Michał Gradziński

Vegetation-controlled modern anastomosing system of the upper Narew River (NE Poland) and its sediments

Abstract The anastomosing system of the upper Narew River consists of a network of interconnected channels. The channels are relatively deep (width/depth ratio 2–10), straight to sinuous, and they lack natural levees. They are characterised by a low water slope and very low stream power. The river is distinctly bedload-dominated and the transport of suspended clastic fines is minimal. Channel deposits consist almost exclusively of medium- to coarse-grained sand. Laterally extensive interchannel areas are flat and covered with peat-forming vegetation. These stable wetlands are flooded for many weeks during high water stages. Except for the channels, the valley fill consists of peat layer reaching 4 m in thickness. The rate of vertical aggradation of the peat deposit is estimated at 1–1.5 mm/year. The radiocarbon dating indicates that the peat layer is predominantly late Holocene in age. The impact of vegetation on the system is overwhelming. Vegetation produces an erosion-resistant peat layer, stabilizes channel banks and slows down the water flow. Vegetation also stimulates aggradation of bedload material on the channel bottom, and contributes to avulsion by blocking the channels. The channel network owes its origin to repeated though infrequent avulsion. Avulsion in the studied system is a small-scale, gradational and slow process. New channels evolve very slowly because of unfavourable hydrologic conditions and the presence of a resistant peat substratum. A new channel eventually intercepts only a part of the flow, while the old channel is still active, though to a limited extent. Although newly formed channels might subsequently be abandoned, long-lasting ones predominate within the system.

Factors controlling growth of modern tufa: results of a field experiment

Abstract A field experiment was performed at four sites in Slovakia and Poland in order to identify factors that influence the growth rate and textures of modern tufas. Two pairs of tablets were placed at each study point, every pair consisting of a limestone tablet and a copper tablet. One pair at each site was changed every three or four months, while the second pair was left for approximately 14 months. Each tablet was weighed before placing and after removal to find the amount of the tufa growth. Tufa growth rate was found to depend on SIcalc. of parent water, though deposition of tufa on limestone tablets was substantially faster than on copper tablets. This result indicates that micro-organisms are essential for more efficient growth of tufa. Tufa growth rate was higher in fast-flowing water than in nearby sluggish flow settings. Fast-growing tufa has crystalline texture or consists of highly encrusted algal filaments. The latter texture is due to faster growth of micro-organisms, forced by rapid crystallization of calcite on their cells. The slow-growing tufa exhibits mainly micritic textures. Clotted micrite with numerous diatoms forms mostly in winter, while encrusted algal filaments are typical for spring and summer growth.

Evolution of Brestovská Cave Based on U-Series Dating of Speleothems

Evolution of Brestovská Cave Based on U-Series Dating of Speleothems The U-series dating indicates five episodes of flowstone growth in Brestovská Cave, namely: ca. 200 ka, ca. 128-88 ka, ca. 82-65 ka, ca. 64-50 ka, and during the Holocene. The age of flowstones and their spatial distribution within the cave prove that the upper storey of the cave was dewatered before 200 ka. At that time the lower storey also existed and was able to carry the whole water flowing through the cave. It suggests that 200 ka ago the water-table was at similar level as it is at present. Hence, one should accept that the valley bottom was then also at the present level. During at least a part of the MIS 6 the growth of speleothems was possible in the cave. It suggests that the cave was located outside the permafrost zone then. Between 50 ka and Holocene, Brestovská Cave was flooded by invasion waters originating from the melting of the Würm glacier; the water-table was additionally raised due to the blockage of a resurgence by glacifluvial sediments. The flooding event caused the destruction of older deposits, including speleothems, and deposition of fine-grained clastics on the cave walls.

The first dating of Cave Ice from the Tatra Mountains, Poland and its implication to palaeoclimate reconstructions

The First Dating of Cave Ice from the Tatra Mountains, Poland and its Implication to Palaeoclimate Reconstructions Lodowa Cave in Ciemniak, which belongs to the dynamic ice cave type, contains the biggest perennial block of cave-ice in the Tatra Mountains. The ice represents congelation type, since it originates from freezing of water which infiltrates the cave. Two generations of ice have been recognized in this cave. They are divided by the distinct unconformity. The ice building both generations is layered. Two moths which were found in the younger generations were sampled and dated by 14C method yielding 195 ± 30 and 125 ± 30 years. Bearing in mind the position in the section and the fact that the cave ice has waned since the 20s of the last century, the age is 1720-1820 AD and 1660-1790 AD respectively. It proves that the ice was formed during the Little Ice Age. Hence, the erosion boundary which underlies this generation records the degradation of ice before the Little Ice Age most probably during the Medieval Warm Period. The ice volume in the cave was substantially smaller before the Little Ice Age than it is today, despite the clear tendency to melting, which has been recognized since 20s of the last century. The older generation of ice is supposed to have its origins in a cold stage between the Atlantic period and the Medieval Warm Period.

Diatom species diversity and their ecological patterns on different substrates in two karstic streams in the Slovak karst

Many karstic streams are threatened both by anthropogenic and climate changes, but little is known about their algal biodiversity and conservation value, especially in the Slovak Karst. Diatom assemblages occurring on seven substrates, including stones, mud, submerged mosses and filamentous algae: Cladophora glomerata, Vaucheria sp., Ulothrix zonata, Spirogyra sp. in two nameless karstic streams in the Krásnohorská Dlhá Lúka Village and the Gombasek Cottage Settlement (the Slavec Village) in the Košice Region of central-eastern Slovakia (the Silická Plateau) were studied. A total of 124 diatom taxa were found at four sites, where epilithic and epiphytic diatom assemblages dominated. Both species’ richness and Shannon-Wiener indices showed congruent biotic integrity. The dominant taxa were alkaliphilous, halophobous-oligohalobous, requiring xeno-oligosaprobic and oligotrophic waters. Diatoms include: Diploneis krammeri, Encyonema ventricosum, Gomphonema acuminatum, Gyrosigma attenuatum, Navicula tripunctata, and Paraplaconeis cracoviensis. The latter species is a new report for Slovakia, reflecting the calcareous, geological nature of the Silická Plateau (the Slovak Karst). Diatom assemblages in two karstic streams consisted mainly of small-celled species of Achnanthidium, Amphora, Caloneis, Planothidium, and Stauroneis. Our results showed that the diatom assemblages were mostly structured by environmental factors of calcium and pH gradients, confirmed by canonical variates analysis (CVA) and Monte Carlo permutation tests. However, unique spatial and biological gradients, specific to different guilds related to each other, were also evident. The Slovak karstic streams should be especially protected and regularly monitored.

Hypogene Speleogenesis in the Karst of Poland—Regional Review

Karstified rocks are widely distributed in Poland; most of them are covered by unconsolidated Cenozoic deposits. Paleozoic and Mesozoic carbonates and Neogene evaporites host numerous paleokarstic features and solution caves, being of polygenetic and multi-stage origin. Works on hydrothermal karst and sulfide ores emplaced in caves of the Silesian-Krakow region, the large paleokarst caves filled with Permian internal sediment or thermal convection model for caves in the Polish Jura date back to the 1970s. Quite well-documented hydrothermal karst is preserved as paleokarstic features in several localities in the Silesian-Krakow region, Holly Cross Mts. and Sudetes. Characteristic cave sediments including crystalline calcite spar, sulfide ores emplaced within hydrothermal cave sediments and solution-collapse breccias are associated with these features. Travertines, which are surface manifestation of hypogene karst, dated through their paleontological assemblage, support their post-Variscan—Permian and Late Triassic age. Their hydrothermal origin was also determined by detailed studies of sediments and fluid inclusions. Less certain, based mainly on studies of relict cave morphology and limited calcite spar, are the Cenozoic—Paleogene and Neogene hypogene events in the Carpathians (Tatra Mts.) and their foreland (Polish Jura). Review of published references and concepts related to hypogene origin of caves and karst in Poland is presented in this contribution.