Layered Sedimentary Rocks Research Articles

The Saint-Leonard Urban Glaciotectonic Cave Harbors Rich and Diverse Planktonic and Sedimentary Microbial Communities.

The terrestrial subsurface harbors unique microbial communities that play important biogeochemical roles and allow for studying a yet unknown fraction of the Earth's biodiversity. The Saint-Leonard cave in Montreal City (Canada) is of glaciotectonic origin. Its speleogenesis traces back to the withdrawal of the Laurentide Ice Sheet 13,000 years ago, during which the moving glacier dislocated the sedimentary rock layers. Our study is the first to investigate the microbial communities of the Saint-Leonard cave. By using amplicon sequencing, we analyzed the taxonomic diversity and composition of bacterial, archaeal and eukaryote communities living in the groundwater (0.1 µm- and 0.2 µm-filtered water), in the sediments and in surface soils. We identified a microbial biodiversity typical of cave ecosystems. Communities were mainly shaped by habitat type and harbored taxa associated with a wide variety of lifestyles and metabolic capacities. Although we found evidence of a geochemical connection between the above soils and the cave's galleries, our results suggest that the community assembly dynamics are driven by habitat selection rather than dispersal. Furthermore, we found that the cave's groundwater, in addition to being generally richer in microbial taxa than sediments, contained a considerable diversity of ultra-small bacteria and archaea.

Seismic site effects in Lisbon: the role of complex geological and morphological conditions

Lisbon’s historical seismicity, socioeconomic importance and population density contribute to a moderate to high seismic risk. The geological setting of the city includes cases of inclined layers, interbedding sedimentary rock layers in soil deposits, sand and clay layers in the same geological unit, leading to cases of shear wave velocity inversion and a large scatter of geotechnical properties within each geological unit. The morphological setting of the city is characterised by the existence of several hills and relatively shallow, stream-carved valleys filled with alluvial deposits. The seismic site effects in Lisbon were assessed through numerical simulation using the linear equivalent method and adopting the two types of seismic action defined in the Portuguese National Annex of Eurocode 8: (i) one-dimensional subsoil models covering the city, at sites where borehole data and geophysical data were available; (ii) two-dimensional subsoil models along three cross-sections representative of the geological settings and morphology. The distribution of amplification factors in the city revealed a pattern related to ground characteristics that impact seismic soil response, such as the presence of high-thickness cover deposits, significant shear-wave variations, alluvial valleys, a crest or significant slope variations and inclined layers. The 2D/1D spectral ratio highlighted the areas were 2D seismic effects are more important. The soil factor determined in the numerical analyses was consistently greater than the soil factor values indicated in Eurocode 8.

Study on the Characteristics and Mechanism of Shield Tunnel Mud Cake Disintegration in Complex Red-Bed Geology

The complex red-bed geology is primarily composed of iron-rich sedimentary rock layers with clay minerals as a major component. The soil water content exceeds 30%, and its high viscosity and water content lead to the easy formation of mud cake on the cutterhead, endangering the safety and progress of construction, which poses a significant challenge for tunnel boring machines (TBMs). The use of dispersants to eliminate mud cake is a common method in engineering projects. This paper presents an improved disintegration experiment instrument to study the disintegration characteristics of mud cake from the red-bed geology under different dispersant solutions, proposing a dispersant formulation suitable for the red-bed geology of the Haizhu Bay Tunnel project. The results indicate that mud cake samples exhibit a moderate disintegration effect in pure water. Furthermore, it has been observed that the disintegration effect decreases as the thickness of mud cake increases. Sodium silicate solution was not suitable for treating the red-bed geological mud cake, while sodium hexametaphosphate and oxalic acid solutions had a good promoting effect on the disintegration of red-bed geological mud cake. However, there was a threshold for the dispersant concentration; exceeding this threshold actually worsened the disintegration effect. Ultimately, the engineering application of a 10% oxalic acid solution, which proved effective in disintegrating the mud cake, significantly enhanced the excavation efficiency in the Haizhu Bay Tunnel project.

Drilling Into Ancient Rock to Learn About Earth’s Past

Geologists are curious to learn what the Earth was like when the planet was young. We want to know about temperature, beaches, soils, climate, rivers, meteorite impacts, and volcanic activity because these factors determined how and where early life could exist. Only the oldest sedimentary rocks have this information, but these are usually covered by younger rocks. Old sedimentary rocks that still “tell a good story” about the history of the Earth are rare. We studied some of these. They are an unimaginable 3.2 billion years old and are found in the Makhonjwa Mountains near South Africa’s border with Eswatini. We had to drill into the Earth to get to them because the surface is covered by forest and grassland. Sedimentary rock layers in these mountains do not lie flat anymore but are vertical, and sometimes even flipped over. To drill through as many layers as possible, we had to drill sideways!

Investigation of the strength behavior and failure modes of layered sedimentary rocks under Brazilian test conditions

As the anisotropic behavior of sandstones and limestone along the Khorramabad-Zal expressway has not been studied, this research aims to examine the impact of layer orientation on the strength characteristics and failure patterns of layered sedimentary rocks using the Brazilian test. For this purpose, a total of 8 rock blocks were gathered from Kashkan sandstones and Sarvak limestones in three different locations along the Khorramabad-Zal highway in western Iran. The core specimens were drilled with 54 mm diameter and parallel to the laminations. Overall 150 disc-shaped specimens were subjected to Brazilian tensile strength (BTS) in ten different anisotropy angles, which refers to the angle between the loading direction and the lamination plane. The findings revealed that the highest and lowest BTS values were obtained at β = 70° and 20° for all three types of rock. After analyzing the samples that experienced the Brazilian test and examining their failure patterns, three primary modes of failure were identified: parallel to the lamination (PL), across the lamination (AL), and curved fracture (CF). Furthermore, the transitional angle, which signifies the point at which the dominant pattern of failure shifts from PL to AL or from PL to CF, was also determined.

Paracoskinolina praereicheli, a Special Kind of Tiny Marine Creature, Found in Ancient Rocks in SE France, Franco-Swiss Jura, and Swiss Pre-Alps During the Dinosaur Era

In this study, we report the discovery of a novel microorganism, Paracoskinolina praereicheli, a diminutive species reminiscent of prehistoric fauna. This organism was identified within ancient geological formations dating back to the era of dinosaur predominance. Specifically, its presence has been noted in sedimentary rock layers located in Southeastern France, the Franco-Swiss Jura, and the Swiss Prealps. Our research provides a detailed description of Paracoskinolina praereicheli, encompassing its morphological characteristics and ecological context. The temporal focus of this study spans the Late Hauterivian to the Early Barremian periods, offering insights into the biodiversity and environmental conditions of these epochs. This discovery contributes significantly to our understanding of microorganism evolution and paleoecology during a critical phase in Earth’s history.

Classification of Polymetallic Ore-Forming Processes and Transitional VMS–SEDEX–MV-type: the Example of the Giant Ozernoe Deposit in Transbaikalia, Russia

This article discusses the general classification approaches and key features of different families of polymetallic deposits, with particular attention to the largest in Eurasia Ozernoe polymetallic deposit located in Western Transbaikalia and thoroughly explored 50 years ago. The main groups (or families) of polymetallic deposits in the English-language literature are identified by brief names: volcanogenic massive sulphide (VMS), sedimentary exhalative (SEDEX), and Mississippi Valley type (MVT). Within these three families of deposits, there are many additional types/subtypes, a large number of which are mostly due to the incompleteness and inconsistency of accumulated knowledge on the genesis of polymetallic deposits. Overall, all Pb–Zn(Ag,Cu) deposits—both those that are considered syngenetic, forming on and near the seafloor (VMS and SEDEX), and epigenetic low-temperature ones (MVT)—demonstrate a wide range of features that distinguish and bring together these families. This also applies to the types and subtypes of mineral deposits identified within them. One of the most complex objects for geological–genetic classification is the Ozernoe deposit studied by the authors, which, in terms of the nature of the host rocks, is intermediate between the end members of all three families: SEDEX, VMS and MVT. The deposit is localized in volcanic–carbonate–terrigenous rocks of the Cambrian Oldynda formation, but the age and stratigraphic affiliation of the ore-bearing series remain a matter of debate. The Ozernoe deposit is a combination of massive sulfide and siderite ore beds, ore breccia horizons, low-carbonate aleuropelite members, limestones, fine detrital tuffites, lavas, and tuffs. The sulfide bodies are confined to several stratigraphic levels, and the main productive unit thickness reaches 230 m. The thickness is comprised of 12 mineral lodes, a series of stratified ore bodies separated by gangue layers of sedimentary and volcaniclastic rocks. The primary ore minerals are pyrite, sphalerite, and galena, while the minor minerals include magnetite, chalcopyrite, marcasite, tetrahedrite, and arsenopyrite. There are two main theories regarding the origin of the ore: volcanogenic–sedimentary and hydrothermal–metasomatic. The hydrothermal–sedimentary theory remains the prevailing hypothesis, but there are many indications that epigenetic hydrothermal–metasomatic and dynamic metamorphic processes have contributed to the formation of the deposit. These include the appearance of sulfide–quartz and quartz–carbonate–sulfide veins and vein zones in fine-grained “layered” ores, with large crystalline sphalerite and galena; multiple signs of ore recrystallization, including the formation of pyrite porphyroblasts and arsenopyrite metacrystals; and the formation of solid pyrrhotite and pyrrhotite–magnetite ores with a lenticular-striped, gneissic structure. These observations suggest that different processes, both hydrothermal–sedimentary and metamorphogenetic–metasomatic, were involved in the formation of the Ozernoe deposit. In other words, primary hydrothermal–sedimentary ores were redeposited by late hydrothermal solutions. Nevertheless, many issues concerning the genesis of the Ozernoe deposit remain unresolved.

Cyclostratigraphy at a tipping point

There are key patterns of variation in the (litho‐) stratigraphical record, which, with advances in computing technology in recent decades, have become amenable to objective numerical analysis. This research has chiefly focused on the search for spatially regular cycles in the sedimentary rock record, since there are theoretical grounds for believing that these would be periodic and thus provide a means of time‐calibrating the stratigraphical records in which they occurred. Less popular lines of research consider the scaling relationships of the tangible, measurable sedimentary rock layers, and of the hiatuses, individually of indeterminate length, that punctuate these layers. Objective source data for all these analyses is provided, on limited (usually decametre) scales, by detailed lithological logging, sampling and dating of sections provided by exposures and cores. An objective global lithostratigraphical database, with larger, kilometre scales, is provided by the widespread practice of electric (wire‐line) logging of deep wells. This involves measurement, at 6‐inch (~15 cm) depth intervals of lithology‐related petrophysical properties. Rapid desk top computer analysis of the hundreds or thousands of readings that comprise these two data series, searches for patterns of variation. This review considers the published evidence for ‘ubiquitous’ cyclicity and its use in chronostratigraphy, despite the contrary claims that stratigraphical records are predominantly random in character.

ЗАГАЛЬНА ГЕОЛОГІЧНА ІСТОРІЯ ЯК ОСНОВА ЄДИНОЇ СТРАТИГРАФІЧНОЇ ШКАЛИ ДОКЕМБРІЙСЬКИХ ПОРІД ПЕРШОТРАВНЕВОГО ТА ГАННІВСЬКОГО РОДОВИЩ КРИВОРІЗЬКОГО ЗАЛІЗОРУДНОГО БАСЕЙНУ

Hannivske deposit of poor magnetite ores is part of the Kryvyi Rih iron ore basin. The deposit is located in the southern part of the Eastern-Hannivka belt at the Northern iron ore district of Kryvbas. Two sets of rocks are involved in the geological structure of the Hannivske deposit: crystalline rocks of the Archaean and Proterozoic, as well as rocks of the Cenozoic sedimentary cover. Archean rocks are represented by plagiogranites and plagiomigmatites of the Dnipropetrovsk Complex (AR2dn) and amphibolites of the Konkska Series (AR3kn). The Proterozoic complex of rocks is formed by the Kryvyi Rih Series (PP1kr), which is divided into five Formations (from bottom to top): Novokryvorizka (PR1nk), Skelyuvatska (PR1sk), Saksaganska (PR1sx), Gdantsivska (PR1gd) and Gleyuvatska (PR1gl). The productive stratum of the Hannivske deposit is the overlying pack of the first ferrous horizon of the Saksaganska Formation of the Kryvyi Rih Series, which, according to the generally accepted stratigraphic scheme of Kryvbas, corresponds to the fifth-sixth ferrous horizon of Saksaganska Formation of Kryvyi Rih Series. Crystalline rocks of the Archaean and Proterozoic are covered by a layer of sedimentary rocks of the Cenozoic: Paleogene (P), Neogene (N) and Quaternary (Q) periods. In the southern part, the Eastern-Hannivka belt (Hannivske deposit) connects with the Pervomayka deposit by a series of numerous sublatitudinal and diagonal faults. In the north-northwest direction, there is a gradual decrease in thickness and wedging of the Eastern-Hannivka belt, including the iron ore stratum. Metasomatic processes in their intense display are observed in the productive stratum of the Hannivske deposit locally, but a significant part of it is covered by weak metasomatic changes. A feature of metasomatic processes was the formation of metasomatic bodies along linear tectonically weakened zones or at their intersection nodes. Multi-stage formation of the Hannivske deposit, active display of various geological processes in the productive and containing stratums (sedimentation, metamorphism, tectogenesis, metasomatosis, hydrothermal, astroblemic phenomena, syngenetic and epigenetic magmatism, hypergenesis, etc.) determined the mineralogical and chemical diversity of the Hannivske deposit ores, the presence in its productive and capacious layers, the manifestation of many metallic and non-metallic minerals, the formation of a complex mineral and raw material base of the deposit.

CURRENT STATE’S CONDITION OF LITHIUM ORE DEPOSITS IN UKRAINE

The paper presents a description of three lithium ore deposits — Shevchenkivske, Polokhivske and the Dobra site. They are the most promising among others in terms of the economic feasibility of their development. Each of them has its advantages and disadvantages. The Shevchenkivske deposit is located in Pryazovsky, and the other two — in the Ingulsk’s megablocks. On the first, the main ore mineral is spodumene, on the second — petalite, on the Dobra site the mixed type is spodumene-petalite. All three deposits are covered by a rather thick layer of sedimentary rocks and weathering crust (up to 100 m). They are located in the steppe zone with a predominantly flat topography. The deposits were discovered at the end of the twentieth century as a result of large-scale regional geological research. They have different degrees of geological study. A common drawback is the lack of core material. Lithium ore reserves and resources up to a depth of 500 m from the day surface are estimated at the specified deposits. Taking into account the constantly growing demand for lithium, investing in the development of these deposits in Ukraine is a promising business.

Geological and geomorphological characteristics of Du Cape at the Cam Mountain, Ninh Hai ward, Ninh Hoa district, Khanh Hoa province to serve as a basis for conservation and exploitation of tourism potential

Du Cape, with the area of about 3 km2, is positioned at the eastern edge of the Cam Mountain, Ninh Hai ward, Ninh Hoa town, Khanh Hoa province. Possessing a north‒south direction, this shoreline section covers a length of about 2.5 km.The section comprisessedimentary cliffs of 15‒25 m. The natural landscape now is unspoiled and attractive. The cliffs consist of layers of sedimentary rock with varying slopes and orientations of 45‒63o at different locations. The northern part of the studied Du Cape has characteristic concave folds. The geological formation in the area, belonging to the La Nga Formation (J2ln). The lower part includes of claystone, siltstone, layered and banded sandstone. The upper part comprises layers of medium‒small‒grained sandstones with varied colors of brown, yellow‒brown and gray‒white. The rock is highly compressed and has a schist structure. Ammonite fossils are typical for the Jurassic period and this type of sedimenthas been discovered in some remaining ones. The topographicorigins of the studied Du Cape could be divided into two groups: erosive and accumulative. Its topographical surfaces are of 6 types: erosion‒landslide slope, eroded and eroded slope, multi‒origin accumulation surface of Quaternary age, sedimentary shelf of marine origin, strip of sand accumulation of marine origin, and deposition of coastal sand. The geological mapping and mineral prospecting methods are used to study in detail the geological and geomorphological features of the area. The obtained results showed that Du Cape merits to be developed into a geological heritage as well as a destination "mountain‒sea tourist area" combining with research and educational activities in the field of Earth Science.

Biostratigraphy of Qala e Jafar Yekavalang district Bamiyan Province

Distinguishing of the geologic age from sedimentary rock layers has been one of the important and basic tasks for geological sciences. The objective is to determine the geological age of the sedimentary layers within the Qala e Jafar of Yekawlang district of Bamiyan province by using fossils. In this study, more than 8 fossil specimens were collected and identified over the sedimentary layers of the study area. Different genus and species of Bivalves, Brachiopods, Echinodermata, Corals, and Gastropods were recorded and presented from Qala e Jafar sedimentary layers. Among them, three index fossils determined the relative age of strata, namely: Pholadomya and Carneithyris Subcardinalis. According to the guide fossils and using the assembly fossils aging method, the second sedimentary layer is aged Maastrichtian, and the third layer is aged Campanian. The specifications and living features of the recorded fossils derive a warm oceanic environment in the Late Cretaceous.

Bedrock surface topography of Latvia

ABSTRACT A new map and digital bedrock surface elevation model of Latvia is presented with a horizontal resolution of 250 m. The local bedrock comprises largely undisturbed layers of Palaeozoic and Mesozoic sedimentary rocks covered by up to 200 m thick Quaternary strata composed mostly of glacigenic and marine sediments. The bedrock surface elevation model and the corresponding map were created by tessellation interpolation of the bedrock surface based on more than 20,000 boreholes and constrained by the present land surface. The known locations of paleo-incisions buried under Quaternary cover are indicated. The new digital map has applications in hydrogeological, environmental, and civil engineering, and fundamental and applied research.

Hydrogeochemical and Isotopic Analyses of Deep Geothermal Fluids in the Wumishan Formation in Xiong’an New Area, China

Abstract Medium-low temperature geothermal resources in the Wumishan Formation, which is the geothermal reservoir, are local enrichment resources in Xiong’an New Area, North China. In this study, 35 water samples were collected from the bedrock of Taihang Mountains and Wumishan Formation in Xiong’an New Area and display the chemical compositions of water samples as well as the stable isotope compositions for hydrogen, oxygen, carbon, sulfur, and strontium. Hydrogeochemical characteristics and isotope compositions of water samples are analyzed to understand the origin and circulation processes of these geothermal fluids. Our results of cold groundwaters in the bedrock of Taihang Mountain indicate a more open oxidation environment, and the HCO3-Ca·Mg-type groundwater also indicates a prevailing carbonate dissolution condition. The deep geothermal fluids in the Wumishan Formation beneath Xiong’an New Area indicate a closed reduction condition, and their hydrochemical types are mainly Cl·HCO3-Na type. The diagram of hydrogen vs. oxygen isotope indicates that the recharge for the deep geothermal fluids in the Wumishan Formation of Xiong’an New Area is mainly from atmospheric precipitation. The high δ13C values (-3.4‰−-4.9‰) are notably controlled by the eluviation of the carbonate rock layers. The δ34S values vary from 18.02‰ to 27.01‰; the relatively high values indicate the eluviation of sedimentary rock layers. The high 87Sr/86Sr ratios (0.70806−0.71270) and the high Sr2+ concentrations (0.69−2.92 mg/L) suggest that the Sr in the deep geothermal fluids originates from the eluviation of both silicates and carbonates. According to the multimineral equilibrium diagram, chalcedony is saturated at the measured temperature of geothermal wells; therefore, we chose chalcedony as a geothermal thermometer for the calculation of the reservoir temperature of the Wumishan Formation, and the results vary from 68.63 to 89.10°C. Our study identifies the geothermal type of the deep medium-low temperature hydrothermal systems and also recognizes their water-rock interaction processes. We get a comprehensive understanding that the geothermal resources in the Wumishan Formation beneath Xiong’an New Area is convection-conduction type, for which potential of geothermal development and utilization is enormous.

Twin tunneling–induced deep-seated landslide in layered sedimentary rocks

Twin tunneling–induced deep-seated landslide in layered sedimentary rocks

Analysis of the effect of synchronization of a group of nonexplosive sources on the results of field work

The article deals with the issues of synchronization of a group of sources for exploration of minerals. A group of 3 impulse sources with different delay times (500,1000,2000 μs) for a two-phase medium is modeled, the upper layer is a water layer 20 meters deep, the lower layer is a layer of sedimentary rocks 350 meters deep. Impulse action is one period of harmonic oscillation with a period of 0.1 s. Time diagrams were recorded at depths of 50 and 100 meters. It is shown that the use of a delay of 2000 μs leads to a halving of the signal amplitude at a depth of 100 meters. The data obtained show that improving the synchronization of a group of sources for the needs of seismic exploration will allow focusing and creating the maximum signal amplitude at a given point.

Fingerprinting the Cretaceous-Paleogene boundary impact with Zn isotopes

Numerous geochemical anomalies exist at the K-Pg boundary that indicate the addition of extraterrestrial materials; however, none fingerprint volatilization, a key process that occurs during large bolide impacts. Stable Zn isotopes are an exceptional indicator of volatility-related processes, where partial vaporization of Zn leaves the residuum enriched in its heavy isotopes. Here, we present Zn isotope data for sedimentary rock layers of the K-Pg boundary, which display heavier Zn isotope compositions and lower Zn concentrations relative to surrounding sedimentary rocks, the carbonate platform at the impact site, and most carbonaceous chondrites. Neither volcanic events nor secondary alteration during weathering and diagenesis can explain the Zn concentration and isotope signatures present. The systematically higher Zn isotope values within the boundary layer sediments provide an isotopic fingerprint of partially evaporated material within the K-Pg boundary layer, thus earmarking Zn volatilization during impact and subsequent ejecta transport associated with an impact at the K-Pg.

Dynamics of phytoproductive functioning of low-mountain steppe landscapes of the Southern Urals

We tested the hypothesis that landscape spatial pattern controlled the range of possible dynamic states. We used NDVI values in 1984-2019 in the low-mountain-steppe landscape in the Southern Urals and calculated Getis-Ord statistic to detect hot and cold spots of high and low green phytomass, respectively. We assessed the stability of hot and cold spots before and after establishment of protective regime and evaluated the contribution of the matter circulation in a catchment geosystem to the stability of phytoproductive functioning. The dynamics of the areas of spots of increased and decreased phytomass in the steppe landscape has a clearly pronounced seasonal variation, determined by the time of increased or decreased evaporation. The frequency of spots of high phytomass increases in the larger catchments. The mode of phytoproductive functioning in small catchments can be more holistic without the persistent areas with a meadow type of functioning. Sub-vertical and inclined bedding of sedimentary rock layers distorts the dependence of hot spots on catchment area. The protective regime in the zonal steppe phytocoenoses stabilizes the dynamics of green phytomass.

Tomography of the dynamic stress coefficient for stress wave prediction in sedimentary rock layer under the mining additional stress

In this study, the tomography of dynamic stress coefficient (TDSC) was established based on a mechanical model of stress wave propagation in bedding planes and a mathematical model of the stress wave attenuation in rock masses. The reliability of the TDSC was verified by a linear bedding plane model and field monitoring. Generally, the TDSC in the dynamic stress propagation of bedding planes increases with the following conditions: (1) the increase of the normal stiffness of the bedding plane, (2) the increase of the incident angle of the stress wave, (3) the decrease of the incident frequency of the stress wave, or (4) the growth of three ratios (the ratios of rock densities, elastic moduli, and the Poisson’s ratios) of rocks on either side of bedding planes. The additional stress weakens TDSC linearly and slowly during the stress wave propagation in bedding planes, and the weakening effect increases with the growth of the three ratios. Besides, the TDSC decreases exponentially in the rock mass as propagation distance increases. In a field case, the TDSC decreases significantly as vertical and horizontal distances increase and its wave range increases as vertical distance increases in the sedimentary rock layers.

Deformation characteristics of sedimentary rock due to continuous changes of moisture content in wetting process

In recent years, the number of cases where tunnels are constructed in sedimentary rock layers has increased. It is essential to investigate the deformation characteristics of sedimentary rocks for predicting tunnel deformation. The mechanical properties of sedimentary rocks are widely varied due to moisture content. The rocks are dried by tunnel excavation and wetted by groundwater gushing or backfilling. It is necessary to grasp the changes of deformation characteristics of sedimentary rocks due to moisture changes. In this study, soaking tests were conducted on Neogene period Japanese tuff sampled at Utsunomiya, Japan. In the test, the cylindrical tuff specimens are air dried by over 240 hours at first. Then the tuff specimens are taken in pure water with measuring deformations in detail. There are no effective stress increases by soaking and only uniform matric suction are acted on the specimen without any restraints. The results demonstrated that strain tensor was reached to stable state for 2 - 3 days, and the value of the normal strain perpendicular to the bedding plane is greater than the other normal components and shear strains are also observed in both cases. Although the orientation of the maximum principal strain is in the near of the bedding orientation at the initial dry state, the orientation are suddenly rotated to the normal orientation of the bedding plane. It means that the principal orientation of anisotropy are rotated due to continuous moisture changes.