Fossil Rock Research Articles

Bioaccumulation of Titanium in diatom Cyclotella atomus Hust.

Diatomaceous earth or diatomite is a fossil rock deposit of diatoms made up of silica and other minerals. A distinguishing feature of diatoms that placed them in the single class of microalgae Bacillariophyceae, is the frustule, a transparent, hard-shelled cell wall. It's interesting to note that the diatom has specific proteins and enzymes for heavy metal detoxification and can intake and store more heavy metals in its frustule. Consequently, an attempt has been made in this study to determine the bioaccumulation of metals in the frustules of the diatom. Hence, a centric diatom was isolated from the freshwater sample collected from the Adyar River, Chennai, Tamil Nadu. The diameter of the cell was 5-7.5µm and 20-23 striations with radial arrangement. A single, dark off-center fultoportula and marginal fultoportula on the striae are found in the diatom. Additionally, one rimoportula between two marginal fultoportula distributed on the striae between the costa was also seen. As a result, the isolated diatom was morphologically identified as Cyclotella atomus Hust. Simultaneously, the bioaccumulation study reveals that the Titanium (Ti) was found accumulated in the frustules of the diatom incubated in the Ti-supplemented culture medium based on the scanning electron microscope-energy-dispersive X-ray analysis (SEM-EDAX). Therefore, the biogenic accumulation and fabrication of Titanium frustules in diatom have advantages in enhancing the efficiency of solar cells.

Barium and strontium isotope fractionation by cyanobacteria forming intracellular carbonates

While barium (Ba) and strontium (Sr) stable isotopes are increasingly used as tracers of biogeochemical processes and paleo-proxies, the role of biotic processes on Ba and Sr isotope fractionation is poorly understood. Here, Ba and Sr stable isotope fractionations were studied in the laboratory using Gloeomargarita lithophora, a cyanobacterium that selectively hyperaccumulates Ba and Sr within intracellular amorphous carbonate biominerals. Our results show that lighter Ba and Sr isotopes are enriched in G. lithophora cells compared to the initial solution by –0.24‰ to –0.03‰ (δ137Ba) and –0.33‰ to –0.01‰ (δ88Sr) depending on the stage of the experiment. The fractionation of Ba and Sr isotopes is distinct in magnitude from that occurring during abiogenic and other known biogenic carbonate formation cases. Additionally, using a Rayleigh fractionation model, the fractionation factors of Ba and Sr isotopes between G. lithophora cells and the fluid (the growth medium), i.e., Δ137Ba(bac-sol) and Δ88Sr(bac-sol), were equal to –0.25‰ and between –0.46‰ and –0.38‰, respectively. Interestingly, δ137Basol and δ88Srsol decreased at the end of Ba and Sr uptake stages back towards their initial values, which caused departures from the Rayleigh fractionation model. This suggests the existence of a back reaction resulting in a Ba and Sr outflux from cells to the solution. Possible hypotheses for this back-reaction include dissolution of amorphous carbonate inclusions in response to cellular stress, or a first-order rate dependence of amorphous carbonate dissolution on the amount of Ba and Sr inside the cell. Our findings suggest that bacteria forming intracellular amorphous carbonates could introduce Ba and Sr isotope variability in environmental records, especially in environments where they thrive. Moreover, the enrichment of lighter isotopes of Ba and Sr during amorphous carbonate formation is consistent with that occurring during the formation of other biogenic carbonates but slightly differs in magnitude, opening a discussion about the possibility to use Δ137Ba(bac-sol) and Δ88Sr(bac-sol) as an indicator of intracellular amorphous carbonate biomineralization in the fossil rock record. Overall, this work highlights the complexity of the biological uptake of alkali-earth metals and stresses the overlooked role of bacteria forming intracellular amorphous carbonates in Ba and Sr biogeochemical cycles.

Using a Lidar-Based Height Variability Method for Recognizing and Analyzing Fault Displacement and Related Fossil Mass Movement in the Vipava Valley, SW Slovenia

The northern slopes of the Vipava Valley are defined by a thrust front of Mesozoic carbonates over Tertiary flysch deposits. These slopes are characterized by a variety of different surface forms, among which recent and fossil polygenetic landslides are the most prominent mass movements. We used the height variability method as a morphometric indicator, which proved to be the most useful among the various methods for quantifying and visualizing fossil landslides. Height variability is based on the difference in elevations derived from a high-resolution lidar-derived DEM. Based on geologic field mapping and geomorphometric analysis, we distinguished two main types of movements: structurally induced movement along the fault zone and movements caused by complex Quaternary gravitational slope processes. The most pronounced element is the sliding of the huge rotational carbonate massif, which was displaced partly along older fault structures in the hinterland of fossil rock avalanches and carbonate blocks. In addition to the material properties of the lithology, the level of surface roughness also depends on the depositional processes of the individual sedimentary bodies. These were formed by complex sedimentary events and are intertwined in the geological past. The sedimentary bodies indicate two large fossil rock avalanches, while the smaller gravity blocks indicate translational–rotational slides of carbonate and carbonate breccia.

Unearthing the Cause of Slow Seismic Waves in Subduction Zones

Researchers look to the fossil rock record to unearth the driving forces for variable seismic speed through subduction zones.

Rock glacier and protalus rampart inventory in Las Salinas river basin, Central Andes of Argentina

This paper presents a detailed rock glacier and protalus rampart inventory from Las Salinas river basin, an arid subtropical mountain hydrological system (between 31°02’ and 31°22’ S latitude) located in the northern sector of the Central Andes of Argentina, where permafrost and cryogenic processes prevail. The inventory is based on a geomorphological characterization by means of optical remote sensing and field description data. The study region covers 630 km2, with 3.25% of the area containing 405±8.2 rock glaciers and protalus ramparts in total, of which 231±2.5 are considered protalus rampart and 49±2 are considered active, 61±1 inactive and 64±3 fossil rock glaciers. Frequency ratio and logistic regression were used as statistical methods to determine the relationship between the distribution of these periglacial landforms and different geological, morphometric and climatic variables as elevation, potential incoming solar radiation, slope, aspect and lithology. Results show that elevation, lithology, and aspect are the most influencing factors for the occurrence of active rock glaciers. According to rock glaciers and protalus ramparts distribution, the permafrost occurrence probability is above 3690 m a.s.l. (current and high periglacial environment). However, some inactive rock glaciers and protalus rampart were found below this elevation, thus between 3300 and 3690 m a.s.l. the landscapes are dominated by an unstable periglacial environment.

Hazards and Disasters in the Geological and Geomorphological record: A key to understanding past and future hazards and disasters and their impact on life

Hazards and disasters have occurred throughout Earth's History and thus the geological record is an important resource for understanding future hazards and disasters and its Impact. The Earth Science Group (ESG) of the Consortium of European Taxonomic Facilities (CETAF) carried out a “Hazard and Disaster Event Survey” to identify Earth Science collections in European museums that represent hazards and disasters throughout the geological record, and recent times. The aim is to use the collections within the survey as an educational and research resource that promotes the importance of museum collections for understanding past and future hazard and disaster events. The survey pinpointed a wide variety of hazards (e.g. earthquakes, volcanism, floods, impact events, etc.), representing a vast time span in Earth’s history (Proterozoic to Holocene), that are documented in the collections of the participating museums. Each hazard and disaster event has been described in terms of how each is preserved (e.g. fossil record or rock record), spatial scale, impact on life and biodiversity, and geological age. The results were published in Research ideas and outcomes journal RIO (https://riojournal.com/article/34087/) as seven examples, which include well-known and less-known events from the survey that have contributed to our understanding of hazard and disaster processes and their impact on life and biodiversity. For better visualisation and education purposes we also created and specialised website, which will be launched during summer 2019. In the presentation we will talk about general conclusions and lessons learnt from the “Hazard and Disaster Event Survey”.

GIS-assisted classification of litho-geomorphological units using Maximum Likelihood Classification, Vipava Valley, SW Slovenia

In the Vipava Valley (SW Slovenia), various types of mass movements occur in a geologically and geomorphologically diverse setting. These comprise various types of landslides, creep, and Quaternary slope deposits of carbonate blocks and recent scree deposits. A general geological setting is represented as Mesozoic carbonate overthrust on Paleogene flysch (alternations of mostly sandstones and marlstones), resulting in steep slopes and mass movements. Our study is based on the automatic classification of various litho-geomorphological units including slope deposits, alluvial deposits, steep carbonate cliffs, flysch, two carbonate plateaus, and Quaternary deposits, based on supervised Maximum Likelihood Classification. Several polygons were used for training in the broader valley area, and later, the method was applied to automatically classify the complete area into the abovementioned six units. For input layers, we used data for elevation, slope, terrain ruggedness index (TRI), and curvature. Results show that generally, the method is suitable for classification of the litho-geomorphological units including slope deposits. However, comparison with a more detailed map, comprising mapped various mass movements indicated that the method correctly predicts high Trnovo plateau carbonates, steep carbonate slopes, translational carbonate blocks, and fossil rock avalanche deposits, and alluvial deposits, but is not able to clearly distinguish between flysch and more recent slope deposits of gravel and breccia due to their similar elevation, TRI, and slope values. The Slano blato mudflow and Stogovce landslide are not recognized. Therefore, this automatic classification can be carefully used to create a guidance map of general occurrences of litho-geomorphological units including slope deposits before going to the field, with the aim of delineation of slope deposits so they can be further studied in detail later in the field. However, such a map cannot be used as a direct substitute map for the geological and geomorphological map obtained in the field due to impossibility in distinguishing among the units with the same properties (elevation, slope, and TRI values).

First cosmogenic geochronology from the Lesser Caucasus: Late Pleistocene glaciation and rock glacier development in the Karçal Valley, NE Turkey

Evidence of widespread alpine glaciations during the Late Pleistocene in mid-latitudes has long attracted attention of researchers. However, there were no studies that contain absolute ages in the Lesser Caucasus despite the fact that it is one of the major glaciated regions in Eurasia. Here, we present first cosmogenic 36Cl surface exposure ages from the Karçal Mountains (41.24° N, 42.06° E, 3431 m a.s.l., above sea level) which is located in the most western part of the Lesser Caucasus in the northeastern Anatolia. In the Karçal Mountains, there are numerous valleys that have experienced significant glaciations since Late Pleistocene. We have investigated one of the largest valleys, the east-facing Karçal Valley, that hosts even a small (2926 m a.s.l.) recent glacier located at above 3000 m a.s.l. Fossil and recent rock glaciers along with lateral and recessional moraines exist in the valley. We conducted the study in two stages. First, we mapped the geomorphological units in the Karçal Valley in detail based on our field works and aerial photography. Later, we collected 10 rock samples from the fossil rock glacier and recessional moraines for cosmogenic 36Cl surface exposure dating. The results outline a glacial chronology that is typical of the Last Glacial Maximum. Although the maximum extent and timing of the glaciation is not exactly known as lateral and terminal moraines were not suitable for sampling, recessional moraines indicate that the Karçal Valley palaeoglacier deglaciation started at least 19.9 ± 1.2 ka ago. Fossil rock glacier samples were dated to 15.7 ± 1.3 ka. These quantitative results are first in the Lesser Caucasus and compatible with previous ages obtained from other valleys in the nearby Eastern Black Sea region, Anatolian and some of the European Mountains.

Timing and new geomorphologic evidence of the last deglaciation stages in Sierra Nevada (southern Spain)

The main objective of this research is to improve knowledge of the deglaciation stages in Sierra Nevada (southern Spain) by applying 36Cl cosmogenic exposure dating to 28 samples from moraine and fossil rock glacier boulders and glacial polished surfaces, in 5 glaciated valleys around Veleta Peak (3396 m asl; 37°03′02″N 3°20′54″W). The results show that shortly before the Last Glacial Maximum (LGM) and during the LGM, the heads of the glacial valleys were occupied by ice tongues, with possible glacial transfluence between the valleys. After 19 ka, a major glacial regression started, but glaciers during the Oldest Dryas (OD) expanded again and refilled the valley bottoms. The glacial advances of the pre-LGM, LGM and OD formed polygenic moraine systems. During the Bølling-Allerød the glaciers receded and probably disappeared. Thereafter, the valley bottoms remained ice-free. During the Younger Dryas (YD) small glaciers developed again, but only in cirques shaped on east-facing slopes. Subsequently, these glaciers started retreating towards their valley heads and finally disappeared completely. With the onset of the Holocene, rock glaciers developed inside the deglaciated cirques on the eastern slopes of some valleys, but only under the most active and protected headwalls did large complex rock glaciers develop and remained active until the mid-Holocene.

Leveraging the power of music to improve science education

ABSTRACTWe assessed the impact of music videos with science-based lyrics on content knowledge and attitudes in a three-part experimental research study of over 1000 participants (mostly K-12 students). In Study A, 13 of 15 music videos were followed by statistically significant improvements on questions about material covered in the videos, while performance on ‘bonus questions’ not covered by the videos did not improve. Video-specific improvement was observed in both basic knowledge and genuine comprehension (levels 1 and 2 of Bloom’s taxonomy, respectively) and after both lyrics-only and visually rich versions of some videos. In Study B, musical versions of additional science videos were not superior to non-musical ones in their immediate impact on content knowledge, though musical versions were significantly more enjoyable. In Study C, a non-musical video on fossils elicited greater immediate test improvement than the musical version (‘Fossil Rock Anthem’); however, viewers of the music video enjoyed a modest advantage on a delayed post-test administered 28 days later. Music video viewers more frequently rated their video as ‘fun’, and seemed more likely to revisit and/or share the video. Our findings contribute to a broader dialogue on promising new pedagogical strategies in science education.

Facies, geometry and growth phases of the Valdorria carbonate platform (Pennsylvanian, northern Spain)

AbstractThe 14 km wide Valdorria outcrop (Pennsylvanian, northern Spain) is one of the few examples of entirely exposed flat‐topped and high‐relief carbonate platforms reported in the fossil rock record. Laterally and vertically traceable stratal patterns expose three phases of growth. Phase I is a 430 m thick platform to slope succession that prograded over 6 km, and is dated as Early Bashkirian (Akavasian–Askynbashian). Phase II aggraded and prograded, exhibiting 180 m thickness of cyclical platform top deposits, dated as Late Bashkirian (Asatauian). Phase III is a mound‐shape structure that developed over the platform top of Phase II as a new phase of platform nucleation. It is 535 m thick and 2 km wide, and dated as Late Bashkirian (Asatauian–Transition interval). The observed changes of growth styles during platform evolution, from a prograding to an aggrading–prograding system, and a rapid aggradational phase, are inferred to be controlled by flexural subsidence in the active Cantabrian foreland basin, at the Variscan orogenic front. The metre‐scale shallowing‐upward cycles of the platform top are most probably due to glacioeustasy, as evidenced by well‐recorded subaerial exposure surfaces superimposed on subtidal deposits, and by a stratal pattern recurrent in a short interval of about 160 kyr. Observations of outcropping Bashkirian cyclothems in an isolated carbonate system, devoid of siliciclastic input, are relevant for a better understanding of the impact of high‐frequency sea‐level fluctuations on the carbonate factory. Moreover, progradation of the platform margin during Phase I reaches a rate of 2500 m/Myr, and 1810 m/Myr during Phase II; rates that are high when compared to other Pennsylvanian examples. The aggradation rate of 447 m/Myr calculated for the Late Bashkirian–Transition interval (Phases II and III; uncorrected for compaction, missing beats and erosion) is uncommonly high in comparison to coeval Pennsylvanian examples. The platform exhibits a self‐nourishing prograding microbial boundstone‐dominated slope. Thus, the slope‐shedding model applies well to Valdorria. However, Phase II recorded eustatic variations able to inhibit the slope microbial boundstone factory during low sea‐level stands; this is marked by common slope red‐stained breccias synchronous to platform top subaerial exposure phases. Contrarily, periods of relative high sea‐level and rapid subsidence in Phase III registered a greater development of cemented microbial boundstone. These observed, partly opposing relationships of sea‐level stands, shedding modes and slope architecture provide an improvement of the currently used slope‐shedding model. The overall architecture of the Valdorria outcrop compares well with that of other contemporaneous platforms, such as Sierra del Cuera and Bolshoi Karatau. Valdorria shares the high‐relief and flat‐topped, steep slopes, cyclothemic patterns and occurrence of karst features with the Pricaspian Basin platforms (Tengiz, Karachaganak and Kashagan), with minor variations in facies distribution of the internal platform. Furthermore, the continuous seismic‐scale outcrop of Valdorria, together with its isolated setting and asymmetrical growth, makes it a very good candidate for potential subsurface analogues of hydrocarbon‐bearing systems.

Systemic Acquired Resistance of Cotton, Soybean and Common Bean to <i>Rhizoctonia solani</i> and <i>Sclerotium rolfsii</i> Induced by Shale Water Seed Treatment

Root rots of cotton, soybean and common bean caused by Rhizoctonia solani and Sclerotium rolfsii are basically soil-borne diseases and are difficult to control through the use of fungicides. One of the alternatives to control these diseases could be through the induction of Systemic Acquired Resistance (SAR). It is believed that shale water as a by-product obtained during the process of extraction of petroleum from fossil rock may act as an inducer of SAR to some pathogens of some crop plants. The objective of the present investigation was to verify the effect of seed treatment with shale water in inducing SAR to R. solani and S. rofsii root rots of cotton, soybean and common bean. Seed treatment experiments were conducted in the greenhouse on seedlings of these three crops using naturally or artificially infested soil with R. solani or with S. rolfsii. Treatments with seeds treated with shale water significantly reduced the average number of plants infected with the two pathogens. Consistent results were obtained in repeated experiments. SAR in cotton and common bean to R. solani varied between 86.16% and 91.13%, while for S. rolfsii in soybean and common bean varied between 84.0% and 57.54% and was long lasting. This is the first report giving strong indication of SAR of the three crops to R. solani and to S. rolfsii. Patent regarding this investigation is obtained with Petrobras, Brazil, under the number IVP 12/039.

Systemic Acquired Resistance of Soybean to Soybean Rust Induced by Shale Water

Shale water as a by-product obtained by Petrobras, Brazil, during the process of extraction of petroleum from fossil rock may act as an inducer of Systemic Acquired Resistance (SAR) to some plant pathogens. The objective of the present investigation was to verify the effect of seed treatment and foliar application with shale water in inducing SAR of soybean to soybean rust under greenhouse and field conditions. In greenhouse experiments, seed treatment alone with shale water significantly reduced the severity of soybean rust and the control efficiency after 11 and 14 days after inoculation was between 54.1% and 57.8%. Whereas seed treatment and only one foliar application with shale water the control efficiency due to SAR 14 and 11 days after inoculation was between 99.7% and 100%, respectively. Such treatments gave similar results under field experiments where the control efficiency of soybean rust was between 79.0% and 99.35% in shale water treated plots as compared to the untreated plots, in 2015. Consequently, this resulted in yield increase between 14.8% and 28.8% depending upon the seed treatment and foliar applications with shale water alone or in mixture with a fungicide. Seed health testing revealed lower number of seeds infected with some pathogens in treatments where either shale water or fungicide was used. Seed treatment and one foliar application were sufficient to induce SAR against soybean rust. This is the first report to demonstrate SAR of soybean to soybean rust induced by shale water. Patent regarding this investigation is deposited with Petrobras, Brazil, under the number EVP 14/022.

Seismic visibility of a deep subduction channel – insights from numerical simulation of high-frequency seismic waves emitted from intermediate depth earthquakes

Abstract. Return flow in a deep subduction channel (DSC) has been proposed to explain rapid exhumation of high pressure–low temperature metamorphic rocks, entirely based on the fossil rock record. Supported by thermo-mechanical models, the DSC is envisioned as a thin layer on top of the subducted plate reaching down to minimum depths of about 150 km. We perform numerical simulations of high-frequency seismic wave propagation (1–5 Hz) to explore potential seismological evidence for the in situ existence of a DSC. Motivated by field observations, for modeling purposes we assume a simple block-in-matrix (BIM) structure with eclogitic blocks floating in a serpentinite matrix. Homogenization calculations for BIM structures demonstrate that effective seismic velocities in such composites are lower than in the surrounding oceanic crust and mantle, with nearly constant values along the entire length of the DSC. Synthetic seismograms for receivers at the surface computed for intermediate depth earthquakes in the subducted oceanic crust for models with and without DSC turn out to be markedly influenced by its presence or absence. While for both models P and S waveforms are dominated by delayed high-amplitude guided waves, models with DSC exhibit a very different pattern of seismic arrivals compared to models without DSC. The main reason for the difference is the greater length and width of the low-velocity channel when a DSC is present. Seismic velocity heterogeneity within the DSC or oceanic crust is of minor importance. The characteristic patterns allow for definition of typical signatures by which models with and without DSC may be discriminated. The signatures stably recur in slightly modified form for earthquakes at different depths inside subducted oceanic crust. Available seismological data from intermediate depth earthquakes recorded in the forearc of the Hellenic subduction zone exhibit similar multi-arrival waveforms as observed in the synthetic seismograms for models with DSC. According to our results, observation of intermediate depth earthquakes along a profile across the forearc may allow to test the hypothesis of a DSC and to identify situations where such processes could be active today.

Rock Glacier Inventory of the Valles Calchaquíes Region (~ 25°S), Salta, Argentina, Derived from ALOS Data

ABSTRACTRock glaciers near the Andean mountains of central and northwestern Argentina provide an important supply of water for agriculture, but data on their number, size, geographic distribution and altitudinal range are poorly known. Here, we provide the first detailed rock glacier inventory of the Valles Calchaquíes region of Salta, Argentina, based on 2.5 m x 2.5 m resolution Advanced Land Observing Satellite PRISM (Panchromatic Remote‐sensing Instruments for Stereo Mapping) satellite images. Rock glacier outlines were manually digitised and a total of 488 were identified, which cover a total area of c. 59 km2. The lower limits of intact and fossil rock glaciers are at c. 4300 m asl and 4100 m asl, respectively. Because rock glaciers are protected by law in Argentina, the inventory provides an important basis for political decision‐making about water resources and for further periglacial and environmental studies in this region. Copyright © 2014 John Wiley & Sons, Ltd.

Natural mineral sorbents for chemical and microbiological purification of potable water

The role of a number of rocks (shungite, glauconite fossil rock, flint) in a chemical and microbiological purification of water was estimated. On the basis of a shungite-dolomite module a simple method for a widescale manufacture of chemically and microbiologically pure potable water with conditionated content of mineral matters was developed.

The influence of terrestrial run off on marine biotic communities: An example from a thrust-top carbonate ramp (Upper Pennsylvanian foreland basin, Picos de Europa, NW Spain)

High-diversity marine biotic communities characterize the lower Kasimovian (Upper Pennsylvanian) carbonates of the Las Llacerias Formation in the Ándara Massif (Picos de Europa Province, Cantabrian Mountains, Spain). The carbonates accumulated on a small thrust-top ramp system. Within the shallow, low-energy and euphotic realms, biotic communities were characterized by abundant photozoans (calcareous algae and cyanobacteria) and heterozoans including filter and suspension feeders (calcareous and siliceous sponges, bryozoans, brachiopods, crinoids), diverse other metazoans (rugose solitary and colonial corals, tabulate corals, bivalves, gastropods and echinoids), benthic foraminifers including very abundant small incrusting “tubiforms” and conspicuous swarms of cement-filled spheres (calcispheres or Penella). Small-sized buildups of chaetetid sponges, syringoporids, branching rugose corals, Anthracoporella and phylloid algae commonly developed in these shallow-water environments. Meanwhile, mud mounds formed at greater water depths, mostly below the lower limit of the phothic zone. The occurrence of such diverse biotic communities and the grain composition of the shallow-water deposits, not recorded in the platform-top successions of the antecedent Bashkirian–Moscovian carbonate shelf (Valdeteja and Picos de Europa formations) are interpreted as linked to increased nutrient levels (mesotrophic to mildly eutrophic conditions) in the actual sea-surface water. The nutrients are inferred to have resulted from land-derived fluxes from the rivers draining the adjacent growing Variscan Orogenic chain. Nutrients were subsequently transported into the narrowed marine shallowing foreland basin located in the eastern side of Pangea, within the palaeoequatorial humid belt. Comparison to the Pennsylvanian Auernig Group in the Carnic Alps allows the discrimination between the influence of land-derived versus upwelling-derived nutrients, providing a useful tool in the interpretation of biotic assemblages in the fossil rock record.

Colorado Front Range Rock Glaciers: Distribution and Topographic Characteristics

ABSTRACTIn the Colorado Front Range, rock glacier distribution has been noted on U.S. Geological Survey maps and in several publications; however, a comprehensive account of distribution is not available. When analyzed in a Geographic Information System (GIS), Digital Elevation Model variables (elevation, slope, or aspect) could reveal unique topographic characteristics of rock glaciers. The objectives of this study are to provide an accurate, complete account of rock glacier locations in a digital format, to compare topographic variables of rock glacier form and activity classes, and to evaluate glacier and rock glacier topographic information. Rock glacier locations were obtained from previous studies and were re-digitized on high-resolution digital orthophotos. Glacier distribution was determined through classification of a satellite image. Topographic information for rock glacier form and activity classes as well as for glaciers was obtained through zonal overlay in a GIS. Results indicate that tongue-shaped rock glaciers occur at higher elevations, have more northerly aspects, and have gentler slopes compared to lobate rock glaciers. Active, inactive, and fossil forms showed typical elevation and aspect gradients. Active rock glaciers are found at the highest elevations and most northern aspects. Inactive rock glaciers are found at lower elevations on all aspects with a tendency to face northeast, and fossil rock glaciers occur at the lowest elevations on all aspects. Topographic variables for all rock glaciers were statistically different compared to glacier locations; however, active tongue-shaped rock glaciers had similar topographic variables compared to glaciers, but lobate forms showed a significant difference. In the Front Range, active tongue-shaped rock glaciers are developed by glacial processes and active lobate forms are the product of periglacial processes.

A Reevaluation of the Origin of Blocky Landforms in Cirques in the Japanese Alps

In the Japanese Alps, only a few rock glaciers associated with mountain permafrost have been identified, although the present lower limit of mountain permafrost is estimated to lie at 2, 500 to 2, 800m a. s. l. and permafrost is considered to have been distributed more widely during the previous cold periods than at present. The purposes of this paper are to reexamine the origin of blocky landforms in cirques, which have often been interpreted as moraines or protalus ramparts, and to reconstruct rock glacier distribution in the Japanese Alps. As a result of air-photo interpretation and field observations, many rock glaciers were identified in the Northern and Southern Japanese Alps. These landforms comprise transverse low ridges and furrows, a continuous marginal ridge, or a tongue or festoon-shaped frontal ridge located at the foot of talus. At one of these landforms, a two-layer structure, comprising a matrix-supported finer debris layer overlain by an open-work bouldery layer, was observed. These morphological and structural characteristics are similar to those of typical fossil rock glaciers, suggesting that the blocky landforms are fossil rock glaciers rather than moraines or protalus ramparts. Therefore attention should be paid to the origin of blocky landforms when past glacial distribution and the paleoenvironment are reconstructed using landforms.

Accidents cassants dans des glaciers rocheux du Beaufortin (Alpes françaises du Nord) : origine gravitaire ou néotectonique ?/Scarps in rock glaciers of Beaufortin (Northern French Alps): a gravity or neotectonic origin?

Abstract In the Beaufortin crystalline group (Savoy, Northern French Alps), the authors have discovered several rectilinear scarps 1 to 5 meters high, which are up-hill facing scarps located at the foot of steep slopes. The detailed geomorphological analysis of two areas (La Légette du Grand Mont, 2366; Tête Rouge, 2219 m) allows to show the continuation of these scarps in fossil rock glaciers and several periglacial and glacial materials, as well as their coincidence with main structural trends (N 25° E to N 40° E). For these scarps, two hypothesis are discussed: the neotectonic one (fault reactivation) and the gravitational gliding of the rock mass in response to the last generalized glacier retreat. In spite of quantitative data concerning the present relative displacements of alpine ranges and earthquakes occurrence in a regional extent (in La Savoie), the first hypothesis cannot be selected for lack of doubtless argument. The second one is consistent with the local morphological context and with different models built for large-scale spreading of steep-sided rock mass.