Using Climber's Guidebooks to Assess Rock Fall Patterns Over Large Spatial and Decadal Temporal Scales: An Example from the Swiss Alps

High‐mountain geomorphic processes enjoy increasing scientific and societal interest. This is because these processes are perceived to be changing more than elsewhere and because their effects on infrastructure and tourism are significant. Rock fall is among the processes that receive most attention due to its presumed intimate relation with permafrost, which is widely degrading. However, over decadal temporal scales and for entire mountain ranges, there is very limited information on the changes in frequency and location of rock fall. This hampers our understanding. Here, I assess the value of information contained in a 146‐year record of climber's guidebooks of the Bernese Alps in Switzerland to derive changes in rock fall danger. The results show that guidebooks’ authors, themselves experienced climbers, perceived increases in rates and changes in positions of rock fall. The increases were mainly reported since the year 2000. It appears that datasets derived from guidebooks can provide valuable context for more detailed, higher resolution data sources.     

Evolution of the Cañadas edifice and its implications for the origin of the Cañadas Caldera (Tenerife, Canary Islands)

The volcano-stratigraphic and geochronologic data presented in this work show that the Tenerife central zone has been occupied during the last 3 Ma by shield or central composite volcanoes which reached more than 3000 m in height. The last volcanic system, the presently active Teide-Pico Viejo Complex began to form approximately 150 ka ago. The first Cañadas Edifice (CE) volcanic activity took place between about 3.5 Ma and 2.7 Ma. The CE-I is formed mainly by basalts, trachybasalts and trachytes. The remains of this phase outcrop in the Cañadas Wall (CW) sectors of La Angostura (3.5–3.0 Ma and 3.0–2.7 Ma), Boca de Tauce (3.0 Ma), and in the bottom of some external radial ravines (3.5 Ma). The position of its main emission center was located in the central part of the CC. The volcano could have reached 3000 m in height. This edifice underwent a partial destruction by failure and flank collapse, forming debris-avalanches during the 2.6–2.3 Ma period. The debris-avalanche deposits can be seen in the most distal zones in the N flank of the CE-I (Tigaiga Breccia). A new volcanic phase, whose deposits overlie the remains of CE-I and the former debris-avalanche deposits, constituted a new volcanic edifice, the CE-II. The dyke directions analysis and the morphological reconstruction suggest that the CE-II center was situated somewhat westward of the CE-I, reaching some 3200 m in height. The CE-II formations are well exposed on the CW, especially at the El Cedro (2.3–2.00 Ma) sector. They are also frequent in the S flank of the edifice (2.25–1.89 Ma) in Tejina (2.5–1.87 Ma) as well as in the Tigaiga massif to the N (2.23 Ma). During the last periods of activity of CE-II, important explosive eruptions took place forming ignimbrites, pyroclastic flows, and fall deposits of trachytic composition. Their ages vary between 1.5 and 1.6 Ma (Adeje ignimbrites, to the W). In the CW, the Upper Ucanca phonolitic Unit (1.4 Ma) could be the last main episode of the CE-II. Afterwards, the Cañadas III phase began. It is well represented in the CW sectors of Tigaiga (1.1 Ma–0.27 Ma), Las Pilas (1.03 Ma–0.78 Ma), Diego Hernández (0.54 Ma–0.17 Ma) and Guajara (1.1 Ma–0.7 Ma). The materials of this edifice are also found in the SE flank. These materials are trachybasaltic lava-flows and abundant phonolitic lava and pyroclastic flows (0.6 Ma–0.5 Ma) associated with abundant plinian falls. The CE-III was essentially built between 0.9 and 0.2 Ma, a period when the volcanic activity was also intense in the ‘Dorsal Edifice' situated in the easterly wing of Tenerife. The so called ‘valleys' of La Orotava and Güimar, transversals to the ridge axis, also formed during this period. In the central part of Tenerife, the CE-III completed its evolution with an explosive deposit resting on the top of the CE, for which ages from 0.173 to 0.13 Ma have been obtained. The CC age must be younger due to the fact that the present caldera scarp cuts these deposits. On the controversial origin of the CC (central vertical collapse vs. repeated flank failure and lateral collapse of mature volcanic edifices), the data discussed in this paper favor the second hypothesis. Clearly several debris-avalanche type events exist in the history of the volcano but most of the deposits are now under the sea. The caldera wall should represent the proximal scarps of the large slides whose intermediate scarps are covered by the more recent Teide-Pico Viejo volcanoes.     

An upper limit to coronal X-rays from single,magnetic white dwarfs

Pointed ROSAT PSPC exposures of 9277 and 6992 sec, directed toward the nearby, single, cool, magnetic white dwarfs GR 290 and EG 250 yielded no counts significantly above the expected background rate. The corresponding flux limits (for an assumed source temperature of l keV) are 1.0 and 1.7 × 10⁻¹⁴erg cm⁻² s⁻¹, within the 0.1–2.5 keV bandpass of the instrument (99% confidence limits). This is more than an order of magnitude below the tentative detection level (for GR 290) and limits (for four other similar stars) obtained from archival Einstein data in 1991. The corresponding limits on coronal electron density are comparable with those implied if cyclotron emission is not responsible for any of the features observed in the optical spectra of magnetic white dwarfs. X-ray data currently provide no evidence for the existence of coronae around these stars. A final long observation (25,000 sec of GD 356) is scheduled for later this year on ROSAT, along with coordinated EUVE observations.     

Study of the spatial and historical distribution of sediment inorganic contamination in the Toulon bay (France)

This study presents trace elements levels in surface and deep sediments of the Toulon bay (SE France) subjected to anthropogenic inputs (navy base, harbors, etc.). The studied elements (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) are defined as priority contaminants in aquatic systems. Fifty-five points scattered on the entire bay were sampled, allowing the determination of contaminants distribution with a high resolution. Several approaches were used to assess the degree of contamination and the potential toxicity of the Toulon bay sediments: comparison to the French legislation, surface-weighted average metal concentrations, enrichment factors (EF), geoaccumulation indices (Igeo), trace element stock calculation and comparison to sediment quality guidelines. A principal component analysis was performed to reveal common behavior of the studied contaminants. Results demonstrated the very high contamination of the small bay, especially in Hg (EF up to 1500), Cu, Pb and Zn, with export to the large bay further governed by hydrodynamics.     

Schooling behaviour and environmental forcing in relation to anchoveta distribution: An analysis across multiple spatial scales

The Peruvian anchovy or anchoveta (Engraulis ringens) supports the highest worldwide fishery landings and varies in space and time over many scales. Here we present the first comprehensive sub-mesocale study of anchoveta distribution in relation to the environment. During November 2004, we conducted a behavioural ecology survey off central Peru and used a series of observational and sampling tools including SST and CO₂ sensors, Niskin bottles, CTD probes, zooplankton sampling, stomach content analysis, echo-sounder, multibeam sonar, and bird observations. The sub-mesoscale survey areas were chosen from mesoscale acoustic surveys. A routine coast-wide (2000 km) acoustic survey performed just after the sub-mesoscale surveys, provided information at an even larger population scale. The availability of nearly concurrent sub-mesoscale, mesoscale and coast-wide information on anchoveta distribution allowed for a unique multi-scale synthesis. At the sub-mesoscale (100s m to km) physical processes (internal waves and frontogenesis) concentrated plankton into patches and determined anchoveta spatial distribution. At the mesoscale (10s km) location relative to the zone of active upwelling (and age of the upwelled water) and the depth of the oxycline had strong impacts on the anchoveta. Finally, over 100s km the size of the productive area, as defined by the upwelled cold coastal waters, was the determining factor. We propose a conceptual view of the relative importance of social behaviour and environmental (biotic and abiotic) processes on the spatial distribution of anchoveta. Our ecological space has two y-axis; one based on self-organization (social behaviour), and the other based on the environmental processes. At scales from the individual (10s cm), to the nucleus (m), social behaviour (e.g. the need to school) drives spatial organization. At scales larger than the school, environmental forces are the main driver of fish distribution. The conceptual ecosystem models presented in this paper may provide the final links needed to develop accurate forecasts of the spatial distribution of anchoveta over multiple scales.     

Impacts of Kelvin wave forcing in the Peru Humboldt Current system: Scenarios of spatial reorganizations from physics to fishers

Because climate change challenges the sustainability of important fish populations and the fisheries they support, we need to understand how large scale climatic forcing affects the functioning of marine ecosystems. In the Humboldt Current system (HCS), a main driver of climatic variability is coastally-trapped Kelvin waves (KWs), themselves originating as oceanic equatorial KWs. Here we (i) describe the spatial reorganizations of living organisms in the Humboldt coastal system as affected by oceanic KWs forcing, (ii) quantify the strength of the interactions between the physical and biological component dynamics of the system, (iii) formulate hypotheses on the processes which drive the redistributions of the organisms, and (iv) build scenarios of space occupation in the HCS under varying KW forcing. To address these questions we explore, through bivariate lagged correlations and multivariate statistics, the relationships between time series of oceanic KW amplitude (TAO mooring data and model-resolved baroclinic modes) and coastal Peruvian oceanographic data (SST, coastal upwelled waters extent), anchoveta spatial distribution (mean distance to the coast, spatial concentration of the biomass, mean depth of the schools), and fishing fleet statistics (trip duration, searching duration, number of fishing sets and catch per trip, features of the foraging trajectory as observed by satellite vessel monitoring system). Data sets span all or part of January 1983 to September 2006. The results show that the effects of oceanic KW forcing are significant in all the components of the coastal ecosystem, from oceanography to the behaviour of the top predators – fishers. This result provides evidence for a bottom-up transfer of the behaviours and spatial stucturing through the ecosystem. We propose that contrasting scenarios develop during the passage of upwelling versus downwelling KWs. From a predictive point of view, we show that KW amplitudes observed in the mid-Pacific can be used to forecast which system state will dominate the HCS over the next 2–6 months. Such predictions should be integrated in the Peruvian adaptive fishery management.     

The Lac Des Iles Palladium Deposit,Ontario, Canada part I. The effect of variable alteration on the Offset Zone

The recently discovered Offset Zone of the Mine Block Intrusion of the Lac des Iles Complex hosts palladium mineralization with unusually high Pd/Pt and Pd/Ir ratios in rocks that range from relatively unaltered norite to amphibolites and chlorite–actinolite–talc schist. Quantitative assessment of the effect of progressive alteration using mineral modes was done using total silicate H₂O as a monitor of reaction progress (ξ = moles H₂O added to form alteration minerals per 100 g of rock). Major mineral modal variations define three reaction regions: (1) ξ?=?0.00–0.03, characterized by epidote/clinozoisite formation and some amphibole; (2) ξ?=?0.03–0.23, characterized by formation of chlorite, amphibole, quartz muscovite/sericite, and calcite after plagioclase?+?pyroxene; and (3) ξ?=?0.23–0.28, characterized by the formation of talc after earlier formed amphibole. Epidote occurs as an incongruent product from the destruction of plagioclase that is itself lost as the reaction proceeds. Pyroxene is altered at about twice the rate of plagioclase, resulting in pyroxene-rich protoliths to be more altered than those relatively enriched in plagioclase. Major elements variations largely reflect variations in the plagioclase/pyroxene ratio of the protolith, but compositional trends suggest a loss of Na with reaction progress. The base metal sulfides chalcopyrite, pyrrhotite, and pentlandite show decreasing abundance with reaction progress, forming pyrite (± magnetite) as an intermediate reaction product that also is lost as the reaction proceeds. Millerite is overall low but increases slightly. A more limited data set on the platinum-group minerals suggests that platinum-group element (PGE)-arsenides increase whereas PGE-sulfides and PGE-Bi-tellurides decrease with reaction progress. Assuming ore element concentrations in the protolith were constant and similar to relatively fresh norites, Pd increases modestly, by 5 %, whereas Pt decreases by about 65 % in the most altered rocks. Similarly, Cu, Au, and S decrease by 60, 82, and 94 %, respectively, in the most altered rocks. The antithetical behavior of Pd and the fact that Pd enrichment is not seen in altered dikes suggest that the Pd originally was enriched in the more melanocratic protoliths that are most extensively altered and that Pd also was lost in part. These results are consistent with the mineralization having been a high-temperature event that predated the amphibolite/greenschist alteration.     

Reassessment of the ‘Abbevillien’ in the perspective of new discoveries from the Lower Palaeolithic and Quaternary sites of Abbeville (Somme,northern France)

North-West Europe yields few traces of early human occupation, in particular for the Acheulean. In this context, the Somme Valley in northern France offers a route to Britain during various Pleistocene low sea levels, and has provided numerous evidence of Lower Palaeolithic human occupation through fieldwork initiated during the 19th century. These localities are associated with the original definition in the 1930s by the French prehistorian Abbé Henri Breuil of the ‘Abbevillien’ (Abbevillian facies), based on lithic pieces including crudely made bifaces recovered in particular in some famous key localities of Abbeville, Carpentier, Léon and Moulin Quignon quarries. The history of the term and its definition subsequently gave rise to debates concerning the chronocultural framework of Palaeolithic assemblages among the scientific community of prehistorians over time, from Jacques Boucher de Perthes, Gabriel de Mortillet, Geoffroy d'Ault du Mesnil, Victor Commont, Henri Breuil and François Bordes. New investigations at these three localities, all associated with the High Terrace of the Somme system, pushed back the age of the expansion of the Acheulean both in northern France and in Western Europe to c. 670–650 000 years. They imply that early hominins were able to settle in North-West Europe during both climatic temperate and cold phases. Our work, including new excavations and associated field observations of the three Abbeville localities involved at the onset of the controversy, allows a re-examination of the Abbevillian and contributes to the discussion of the history of Prehistoric Science and the Earliest ‘Acheuleans’ in North-West Europe.     

Tracing the temporal evolution of soil redistribution rates in an agricultural landscape using 239+240Pu and 10Be

Two principal groups of processes shape mass fluxes from and into a soil: vertical profile development and lateral soil redistribution. Periods having predominantly progressive soil forming processes (soil profile development) alternate with periods having predominantly regressive processes (erosion). As a result, short-term soil redistribution – years to decades – can differ substantially from long-term soil redistribution; i.e. centuries to millennia. However, the quantification of these processes is difficult and consequently their rates are poorly understood. To assess the competing roles of erosion and deposition we determined short- and long-term soil redistribution rates in a formerly glaciated area of the Uckermark, northeast Germany. We compared short-term erosion or accumulation rates using plutonium-239 and -240 (^239+240Pu) and long-term rates using both in situ and meteoric cosmogenic beryllium-10 (¹⁰Be). Three characteristic process domains have been analysed in detail: a flat landscape position having no erosion/deposition, an erosion-dominated mid-slope, and a deposition-dominated lower-slope site. We show that the short-term mass erosion and accumulation rates are about one order of magnitude higher than long-term redistribution rates. Both, in situ and meteoric ¹⁰Be provide comparable results. Depth functions, and therefore not only an average value of the topsoil, give the most meaningful rates. The long-term soil redistribution rates were in the range of −2.1 t ha^-1 yr^-1 (erosion) and +0.26 t ha^-1 yr^-1 (accumulation) whereas the short-term erosion rates indicated strong erosion of up to 25 t ha^-1 yr^-1 and accumulation of 7.6 t ha^-1 yr^-1. Our multi-isotope method identifies periods of erosion and deposition, confirming the ‘time-split approach’ of distinct different phases (progressive/regressive) in soil evolution. With such an approach, temporally-changing processes can be disentangled, which allows the identification of both the dimensions of and the increase in soil erosion due to human influence. © 2019 John Wiley & Sons, Ltd.