rhizoctonia spp, were hypovirulent on radish, whilst all isolates of R. zeae were highly virulent, Hypovirulent strains were isolated most frequently by the plant debris particles isolation method, Hypovirulent isolates of R. solani belonged to anastomosis group 4, whilst the hypovirulent binucleate Rhizoctonia isolates belonged to AG A, AG Ba, AG G, and AG O.Thirty‐two isolates of Rhizoctotria spp, selected for hypovirulence on radish were tested on cucumber in vitro. Only five binucleate Rhizoctonia isolates and one R. solani isolate were hypovirulent on both species, and these isolates were also hypovirulent on seven other crop species. Cucumber showed wide variation in disease susceptibility to different isolates but hypovirulent isolates exhibited a consistent reaction on five different host cultivars, Pathogenicity tests using cucumber grown in soil also showed consistent reactions with isolates selected either for hypovirulence or virulence. The results support the use of cucumber in bioassays for identifying hypovirulent isolates of binucleate Rhizoctonia spp.
EVAPORITE TYPE DOLOMITE IN SALT FLATS OF WESTERN UTAH
Authors: BISSELL H. J. , CHILINGAR G. V. 
Published: June 2006

SummaryBeds of fairly pure to impure dolomite, varying in thickness from 1 mm to 1 ft., occur widely throughout a large part of the Salt Flats of the Great Salt Lake Desert in Western Utah. Most of the sediments studied evidently formed within the past few tens of thousands of years (as dated by C14 methods), during late Lake Bonneville and Recent time. Alternating dark and light layers of dolomite, carbonate‐bearing clays, and clays make up the upper few feet of sediment that was sampled. Dark layers however, are significantly higher in silicates plus SiO2, content and have approximately twice as much Mg2+ as the light layers. The writers suggest that the process of dolomite‐formation was hastened by elevated temperatures, occasioned by solar absorption through a saltcrust “window” over the salt pans. Results of this study indicate that the dolomite is possibly of secondary origin (replacement type). Enough information is not available at this time in order to determine the duration of diagenetic dolomitization in terms of days, weeks or years, nor is it known if the diagenetic alteration of calcite to dolomite occurred at the sediment‐water interface or after burial (or both at different times).
PETROLOGY AND PALEOGEOGRAPHY OF THE WARRENSBURG CHANNEL SANDSTONE, WESTERN MISSOURI
Authors: DOTY ROBERT W. , HUBERT JOHN F. 
Published: June 2006

SUMMARYThe approximately 100‐foot thick Warrensburg sandstone (Nowata formation, Marmaton group, Pennsylvanian Desmoinesian Series, western Missouri) fills a valley‐shaped erosional channel. The rapidly lensing fluvial sediments are sandstones (45%) and siltstones and shales (50%), with subordinate basal conglomerate and coal. Sediment transport was southward, parallel to the north‐south channel. These fluvial sediments formed in a stream channel previously cut across a low coastal plain during a temporary retreat of the sea.The Warrensburg sandstone samples are a homogeneous group of fine‐grained to medium‐grained quartzose graywackes and micaceous quartzites. The grains, omitting 10% clayey matrix and 10% iron‐oxide and silica cements, average 47% common quartz, 34% metamorphic detritus (slate, phyllite, schist, highly undulose unit quartz, schistose and pressure metaquartzites, and mica), 14% plutonic detritus (feldspar and vein quartz), and 5% sedimentary grains (“second‐cycle” rounded quartz and chert). The accessory heavy mineral assemblage also reflects a mixture of metamorphic and plutonic detritus with subordinate “second‐cycle” grains (21% rounded zircon and tourmaline among the detrital, transparent, non‐micaceous grains). The distant sources of detritus in the Warrensburg and other Desmoinesian channel sandstones of Missouri are typified by metamorphic and subordinate feldspathic crystalline rocks.The average 10% feldspar (largely K‐feldspar) among the grains and 8% garnet among the detrital, transparent, non‐micaceous heavy minerals in the Warrensburg sandstone, in contrast to the near absence of these minerals in Desmoinesian channel sandstones of western Pennsylvanian, suggests that the principal sources were the Transcontinental Arch and Canadian Shield to the north and northeast. The Appalachian metamorphic belt is not as important a source area for the Western Interior Basin as previously generally thought.
UNTERSUCHUNGEN ZUR KALKFÄLLUNG UND KALKLÖSUNG AM WESTRAND DER GREAT BAHAMA BANK
Authors: SEIBOLD EUGEN 
Published: June 2006

SUMMARYIn the summer of 1959, temperature, Eh, pH, chlorinity and alkalinity of sea and interstitial water were measured in the westernmost part of Great Bahama Bank and in Florida Bay (Fig. 1).Boring organisms, especially algae, grazing snails and inorganic processes are deepening solution basins there (Fig. 2, 3, 5, 6). Carbonate balance in the Bimini lagoon is influenced by the activity of grass (Fig. 8), algae and animals with carbonate tests and shells, and physicochemical differences between day and night, high and low water. Inorganic precipitation of calcium carbonate seems to be small compared with the losses due to incorporation into organisms. In Florida Bay saturation is partly influenced by plants also. Supersaturation can be high and wind action stirs up countless small carbonate particles (Fig. 7). This suggests that inorganic precipitation must occur. Calcium carbonate precipitation as outlined by Smith (1940) was observed on Great Bahama Bank even in the mixed waters of the westernmost parts and in the interstitial water of moving oolitic sand.
CHANNELS FROM THE UPPER CARBONIFEROUS COAL MEASURES OF SOUTH WALES
Authors: BLUCK BRIAN J. , KELLING GILBERT 
Published: June 2006

Sandstone‐filled channels occur widely in the Upper Carboniferous (Westphalian) rocks of South Wales. Subsurface and outcrop studies of channels and associated structures in three formations within the Westphalian sequence reveal significant regional variations in orientation, transverse profile, geometry and lithology of fill. The pattern of channel‐orientation in each formation is consistent with the system of palaeocurrents derived from independent studies of cross‐bedding and indicates that in the lowest Westphalian (Basal Coal Measures) derivation was principally from the north and east, with intermittent supply from the south, whereas in the Upper Westphalian material was derived mainly from the south and east but with substantial contributions from the north.Formation of the channels is ascribed to fluvial erosion and filling. The mutually consistent regional variations in channel‐parameters are compared with the conspic‐ uous changes in lithofacies and interpreted as indicating diRerences in Auviohydraulic locale within the original basin of sedimentation.
THE APPLICATION OF A CHEMICAL STAINING TECHNIQUE TO A STUDY OF DEDOLOMITISATION
Authors: EVAMY B. D. 
Published: June 2006

A staining technique is described which detects variations in ferrous iron content within calcite and dolomite, whilst simultaneously differentiating the dolomite from the calcite. The application of this technique to a study of dedolomitisation is pre‐ sented.Ferroan dolomite, in certain pyrite bearing limestones of the southern Jura, is shown to have been dedolomitised, that is replaced by calcite, while at the same time the pyrite content of the rock was oxidised to haematite. One of the oxidation products of the pyrite is considered to have caused the dedolomitisation.
TEXTURAL STUDIES OF GRADED BEDDING. OBSERVATION AND THEORY
Authors: SCHEIDEGGER ADRIAN E. , POTTER PAUL EDWIN 
Published: June 2006

SUMMARYPublished data and new observations from the Tertiary and Ordovician show that non‐multiple, continuously graded beds from turbidite sequences have size decline curves that are either convex, concave, or straight.Utilizing a physical model and knowledge of fluid mechanics of turbulent transport, a formula relating both median and maximum grain‐size to height above the base of the graded bed was obtained. This analysis suggests that the shape of the size decline curve in a continuously graded bed depends on the initial size distribution of particles carried by the turbulent current.
RED BEDS IN NORTHEASTERN NIGERIA
Authors: JONES G. P. 
Published: June 2006

SUMMARYRed beds are present in the dominantly drab Bima Sandstone at two main localities in northeastern Nigeria. Their lithology and petrography are described and chemical analyses quoted. It is deduced that the climate at the source area was conducive to the production of red soils. Alternating humid and dry periods are believed to have provided the conditions favourable for the accelerated erosion of a provenance of igneous and metamorphic rocks of marked relief. For the most part the pigment appears to have been finely‐divided material that was sorted prior to deposition; local environmental conditions determined whether the pigment subsequently remained red or was reduced. The association of oxidising and reducing conditions with shallow‐water sedimentary structures may best be explained by the postulation of seasonal flooding of an alluvial plain in a savanna‐type environment.
THE CLASSIFICATION OF CROSS‐STRATIFIED UNITS, COMMENT ON A PAPER BY J. R. L. ALLEN
Authors: CROOK KEITH A. W. 
Published: June 2006

SUMMARYExamination of the criteria employed by ALLEN (1963) in his classification of cross‐stratified units suggests (a) that an additional criterion, the three‐dimensional shape of cross‐strata, should be used in describing and recognizing varieties of cross‐stratification, (b) that the character of the lower bounding surface of sets should be expressed in descriptive rather than genetic terms, and (c) that in describing the relation between cross‐strata and lower bounding surfaces, an additional term, asymptotic, should be used.The recent discussion of the morphological features of cross‐stratification by ALLEN (1963) represents a significant advance in our appreciation of the variability of this type of sedimentary structure. The valuable classification of McKEE and WEIR (1953) generated a concern for precise description of cross‐stratification which has, in 10 years, made the classification inadequate. Allen's proposed classification, based as it is on observable morphological criteria and utilising a nongenetic terminology, should promote further rapid progress.Allen has discussed the problems that arise in naming varieties of cross‐stratification. He very properly avoids terms with genetic implications and his use of Greek letters results in commendably brief names. Almost inevitably, his chosen nomenclature is not readily applicable in the field due to the difficulty of remembering which letter is associated with which assemblage of morphological features. This difficulty will increase as the number of defined varieties increases. It seems probable that workers will prefer for the most part to give names to varieties of cross‐stratification only in the laboratory where reference to literature can be made. The basis for recognition of varieties will be detailed field notes and photographs of morphological features. Nor is this undesirable, for it necessitates the making of detailed observations in the field which will lead to the recognition of new varieties. An easily remembered nomenclature too often leads to the suppression of significant differences in the interests of “pigeon‐holing” the structure in question.It is therefore important that all significant morphological features should be noted. Consideration of the differences between certain varieties of cross‐stratification.
MATRIX OF TURBIDITES: EXPERIMENTAL APPROACH
Authors: KUENEN PH. H. 
Published: June 2006

SUMMARYThe matrix (< 40 μ) of turbidites forms a possible clue to the density of turbidity currents and the origin of the graywacke matrix. Experiments in a circular flume provide a mechanism to study the relation between composition of suspensions at various speeds and their deposits. There is a close analogy to the lower part of turbidity currents. The lutum content of samples with median diameters greater than 400 or 500 μ is found to correspond to the suspended load of the pore water. The higher value for finer deposits can be recalculated to suspension concentration by use of the “sedimentation factor”. Hence, each turbidite carries, as it were, a sample of its depositing current. The lutum content depends not on the ratio of sand to lutum in the current, as tacitly assumed by many authors, but mainly on the ratio lutum to water, although also influenced by velocity.The average lutum density of coarser recent deep‐sea sands is 1‐2%. This indicates turbidity currents with 5‐10% lutum by weight (density 1.03–1.07). The sand must be added to ascertain the current density. In first approximation turbidity currents tend to have densities at their nose of 1.1–1.2, but higher and much lower values also occur.The maximum original lutum percentage of coarse turbidites is below 10%. Higher values are very scarce and are due to post‐depositional mixing, or we are dealing with slides. However, in fine‐grained turbidites there is more matrix up to 20% for a median of 100 p. Hence, coarse graded marine graywackes with 20 or more per cent matrix are presumably weakly metamorphic turbidites, that originally held the same modest amount of lutum as recent turbidites of the same grain size. The Trask sorting of the experimental deposits is very good, like the average of natural turbidites. Most cumulative curves of turbidite grain‐size analyses on arithmetic probability paper show a characteristic bend in fine sand or silt sizes.
SEDIMENTATION IN A MEANDERING ESTUARY1
Authors: LAND LYNTON S. , HOYT JOHN H. 
Published: June 2006

SUMMARYSand is being deposited in a meandering estuary separating Sapelo and Blackbeard Islands, Georgia, in the channel of the estuary and on two point bars associated with meanders. Sand is being eroded by the meandering channel from slightly lithified Pleistocene and unconsolidated Holocene strandline deposits, and is being redeposited by the ebb tidal currents. The estuary‐channel deposits are coarse grained and their grain‐size decreases down ebb current from the source outcrops. The point bars are elongated in the direction of the ebb current, and increase in grain‐size from their crests downward as they grade into the channel deposits. Festoon cross‐bedding and ripple marks on the point bars record the ebb direction, while elongate plant fragments are preferentially oriented normal to the bar elongation (current). Horizontally stratified muds and muddy sands are being deposited behind the bars, and contain a rich fauna (primarily annelids, arthropods, and molluscs). However, the fauna is represented in the deposits more by burrows and disturbed stratification than by preserved organisms. The sands of the bars and channel are biologically less productive, but the bioclastic content of the sediment is high.
SOME FLUME EXPERIMENTS WITH A FINE SILT
Authors: REES A. I. 
Published: June 2006

SUMMARYFour flume experiments have been performed in which the behaviour was investigated of a bed of fine silt under running water with and without an excess of material introduced into suspension.In the presence of excess material, bed features were formed in the tangential stress range 0.1 < θ < 0.4, and the bed was found to remain plane in the ranges 0 < θF < 0.1 and 0.4 < θF < 1.3. In the absence of excess material the stable condition over the entire range appeared to be that of the plane bed.Dual values of the threshold stress for grain movement were postulated to explain these results, and a relationship has been found between the magnitude of the tangential stress and the upstream slope of the features.
AN OBJECTIVE EVALUATION OF THE SEDIMENTARY STRUCTURAL COMPLEXITY OF A FLUVIAL BAR
Authors: DAVIES DAVID K. , EHRLICH ROBERT 
Published: June 2006

SUMMARYThe objective characterisation of sedimentary structures has not had as robust a development as more qualitative approaches. Using KRYNINE'S definition (1948, p. 145) that sedimentary structure is the “visible expression of non‐uniformity in texture and composition”, a method is here developed that yields data which are a function of the thickness and orientation of the visually homogeneous elements that, juxtaposed, comprise a sedimentary structure. This method, based upon a progressive enlargement of the field of vision about a point until the included area is first non‐uniform, yields a series of diameters which are related to both structural type and sampling plan. Exposures of sediment on a point‐bar in the Mississippi River were studied in this manner and it was determined that the method efficiently discriminated between structural varieties, and additionally allows the structural complexity of a point‐bar to be given a succinct quantitative description.
BED THICKNESS AND GRAIN SIZE: GRADED BEDS
Authors: POTTER PAUL EDWIN , SCHEIDEGGER ADRIAN E. 
Published: June 2006

SUMMARYData from Ordovician and Tertiary turbidites and from the Hekla ash fall show good correlation between bed thickness and grain size. Most of the thicker beds are coarser grained. The relation between bed thickness and grain size in graded beds can be explained by a theory which uses a sedimentation formula based on the decay law of turbulence in the deposition zone of a turbidity current.
TEXTURAL CLASSIFICATION OF SEDIMENTS
Authors: LINK ALBERT G. 
Published: June 2006

SUMMARYIn the light of present‐day requirements and the author's personal experience, existing systems of nomenclature and classification of sediments on a textural basis need revision. A system is proposed that is based on a three end‐member relationship involving sand‐, silt‐ and clay‐size particles. The construction, nomenclature and application proposed, fulfils the purpose of a classification because it is simple, easily remembered, practical, has wide application, is needed; and above all it groups sediments into useful categories that make communication more effective and easier.
THIN‐SECTION SIZE ANALYSIS: A FURTHER NOTE
Authors: STAUFFER PETER H. 
Published: June 2006

SUMMARYCriticisms by VAN DER PLAS (1962) of thin‐section point counting as a method of size analysis appear to be based on confusion between number percent and volume percent. Points are samples of volume, and point counts yield volume percents. This is as much true of size classes as of other types of constituents, though distortions are caused in the distribution by the sectioning effect. The “ribbon” method advocated by Van der Plas counts individuals rather than points and hence yields number percents. The two types of statistic are fundamentally different.
LAMINA, LAMINASET, BED AND BEDSET
Authors: CAMPBELL CHARLES V. 
Published: June 2006

SUMMARYFrom smallest to largest, the component layers of a sedimentary body are laminae, laminasets, beds and bedsets. Different arrangements of these layers characterize different types of sedimentary bodies and identify different depositional processes. Concepts of these layers are redescribed because previous definitions are not adequate for modern quantitative descriptions of sedimentary bodies. The four kinds of layers are genetically similar; when compared with each other, they differ principally in areal extent and interval of time for formation. Because beds are usually the most readily recognized layers, they are considered the basic “building blocks” of sedimentary bodies.Beds are bounded by depositional surfaces termed bedding surfaces; each surface is practically synchronous, and a bed can be considered an informal time stratigraphic unit of limited areal extent and of relatively short time span. This concept broadens the scope of intrabasinal correlations, permitting time correlations more refined than possible using fossils or radioactive age dating. Also, a better understanding of the mode of genesis and recognition of distinguishing characteristics of different types of sedimentary bodies follow from this concept.
BED THICKNESS AND GRAIN SIZE: CROSS‐BEDDING
Authors: SCHEIDEGGER ADRIAN E. , POTTER PAUL EDWIN 
Published: June 2006

SUMMARYQualitative and quantitative observations show a general positive correlation between grain size and thickness of cross‐bedded units. Greater sand‐wave height correlates with greater turbulence which permits more and coarser grains to be transported. A theory is developed which qualitatively explains these relationships.