characteristics features and compaction of plant tissues traced from permineralized peat to coal in pennsylvanian coals desmoinesian from the illinois basin abstract plant tissues were traced from coal balls to coal to identify and distinguish their characteristic structures in coal and to determine compaction ratios for specific tissues comparison of average cell sizes of lycopod aerial periderm in coal ball peat and coal gave compaction ratios ranging from 7 1 to 19 1 some of this compaction took place by three dimensional contraction of the periderm so that the shapes of the cells in cross section were not greatly changed compaction ratios of other tissues ranged from 3 1 to 60 1 tissues traced into vitrinite include lycopod stem periderm stigmaria periderm diaphorodendron cortex myeloxylon pennsylvanioxylon wood and bark marattialean fern leaves psaronius outer roots and stigmaria rootlets tissues traced into fusinite or semifusinite include lycopod stem periderm myeloxylon and psaronius inner roots cordaitean leaves cordaianthus and marattialean fructifications were identified in coal and coal balls from the same layer the coal balls were from the herrin springfield and houchin creek coal members of the carbondale formation desmoinesian series pennsylvanian system and an unnamed coal in indiana equivalent to the murphysboro coal member in illinois staunton formation desmoinesian series pennsylvanian system thin sections and etched polished blocks were characterized by light and sem microscopy

a comparison of shear and buoyancy driven planetary boundary layer flows abstract planetary boundary layer pbl flows are known to exhibit fundamental differences depending on the relative combination of wind shear and buoyancy forces these differences are not unexpected in that shear instabilities occur locally while buoyancy force sets up vigorous thermals which result in nonlocal transport of heat and momentum at the same time these two forces can act together to modify the flow field in this study four large eddy simulations less spanning the shear and buoyancy flow regimes were generated two correspond to the extreme cases of shear and buoyancy driven pbls while the other two represent intermediate pbls where both forces are important the extreme cases are used to highlight and quantify the basic differences between shear and convective pbls in 1 flow structures 2 overall statistics and 3 turbulent kinetic energy tke budget distributions results from the two intermediate les cases are used to develop and verify a velocity scaling and a tke budget mode

regional aeolian dynamics and sand mixing in the gran desierto evidence from landsat thematic mapper images spatial variations in sand composition were mapped on a regional scale in a terrestrial sand sea the gran desierto of sonora mexico mesoscale mapping on a satellite image base allowed quantitative interpretation of the dynamic development of sand sheets and dunes the results were used to interpret the quaternary geologic history of the tectonically active region at the mouth of the colorado river landsat thematic mapper multispectral images were used to predict the abundance of different mineralogies of sand grains in a mixed aeolian terrain a spectral mixing model separated the effects of vegetation and topographically induced shading and shadow from the effects produced by different mineral and rock types compositions determined remotely agreed well with samples from selected areas within the spectral limitations of the thematic mapper a simple discrimination capability for active versus inactive sand surfaces is demonstrated based upon differences in the percentage of low albedo accessory grains occurring on dormant aeolian surfaces a technique for discriminating between low albedo materials and macroscopic shade is implemented by combining thermal images with the results of the spectral mixing model the image analysis revealed important compositional variations over large areas that were not readily apparent in the field

the contribution of shear to the evolution of a convective boundary layer the role of shear in the development and maintenance of a convective boundary layer is studied by means of observations and large eddy simulations less particular emphasis is given to the growth of the boundary layer and to the way in which this growth is affected by surface fluxes of heat and moisture and entrainment fluxes this paper analyzes the processes that drive the latter mechanism which accounts for approximately 30 of the growth of the mixing layer typically it is found that under pure convective conditions without shear the entrainment buoyancy flux at the inversion is about 220 of the surface buoyancy flux this value is widely used for entrainment rate closures in general circulation models the data collected during the atmospheric radiation measurement campaign allow one to introduce realistic vertical profiles and surface fluxes into the les runs and to compare the simulation results with the observed evolution of the boundary layer height during a convective situation with high entrainment rates and high geostrophic winds the analysis of the turbulent kinetic energy tke budget shows that the inclusion of geostrophic winds which produce shear at the surface and in the entrainment zone modifies the vertical profile of the various terms in the tke budget as a consequence the entrainment flux is enhanced resulting in increased growth of the boundary layer the numerical experiments and the observations enable one to validate the efficiency of earlier representations based on the tke equation which describe the evolution of the ratio between entrainment and surface buoyancy fluxes the proposed parameterization for the entrainment and surface buoyancy flux ratio b which includes the main buoyancy and shear contributions is in good agreement with the les results some aspects of the parameterization of b for instance the absence of entrainment flux and its behavior during the transition between convective to neutral conditions are discussed

parametrization of the depth of the entrainment zone above the daytime mixed layer a new parametrization for the depth of the daytime entrainment zone is presented it is derived from a simple energy budget in which the eddy velocity in the mixed layer penetrating the overlying stable entrainment zone is taken to be proportional to the characteristic top down velocity scale it gives a better ordering of the data of two earlier studies by deardorff et al and boers and eloranta as compared with traditional parcel theory based on the bottom up velocity scale furthermore it can be seen that the data from the two studies belong to different regimes of the characteristic scaling parameter

the turbulent structure and diurnal growth of the saharan atmospheric boundary layer the turbulent structure and growth of the remote saharan atmospheric boundary layer abl is described with in situ radiosonde and aircraft measurements and a large eddy simulation model a month of radiosonde data from june 2011 provides a mean profile of the midday saharan abl which is characterized by a well mixed convective boundary layer capped by a small temperature inversion 1k and a deep near neutral residual layer the boundary layer depth varies by up to 100 over horizontal distances of a few kilometers due to turbulent processes alone the distinctive vertical structure also leads to unique boundary layer processes such as detrainment of the warmest plumes across the weak temperature inversion which slows down the warming and growth of the convective boundary layer as the boundary layer grows overshooting plumes can also entrain freetropospheric air into the residual layer forming a second entrainment zone that acts to maintain the inversion above the convective boundary layer thus slowing down boundary layer growth further a single column model is unable to accurately reproduce the evolution of the saharan boundary layer highlighting the difficulty of representing such processes in large scale models these boundary layer processes are special to the sahara and possiblyhot dry desertenvironmentsingeneral andhaveimplicationsforthelarge scalestructureofthesaharan heat low the growth of the boundary layer influences the vertical redistribution of moisture and dust and the spatial coverage and duration of clouds with large scale dynamical and radiative implications

the geology and palynology of lower and middle pennsylvanian strata in the western kentucky coal field abstract the western kentucky coal field is the southern tip of the eastern interior or illinois basin pennsylvanian rocks in this area which include conglomerate sandstone siltstone shale limestone and coal were deposited primarily in coastal deltaic settings at a time when western kentucky was located close to the equator this paper discusses temporal changes in regional sedimentation patterns and coal forming floras of lower and middle pennsylvanian strata in the western kentucky coal field lower pennsylvanian strata of the caseyville formation are characterized by paleovalley filling sedimentation patterns and extabasinal quartz pebbles caseyville formation coals are characteristically thin and discontinuous and were strongly influenced by subsidence within underlying paleovalleys and the dissected lower pennsylvanian paleotopography caseyville coals are commonly dominated by lycospora but can also have variable palynofloras which probably reflects variable edaphic conditions and edge effects within small patchy paleomires tradewater formation strata show increased marine influences and tidal estuarine sedimentation especially in the middle and upper parts coal beds in the lower part of the tradewater typically are thin and discontinuous although some economically important beds are present coals become thicker more abundant and more laterally persistent towards the top of the formation palynologically lower and middle tradewater formation coals are dominated by lycospora but begin to show increased amounts of tree fern spores middle and upper tradewater coals are thicker and more continuous and contain high percentages of tree fern spores in addition cordaite pollen is locally abundant in this interval carbondale and shelburn desmoinesian strata are much more laterally continuous and occur within classic cyclothems that can be traced across the coal field cyclothems have long been interpreted as being eustatically driven and glacio eustacy controlled not only sedimentation but also the formation of desmoinesian paleomires palynologically carbondale and shelburn coals are either dominated by lycospora or have heterogeneous palynofloras palynologic and coal quality data suggest that hydrologic base level may have been the primary control on desmoinesian paleomires rather than paleoclimate as the coals display rheotrophic rather than ombrotrophic characteristics

vegetational history of the springfield coal middle pennsylvanian of illinois and distribution patterns of a tree fern miospore thymospora pseudothiessenii based on miospore profiles abstract the vegetational history of the springfield no 5 coal member in the southwestern and southeasternmost portion of the illinois basin is reconstructed from palynological profiles of the coal seam in most parts of the swamp dominance was shared by arborescent lycopods that produced lycospora granulata and two tree ferns that produced thymospora pseudothiessenii and laevigatosporites globosus the profiles suggest that populations of the thymospora producing tree fern occupied sites for long periods in the southwestern portion of the basin vegetation changes can be correlated to the splitting of a coal in the proximity to a paleochannel a greater understanding of the ecological requirements of some of the spore taxa of the springfield coal is seen by the patterns of the same taxa in surrounding spoon and carbondale coals some taxa appear to be more generalists and other more specialists that are more restricted to a certain type of coal

a new measure of entrainment zone structure 1 a wavelet covariance algorithm designed to objectively identify the upper and lower limits of the local transition zone between boundary layer and free troposphere is applied to the output fields from a series of large eddy simulations of the convective atmospheric boundary layer a new measure of entrainment zone structure is defined the normalized difference between the standard deviations of the local transition zone limits this is found to be a function of the convective richardson number and a predictor of normalized entrainment rate this provides a robust and objective means for determining the richardson number from remote sensing observations and the basis for determining the entrainment rate

dust production by abrasion of eolian basalt sands analogue for martian dust dust is nearly ubiquitous on mars covering much of the planet s surface having been redistributed by dust storms analysis of dust via landed instrumentation indicates a basaltic composition for its protolith the same is interpreted for the dark dune sands encountered at rover field sites in this paper we used samples of aeolian sands derived from basaltic volcanoes in an experiment to simulate dust production from basalt dune sands within an abrasion chamber in addition we used samples from gypsum dunes because gypsum is found within dune fields on the northern plains of mars the results expressed as weight of sample reduced to dust show a remarkably broad range over four orders of magnitude aeolian abrasion of basalt sands can produce similar amounts of dust as is the case for some desert sands on earth some plausible mars analogue materials can produce large amounts of dust suggesting that aeolian movement of basaltic sand and volcanic sediments on the surface of mars is a potential source of fine grained sediment or dust

the so called paleophytic mesophytic transition in equatorial pangea multiple biomes and vegetational tracking of climate change through geological time abstract the paleophytic mesophytic and cenophytic were originally conceptualized as chronostratigraphic intervals not specific floras and were used principally in that way for about 100 years they supposedly reflected massive irreversible biotic changes on land that were thought to have happened about half a geological period prior to the changes in marine faunas that mark the more traditional geological era boundaries the terms were applied initially only to terrestrial rocks from the euramerican portions of equatorial pangea especially parts of central europe where the boundary between the paleophytic and mesophytic the eras of interest here was placed at the top of the german rotliegends more recently the terms have been coopted to describe vegetation types not chronostratigraphic units even to the point where specific linnean ordinal or class level clades evolutionary lineages of plants have been attributed solely to one vegetation type or the other at a global level furthermore the paleophytic mesophytic transition has been recognized in the largely taxonomically distinct vegetation types of temperate as well as the equatorial paleolatitudes the result of this conceptual coopting of terms that already were of questionable value is a blurring of the concepts almost to the point of meaninglessness a reading of the literature indicates confusion in terms of what represents the paleophytic flora vs the mesophytic flora the botanical basis for the floras and the taxonomic scale at which they can be recognized the geographic pattern and temporal correlation of the supposed transition and the evolutionary and ecological significance of the vegetational changes these terms supposedly capture we propose that these terms be completely and utterly abandoned as confusing and worse yet misleading evidence suggests that paleozoic vegetation tracked climate which should not come as a surprise in light of what is known of plant dynamics in the holocene and recent furthermore the evidence for a global paleophytic vs mesophytic vegetation is simply unsubstantiated by the fossil record rather there appears to have been a complex of global species pools reflecting climate at many spatio temporal scales the vegetational changes occurring in the late paleozoic thus can be understood best when examined as spatial temporal changes in biome scale species pools responding to major global climate changes locally and regionally manifested

changing patterns of pennsylvanian coal swamp vegetation and implications of climatic control on coal occurrence abstract improved regional and interregional stratigraphic correlations of pennsylvanian strata permit comparisons of vegetational changes in euramerican coal swamps the coal swamp vegetation is known directly from in situ coal ball peat deposits from more than 65 coals in the united states and europe interpretations of coal swamp floras on the basis of coal ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps changes in composition of pennsylvanian coal swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate paleobotany and paleogeography of the euramerican province indicate a moist tropical paleoclimate rainfall runoff and evapotranspiration were the variable climatic controls in the distribution of coal swamp vegetation peat accumulation and coal resources in relative terms of climatic wetness the pennsylvanian period is divisible into five intervals which include two relatively drier intervals that developed during the lower middle and middle upper pennsylvanian transitions the climate during early pennsylvanian time was moderately wet and the median in moisture availability early middle pennsylvanian was drier probably seasonally dry wet late middle pennsylvanian was the wettest in the midcontinent early late pennsylvanian was the driest and late late pennsylvanian was probably the wettest in the dunkard basin the five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation regional differences in basinal geology and climate were significant variables but the synchronous control of paleoclimate was of primary importance

dark material in the polar layered deposits and dunes on mars viking infrared thermal mapping and bistatic radar data suggest that the bulk density of the north polar erg material is much lower than that of the average martian surface or of dark dunes at lower latitudes we have derived a thermal inertia of 245 280 j m 2 s 1 2 k 1 5 9 6 7 10 3 cal cm 2 s 1 2 k 1 for the proctor dune field and 25 150 j m 2 s 1 2 k 1 0 6 3 6 10 3 cal cm 2 s 1 2 k 1 for the north polar erg the uniqueness of the thermophysical properties of the north polar erg material may be due to a unique polar process that has created them the visible and near infrared spectral reflectance of the erg suggests that the dark material may be composed of basalt or ferrous clays these data are consistent with the dark material being composed of basaltic ash or filamentary sublimate residue fsr particles derived from erosion of the layered deposits dark dust may be preferentially concentrated at the surface of the layered deposits by the formation of fsr particles upon sublimation of water ice further weathering and erosion of these areas of exposed layered deposits may form the dark saltating material that is found in both polar regions dark fsr particles may saltate for great distances before eventually breaking down into dust grains re mixing with the global dust reservoir and being recycled into the polar layered deposits via atmospheric suspension

persistence of late carboniferous tropical vegetation during glacially driven climatic and sea level fluctuations abstract the late carboniferous glaciation reached its peak during the latter part of the westphalian late desmoinesian in the tropical illinois basin this was the time of deposition of the carbondale and lower modesto formations characterized by the cyclic repetition of major coal deposits black shales limestones gray shales and sandstones these lithological changes evidence repeated major fluctuations in climate and sealevel fossil floras from the tropical ever wet to seasonally wet terrestrial lithofacies coals and shales above coals remain compositionally similar throughout the 1 1 5 m y time interval floras from coals known from coal balls and palynology characteristically were composed of three major plant communities the wettest sites were dominated by monocarpic lycopsids intermediate sites were dominated by polycarpic lycopsids and areas subject to fires and intermittent flooding were dominated by medullosans and the small lycopsid paralycopodites clastic substrate environments were dominated by ferns and pteridosperms and conform to a single biozone indicating their compositional unity and distinctness from earlier and later assemblages the composition of lowland floras is poorly known from times between the deposition of coals and associated terrestrial rocks intervals during which most of the lowlands were flooded and marine rocks were being deposited consequently the temporally intermittent recurrence of lowland floras despite repeated widespread environmental disruption may be explained either by vegetational persistence and migration of floras or repeated disruption and reassembly several lines of evidence suggest persistence as a likely explanation

individual particles and martian aeolian action a review abstract evidence for aeolian activity on mars is presented sand sized particles of quartz and basalt were abraded in the laboratory under characteristic earth and martian velocity and pressure conditions and the types of surface features relief were studied with the scanning electron microscope in addition silt and clay produced under these conditions was examined with both scanning and transmission electron microscopy during the experiments electrostatic aggregates of clay and fine silt were produced electrostatic charging by mechanical abrasion seems to have occurred and may be related to the presence of aggregates on mars abrasion appears to be more vigorous under martian than earth conditions given the same mineralogy and particle sizes on the two planets this is probably due to the higher velocities required for martian aeolian activity electrical charging due to particle breakage may be important on mars as deduced from simulation experiments and the data from the viking orbiters and landers additionally experiments with basalt at high abrasion velocities suggests that mineral surfaces on mars may be structurally deformed thus weathering might be more rapid if water were present in the atmosphere and regolith finally during laboratory aeolian abrasion submicron sized quartz particles were produced but material of this type is not found in sediments on earth fine grained sediments should be reexamined to look for these fine particles as the production of clay sized material has important consequences both for erosion and weathering on earth and mars

paleobotanical and paleoecological constraints on models of peat formation in the late carboniferous of euramerica abstract the dominant plants of the late carboniferous lowland tropics were taxonomically and structurally distinct from those of any later time periods dominance was distributed among lycopsids ferns sphenopsids pteridosperms and cordaites and each of these groups had distinctive and different ecological preferences and amplitudes peat forming habitats were dominated by lycopsids throughout the westphalian with a significant cordaitean element in the middle westphalian during the stephanian tree ferns were dominant following major extinctions near the westphalian stephanian transition each of the major plant groups had distinctive architectures and tissue composition trees contributed up to 95 of the peat biomass and tree forms of lycopsids psaronius and medullosa lack good modern analogues the cordaites were the only woody plant group to contribute significantly to peat and then only during the mid westphalian structurally wood like lycopsid bark is the major woody tissue encountered in most westphalian coals tree ferns and pteridosperms were largely parenchymatous in construction the stigmarian root systems of lycopsids also were largely parenchymatous the tissue structure of these dominant plant suggests the need for extreme caution in the inference of mire ecological conditions or vegetational structure from coal petrographic data peat formed under arborescent ferns or pteridosperms or peat repeatedly exposed to decay and rerooting by stigmarian root systems of lycopsids would have a distinctly non woody signature and yet would have formed in a forested environment a summary is presented of the autecology and synecology of mire plants emphazing the structural framework provided by lycopsids during the westphalian certain constraints in the links between peat biomass and miospore palynology are discussed in terms of over representation under representation and non representation the formulation of smith s four phase hydroseral model is discussed and compared with more recent data available from plant paleoecology the current debate over an ombrotrophic vs rheotrophic origin of late carboniferous peats relies in large part on paleobotanical data almost entirely palynological in combination with petrographic analyses ecological studies of miospores and of coal ball and compression macrofossils and the linkage of miospores to source plants permit the re evaluation of mire successional models evidence for tree lycopsids sphenopsids pteridosperms and cordaites suggests growth mainly in rheotrophic mires tree ferns are likely candidates for growth in domed mires although evidence is ambiguous and some tree ferns clearly grew under rheotrophic conditions densospores produced by at least sporangiostrobus lycopsid subtrees have been considered diagnostic of ombrotrophic conditions abundant evidence refutes this simplistic interpretation and suggests broad ecological amplitudes for densospore producers including growth under rheotrophic conditions although plant fossils alone can not resolve most of the major debates in modern coal geology paleobotany does contribute significantly to our understanding of ancient mires an approach combining paleobotanical data with petrography sedimentology and geochemistry on a case by case basis is most likely to produce a clear picture

dynamics of sheared convective boundary layer entrainment part i methodological background and large eddy simulations abstract the reported study examines the dynamics of entrainment and its effects on the evolution of the dry atmospheric convective boundary layer cbl when wind shear is present the sheared cbl can be studied by means of direct measurements in the atmosphere laboratory studies and numerical techniques the advantages and disadvantages of each technique are discussed in the present paper which also describes the methodological background for studying the dynamics of entrainment in sheared cbls for the reported study large eddy simulation les was chosen as the primary method of convective entrainment investigation twenty four les runs were conducted for cbls growing under varying conditions of surface buoyancy flux free atmospheric stratification and wind shear the simulations were divided into three categories cbl with no mean wind ns cbl with a height constant geostrophic wind of 20 m s 1 gc and cbl with geostrophic wind shear gs in the simulated cases the sheared cbls grew fastes

uplands lowlands and climate taphonomic megabiases and the apparent rise of a xeromorphic drought tolerant flora during the pennsylvanian permian transition abstract the late mississippian and pennsylvanian have been referred to as the coal age due to enormous paleotropical peat accumulations coal beds numerous fossil floras have been collected from these coals and their associated seat earth paleosols and roof shales over more than two centuries leading to the inference of vast swampy wetlands covering the pangean tropics during the pennsylvanian in contrast the permian tropics are characterized as more arid with sparser and more heterogeneous vegetation than inferred for the pennsylvanian in the tropics the pennsylvanian to permian transition has been described as a changeover from a pteridophyte dominated paleophytic flora to a seed plant dominated mesophytic flora this view notwithstanding floras dominated by xeromorphic seed plants also are well known from the pennsylvanian tropics some authors have characterized these plants as being occupants of uplands subsequently transported into basinal lowland preservational environments in this model uplands are well drained causing areas of drought under otherwise everwet climates in this paper we present an alternative interpretation that the apparent transition in pennsylvanian permian tropical vegetation reflects two types of taphonomic megabias first is a preservational megabias strongly favoring the vegetation of humid climates over that of seasonally dry climates accordingly tropical plant preservational potential fluctuated in concert with late paleozoic ice age glacial interglacial oscillations and contemporaneous sea level and climatic changes second is an analytical megabias strongly favoring the discovery and collection of the wetland biome from pennsylvanian strata overlooking the less frequently and more poorly preserved drought tolerant biome by permian times vast wetlands and their fossil record had largely disappeared from central pangea although continuing in cathaysia making drought tolerant vegetation more visible to searchers without changing its preservational circumstances we demonstrate that the upland model is untenable being inconsistent with the principles of plant biogeography and with geological aspects of the fossil record

palaeoclimatic and site specific conditions in the early permian fossil forest of chemnitz sedimentological geochemical and palaeobotanical evidence abstract as significant indicators of deep time palaeoclimate a number of new palaeontological pedological and geochemical characteristics are provided for the chemnitz fossil lagerstatte to depict more precisely its environmental conditions for the first time several lines of evidence indicate that this fossil forest instantaneously preserved by volcanic deposits once received an annual precipitation of around 800 1100 mm but grew on a nearly unweathered palaeosol although the composition of this rich and diverse t0 assemblage suggests a hygrophilous dense and multi aged vegetation dominated by conservative lineages the habitat was affected by environmental disturbances and pronounced seasonality repeated changes in local moisture availability are suggested by geochemical proxies the co occurrence to intergrowth of calcic and ferric glaebules in the palaeosol and developmental traits of perennial vegetational elements specific substrate adaptation is reflected by different root systems and cyclic growth interruptions recorded in the stems branches and roots of long lived woody plants many differentially adapted terrestrial animals complete the more comprehensive reconstruction of a late sakmarian ecosystem and its climatic and preservational controls albeit spatially confined this diverse in situ record may contribute to understand wetland dryland dynamics of sub tropical northern hemisphere pangaea

confirmation of carboniferous clastic swamp communities tropical lowlands dominated by arborescent lycophytes are the principal foci for our understanding of carboniferous peat and non peat accumulating coastal swamps1 2 suggested palaeoeco logical interpretations of various lycophytes and accessory vegetation have been based on transported compression assemblages3 4 and palynomorphs5 6 or in situ permineralized peats7 where transported macrodetritus resulting in compression assemblages is used to reconstruct past vegetational patterns taphonomic factors tend to bias the preserved flora8 11 taken alone or out of depositional context the heterogeneity of an assemblage most probably bears little or no relationship to that of the original contributing communities gastaldo9 suggests that reconstructions should be based on the autecology of erect in situ plants because with peats permineralized in situ precise resolution in time of laterally equivalent vegetation is difficult here i document an erect in situ early pennsylvanian lycophyte swamp which provides the first confirmatory evidence for previously hypothetical ecological amplitudes

coal facies studies in the eastern united states coals in the eastern united states east of the mississippi river have been the subject of a number of coal facies studies going back to the 19th century such studies would not necessarily fall within a strict modern classification of coal facies studies but if a study encompassed some aspects of paleobotany palynology petrology geochemistry or sedimentology we assumed that some data and interpretations may be of use in evaluations of the facies references are presented as a guide for further research with annotation in the tables

changes in dominance patterns in upper carboniferous plant fossil assemblages upper carboniferous pennsylvanian terrestrial clastic rocks from north america and europe contain compression impression plant fossil assemblages that represent the remains of plant communities that grew on floodplains levees and other clastic facies of fluvial and deltaic lowlands quantitative analysis of 66 plant fossil assemblages spanning the entire late carboniferous demonstrates that before the middle of the westphalian d stage the majority of plant fossil assemblages are dominated by pteridosperms and sphenopsids lycopods and cordaites dominate only a few assemblages counted ferns do not dominate any assemblages these findings contrast sharply with the dominance of lycopods reported by others from coal swamps of the same time interval above the middle of the westphalian d however one third of the compression impression assemblages counted are dominated by ferns the change in dominance pattern in compression impression plant fossil assemblages occurs half a stage earlier than the previously reported change from lycopod dominated to fern dominated assemblages at the westphalian stephanian boundary in coal swamps a trend toward dryer climate during westphalian d apparently influenced plants growing on better drained alluvial soils earlier than those growing on water logged soils of contemporaneous coal swamps

palynological correlation of major pennsylvanian middle and upper carboniferous chronostratigraphic boundaries in the illinois and other coal basins

wind driven particle mobility on mars insights from mars exploration rover observations at el dorado and surroundings at gusev crater 1 the ripple field known as el dorado was a unique stop on spirit s traverse where dust raising active mafic sand ripples and larger inactive coarse grained ripples interact illuminating several long standing issues of martian dust mobility sand mobility and the origin of transverse aeolian ridges strong regional wind events endured by spirit caused perceptible migration of ripple crests in deposits sse of el dorado erasure of tracks in sandy areas and changes to dust mantling the site localized thermal vortices swept across el dorado leaving paths of reduced dust but without perceptibly damaging nearly cohesionless sandy ripple crests from orbit winds responsible for frequently raising clay sized dust into the atmosphere do not seem to significantly affect dunes composed of more easily entrained sand sized particles a long standing paradox this disparity between dust mobilization and sand mobilization on mars is due largely to two factors 1 dust occurs on the surface as fragile low density sand sized aggregates that are easily entrained and disrupted compared with clay sized air fall particles and 2 induration of regolith is pervasive light toned bed forms investigated at gusev are coarse grained ripples an interpretation we propose for many of the smallest linear light toned bed forms of uncertain origin seen in high resolution orbital images across mars on earth wind can organize bimodal or poorly sorted loose sediment into coarse grained ripples coarse grained ripples could be relatively common on mars because development of durable well sorted sediments analogous to terrestrial aeolian quartz sand deposits is restricted by the lack of free quartz and limited hydraulic sediment processing

cyclic changes in pennsylvanian paleoclimate and effects on floristic dynamics in tropical pangaea abstract wetland floras narrowly define perceptions of pennsylvanian tropical ecosystems the so called coal age such wetlands reflect humid to perhumid climate leading to characterizations of pennsylvanian tropics as everwet swampy these views are biased by the high preservation potential of wetlands sedimentation patterns paleosols and fossil floras indicate the presence of vegetation tolerant of subhumid to dry subhumid perhaps semi arid climate in basins between peat formation times understanding the significance of this seasonally dry vegetation has suffered from conceptual and terminological confusion a clearer view has emerged as models for framing the data have improved basinal floras typical of seasonally dry conditions relatively low soil moisture regimes are well documented but mainly from isolated deposits some of the earliest dominated by primitive pteridosperms flozfern floras occur in clastic rocks between european early pennsylvanian coal beds later early pennsylvanian fern cordaitalean vegetation different from coal floras is preserved in marine goniatite bullions conifers are first suggested by late mississippian potoniesporites pollen about the same time in north america broadleaf foliage lesleya and megalopteris occur in basin margin settings on drought prone limestone substrates the best known xeromorphic floras found between coal beds appear in the middle through late pennsylvanian containing conifers cordaitaleans and pteridosperms the middle pennsylvanian appearances of this flora are mainly allochthonous though parautochthonous occurrences have been reported parautochthonous assemblages are mostly late pennsylvanian the conifer flora became dominant in western and central pangaean equatorial lowlands in earliest permian location of the humid perhumid wetland flora during periods of relative dryness though rarely discussed is as or more perplexing than the spatial location of seasonally dry floras through time wetland plants had few migratory options and possibly survived in small refugia within and outside of basins coupled oscillations in climate sea level and vegetation were driven most likely by glacial interglacial fluctuations perhaps controlled by orbital cyclicity

vegetational zonation in a swamp forest middle pennsylvanian illinois basin u s a indicates niche differentiation in a wetland plant community abstract a rich fossil flora occurs in the roof shale of the middle pennsylvanian moscovian age springfield coal flanking the galatia channel a river deposit approximately 1 km in width and 150 km long partially contemporaneous with the springfield peat swamp siltstone and sandstone 30 m thick were deposited in the channel during the final estuarine phase the river formed under seasonal subhumid climate during early deglaciation as marine waters retreated from the land surface it existed continuously through glacial maximum under increasingly humid climate as a low sediment or black water river with peat along its flanks during early deglaciation under subhumid climate and sea level rise the river became a sediment laden estuary drowning the peat swamp and burying vegetation in place under extensive mudflats this buried flora was studied in three underground mines in southern illinois permitting vegetation to be characterized spatially three transects comprising 100 sites a total linear distance of 12 km reveal distinct zonation perpendicular to the channel margin an innermost belt 0 5 to 2 5 km wide consists almost exclusively of the pteridosperm neuropteris flexuosa north of a river bend three belts succeed the n flexuosa zone mixed pteridosperms and marattialean tree ferns mixed arborescent lycopsids and marattialians lycopsids with rare marattialians south and inside the same bend n flexuosa is succeeded by mixed lycopsids particularly sigillaria and marattialean ferns within the transects marattialian ferns have wider distribution than other groups suggesting broader environmental tolerances neuropteris flexuosa channel margin mono dominance may reflect high sedimentation rates elevated nutrient conditions or floating seed dispersal lycopsid dominance in interior areas conforms with tolerance of deep standing water the spatial scale examined affects our perception of community assembly overall distinct vegetational zonation suggests niche assembly however within vegetational bands there is considerable small scale spatial variation suggesting stochastic properties

stratigraphic and interregional changes in pennsylvanian coal swamp vegetation environmental inferences abstract quantitative analysis of pennsylvanian coal swamp vegetation provides a means of inferring organization and structure of communities distribution of these communities further provides inferences about environmental factors including paleoclimate our observations are based on in situ structurally preserved peat deposits in coal ball concretions from 32 coal seams in the eastern one half of the united states and from several seams in western europe and on spore assemblages from more than 150 seams there were three times of particularly significant and nearly synchronous vegetational changes in the midcontinent and appalachian coal regions during the pennsylvanian period each was different in kind and magnitude the first marked changes occurred during the early part of the middle pennsylvanian with the fluctuating decline in the high level of lycopod dominance the abundance of cordaites increased there was a rise in the occurrences of the lycopod herbs to form intercalated marshlands and an overall increase in floral diversity changes ensuing from this time also include shifts in dominant species of lycopod trees and a sustained rise in abundance and diversity of tree fern spores the next significant time of change was during the middle part of the middle pennsylvanian representing both a culmination of earlier trends and expansions of cordaites in the midcontinent where there was a maximum change in species without net loss of diversity tree ferns and medullosan pteridosperms attained subdominant levels of abundance and diverse lycopod species dominated except in the atokan desmoinesian transition of the midcontinent the third and sharpest break occurred near the middle late pennsylvanian boundary when extinctionsof the dominant coal swamp lycopods allowed development of tree fern dominance the late pennsylvanian coal swamps apparently were colonized or recolonized mainly by species from outside coal swamps rather than by the survivor populations of the middle pennsylvanian swamps paralleling the changes in floras through the pennsylvanian are changes in preservational aspects of the peat these include a decline in shoot root ratios from approximately 1 to

paleoecology of the late pennsylvanian age calhoun coal bed and implications for long term dynamics of wetland ecosystems quantitative plant assemblage data from coal balls miospores megaspores and compression floras from the calhoun coal bed missourian of the illinois basin usa are used to interpret spatial and temporal changes in plant communities in the paleo peat swamp coal ball and miospore floras from the calhoun coal bed are dominated strongly by tree ferns and pteridosperms and sigillarian lycopsids are subdominant depending on geographic location within the coal bed although the overall composition of calhoun peat swamp assemblages is consistent both temporally and spatially site to site differences and short term shifts in species dominance indicate local topographic and hydrologic control on species composition within the broader context of the swamp statistical comparison of the calhoun miospore assemblages with those from other late pennsylvanian coal beds suggests that the same basic species pool was represented in each peat swamp landscape and that the relative patterns of dominance and diversity were persistent from site to site therefore it appears that the relative patterns of proportional dominance stayed roughly the same from one coal bed to the next during late pennsylvanian glacially driven climatic oscillations

place vs time and vegetational persistence a comparison of four tropical mires from the illinois basin during the height of the pennsylvanian ice age abstract coal balls were collected from four coal beds in the southeastern part of the illinois basin collections were made from the springfield herrin and baker coals in western kentucky and from the danville coal in southwestern indiana these four coal beds are among the principal mineable coals of the illinois basin and belong to the carbondale and shelburn formations of late middle pennsylvanian age vegetational composition was analyzed quantitatively coal ball samples from the springfield herrin and baker are dominated by the lycopsid tree lepidophloios with lesser numbers of psaronius tree ferns medullosan pteridosperms and the lycopsid trees synchysidendron and diaphorodendron this vegetation is similar to that found in the springfield and herrin coals elsewhere in the illinois basin as reported in previous studies the danville coal sample which is considerably smaller than the others is dominated by psaronius with the lycopsids sigillaria and synchysidendron as subdominants coal balls from the springfield coal were collected in zones directly from the coal bed and their zone by zone composition indicates three to four distinct plant assemblages the other coals were analyzed as whole seam random samples averaging the landscape composition of the parent mire environments this analysis indicates that these coals separated from each other by marine and terrestrial clastic deposits have essentially the same floristic composition and thus appear to represent a common species pool that persisted throughout the late middle pennsylvanian despite changes in baselevel and climate attendant the glacial interglacial cyclicity of the pennsylvanian ice age patterns of species abundance and diversity are much the same for the springfield herrin and baker although each coal both in the local area sampled and regionally has its own paleobotanical peculiarities despite minor differences these coals indicate a high degree of recurrence of assemblage and landscape organization the danville departs dramatically from the dominance diversity composition of the older coals presaging patterns of tree fern and sigillaria dominance of late pennsylvanian coals of the eastern united states but nonetheless built on a species pool shared with the older coals

common ground between two british pennsylvanian wetland floras using large first hand datasets to assess utility of historical museum collections abstract studies on the macrofloral record of the pennsylvanian palaeotropical peat forming wetlands coal swamps depend heavily on historical collections in museums this paper examines the robustness of such collections for macrofloral studies 110 000 individually recorded specimens from south wales field collected by david davies during the early 20th century were compared with the 6500 museum voucher specimens derived from them eventually intended for a representative teaching collection this showed that the voucher collections accurately reflect the order of abundances of the plant groups as documented in the field records but not their actual numerical abundances these welsh data were then compared with the available museum collections for similar aged macrofloras in the nearby bristol somerset coalfield cluster analyses and detrended correspondence analyses were performed 1 on the raw data recorded on the museum labels 2 on standardised data that were updated to reflect the currently accepted taxonomy for these fossils and 3 on standardised data in which single occurrences of taxa have been removed the results suggest that unstandardised museum collection data can reveal meaningful biostratigraphical and biogeographical patterns but that these become clearer with the standardised data the effect of removing the singleton taxa was less clear although it did provide a slightly enhanced resolution with cluster analysis whilst previous studies have considered these to be separate basins with the bristol somerset coalfield being proximal to south wales on the mid pennsylvanian variscan front results show an overall consistency between the two basins and suggest a common gene pool and vegetational physiognomy as well as a general stasis through time based on relatively stable environmental and growth conditions the study confirms that even unrevised historical collections can provide some data to help understand the dynamics of these systems however it also underlines the importance of taxonomy in such studies as it helps improve both the biostratigraphical and biogeographical resolution

palaeoecological and possible evolutionary effects of early namurian serpukhovian carboniferous glacioeustatic cyclicity early namurian serpukhovian carboniferous sedimentary cycles in the throckley and rowlands gill boreholes near newcastle upon tyne uk consist of fossiliferous limestones overlain by usually unfossiliferous black mudstone followed by sandstones and often by thin coal seams sedimentological and regional geological evidence suggests that the largest are high amplitude cycles probably of glacioeustatic origin 13 c bulk organic matter delineates marine and non marine conditions because of the large difference between terrestrial and marine 13 c and indicates that full marine salinity was only intermittent and resulted from glacioeustatic marine transgression superimposed on a background of inundation by freshwater from large rivers which killed off the marine biota palynology suggests that plant groups including ferns and putative pteridosperms were affected by changing sea level and that there is a theoretical possibility of connection between cyclicity and the first appearance of walchiacean conifer like monosaccate pollen such as potonieisporites long term terrestrial and marine increasing 13 c organic may reflect the onset of major glaciation in gondwana as there is evidence to suggest that the two are coeval but no specific mechanism can be suggested to link the trends

structure of the entrainment zone capping the convective atmospheric boundary layer the authors use large eddy simulation les to investigate entrainment and structure of the inversion layer of a clear convectively driven planetary boundary layer pbl over a range of bulk richardson numbers ri the les code uses a nested grid technique to achieve fine resolution in all three directions in the inversion layer extensive flow visualization is used to examine the structure of the inversion layer and to illustrate the temporal and spatial interaction of a thermal plume and the overlying inversion it is found that coherent structures in the convective pbl that is thermal plumes are primary instigators of entrainment in the ri range 13 6 ri 43 8 at ri 5 13 6 strong horizontal and downward velocities are generated near the inversion layer because of the plume interface interaction this leads to folding of the interface and hence entrainment of warm inversion air at the plume s edge at ri 5 34 5 the inversion s strong stability prevents folding of the interface but strong horizontal and downward motions near the plume s edge pull down pockets of warm air below the nominal inversion height these pockets of warm air are then scoured off by turbulent motions and entrained into the pbl the structure of the inversion interface from les is in good visual agreement with lidar measurements in the pbl obtained during the lidars in flat terrain field experiment a quadrant analysis of the buoyancy flux shows that net entrainment flux or average minimum buoyancy flux wu min is identified with quadrant iv w2u1 0 motions that is warm air moving downward plumes generate both large negative quadrant ii w1u2 0 and positive quadrant iii w2u2 0 buoyancy fluxes that tend to cancel the maximum vertical gradient in potential temperature at every x y grid point is used to define a local pbl height zi x y a statistical analysis of zi shows that skewness of zi depends on the inversion strength spectra of zi exhibit a sensitivity to grid resolution the normalized entrainment rate we w where we and w are entrainment and convective velocities varies as ari21 with a 0 2 in the range 13 6 ri 43 8 and is in good agreement with convection tank measurements for a clear convective pbl the authors found that the finite thickness of the inversion layer needs to be considered in an entrainment rate parameterization derived from a jump condition

properties of electrostatic aggregates and their possible presence on mars abstract experiments indicate that at the high wind velocities characteristic of portions of the martian surface sand sized particles will break down to silt and clay which will then inevitably form sand sized aggregates basalt and olivine aggregates held together by electrostatics were produced in an eolian abrasion device and their mass properties studied it was difficult to examine aggregates after formation as they separate and reform with very little handling since electrostatic binding forces are quite weak it is shown that aggregates range from 60 to more than 600 m in diameter that they generally are spheroidal in shape and become more elongate with increasing size and that they tend to be layered with the inner portions more tightly bound than outer layers after about one and one half years some aggregates lose their charge which is replaced with moisture the aggregates retain their original sizes and shapes none of the properties of electrostatic aggregates so far investigated are incompatible with the presence of these materials on mars

paleoecology of the springfield coal member desmoinesian illinois basin near the leslie cemetery paleochannel southwestern indiana abstract the springfield coal member carbondale group petersburg formation of indiana is split locally in warrick and gibson counties indiana by clastic rocks of the folsomville member carbondale group petersburg formation that represent the leslie cemetery paleochannel part of a large interconnected paleochannel system in the springfield coal bed this study incorporated analysis of miospore and megaspore assemblages coal petrography plant compression fossils and conodonts from the coal and clastic split to document changes in the swamp and its vegetation in response to the activity of the leslie cemetery paleochannel palynological and petrographic data indicate that environmental conditions and vegetation in the lower bench of coal near the leslie cemetery paleochannel were similar to those found in profiles through the coal bed at sites near the larger more extensive galatia paleochannel miospore floras of the high vitrinite lower bench of coal were dominated by tree fern miospores with those of lycopsids ranking second in abundance megaspore assemblages were dominated by lycopsid megaspores near the contacy between the lower bench of coal and clastic split medullosan prepollen increases in abundance and fusain bands are more common which may indicate the occurrence of fire either within or outside the swamp vegetation in the folsomville member and upper bench of coal differ markedly from that of the lower bench of coal plant megafossils from the folsomville member indicate dominance by pteridosperms and or lycopsids and folsomville member miospore assemblages are dominated by lycopsid miospores most typically found in mudstones including lycospora torquifer and higher than normal abundances of granasporites medius in the transition from clastic rocks of the folsomville member to the upper bench of coal miospores of ecotonal lycopsids paralycopodites reach their peak abundance pteridosperms dominate megafossil assemblages and inertinite levels are relatively high at higher levels of the upper bench of coal vitrinite levels are higher and miospore assemblages are dominated by lycopsid miospores typical of coal swamps lycospora granulata l pusilla the presence of conodonts in coalballs in the upper bench of coal and spirorbid worms in the split indicate that the paleoswamp may have received some marine or brackish water influence higher than normal salinity levels may explain the vegetational changes observed in the upper bench of coal near the leslie cemetery paleochannel

paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks climate is a primary control on sediment flux from continental sources into sedimentary systems in warm climates siliciclastic input is greatest under highly seasonal rainfall nonseasonal conditions favor formation of end member chemical rocks perennially wet climates are conducive to coal formation whereas dry climates produce carbonates and or evaporites stratigraphic repetition of siliciclastic and chemical rocks therefore appears to be related to paleoclimate cycles as well as to transgressive regressive events and tectonics