Silty Deposits Research Articles

Magdalenian settlement on the edge of the loess island: A case study from the northern foreland of the Carpathians (SE Poland)

Abstract The subject of interdisciplinary studies was the Magdalenian archaeological site and its vicinity situated in the SE part of Kolbuszowa Plateau (Sandomierz Basin, SE Poland). The results of geoarchaeological analysis were not limited only to the area of archaeological excavations, but also include a wider background. From palaeogeographical point of view very important was the geomorphical location of the camp on the periphery of unique loess island close to valley of San River (tributary of Vistula). Analyzed soil profiles – with cultural layer very attractive for archaeologists – represent facies of sandy-silty deposits mainly formed by deluvial and aeolian processes active in the margin of a quite large, morphologically diversified loess island. The lower part of the studied sediments was deposited simultaneously with the youngest loesses, which were accumulated in the close proximity. The deposition of sandy-silty deposits continued during Late Glacial and ended in Younger Dryas when in the adjacent loess zone there were formed stratified silty deposits of deluvial-aeolian origin. This spatial variability of deposits, which were accumulated in a small area, resulted undoubtedly from local conditions and favoured the development of different plant communities at the time when the camp was functioning. Geological research carried out in the Kolbuszowa Plateau provided an answer to the question about the time and conditions of the stay of Magdalenian hunters. This stay coincided with the period of stopped activity of aeolian-slope processes and stabilization of ground surface by grass vegetation when the big meandering river functioned in the deepened valley. Place for the camp was undoubtedly selected on account of its geomorphological qualities – location on the slope sheltered from westerly winds and with extensive view over the surrounding area, at the confluence of two rivers. According to presented data, small groups of Magdalenian hunters appeared on the loess island and in its immediate surroundings in the Allerod. Advantages of this area were as follows: geographical situation near the main migration route, the proximity to the junction of ecological corridors, diversified relief with good observation points and safe places for camp location, access to water and diverse vegetation cover with forests as well as grass areas attracting the game. Finally, despite the peripheral nature of settlement and generally poor traces of stay of the Magdalenian groups in SE Poland, both the features of lithic inventories and settlement strategies fit perfectly with the picture of the Magdalenian complex in Central Europe.

Seismic slip on the west flank of the Upper Rhine Graben (France–Germany): evidence from tectonic morphology and cataclastic deformation bands

Abstract The Upper Rhine Graben (URG) is a seismically active tectonic structure in intraplate Europe. Large and moderate earthquakes have occurred along the URG in the past but no coseismic surface faulting has been reported so far. We investigated active faulting along the western edge of the northern URG and identified the 25 km-long linear Riedseltz–Landau normal fault scarp as a major tectonic structure affecting late Pleistocene and Holocene deposits. The fault zone is exposed in the Riedseltz quarry where it affects Pliocene sand and gravels and overlying late Pleistocene (Wurm) units. These units have not been buried deeper than a few tens of metres and yet the fault zone contains cataclastic deformation textures. Cataclasis is demonstrated by spalling and transgranular fractures in quartz grains concentrated in deformation bands with reduced grain size. The observed microstructures suggest multiple phases of deformation with cataclasis followed by emplacement of a prominent Fe-oxide matrix into deformation bands, and later emplacement of a clay-rick matrix into fractures. Previous geological and geophysical studies along the fault show late Pleistocene (Wurm) loess deposits ( c. 24–10 ka before present) and early Holocene sand–silty deposits with individual or cumulative 1.5 and 0.7 m surface slip, respectively. Field observations and previous results from shallow geophysics provide a minimum 0.15 mm a −1 time-averaged slip rate. The Riedseltz fault parameters integrated in a dislocation model suggest a minimum Mw 6.6 earthquake as a plausible scenario in the northern URG. The observations of cataclasis in shallowly buried sediments coupled with observations of the late Quaternary fault scarp call for palaeoseismic studies that may document the occurrence of a larger earthquake on the western edge of URG. Surface faulting of young, shallowly buried sediments associated with cataclasis provides new evidence for assessing the occurrence of large earthquakes and seismic hazard assessment in the northern URG.

Upper Pleistocene palaeoenvironmental changes at the Zwierzyniec site, central Poland

The paper presents the data on an Eemian–Late Glacial sedimentary sequence from the Zwierzyniec site, central Poland. A number of boreholes document one or two organic layers that occur beneath one or two horizons of clayey and silty deposits of ice-dammed lakes. This study demonstrates to which extent the Zwierzyniec site can contribute to a better understanding of the palaeoenvironmental changes during the Eemian–Vistulian time-frame in central Poland. To study it, a multi-proxy approach was applied, involving: palynological and plant macrofossil analysis, study of rounding of quartz grains and morphology of their surface, and investigations of sand mineralogy and till petrography. The results show that a till bed is overlain by a sandy series corresponding to the glacial-interglacial transition. Either one or two distinct peaks of organic accumulation are evidenced by peat horizons. The lower horizon records spectra with hazel and hornbeam, and did, therefore, accumulate in the Eemian. Observed only in some boreholes, the upper peat horizon marks the Brorup (or the lower part of the Rederstall stadial) represented by forest-steppe conditions with patchy mosaics of larch and further transition into sedges and herbaceous taxa. Localized in between the two peat sequences, the sandy horizon marks a long-lasting aeolian transformation with weathering by frost in the Early Vistulian. Again, significant changes of the palaeoenvironmental regime occurred, and are manifested in the one or two horizons of the glaciolacustrine sediments. This corresponded to the last glaciation in the region, when the ice-dammed lakes formed during the Main Stadial.

Mud volcanoes in central Italy: Subsoil characterization through a multidisciplinary approach

Mud volcanoes are common geological phenomenons observed worldwide as in Italy. They are well described in the scientific literature for their morphological, tectonic and hydrogeological features. They represent not only a relevant geological and geomorphological interest but also not negligible elements of hazard and risk associated with the presence of soft and pliable sediments and with the possible unexpected emission of gas and mud. Therefore, the understanding of their structure and hydrogeological circuits in the subsurface is an important key to define hazard and risk conditions in the adjacent areas.This paper deals with a multidisciplinary study including geophysical and hydrochemical surveys undertaken at the Pineto (central Italy) mud volcano site to achieve an interpretative conceptual model explaining the shallow upward migration of deep mud fluids. Shallow electrical and seismic imaging of the mud volcano was obtained using two dimensional and three dimensional (2D–3D) electrical resistivity tomography and 2D reflection seismic surveys. The hydrochemical properties of the rising fluids were assessed by means of seasonal measurements of the chemical–physical parameters, the concentrations of major ions, and some natural isotopes. This mud volcano or mud lump appears as a dome of about 15×10m in size. The height of the crater is 2m approximately, while the diameter of the crater is 2.5m. Emission of fluids and solids (cold brine, mud, gas) occurs from this crater. Upper Pliocene–lower Pleistocene foredeep pelitic deposits (over-compacted clays with silty–sandy levels) overlain by clayey–silty deposits crop out in the area. The survey results seem to reveal that the uprising of deep fluids does not occur exactly below the mud volcano at present. Instead, a high conductivity body is present within a fractured zone in the pelitic deposits at 60m approximately to the ENE. The probable occurrence of a high permeability layer approximately between 20 and 30m below ground level, confined by clay deposits, gives rise to an overpressured mud fluids reservoir. Mud fluids appear to be flowing toward the surface from the reservoir up to the mud volcano crater. The interpretative conceptual model proposed by the authors is a first attempt to explain the shallow upward migration of deep mud fluids in this central Italy mud volcano. The results can be used to identify the uprising of fluids with similar chemical–physical properties even in areas where the superficial and morphological evidence of the volcanic bodies have been obliterated or covered.

Measurements of Texture of Soils Formed from Glaciolimnic Sediments by Areometric Method, Pipette Method and Laser Diffraction Method

Abstract The aim of the research was to compare the results of texture analyses of glaciolimnic sediments deposited in the basins of ice-dammed lakes origin in north eastern Poland. The study was carried out using aerometric method, pipette method and laser diffraction method. The studied soils were classified as Haplic and Mollic Vertisol, Vertic Cambisol, and Gleyic Chernozem. The soils were formed from clayey (clay, heavy clay), loamy (loam, clay loam, sand clay loam) and silty (silt loam, clay loam) deposits. The studied soils did not contain fractions > 2.0 mm. The amounts of clay fraction (< 0.002 mm) measured by areometric and pipette methods were similar and strongly correlated. In comparison to laser diffraction method, these amounts were 3-4-fold higher. The sub-fraction of fine silt (0.02-0.002 mm) predominated in soil formations analyzed by laser diffraction method. In comparison to areometric or pipette method, the amounts of fine silt were 2-4 fold higher. Basing on the calculated sedimentological indices, it was stated that the examined soils were well sorted and the mean grain diameter (GSS) was very low and did not exceed 0.005 mm in areometric and pipette methods, and 0.011 mm in laser diffraction method for clay sediments.

Loess and soils in the eastern Ebro Basin

Wind-blown sandy and silty deposits were formed during the late Quaternary in the NE Iberian Peninsula. They are the most significant in the West Mediterranean region, together with those described in the Tagus River basin (Iberian South Subplateau), forming small scattered patches across parts of the SE Ebro Depression and SW Catalan Mediterranean Range. Two major depositional environments are distinguished. The first (largest) outcrop covers the lower Ebro reaches on the SE border of the Ebro Depression, the Prelitoral Coastal Range and the Móra d'Ebre Basin. A second outcrop, to the north, consists of a few patches scattered over a wide amphitheatre surrounding the western tributaries of the Segre River, from the wind-exposed Segrià platforms to the Almenara Range in its northernmost part. They consist of highly sorted fine sands and silts, 1–12 m thick (though most typically 3–4 m thick), and coarser than typical loess. They are highly uniform, lack any sedimentary structures and are pale ochre. The deposits are calcareous (30–45% CaCO3), basic to alkaline and with some soluble salts.Five selected sequences of primary loess (namely Mas de l'Alerany, Tivissa, Guiamets, Batea and Almenara) were studied to ascertain deposit characteristics and soil development. All sections show a consistent vertical granulometric variability that may be attributed to wind intensity changes, and hinders the recognition of spatial particle size distribution. Pedogenesis is mostly related to calcium carbonate redistribution, which accumulates as nodules, large rhizocretions or biogenic calcite. Secondary gypsum (Batea and Almenara sequences) is probably related to primary gypsum blown from the source areas that was redistributed by leaching and precipitation at the bottom of the profiles. In a few places (Mas de l'Alerany outcrop) a fersialitic, rubefacted-recalcified soil indicates the presence of an older generation of loess. While the dominant WNW winds and particle coarseness suggest that the loess originates from nearby alluvial fans and fluvial plains, the presence of gypsum and Mg anomalies may be evidence of more distant sources of the Central Ebro Depression and Ondara-Corb alluvial fans.Optical Stimulated Luminiscence (OSL) ages for the more recent deposits (Guiamets, Batea, Almenara) are between 18 and 34 ka, while the old Mas de l'Alerany sequence is more than 115 ka. These ages indicate loess deposition during the last cold phases of the Quaternary and with pedogenesis occuring during warm interglacial periods.

Experimental evaluation of shear strength behaviour of plastic and non-plastic silts

Silt is available in many parts of the world in combination with sands and clays. However, due to lack of clear understanding of its engineering behaviour, most of the time it is interpreted in terms of either sands or clays. Structures that are usually built on silty soils are designed to take into account design procedures developed for sandy or clayey soils. Presence of silts in combination with varying amount of sand and clays produces silt that is either plastic or non-plastic in nature. Silt is available in and around the Delhi region, in a majority mixture along with fine sands, which is non-plastic in nature. On the other hand silty deposits found in offshore Bombay High region are found in abundance along with significant amounts of clays and are termed as plastic silts. In this paper a comparison of the stress-strain behaviour of plastic and non-plastic silts is carried out under triaxial compression loading during both drained and undrained conditions. Two representative samples each from Delhi and Bombay High regions were considered for this comparison and results of stress-strain under four sets of confining pressure are discussed in detail. It is observed from this study that behaviour of silts is mainly dependent on the composition and structure of the resultant soil matrix. It is concluded from the results that shear strength parameters as well as volume change/pore pressure response of silty soils is dominated by the constituent soil present along with the silt. It is seen from the comparative behaviour of non-plastic and plastic silts that the presence of sand and clays has a governing effect on pore pressure development and the resultant friction angle. The study also corroborated that the nature of silt is transitional both in the case of plastic and non-plastic forms.

Assessment of liquefaction potential of Erzincan Province and its vicinity, Turkey

One of the most important causes of damages after the earthquakes is the soil liquefaction. Liquefaction can be defined as temporary loss in strength of saturated sandy and silty deposits under transient and cyclic loadings due to excess pore water pressure. This study includes determination of liquefaction potential in Erzincan city center and its vicinity. Due to the proximity of the North Anatolian Fault Zone, in a probable earthquake, Erzincan Province is thought to be affected. In this context, the earthquake scenarios were produced using the empirical expressions. Liquefaction potential for different earthquake magnitudes was determined. These earthquake magnitudes were selected as 6.0, 6.5, 7.0, 7.5, respectively. Liquefaction potential was investigated using standard penetration test (SPT) data. The first stage of the study, 63 boreholes in different locations was drilled and SPT was performed. Disturbed and undisturbed soil samples were taken from these boreholes. Laboratory testing was performed to determine physical properties of soil samples, and liquefaction potential analyses were examined using three methods, namely Seed and Idriss (J Soil Mech Found Div ASCE 97(9):1249–1273, 1971), Tokimatsu and Yoshimi (Soil Found 23(4):56–74, 1983), Iwasaki et al. (Soil liquefaction potential evaluation with use of the simplified procedure. International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, St. Louis, pp 209–214, 1981). In order to complete liquefaction analysis within a short time, MATLAB program was prepared. Liquefaction potential analyses were carried out with the MATLAB program. At the final stage of this study, liquefaction potential maps were prepared for different earthquake magnitudes. The expected results will be shared with the local authorities and important engineering remedial measurements will be proposed to prevent further life losses and to mitigate property losses.

Marchantites huolinhensis sp. nov. (Marchantiales) – A new fossil liverwort with gemma cups from the Lower Cretaceous of Inner Mongolia, China

A new fossil liverwort species Marchantites huolinhensis R.Y. Li & B.N. Sun sp. nov., is founded based on twenty-seven fossil specimens collected from the Lower Cretaceous Huolinhe Formation in Huolinhe Basin of Inner Mongolia, China. The fossil liverwort is characterized by thalloid and prostrate gametophyte, and elliptical–circular gemma cups. Thallus is strap-like, dichotomously branched and with prominent costa. Imbricate ventral scales are in two rows and smooth and unicellular rhizoids are produced in considerable numbers around the costa. Cells on prominent costa are elongated and parallel to the long axis of the thallus. The relatively complete gametophyte, gemma cups, ventral scales and rhizoids indicate that they were likely to be autochthonously buried in dysoxic or anoxic silty deposits. Marchantites huolinhensis, along with other fossil records from other localities and age, indicates that the Marchantiales was already diverse in the Early Cretaceous and its morphological evolution is very slow.

Quaternary evolution of the Cordillera Frontal piedmont between c. 33° and 34°S Mendoza, Argentina

Abstract The piedmont of Cordillera Frontal between c. 33° and 34°S (Mendoza, Argentina) is a highly populated area deeply modified by human activities, known as Valle de Uco. It is situated within the borderland region of the geological provinces of Cordillera Frontal and Cuyo basin. The landscape is dominantly composed of both erosional and depositional landforms made of fluvio-aeolian deposits fractured and folded by tectonic processes together with some landforms of volcanic origin. Alluvial fans, related to several aggradational cycles of Quaternary age, are the most remarkable geomorphological units. Several tectonic features are present giving rise to conspicuous morphological features. Some of the streams are structurally controlled by faults while several drainage anomalies that indicate active tectonic processes have been identified. The Late Quaternary alluvial sequences, dominantly comprising sandy and silty deposits of volcaniclastic composition and secondarily metamorphic rocks, represent the fine-grained sedimentary facies of the fluvial systems accumulated in a distal fan environment. The alluvial deposits have been incised by several episodes of erosion since Pleistocene time.

Evaluation of secondary compression of sands and silts from CPTU

The estimate of secondary compression behaviour of sandy and silty deposits is not routinely taken into account in the classical settlement calculation, due to its generally limited contribution to the total amount of strains. However, such soils exhibit a non-negligible time-dependent behaviour and the prediction of their long-term response may sometimes be important. This paper explores the capability of the piezocone test as an effective tool to estimate the one-dimensional secondary compression characteristics of sands and silts. The approach is mainly based on the observation that frictional response essentially governs both secondary compression of granular soils and cone resistance, hence it seems reasonable to establish a valid correlation among them. The study uses part of the field data assembled over the last years at the Treporti Test Site (Venice, Italy), within an extensive research project aimed at analysing the stress-strain-time response of the predominantly silty sediments forming the Venetian lagoon subsoil. Empirical, site-specific correlations for estimating the secondary compression coefficient from cone resistance are proposed. The regression analyses indicate that the estimate is slightly improved if the cone resistance-based correlations include a variable accounting for the different pore pressure response associated to the drainage conditions around the advancing cone.

Shear wave velocity as function of cone penetration test measurements in sand and silt mixtures

A database of research-quality piezocone test (CPTU) results and shear wave velocity Vs measurements, assembled in the context of an ambitious research project carried out at the Treporti test site (Venice, Italy), has been interpreted in order to study the seismic response of the predominantly silty sediments forming the Venetian lagoon basin as well as to explore potential correlations for such intermediate soils. The experience gained so far with the Treporti database and other field data collected in the lagoon area has shown that the mechanical behavior of Venetian soils cannot be easily interpreted using the existing and well-established CPTU-based approaches, hence the interest in examining whether or not the seismic response of these sediments, expressed in terms of shear wave velocity, follows the framework published for other soils. The applicability to the available data of a number of existing correlations, originally developed either for sands or fine sediments, has been first investigated and updated relationships have been then suggested. Furthermore, the small-strain stiffness calculated from Vs measurements has been compared with the field stiffness derived from the observed performance of a full-scale test embankment built in the Treporti site, so as to verify common design assumptions. The verification and calibration of existing approaches are likely to constitute a useful contribution to the practice of geotechnics not only in the Venetian lagoon area, but also in the silty deposits usually present in the surrounding alluvial plain and other similar depositional environments, allowing rapid estimates of seismic soil classification as well as small-strain stiffness properties for preliminary design or at sites where only cone penetration data are available.

Peculiarities of sedimentation conditions in the oxbow lakes of Dubysa River (Lithuania)

Abstract Abundant wood remains and buried trees have been found in the western part of Lithuania near Zakeliškiai and Lyduvėnai on Dubysa River (a tributary of Nemunas River) where deposits are rich in organic remnants and buried soils. In Zakeliškiai and Skiručiai sections of Dubysa River oxbow sediments were investigated by various methods (dendrochronological, carbonate, granulometric, pollen and mollusc fauna analysis). In addition, these sections were dated using the radiocarbon method. Samples were collected from deposits of Dubysa River outcrops. The studied oxbow lakes have existed for more than 5 thousand years (from ca. 4300 BC to 1000 AD). During this period organic rich deposits with trees and branches were formed in the oxbow lake. This indicates that at the end of Atlantic, during Subboreal and in the early Subatlantic periods there was a forest growing that contained mainly oaks which were falling down into an oxbow lake and later were covered by sandy and silty deposits. The granulometry of alluvial deposits, as well as the mixture of medium-grained sand and silt show different stages of Dubysa River palaeochannel formation: riverbed and oxbow lakes. Three climate warming cycles were revealed according to carbonate analysis data in all investigated sections. The rheophile thermophilous Holocene age molluscs species Bithynia tentaculata L., Unio cf. crassus Philipsson, Pisidium amnicum (Müller), Theodoxus fluviatilis (Linnaeus) have been found. The pollen composition and sequences have been divided into five local pollen assemblage zones (LPAZ) and described according to pollen spectra in each zone. In this way it is possible restore palaeoclimatic coherent evolution, trends and cyclical change.

A laboratory study of dynamic sorting of fine, non-cohesive particles by steady, unidirectional currents

Abstract The conceptual model of non-cohesive ‘sortable silts’ in deep-sea muds that result from local, current-driven processes of size fractionation during entrainment and deposition has proven to be a useful tool for inferring qualitative changes in the intensities of past, deposit-forming currents. The degree to which sorting processes can be characterized quantitatively is as yet unclear. This study examines the relationship between bed shear stress and the partitioning of grain size in bed sediments and the source suspension in well-constrained laboratory channel flows. Results from flume experiments using glass microspheres with diameters in the range 13–44 μm and deposited from channel flows with bed shear stresses of 0.1–0.5 Pa indicate that little or no sorting is resolved by mean or median measures of the size of silt carried in source − suspension transport. A small effect appears in modal measures of suspended sediment size. Fine-particle beds generated under experimental flows consisted of local textural environments associated with near-bed transport phenomena; these include i) linear ‘streaks’ and ii) isolated, dune-like bedforms. Selective sampling of such features revealed, respectively: i) a minor but systematic increase in grain size of particle streaks with increasing shear stress imposed by the formative flow and ii) inconsistent textural response to shear stress among spatially-separated dunes with notable variability, ca. 10%, in central measures of grain size, such that no systematic sorting in the bedforms is apparent. These findings suggest that local sorting by grain size of fine particles in near-bed transport may be a more significant, if still subtle, contributor to silt-bed texture variability than an entrainment-derived process affecting material in the bed and parent suspension overall, as proposed in the original sortable-silt hypothesis. On the other hand, our results are not inconsistent with a mechanism of simple advective sorting, proposed by others, by which the characteristic size of a silty deep-sea deposit reflects its source-to-sink distance and the average transport velocity of the deposit-forming current.

Floodplain hydraulics in a glaciated bedrock river valley

Data and one dimensional, unsteady theory document the average, seasonal, and diurnal hydraulics of an unconfined aquifer in the surficial floodplain deposit of the Neponset River, which flows through a glaciated bedrock valley in eastern Massachusetts. The 20 m thick silty sand deposit has a permeability of 1.4 × 10−11 m2, a porosity of 0.37, a 600 m halfwidth, and an infiltration coefficient of 0.39. The steady water table is parabolic with a 0.60 m value at the valley wall that implies an average 33-year travel time across the floodplain in response to an average recharge rate of 7.0 × 10−9 m/s. Seasonal hydraulics are governed by the floodplain porosity and marked by periodicity of the river (0.48 m amplitude) and recharge (1.9 × 10−8 m/s amplitude), which maintain flow from the floodplain into the river year round. Attenuation of the diurnal fluctuations suggests that the specific yield ranges from 0.05 to 0.14, and yields horizontal flow excursions of 1 m scale near the riverbank.

Numerical Simulation of Dynamic Compaction at Dredger Fill Silty

Current practice of Dynamic compaction (D.C) depends mainly on field trials, past experience, and empirical equations based on reported records. In this paper, a numerical model is used to study the effectiveness of supplemental drains on densification of saturated dredger fill silty deposits during D.C. Typical numerical results are discussed using propose numerical model.

Numerical Simulation of Dynamic Compaction at Dredger Fill Silty

Current practice of Dynamic compaction (D.C) depends mainly on field trials, past experience, and empirical equations based on reported records. In this paper, a numerical model is used to study the effectiveness of supplemental drains on densification of saturated dredger fill silty deposits during D.C. Typical numerical results are discussed using propose numerical model.

Carta geologica dell’area urbana di Bari in scala 1:25.000

Notes to the geological map of the urban area of Bari (southern Italy) 1:25.000 scale.This paper shows the results coming from the detailed geological mapping performed on the urban area of the city of Bari (Puglia region, southern Italy). It is a large area (about 50 km2), with many inhabited places, and intensely urbanized. For this reason a geological map that could provide an up-to-date and useful tool for professional geologists daily working on the region, was realized.The area represented in the geologic map of the urban area of the city of Bari, at the scale 1:25.000, lies on the eastern Murge, which represents the central part of the Apulian foreland, the south-Apennines foreland. In the Murge area, the foreland is characterized by a thick Mesozoic sedimentary succession overlain by relatively thin and discontinuous Quaternary deposits. Locally, the exposed Mesozoic succession is about 150 m thick, and is represented by a part of the Calcare di Bari Fm, made up of biopeloidal and peloidal wackestones/packstones alternated with stromatolitic bindstones with frequent intercalations of dolomitic limestones and grey dolostones. Depositional environments are related to a low-energy inner-platform depositional system and biostratigraphic data allowed us to refer the age of the succession cropping out in the city of Bari to the Late Albian-Early Cenomanian.The lower Pleistocene Calcarenite di Gravina Fm unconformably lies on the Calcare di Bari Fm. The lower boundary is transgressive and is locally marked by reddish residual deposits (terra rossa) and/or by brackish silty deposits passing upward to shallow-water calcarenites rich in bioclasts. Basically this formation is made up of litho-bioclastic calcarenites and calcirudites with packstone/grainstone texture, rich in mollusks, red algae, serpulids, echinoids and benthic foraminifers. The thickness of this unit ranges from few metres up to 20 m, and its depositional environments are related to alluvial or offshore systems. The age is early Pleistocene (Gelasian?-Calabrian). Regionally, the Calcarenite di Gravina Fm represents the record of the lower Pleistocene subsidence of the Apulia foreland.The Murge supersynthem groups all the marine terraced deposits unconformably lying on all older units and consists of a heterogeneous assemblage of mixed silicoclastic and carbonate sediments formed in shallow-marine and transitional environments. The thickness of the three synthems forming the supersynthem is usually few metres thick and the age ranges from middle to late Pleistocene. These synthems record a phase of regional uplift which started at least from middle Pleistocene; this uplift, in combination with the Pleistocene glacioeustatic oscillations, produced several relative sea-level changes which caused the distribution of these synthems to different altitudes above sea level.The lame delle Murge supersynthem groups all the terraced alluvial deposits cropping out in the studied area. These deposits unconformably lie on the previous units and are placed at different heights inside little canyons, characterizing the area and locally named lame. These deposits consist of either well cemented or poorly cemented carbonate conglomerates with a reddish silty-sandy matrix. The thickness of these deposits ranges from few metres up to 10 m and the age is middle Pleistocene-late Pleistocene.The picture is completed by upper Pleistocene-Holocene actual and present-day alluvial deposits, made up of carbonate gravels with reddish fine-grained matrix.

Evidence for periodic, Holocene loess deposition in kettles in a sandy, interlobate landscape, Michigan, USA

Abstract Loess deposits are common in mid-continental North America, but are rare in Michigan, and most loess found in this region is of last-glacial age. We report on evidence for Holocene-age, silt-dominated deposits found in kettle bottoms, which we interpret as loess. These silty deposits contrast with the broader interlobate landscape, which is composed of glaciofluvial materials dominated by medium and fine sands (125–500 μm). The abrupt lateral edges of the silty deposits, and their unique textural properties relative to the surrounding landscape, suggest that the silts were not washed from kettle backslopes. Rather, we suggest that the silts originated as loess that was episodically deposited in kettle bottoms across the Upland. Later, loess that may have been deposited on backslopes was occasionally redeposited into the centers of vegetated kettles, along with some background sands, by wind and water. Evidence in support of our conclusions includes (1) the fine-silty textural characteristics of the sediments, set within an otherwise sand-dominated landscape, (2) depositional sequences of charcoal-rich paleosols, intercalated within the otherwise “clean” kettle bottom silts, pointing to episodes of loess deposition interspersed with periods of slope stability and pedogenesis, and (3) increased silt contents within the upper meter of sandy soils on nearby stable uplands. Radiocarbon ages on bulk charcoal from nine paleosols within the kettle-bottom silt deposits fall mainly within the early Holocene. These deposits and 14C ages provide the first evidence of Holocene loess in the Great Lakes region, some of which probably originated from the nearby Muskegon River floodplain.

Late Glacial vegetation, sedimentation and ice recession chronology in the surroundings of Lake Prossa, central Estonia

Pollen records from Lake Prossa, located in the Saadjarv Drumlin Field, indicate rather homogeneous pollen spectra in the pre-Allerod period and a thick sediment sequence suggesting high input of mineral matter and erosion. This period is characterized by pioneer vegetation with dwarf-shrubs. At the beginning of the Allerod, Salix, Artemisia and redeposited temperate and thermophilous taxa prevailed in pollen spectra, referring to shrub tundra conditions, followed later by Betula and Pinus(?) arrival. Silt with organic debris deposited. Vegetational set-back and tundra plant species with scattered birches and silty deposits containing abundantly Drepanocladus fragments characterize the Younger Dryas stadial. The sedimentation rate decreased markedly and was followed by a hiatus at the beginning of the Holocene. The AMS 14 C dates, and microfossil and sedimentological data show that the ice front receded and stratified sediments started to deposit about 14 200-14 300 cal yr BP, permitting specification of poorly constrained ice recession chronology in central Estonia.