In search of marine terraces from Central Dobrogea (Casimcea Plateau, Western Black Sea). Preliminary inquires on distribution, extension and vertical crustal movements

Casimcea Plateau is an uplifted (exhumated) peneplain cut in Proterozoic green–schists and one of the oldest tec­tonic units around the Black Sea. Despite its overall monotonous physiognomy, the plateau is crossed by Casimcea Valley and presents a seaward façade to the east which preserves (sub)horizontal surfaces as testimonies of the paleoenvironmental changes (sea level and climate). This research aims to identify the marine and fluvio–marine terraces and to define their vertical distribution based on the morphometric analysis of two study sites (north – Ceamurlia; south – Tașaul Lake) using EU-DEM. 6 levels were identified as possible marine terraces within the 2–50 m altitude range and also some inferences were made concerning the age of the lower three levels. Also, the present work highlights a differential (stronger) uplift of the northern sector between Peceneaga – Camena and Ostrov – Sinoe faults reflected by both the elevation difference of 5–6 m between the terraces staircases identified at the two sites and by the elevation gaps analysed on an array of cross-fault transects carried on over Ostrov – Sinoe fault.

Snow–avalanche history reconstructed with tree rings in Parâng Mountains (Southern Carpathians, Romania)

Snow avalanches are a common phenomenon in Parâng Mountains (Southern Carpathians, Romania) perturbing tourism activities and associated infrastructures, damaging forests, and causing fatalities. Its past history is an es­sential information to gather while assessing the hazard zonation areas. Usually, in Romania snow–avalanche activ­ity occurring in forested areas are neither monitored, nor recorded by historical archives. In these areas, environ­mental archives such as tree rings may provide useful information about the past avalanche activity. The purpose of the present study is to reconstruct snow–avalanche history with tree rings along a path located below Cârja Peak (2405 m a.s.l.), an area where past snow–avalanche activity still remains underestimated. In this sense, 57 Norway spruce (Picea abies (L.) Karst.) trees showing clear signs of disturbance by snow avalanches were sampled and the growth anomalies associated with the mechanical impact produced by snow avalanches on trees were identified within their rings and served to reconstruct past events. The reconstructed chronology covers the period 1994–2018 showing the occurrence of a minimum of 11 major events, with an average return period of 2.1 years. Tree–ring records provided the most consistent avalanche event chronology in the study area. Although the lim­ited extension of the chronology back in time, a better understanding of snow–avalanche history which may be gained through dendro­chronological reconstructions represent nonetheless useful and pertinent information to consider before the imple­mentation and development of infrastructure in this mountain avalanche–prone area.

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.

Analysis of the difference in depths and variation in slope steepness of the Sunda Trench, Indonesia, east Indian Ocean

The paper discusses geomorphology of the Sunda Trench, an oceanic trench located in eastern Indian Ocean along the Sumatra and Java Islands of the Indonesian archipelago. In particular, it analysis the difference in depths and variation in slope steepness between the two segments of the trench: the southern Java transect (coordinates 108.8°E 10.10°S to 113.0°E 10.75°S) and the northern Sumatra transect (97.5°E 1.1°S to 101.0°E 5.5°S). The thematic maps and geomorphological modelling were plotted using Generic Mapping Tools (GMT). The materials include high-resolution data on topography, geology and geophysics: GEBCO 15 arc-minute resolution grid, EGM2008 2.5 minute Earth Gravitation Model of 2008, GlobSed global 5‐arc‐minute total sediment thickness and vector geological datasets. In addition to the GEBCO-based bathymetric data, geological, topographic and geophysical maps, the results include enlarged transects for the Java and Sumatra segments, their slope gradients and cross-section profiles, derived from the bathymetric GEBCO dataset. The geomorphology framework of the Sunda Trench is largely controlled by the subduction of the Australian plate underneath the Sunda microplate. The geological processes take place in basin of the Indian Ocean at different stages of its evolution and influence the nature of the submarine geomorphology and geometric shape of the trench. Sunda Trench is seismically active part of the Pacific Ring of Fire. A large number of the catastrophic earthquakes are recorded around the trench. The histograms shows variation in depths along the segments of the Sumatra and Java. The Java segment has a bell-shaped data distribution in contrast to the Sumatra with bimodal pattern. The Java segment has the most repetitive depths at -2,500 to -5,200 m. The Sumatra transect has two peaks: 1) a classic bell-shaped peak at depths -4,500 m to -5,500 m; 2) shelf area with a peak from 0 to -1,750 m. The data at middle depths (-1,750 to -4,500 m) have a frequency <300 samples. The most frequent bathymetry for the Sumatra segment corresponds to the -4,750 m to -5,000 m (2,151 samples). Comparing to the Sumatra segment, the Java segment is deeper. For the depths >-6,000 m, there are only 138 samples for the Sumatra while 547 samples for Java. Furthermore, Java segment has more symmetrical geometric shape while Sumatra segment is asymmetric, one-sided. The Sumatra segment has a steepness of 57.86° on its eastern side (facing Sumatra Island) and a contrasting 14.58° on the western part. The Java segment has a steepness of 64.34° on its northern side (facing Java Island) and 24.95° on the southern part (facing Indian Ocean). The paper contributes to the studies of the submarine geomorphology in Indonesia.

Investigating land surface deformation using InSAR and GIS techniques in Cluj–Napoca city’s most affected sector by urban sprawl (Romania)

The last three decades have marked an unprecedented urban expansion of the city of Cluj-Napoca, leading to strong anthropogenic influences on the natural environment and important changes in the land-use. Due to the specific morphology of Cluj area, characterized by limited available plane surfaces which are insufficient to support the urban expansion, more and more territories with slopes between 5°-26° are used for constructions. These areas are marked by high risks of mass movements due to their specific geological and geomorphological characteristics, therefore the present study proposes a more detailed and complex GIS and remote sensing analysis of the western urban part of Cluj-Napoca, in order to highlight the main changes of the city and the consequences of the human actions. One of the most used radar interferometry (InSAR) technique was applied in order to detect land deformations that can threaten the infrastructure and the population. Sentinel-1B SAR imagery were processed by the DInSAR methodology, resulting in a land deformation map, which represents an important support in generating the vulnerability assessment. Based upon this evaluation, we concluded that the most vulnerable neighbourhoods to land deformations from the western part of the city are the peripheral ones, as following: Dâmbul Rotund, Bună Ziua, Europa, Mănăștur, West Iris and Făget, proving that human activity and the geological setting are the main triggering factors of the discussed phenomenon.

The effects of biocrusts on soil parameters in a semi-arid pediment at north-eastern Iran

The biocrusts are organized by soil-surface communities of biota that live within or on the very top of soil surface and play an important role in soil conservation. They include lichens, mosses, fungi, cyanobacteria, eukaryotic algae, and other heterotrophic bacteria. The interaction between biocrusts and soil is very important and good awareness from that help to better manage soil specially in arid and semi-arid areas. The linkage between cyanobacteria species and soil physicochemical parameters and mineralogy in two geomorphic zones in the northeastern Iran was studied. Samples were collected in summer along a linear transect by using 50 x 50 cm quadrates for each study zone. Individual mineral soil particles were analyzed by a scanning electron microscopy (SEM). The amounts of Na, K, Ca, and Mg contents as well as EC and SOC altered significantly between two study zones. Biocrusts increased levels of organic carbon, pH, calcium carbonate, exchangeable sodium and potassium percentages. The main soil properties of SOC, CaCO3 and amount of clay changed among biocrust sand bare soils.

Detection of the piping processes analyzed through the Self Potential method, in the peripheral area of the Dognecei Mountains

The water movement in the soil contributes to entrainment of particles of varying sizes, and over time, some tendency for the orientation of this flow may occur. In the areas with particular soil characteristics, an internal discrete drainage network appears, that manifests differently depending on the causative factors. The aim of the recording and monitoring of this concentrated water flow movement that contributes to soil erosion as a pipe network through a geophysical method is to understand its evolution. Using a method such as the Self Potential (SP) allows the study of the piping processes in a quantitative manner. In the peripheral area of the Dognecei Mountains, specifically near the Doclin village, it was analyzed one such area in which this process occurs.It was analyzed the evolution of a site in periods with different climatic parameters which are the ones that act as the active elements.The amplitude of the SP values (mV) differs based on the causative environmental factors, with negative values in the dry period and positive values when the soil is wet, the values having fluctuation up to 15 mV. The piping processes contribute to soil degradation and the knowledge of the areas affected by this processes and particularly of the factors influencing its occurrence can be achieved with good results by using the Self Potential method.

Historical geomorphic analysis of Someșul Mic River (NW Romania) channel spatial and temporal behavior, as a background for the assessment of present day morphological state of the river

In the context of the increased interest on integrating the complex spatial and temporal response of fluvial systems to human impacts into the process of assessing the ecological state of the rivers and in promoting a sustainable river management European countries have developed a multi–scalar, hierarchical, process based hydro–morphological framework focused on understanding the river functioning and evolution as a basis for interpreting current conditions. In this context, the goal of this paper is to demonstrate the usefulness of systematic historic and present day geomorphic analysis along channel reaches with distinct typologies in order to generate a better image of river morphology as a background for assessing its present morphological state. The historical geomorphic analysis of Someșul Mic River’s channel dynamics during the past 250 years has shown that the main controlling factor is climate through its centennial – decadal scale variations in magnitudes and amplitudes of flood events, while the local geological conditions and hydrotechnical works having subordinate effects. The reference condition in assessing the present day morphological state of the river was defined based on channel typology and dynamics between AD 1860 – AD 1970, reflecting a river state far from a pristine condition, but characterized trough human impacts maintained bellow the river sensitivity to disturbances. The Morphological Quality Index (MQI) was calculated for 17 distinct channel reaches. Its values indicate the high geomorphic degradation of the river induced by hydrotechnical interventions along the channel. Very poor conditions are concentrated mainly along the upper reaches of the river, while further downstream the river is in a dominantly moderate deterioration state. The resulted image has the potential to better identify the critical reaches along this river, and the main disturbatory elements acting on them, in order to support better projections on possible channel trajectories andsubsequently river management actions.

Multi–risk quantitative assessment in Reghin city, Transylvania, Romania

Multi–risk assessment supposes an integrated analysis of various processes and phenomena generating risks across the territory, highlighting the individual and cumulative impact at different levels of analysis. This paper aims at creating an assessment model of multi–risk generated by the cumulative effects of landslides and floods, processes considered as significant in the study area, the administrative unit of the city of Reghin in the Transylvanian Basin. To obtain the multi–risk, two GIS spatial analysis models have been created. The first model means to identify the probability of landslide occurrence (built on GIS databases in vector and raster format, correlatively analysed by means of spatial analysis functions and equations), and is adapted according to legislative regulations stipulated in the Government Decision no. 447/2003. The second one is a database regarding the floodable area with a 1% probability in raster format, resulted from a nation–wide model created to identify the flooded areas.The multi–risk map was created using the mediation method, in which every class of individual (geomorphological or hydrological) hazard receives equal weight within the final result. As a consequence of applying the above–mentioned models, we obtained areas with different probabilities for cumulative risk processes, which are rendered as favourable or restrictive in terms of locating different structures (roads, settlements, functional areas, shopping centres). According to the degree of validation, these may be used for a more precise determination of the development areas and for territorial planning.

Morphological changes in the proximity of the Greek colonies founded along the western (Romanian) Black Sea coast: Orgame, Histria, Tomis, and Kallatis

This paper is a review of the up to date knowledge about the coastal environmental transformations around the Greek settlements along the present–day Romanian shoreline. The aim is to define a general pattern of the morphological configuration the Greeks were looking for when establishing their colonies. Existing quantitative and qualitative database on shoreline evolution both along the low lying deltaic sector (N) and along the soft rock cliffs along the southern sector of the present–day Romanian coast together with the present day morphological configuration analysis at each study site were used to assess large spatial (~180 km alongshore) and temporal scales (ca. 2500 yrs) of coastal behavior. The coastal dynamics during the late Holocene was controlled by the deltaic lobes development along the northern part of the present day Romanian coast which led to important shoreline progradation and subsequent isolation from the shoreline of Histria and Orgame Greek cities. The continuous sediment input depletion, sea level rise, storms set-up, longshore transport system and local tectonic activity drove the cliff line retreat along the southern sector, with important parts of the Tomis and Kallatis settlements being lost to the sea.