Modelling the responses of mature forest trees to air pollution

Systems analysis of the responses of forest trees to air pollutants led to mathematical models which represent the essential life processes of mature trees (photosynthesis, respiration, growth etc.) under ‘normal’ conditions and — especially — under pollution strees. Computer simulations using these models have made it possible to test and analyse the consequences of — known or hypothetical — pollution effects. The simulation runs have led to the identification of three distinct behavioural modes (growth, stagnation, breakdown) and corresponding stable and unstable system states. The results have produced new insights and contributed to the understanding of the dieback process of spruce and beech trees. The presentation will concentrate on the most recent and most complex of the hitherto existing models, theBeech model.     

Rock mass characterization using photoanalysis

Summary Rock formations are distinguished from each other by measuring first the properties of the intact rock, and second those of the jointing. Whereas simple methods are available for measuring intact rock properties, those available for measuring jointing remain slow, expensive, and sometimes dangerous. Digitized photographs (photoanalysis) may provide a solution. In this paper, the new techniques of photoanalysis are reviewed together with applications, promising areas for research, and also some obstacles that remain to be overcome. Aspects of the rock mass that lend themselves to photoanalytical measurement include those of individual joints, such as persistence, orientation and roughness, and those relating to the mass as a whole, such as block size and the spacing or intensity of jointing. Photoanalysis can also be applied to measurement of blasting. It allows characterization of the rock about to be blasted, helping the engineer to predict fragmentation and to design an appropriate blasting pattern. Afterwards, the same methods can be used to measure fragmentation, overbreak and backbreak, for quality control and for diagnosis of problems.Presented at the 28th US ROck Mechanics Symposium, Tucson, Arizon, 29 June–1 July 1987.     

Differential behaviour of the Rb-Sr and K-Ar systems of spilitic flows and interbedded metasediments: the spilite group of Erquy (Brittany,France). Paleomagnetic implications

The Erquy series (Côtes du Nord, France) consists, in its upper part, of spilitic pillow lavas with some interbedded volcano-sedimentary horizons.The Rb-Sr system of the pillows allowed the construction of a whole-rock isochron at 482±10 M.a. with an initial⁸⁷Sr/⁸⁶Sr ratio of 0.7055±0.0002. These rocks and the associated keratophyres give, on the other hand, K-Ar ages of 285±16 M.a. interpreted as the consequence of late-hercynian tectonism.A volcano-sedimentary horizon interbedded with such pillow flows has been studied from petrographic, mineralogical, geochemical and isotopic (Rb-Sr and K-Ar) points of view. The sequence keeps a sedimentary memory. Its clay fractions <2 m and corresponding whole-rocks fit an isochron which is identical to that of the volcanic rocks: 494±11 M.a. with an initial⁸⁷Sr/⁸⁶Sr ratio of 0.7052±0.0005. The clay fractions give K-Ar data at about 450 M.a., but those which contain important amounts of volcanic glass, at the top of the horizon, have K-Ar values as low as 400 M.a., and those which contain almost no glass have a K-Ar age close to the Rb-Sr age at 480 M.a.This study emphasizes the possibility of a complete reset of the K-Ar system of spilitic rocks by a tectonic event without notice-able temperature increase. This result may have important implications on combined paleomagnetic and K-Ar studies: it seems that a least for spilites and keratophyres, the Curie point and Ar blocking temperature can be very different.     

Automatic determination of 3D orientations of fossilized oyster shells from a densely packed Miocene shell bed

International Journal of Earth Sciences - Shell beds represent a useful source of information on various physical processes that cause the depositional condition. We present an automated method to...     

Time series assessment on landslide occurrences in an area undergoing development

This study assesses the influence of development on landslide occurrences in a rapidly developing area, Kota Kinabalu in Sabah Malaysia, across three assessment years (1978, 1994 and 2010). Two development indicators, land use and road density, were used to measure the influence of development on landslide occurrence. Land use was classified into four categories (barren, forest, developed and other), and road density was classified into low (< 50 m/40 000 m²), moderate (50–150 m/40 000 m²) and high (> 150 m/40 000 m²). Landslide density analysis was used to calculate the concentration of landslide for the different land use and road density categories. The number of landslides in developed areas increased from 19 landslides/100 km² in 1978, to 29 landslides/100 km² in 1994 and to 50 landslides/100 km² in 2010, mirroring an increase in land use for development purposes from 8 per cent in 1978 to 27 per cent in 2010. Landslide density also gradually increased in the high road density class from 10 landslides/100 km² in 1978, to 30 landslides/100 km² in 1994 and 62 landslides/100 km² in 2010. These results show that road construction activities influence landslide occurrences.     

Chronology of Upper Pleistocene sequences at Sidi Messaoud (wadi Noun, southwestern Morocco) based on C, optical and U-series dating

The Sidi Messaoud site provides a 40 m thick sedimentary infilling of great importance for the study of environmental changes and landscape evolution during the Upper Pleistocene in the Western Sahara. In this study, chronological results obtained by the ¹⁴C, U-series and optical dating techniques are compared. Each individual age, depositional environment and post-deposition history of the various samples are evaluated, in order to explain the methodological reasons for discordances and concordances. Stratigraphic and palaeoenvironmental implications for the last 120 ka history in southwestern Morocco are also inferred: the wadi Noun gorges had been incised before MIS 5, and later, during MIS 3, the valley has been filled in with a mean sedimentation rate of 1 m/ka.