Bedrock Type Research Articles

87Sr/86Sr isotope ratios in trees as an archaeological tracer: Limitations of linking plant-biomass and bedrock Sr isotope signatures

Assuming that strontium (Sr) isotope ratios in trees mirror the bedrock isotope signal, between-site 87Sr/86Sr comparisons can serve as a powerful tool in archaeological wood provenance studies. Here we discuss the strengths and weaknesses of this approach using Sr isotope data for bedrock, trees and rainfall collected at seven sites in the Czech Republic. The study included basalt, durbachite, granite, paragneiss, limestone and phyllitic slate. The range of 87Sr/86Sr ratios of these bedrock types was extremely large (0.704–1.743). The investigated tree species included oak, pine, and spruce. Within-tree variability in 87Sr/86Sr ratios (~0.010) was two orders of magnitude smaller than the variability in Sr ratios across the studied bedrock types. Oak and pine growing on identical bedrock exhibited statistically indistinguishable 87Sr/86Sr ratios. In four types of spruce tissues from a particular site, the 87Sr/86Sr ratios were indistinguishable, while significantly different from spruce tissues at another site. The 87Sr/86Sr ratios of the wood differed from those of bedrock, converging to the 87Sr/86Sr ratio of rainfall (0.709–0.714). Even at a 450-km distance from the nearest sea, atmospheric Sr partly originated from sea-spray. Incorporation of atmospheric Sr in trees often results in overlapping 87Sr/86Sr ranges and hampers source identification of archaeological wood.

Geogenic organic carbon in terrestrial sediments and its contribution to total soil carbon

Abstract. Geogenic organic carbon (GOC) from sedimentary rocks is an overlooked fraction in soils that has not yet been quantified but influences the composition, age, and stability of total organic carbon (OC) in soils. In this context, GOC is the OC in bedrock deposited during sedimentation. The contribution of GOC to total soil OC may vary, depending on the type of bedrock. However, no studies have been carried out to investigate the contribution of GOC derived from different terrestrial sedimentary rocks to soil OC contents. In order to fill this knowledge gap, 10 m long sediment cores from three sites recovered from Pleistocene loess, Miocene sand, and Triassic Red Sandstone were analysed at 1 m depth intervals, and the amount of GOC was calculated based on 14C measurements. The 14C ages of bulk sedimentary OC revealed that OC is comprised of both biogenic and geogenic components. The biogenic component relates to OC that entered the sediments from plant sources since soil development started. Assuming an average age for this biogenic component ranging from 1000–4000 years BP (before present), we calculated average amounts of GOC in the sediments starting at 1.5 m depth, based on measured 14C ages. The median amount of GOC in the sediments was then taken, and its proportion of soil mass (g GOC per kg−1 fine soil) was calculated in the soil profile. All the sediments contained considerable amounts of GOC (median amounts of 0.10 g kg−1 in Miocene sand, 0.27 g kg−1 in Pleistocene loess, and 0.17 g kg−1 in Red Sandstone) compared with subsoil OC contents (between 0.53 and 15.21 g kg−1). Long-term incubation experiments revealed that the GOC appeared comparatively stable against biodegradation. Its possible contribution to subsoil OC stocks (0.3–1.5 m depth) ranged from 1 % to 26 % in soil developed in the Miocene sand, from 16 % to 21 % in the loess soil, and from 6 % to 36 % at the Red Sandstone site. Thus, GOC with no detectable 14C content influenced the 14C ages of subsoil OC and may partly explain the strong increase in 14C ages observed in many subsoils. This could be particularly important in young soils on terrestrial sediments with comparatively low amounts of OC, where GOC can make a large contribution to total OC stocks.

소백산맥 중부 지역의 하안단구와 하각률

This study tried to reveal distribution of incision rate and the factors from fluvial terrace deposits on the western and eastern slopes in the Middle Sobaek Mountain Range, using OSL age dating and topographical analysis. An average incision rate of 0.220 m/ka was estimated in the western slope streams, while the streams on the eastern slope showed a lower average incision rate of 0.121 m/ka. These results seem to indicate that the study area experienced an asymmetric uplift. Patterns of incision rate in the study area were different from those in the Northern Sobaek Mountain Range, probably suggesting that the Sobaek Mountain Range experienced spatially different uplift patterns. Among the factors, which were considered to influence on distribution of incision rate in the study area (e.g., altitude of sampling point, distance from divide, distance from axis, channel width, and bedrock type), distance from axis showed the strongest relationship with incision rate. Therefore, uplift is thought to be the most significant factor in distribution of incision rate in the Middle Sobaek Mountain Range.

Bedrock and climate jointly control the phosphorus status of subtropical forests along two elevational gradients

Terrestrial carbon sequestration is constrained by the supply of soil phosphorus (P). Climate and bedrock are two key independent drivers of soil P supply. Their potential interactions with soil P supply remains poorly understood. To address this issue, we examined the P status of subtropical forests in southern China along two adjacent elevational gradients with contrasting bedrock types (granite vs. slate). The results show that the P concentration of granite was significantly lower than that of slate. Accordingly, the P concentration of mineral soil, litter, and fine-root P on the granite was significantly lower than that on the slate. In contrast, their ratios to the bedrock P concentration were higher in the granite transect than in the slate transect. Moreover, we found a stronger nutrient uplift effect on P in the P-poor transects. Although bedrock P concentrations were constant along elevation, topsoil total P, soil labile inorganic P (Pi), soil labile organic P (Po), and soil moderately labile Pi concentrations showed a significant increasing trend with elevation on both transects. Multivariate linear regression models revealed that bedrock P explained more variation of plant and soil P than did climate. Soil moderately labile Po concentration showed contrasting elevational patterns on different bedrock types, which indicated an interactive effect between bedrock P concentration and climate on the soil moderately labile Po concentration. The Pearson correlation analysis indicated that plant and soil P measures were more tightly coupled in the P-poor transect than in the P-rich transect. These results indicate that the P status of subtropical forests is determined predominantly by the bedrock P concentration and by its interaction with climate. Our results suggest that predictions of ecosystem P status and its responses to climate change can be improved significantly by incorporating local-scale parent material properties into the modeling frameworks.

Distribution, Drivers, and Threats of Aluminum in Groundwater in Nova Scotia, Canada

Increased rates of acid deposition derived from the burning of fossil fuels over the last century have resulted in the acidification and increase in aluminum (Al) levels in freshwaters and soils in sensitive areas. While the acidification of surface waters such as lakes and rivers has been extensively studied, the acidification status and resulting Al concentrations in groundwater are poorly understood. Here we aim to describe the distribution of Al in groundwater across the province of Nova Scotia, Canada. We investigate the hydrogeological conditions that influence Al concentrations in groundwater and compare Al concentrations to legislated threshold levels for human and aquatic health. We found groundwater Al concentrations to be highest in areas underlain by plutonic and metamorphic bedrock types as well as surficial aquifers, with pH and organic carbon concentrations having the strongest correlation with groundwater Al concentrations. Few samples exceed the maximum acceptable concentration of 2900 µg/L released by Health Canada (2021), but these exceedances are important to highlight given the challenges with respect to Al treatment in private domestic wells and our evolving understanding of Al impacts to human health. High concentrations of Al in groundwater may also be exported to surface waters such as rivers and lakes, where they can be harmful to aquatic populations such as Atlantic salmon (Salmo salar). We recommend that private well owners test their water supplies for Al, and that further studies on Al export from groundwater to surface water be carried out in the most high-risk areas coincident with important Atlantic salmon river watersheds.

Loess Classification by Region Using Machine Learning Property Values and Reliability Assessment Methods

Majority of the loess in Korea is the soil that is formed during rock weathering, and its characteristics vary widely depending on the bedrock type, degree of weathering, and climatic conditions. Consequently, it is necessary to acquire objective data on loess based on its location of production and corresponding properties. Therefore, the purpose of this study is to assess the basic properties of nine representative loess samples. The amount of water required to knead each of these samples was calculated using the standard cement leading method; further, properties including hardness, cohesiveness, springiness, adhesiveness, fracturability, chewi-ness, gumminess and resilience were measured using a texture analyzer. Three machine learning approaches were adopted to classify the samples based on the measured features, namely: support vector machine (SVM), k-nearest neighbors (KNN), and deep neural network (DNN). The results showed that SVM produced the highest training and test classification accuracy; meanwhile, DNN presented the best generalization ability.

Discovery of cryptic plant diversity on the rooftops of the Alps

High elevation temperate mountains have long been considered species poor owing to high extinction or low speciation rates during the Pleistocene. We performed a phylogenetic and population genomic investigation of an emblematic high-elevation plant clade (Androsace sect. Aretia, 31 currently recognized species), based on plant surveys conducted during alpinism expeditions. We inferred that this clade originated in the Miocene and continued diversifying through Pleistocene glaciations, and discovered three novel species of Androsace dwelling on different bedrock types on the rooftops of the Alps. This highlights that temperate high mountains have been cradles of plant diversity even during the Pleistocene, with in-situ speciation driven by the combined action of geography and geology. Our findings have an unexpected historical relevance: H.-B. de Saussure likely observed one of these species during his 1788 expedition to the Mont Blanc and we describe it here, over two hundred years after its first sighting.

Syntaxonomy, diversity and distribution of the vegetation of rock crevices, clefts and ledges in the colline and montane belts of Central Pamir-Alai and Western Tian Shan Mts (Middle Asia)

Mountain areas are very often considered to be biodiversity hotspots. Rocks are one of the most unique habitats and serve as a suitable biotope for many endemic and specialized plant species. Here we present the results of the vegetation studies conducted in central and eastern Pamir-Alai and the south-western Tian Shan mountains in 2013‒2019. Based on 334 phytosociological relevés we propose a synopsis of the rock communities of the montane and colline zones of eastern Middle Asia. As a result of our research, we distinguish 17 communities defined into five groups of petrophytic vegetation within the Caricion koshewnikowii alliance. We describe 11 new associations: Feruletum bucharicae, Scrophularietum glabellae, Asperulo albiflorae–Kafirniganietum hissaricae, Scutellarietum immaculatae, Campanuletum eugeniae, Silenetum kuschakewiczii, Rosularietum platyphyllae, Spireaetum pilosae, Silenetum lithophilae, Campanuletum albertii, and Rhinactinidietum limoniifoliae. Distinctiveness of environmental conditions together with the species composition of the phytocoenoses within the montane and colline belts of eastern Middle and Central Asia make the investigated vegetation among those with the highest specific diversity and richness of endemisms in the whole area. The main factors that determine the species composition of the investigated vegetation seem to be phytogeography, altitude, bedrock type, and exposition. Supplemental data for this article is available online at https://doi.org/10.1080/11263504.2021.1922531 .

Geological load and health risk of heavy metals uptake by tea from soil: What are the significant influencing factors?

As one of the most popular beverages around world, factors influencing transfer of heavy metals from soil to tea leaves is crucial to investigate and assess health risk through tea drinking. Parent material (PM), soil and tea samples from Anhui province, typical tea producing area in China were collected in this study. To find out distribution characteristics of heavy metals in tea and soil, and influencing factors for transfer process, variables of plantation factors, soil properties and geological background were taken into account. The results showed that weathering pedogenic process could be the main release source of heavy metals in soil under the acid environment for tea growth. More than 75% of soil Cd, Hg, Pb and Zn exceeded background. However heavy metals in tea samples were below the limits of China, WHO and EU standards. Soil organic matter and redox process influenced the distribution and transfer of As, Pb, Cd and Hg in soil and tea. While geochemical behaviours of Cr, Cu, Ni and Zn were mainly related to soil pH and iron oxides in tea garden. The method of classification and regression trees (CART) showed clones of tea type, bedrock type, soil texture, soil organic and fertilizer application were identified as the main factors influencing transfer factors of heavy metals from soil to tea. The specific types of tea grown in the soil with sandy clay and bedrock of granite/granodiorite and shale should be given more monitoring. The non-carcinogenic hazard quotients (HQ) and cancer risk (Risk) through tea drinking were primarily caused by Pb and Cd respectively. To reduce the potential health risk from tea, application of organic and/or compound fertilizer were thought to be the effective management strategy for tea plantation.

Morphological variability of Argynnis paphia (Lepidoptera: Nymphalidae) across different environmental conditions in eastern Slovakia

The contrasting habitats providing a heterogenous environment are considered to affect morphological traits of Lepidoptera due to their adaptability to various selection pressures under such conditions. The morphological and genetic variability of the butterfly Argynnis paphia (Nymphalidae) were studied with a focus on populations across different environments of the Western Carpathians. Male individuals were collected from five sites differing in elevation, type of bedrock, vegetation and climatic region. Morphometric analyses indicated significant variability in reproductive (genitalia width) and non-reproductive (forewing shape and size) traits. The most significant differences were recorded between the locality Bacova, representing the highest elevation, and other localities. The statistical analyses revealed the correlation of wing morphology with elevation, bedrock type and annual average temperature, while morphological differences of valvae structures were correlated with altitude. We concluded that size and shape of wings but also male genitalia vary among populations of A. paphia from different regions in response to environmental conditions.

Role of environmental filtering and seed source availability in natural regeneration processes following large-scale disturbances in mountain forests

The relative importance of environmental factors and species pool in natural regeneration processes is still intensively disputed. Is environmental filtering especially important for species with higher requirements for temperature and soil fertility? Is the seed source limitation especially pronounced among tree species with lower dispersal abilities? Trees, seedlings and saplings measurements were conducted in 600 plots of 0.05 ha distributed in a regular grid in the Tatra Mountains (elevation range 817–1797 m a.s.l.). Boosted regression trees were used to analyse the relationships between the numbers of young trees, factors acting as environmental filters and the potential seed source availability. The most important factor affecting the distribution of young trees of most species was elevation; bedrock type was the second most important factor for Acer pseudoplatanus, while potential solar radiation was important for Sorbus aucuparia. The relationship between the presence of mature trees and abundance of young ones was strong in Fagus sylvatica, moderately strong in A. pseudoplatanus, and weak in Picea abies, Abies alba and S. aucuparia. The role of environmental factors in shaping the abundance of young trees varies strongly among species, while the seed source availability is very important for large-seeded trees.

Morphological and Spectral Diversity of the Clay-Bearing Unit at the ExoMars Landing Site Oxia Planum.

The European Space Agency and Roscosmos' ExoMars rover mission, which is planned to land in the Oxia Planum region, will be dedicated to exobiology studies at the surface and subsurface of Mars. Oxia Planum is a clay-bearing site that has preserved evidence of long-term interaction with water during the Noachian era. Fe/Mg-rich phyllosilicates have previously been shown to occur extensively throughout the landing area. Here, we analyze data from the High Resolution Imaging Science Experiment (HiRISE) and from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instruments onboard NASA's Mars Reconnaissance Orbiter and the Colour and Stereo Surface Imaging System (CaSSIS) onboard ESA's Trace Gas Orbiter to characterize, at a high spatial resolution, the morphological and spectral variability of Oxia Planum's surface deposits. Two main types of bedrocks are identified within the clay-bearing, fractured unit observed throughout the landing site: (1) an orange type in HiRISE correlated with the strongest detections of secondary minerals (dominated by Fe/Mg-rich clay minerals) with, in some locations, an additional spectral absorption near 2.5 μm, suggesting the mixture with an additional mineral, plausibly carbonate or another type of clay mineral; (2) a more bluish bedrock associated with weaker detections of secondary minerals, which exhibits at certain locations a ∼1 μm broad absorption feature consistent with olivine. Coanalysis of the same terrains with the recently acquired CaSSIS images confirms the variability in the color and spectral properties of the fractured unit. Of interest for the ExoMars mission, both types of bedrocks are extensively outcropping in the Oxia Planum region, and the one corresponding to the most intense spectral signals of clay minerals (the primary scientific target) is well exposed within the landing area, including near its center.

Similar successional development of functional community structure in glacier forelands despite contrasting bedrocks

AbstractQuestionsPrimary plant succession is expected to be driven by habitat filtering and competitive exclusion. However, such findings typically come from experimental or single‐site case studies. As a result, we lack field studies that investigate the functional community structures across successional series with differing site conditions. Here, we address the following question: how do plant trait patterns and functional diversity change along two chronosequences with distinct bedrocks?MethodsWe established two soil chronosequences with contrasting bedrock types (siliceous vs calcareous) in the Swiss Alps spanning a terrain age gradient of 13,500 years. We analysed plant ecological strategies at 40 plots per glacier foreland relating six functional traits to terrain age using RLQ analysis. We used the variation in plant ecological strategies revealed by RLQ analysis to calculate indices of functional diversity and analysed their temporal development with terrain age.ResultsThe RLQ analysis revealed that canopy height and dispersal type were significantly associated with terrain age. In both glacier forelands, functional richness (FRic) increased with terrain age, suggesting similar development of niche differentiation along the chronosequences, irrespective of bedrock types. In addition, we observed a decrease of functional evenness (FEve) and functional divergence (FDiv) in both sites, indicating an overall trend to habitat filtering.ConclusionsThe results support the idea of a similar development of functional community structure along the two chronosequences, underlining the deterministic model of functional structure during succession. The functional approach of this study improves knowledge of the adaptive strategies of plant communities colonising glacier forefields and highlights the potential of comparing successional series with differing site conditions to gain a deeper understanding of successional drivers and underlying mechanisms.

Observed changes in chronic and episodic acidification in Virginia mountain streams in response to the Clean Air Act and amendments

Reductions in acidic deposition following the 1990 Amendments to the Clean Air Act have led to improvements in the acid/base status of many freshwater bodies in the eastern United States, but such recovery has not been as widespread in Virginia mountain streams. In the current analysis, water chemistry trends are determined for 63 streams within Shenandoah National Park, Virginia, and surrounding national forests, where water samples have been collected on a quarterly basis from 1987 to 2019. Over this timeframe, a majority of the most acid-sensitive streams – those with watersheds underlain by siliciclastic bedrock – have experienced reductions in acid neutralizing capacity (ANC). This outcome, which differs from the modest recovery predicted by earlier modeling studies, is likely due to further depletion of soil base cations and perhaps increases in organic acids. Meanwhile, stream water pH has increased for all watershed bedrock types, averaging between 0.05 and 0.10 pH units per decade. High-flow sampling was conducted at three sites from 1992 to 2019, revealing an assessment of episodic acidification that is more encouraging than that of chronic acidification. For two of these sites, pH during high-flow conditions increased much more rapidly than pH during low-flow conditions. Steep reductions in sulfur deposition over the three decades since the 1990 Amendments have led to a “flushing” of sulfate from shallow soils, which has contributed to the improved acid/base status during episodes of high flow. The findings suggest that continued low acidic deposition rates will lead to further improvements in stream water quality, with the timescales of recovery dependent upon bedrock geology of the watersheds.

Phytosociological Analysis of Natural and Artificial Pine Forests of the Class Vaccinio-Piceetea Br.-Bl. in Br.-Bl. et al. 1939 in the Sudetes and Their Foreland (Bohemian Massif, Central Europe)

Research Highlights: Differentiation of Scots pine forests of the class Vaccinio-Piceetea in Poland has been the subject of numerous studies, including revisions. Despite that, the area of southwestern Poland was hitherto practically unexplored in this respect. Background and Objectives: The aim of this work was therefore (i) to present the diversity of the pine forests in the Sudetes and their foreland; (ii) to compare the ecology of studied communities. Materials and Methods: We analyzed 175 phytosociological relevés collected between 1991 and 2020 in natural and anthropogenic pine stands. To identify vegetation types, we used the modified TWINSPAN algorithm; principal coordinate analysis, distance-based redundancy analysis and permutational tests were applied to identify the variation explained and the main environmental gradients shaping the studied plant communities. Results: Five associations were distinguished: thermophilous Asplenio cuneifolii-Pinetum sylvestris Pišta ex Husová in Husová et al. 2002, which develops on shallow soils over ultrabasic substrates, Hieracio pallidi-Pinetum sylvestris Stöcker 1965, which prefers outcrops of acidic rocks; Betulo carpaticae-Pinetum sylvestris Mikyška 1970, which is relict in origin and occurs on the upper Cretaceous sandstones, the peatland pine–birch forests of the Vaccinio uliginosi-Betuletum pubescentis Libbert 1933 and the Vaccinio myrtilli-Pinetum sylvestris Juraszek 1928. Moreover, community Brachypodium sylvaticum-Pinus sylvestris with the occurrence of many thermophilous and basiphilous species was also found on limestone substratum. The analysis of the species composition of pine plantations established on deciduous and mixed forests habitats revealed that these anthropogenic communities were marked by a random combination of species in which a certain group of common forest generalists participated. The distinguished communities differed clearly among each other also in habitat characteristics. Particularly important for their differentiation were soil reaction and nutrients, supported by differences in moisture, temperature and light availability. Apart from the edaphic factors, altitude and the bedrock type proved to be equally important. Conclusions: Our study provides new remarks to the typology and synecology of pine forest communities in SW Poland.

Temperature sensitivity of CO2 efflux in soils from two alpine elevation levels with distinct bedrock types

Predicted increase in climate warming will affect soil organic carbon (SOC) dynamics in vulnerable cold alpine environments. In contrast to freeze and thaw cycles, less is known about the effects of temperature regimes in the range between 2 and 10 °C on SOC availability to soil microorganisms. For this reason, CO2 efflux, extracellular enzyme activities and microbial communities were measured in an incubation experiment with three temperature treatments: (T1) continuous 10 °C, (T2) cooled down to 2 °C, and (T3) rewarmed from 2 to 10 °C. Two forest soils at low elevation and two grassland soils at high elevation were taken from two sites with distinct bedrock types (limestone at Hochschwab, gneiss and schist at Rauris). The CO2 efflux did not differ significantly between the elevation levels at the two sites. In the continuous warm treatment T1, the relative decline in CO2 efflux was stronger in the two Rauris than in the two Hochschwab soils during the 0–123 days period. In the cooling treatment T2, the cumulative ΣCO2C efflux of the Hochschwab soils was lowered by 32% and that of the Rauris soils by only 19% compared with T1 during the 30–123 days period. In the rewarming treatment T3, the ΣCO2 efflux was on average 33% higher than that of treatment T1 during the 91–123 days period, ranging from +8% to +62%. Phospholipid fatty acid (PLFA) composition and extracellular enzyme activities were not markedly affected by incubation time or temperature treatments. The differences in bedrock properties had stronger effects on the ΣCO2 efflux, enzyme activities as well as total PLFA content and composition than elevation level or vegetation. Other, largely unknown factors control the rewarming effects on the mobilisation of a labile SOC pool.

Microbial necromass formation, enzyme activities and community structure in two alpine elevation gradients with different bedrock types

Microbial necromass is an important part of soil organic carbon (SOC), but the changes in its contribution along elevational gradients and soil types are poorly understood. At two sites, the alkaline site Hochschwab and the acidic site Rauris, soil samples from three elevation levels and depths were analysed for amino sugars as microbial necromass indices, extracellular enzymes, and phospholipid fatty acids (PLFA) as microbial biomass indices. The three elevation levels at each site represented similar temperature and precipitation regimes. Microbial necromass contribution to SOC was lower (26%) at the alkaline site than at the acidic site (37%), indicating lower transformation of microbial biomass into stable SOC and support the increased accumulation of fungal necromass under N limitation at Hochschwab. Fungi generally dominate microbial necromass, with 88% at Hochschwab and 77% at Rauris. At the alkaline site Hochschwab, phenoloxidase, peroxidase and phosphatase enzymes activities were lower by 96%, 98% and 75%, respectively than at the acidic Rauris site, but not those of the hydrolytic enzymes β-glucosidase, exo-glucanase, exo-chitinase, and protease, indicating retarded decomposition of plant residues. Gram positive bacteria dominate bacterial biomass at both sites, with 70% at Hochschwab and 72% at Rauris. The higher fungal to bacterial PLFA ratio suggest increased contribution of fungi to total microbial PLFA at Hochschwab due to the better adaptability of fungi to the site-specific environmental conditions. Effects along alpine elevation gradients depend on vegetation induced changes in soil properties, which interact with bedrock properties.

GIS-based multi-criteria analysis for nuclear power plant site selection in West Kalimantan

Nuclear power is set as the highest priority to slow global warming, so the construction of a nuclear power plant (NPP) using nuclear reactors as a source of heat energy is initiated to produce pollution-free electricity. Bengkayang and Mempawah Regencies in West Kalimantan provinces are selected as prospective NPP locations based on the exclusion and discretionary criteria. The exclusion criteria consist of the geological structure, types of bedrock, the existence and sufficiency of the cooling water, proximity to the population center, and terrain shape. Meanwhile, the discretionary criterion is proximity to the road network. This study aims to map and analyze the exclusion and discretionary criteria for potential NPP. The multi-criteria analysis in this study includes screening analysis, regional suitability analysis, and descriptive spatial analysis. It is performed using the Geographic Information Systems (GIS) technique on spatial data information. The screening process produced six potential locations to be used as NPP. Five locations are in Bengkayang Regency, precisely in Sungai Raya Kepulauan District and Sungai Raya District. Another location is in Mempawah Regency, precisely in Sungai Kunyit District.

Assessment of ultimate load of drilled shaft socketed in rocks based on pile load tests

To investigate the settlement characteristics of drilled shaft socketed into igneous, metamorphic, or sedimentary rock, experimental results of the pile load tests were thoroughly collected in 20 different locations, clearly tabulated, and extensively compared with the standards for assessment of ultimate load. Total and elastic settlement patterns of drill shaft were completely dependent on the socketed pile length, the imposed load, the pile diameter, and the shear stress in bedrock, whereas residual settlement did not depend on the factors. It was also observed that the trends of total, residual, and elastic settlements were independent on bedrock types. Comparison between the experimental data and the standards shows that the total and residual settlements of large drilled shaft socketed in bedrock were too high to determine the ultimate load, and the reasonable amount of total or residual settlement measured from pile load test is proposed to assess the ultimate load capacity of drilled shaft socketed in bedrock.

Rock glaciers in mixed lithologies: a case study from Northern Pirin

Rock glaciers are lobate or tongue-shaped assemblages of poorly sorted, angular-rock debris and ice, commonly found in high mountain environments, which move as a consequence of the deformation of internal ice (Giardino and Vitek, 1988; Barsch, 1996). However, in most research works, when discussing the formation of these features, the focus has been mainly on the past or present climatic conditions. The systematic observations of the distribution of relict rock glaciers in the mountains of the Balkan Peninsula indicate however that geological setting, represented by bedrock type and composition, and the pattern of fault lines, is not less important for the formation and evolution of these landforms. The present article is focused on rock glaciers in the high mountain zone of the Pirin Mounains (Bulgaria), which are formed in mixed lithology, with participation of both silicate rocks (granite, gneiss) and carbonate rocks (marble). In fact, these rock glaciers are the only ones of a typical morphology that exist in the glaciokarstic marble area of Northern Pirin. What is common for all locations where such rock glaciers are found is that the marble layer, which is on top, is quite thin (few metres to few hundreds of metres). In such conditions, the rock glacier formation occurred following the mechanism typical for silicate rocks, but using marble debris and block material instead. The observed forms are characteristic only for marginal zones, along the contact line between silicate and carbonate high mountain environments.