New Insights Into the Genesis of the “Poznań Clays” – Upper Neogene of Poland

The present study focuses on the upper Neogene deposits, called the “Poznań Clays”, that cover more than 75,000 km2 of Poland. They are situated between the first mid- Polish lignite seam and the glaciogenic deposits of the Pleistocene age. Lithostratigraphically, the “Poznań Clays” belong to the uppermost portion of the lignite-bearing Grey Clays Member and the whole Wielkopolska Member (Poznań Formation). The examined fine-grained sediments include mud-rich floodplain deposits with palaeosol remnants and large sandy-muddy or muddy palaeochannel bodies. Therefore, taking into account facies analysis, cross-sectional geometry, and the planform of the palaeochannels, it can be stated that the “Poznań Clays” formed in the environment of a late Neogene anastomosing river.

Revised stratigraphy of the middle Simcoe Group (Ordovician, upper Sandbian–Katian) in its type area: an integrated approach

The Upper Ordovician Bobcaygeon Formation of southern Ontario is a widespread unit that spans the Sandbian–Katian stage boundary and contains exceptionally preserved invertebrate fossil assemblages, including the famed ‘Kirkfield echinoderm fauna.’ However, the precise correlation of this interval remains poorly understood. This paper presents new data on high-resolution sequence and carbon isotope chemostratigraphy of the Bobcaygeon interval based on new quarry exposures and introduces refined definitions of unit boundaries based on allostratigraphic criteria. Sequence, chemo-, and biostratigraphic evidence indicate that the Bobcaygeon Formation represents a composite unit as it encompasses a major erosional unconformity. The Coboconk and Kirkfield formations, described in the early 20th century, were merged into a single unit, the Bobcaygeon, out of concern that the original lithostratigraphic divisions would be conflated with biostratigraphic zones of the same names. However, these biostratigraphic zones are no longer favoured, and the lower member of the Bobcaygeon is here elevated again to the status of formation (Coboconk Formation) and represents the uppermost portion of the Sandbian M4 sequence. The middle and upper members of the Bobcaygeon, herein reassigned to the Kirkfield Formation, represent the upper Sandbian to lower Katian M5A and M5B sequences recognized widely in the eastern and central United States. The term Bobcaygeon is retained and elevated to the rank of subgroup. The Kirkfield Formation is divided into three members and contacts are refined, placing a 1–2 m transgressive grainstone at the base of each sequence. These units are correlated with equivalent strata of New York and the Cincinnati Arch.

Geophysical signature of a World War I tunnel-like anomaly in the Forni Glacier (Punta Linke, Italian Alps)

Global warming and the associated glacier retreat recently revealed the entrance to an ice–rock tunnel, at an altitude of ~3600 m a.s.l., in the uppermost portion of the Forni Glacier in the Central Italian Alps. The tunnel served as an entrance to an Austro-Hungarian cableway station excavated in the rocks during the Great War just behind the frontline. A comprehensive geophysical survey, based on seismic and ground-penetrating radar profiling, was then undertaken to map other possible World War I (WWI) remains still embedded in the ice. The ice–rock interface was reconstructed over the entire saddle and in the uppermost portion of the glacier. A prominent linear reflector was surprisingly similar to the common response of buried pipes. The reflector orientation, almost longitudinal to the slope, does not seem to be compatible with a glacial conduit or with other natural features. Numerical simulations of a series of possible targets constrained interpretation to a partly water-filled rounded shape cavity. The presence of a preserved WWI tunnel connecting Mount Vioz and Punta Linke could be considered a realistic hypothesis. The Forni glacier could be still considered polythermal and comprised of cold ice without basal sliding in its top portion.

Variable Mantle Lies Below Ancient Pieces of Earth's Crust

Underneath old and stable pieces of Earth's crust in North America, the mantle's uppermost portion contains multiple layers that change the velocities of seismic waves.

Taxonomic review of the genus Trichomycterus Valenciennes (Siluriformes: Trichomycteridae) from the laguna dos Patos system, Southern Brazil

The species of the genus Trichomycterus inhabiting the laguna dos Patos system are reviewed and five species are recognized. Trichomycterus tropeiro Ferrer & Malabarba has a restricted range and is endemic to the uppermost portion of the rio das Antas. Trichomycterus balios, n. sp., is distributed in the upper portion of the rio das Antas and rio Caí basins. Trichomycterus diatropoporos, n. sp., is endemic to the rio da Prata basin, a tributary of the rio das Antas. Trichomycterus poikilos, n. sp., is widely distributed in the upper portion of the rio Jacuí basin and tributaries of the rio Taquari-Antas. Trichomycterus brachykechenos, n. sp., is endemic to the upper portion of the rio dos Sinos. The new species are distinguishable from most congeners, except for T. davisi, T. mboycy, T. naipi, T. payaya, T. papilliferus, T. perkos, T. plumbeus, and T. tropeiro by the lower number of pectoral-fin rays (I+5-6) and by the first pectoral-fin ray not prolonged as a filament. Other characters distinguish the new taxa from these eight species. The distribution of the genus in the laguna dos Patos system is discussed and a taxonomic key is provided.

Proteoid root mats bind surface materials in Hawkesbury Sandstone biomantles

Sediment yield following bushfire on Hawkesbury Sandstone hillslopes is highly variable and catastrophic stripping of soils often does not occur as anticipated. Proteoid root mats were examined as a potential mechanism for limiting catastrophic stripping of Hawkesbury Sandstone biomantles. It was found that surface and subsurface proteoid root mats were widespread and concentrated in the uppermost portion of the soil profile. The proteoid roots bound mineral soil from the size of clay to gravel. The roots were observed growing up into the leaf litter and bound leaf litter to the mineral soil surface. It is concluded that proteoid root mats bind surface materials in Hawkesbury Sandstone biomantles and are sufficiently widespread to account for the stability of soil materials that appear to be unprotected following bushfire.

An Upper Mississippian trace-fossil assemblage from the Tar Springs Sandstone, southern Illinois

A trace-fossil assemblage is exposed in the uppermost portion of an interpreted tidal sand-flat deposit in the Upper Mississippian Tar Springs Sandstone in southwestern Illinois. Sedimentary structures, indicative of a tidal origin for this unit, include herringbone crossbeds, flaser and lenticular beds, reactivation surfaces, small channel scours, and shrinkage cracks. The trace fossils include trackways, trails, feeding structures, dwelling burrows, and escape structures. Vertical dwelling and escape structures dominate the assemblage with lesser numbers of horizontal and inclined traces. The ichnological and sedimentological characteristics are diagnostic of the Skolithos ichnofacies. Preservation of the assemblage at the top of the Tar Springs Sandstone was the result of substrate stabilization as the tidal flat subsided and was transgressed. The present trace-fossil assemblage probably was formed by a combination of a pre-omission tidal-flat suite and an omission suite formed during and after the transgression. Preservation of the assemblage suggests a passive transgression with minimal scouring and reworking of the tidal-flat deposit.

IV.—Geological and Historical Notes on the Occurrence of a Fauna, Chiefly of Permian Affinities, Associated with a Carboniferous Flora in Gas-coal in the Uppermost Portion of the Bohemian Coal-Strata

As Dr. Anton Fritsch of Prague has brought the relics of Permian animals (Sauria and Fishes) from the Gas-coal of Nürschan and from the “Schwarte,” near Rakonitz, before the Meeting of the British Association at Glasgow in September last, it will certainly not be without interest, to give some geological and historical notes on this most important occurrence, and I may, I trust, be allowed to do so in the Geological Magazine.