The spectacular fossils of the ‘water margin’: the Cambrian biota of Chengjiang,Yunnan, China

Shi Nai'an's fourteenth century Chinese epic ‘Water Margin’ tells of the release of 36 heavenly spirits and 72 baleful stars from their captivity beneath a tablet of stone at Mount Longhu in Jiangxi Province. They are reincarnated as the 108 heroes of the Liangshan marsh in Shandong Province, who rise against an unjust world. The virtuous exploits of the ‘108’ were brought to life through the cathode‐ray screens of 1970s television sets, as the TV series The Water Margin introduced heroes like Lin Chong battling his evil nemesis Gao Qiu. Far to the west of Jiangxi Province and several hundred years after the Water Margin during the summer of 1984, a young scientist from Nanjing was working amongst the hills and lakes of southern Yunnan Province. He too overturned a stone slab, releasing from their half‐billion year captivity a cornucopia of new Chinese legends. His name was Xianguang Hou and he had made one of the most momentous fossil discoveries in history, uncovering the exceptionally preserved marine fossils of the Chengjiang biota from the ancient water margin of Cambrian seas.     

Kīlauea,Hawai’i,puts on a ‘once‐in‐a‐century’ show

Kīlauea is the youngest of five basaltic shield volcanoes on the island of Hawai’i. It is located to the south‐east of the much larger Mauna Loa volcano, and rose above sea level about 100 ka ago. Kīlauea is one of the most monitored, and arguably the best understood volcanoes on Earth, providing scientists with a good understanding of its current eruption, in which magma rises from depth and is stored beneath its 4 × 3.2 km summit caldera in an underground reservoir. The reservoir is connected to a lava lake within a crater called Halema’uma’u, which is situated on the floor of the caldera. When magma drains from the summit area it travels in underground conduits and emerges on the flanks of the volcano at a rift zone, where it erupts through fissures. The magma is sometimes stored in other reservoirs along the way. This link between summit magma storage and fissure eruptions on the flanks has occurred thousands of times at many Hawai’ian volcanoes. The current eruptive episode is, however, a ‘once‐in‐a‐century’ show, because it is the first time since 1924 that fissure‐fed lava flow eruptions have been accompanied by significant explosive eruptions within Halema’uma’u Crater. This gives scientists a unique opportunity to use modern methods to understand exactly how such hazardous explosions happen at Kīlauea, a volcano that receives about 2 million visitors a year.     

Pyrite—‘fool's gold’ or misunderstood mineral?

Pyrite (FeS₂) is the most abundant sulphide mineral in the Earth's crust, and with its characteristic shape and appearance, is easily one of the most recognizable. Yet, pyrite has a somewhat tarnished reputation with many considering it to be waste material and of little economic importance, never-mind interest. This assessment however, is misleading and a considerable volume of current research focuses upon the unique characteristics and formation of pyrite. Indeed, with its potential for revealing the very foundations of life, as well as maximizing the discovery and exploitation of society's future metallic resources, pyrite may be of much greater interest and benefit than many geologists realize.     

Gesher Benot Ya'aqov—the ‘Bar’: An acheulian assemblage

The renewed investigations of the Benot Ya'aqov site resulted in the discovery of a bar-like depositional structure located on the eastern bank of the Jordan River (southern Hula Valley, Israel). Its interdisciplinary study resulted in the identification of four lithofacial fluvial units, all tilted (20–25 degrees dip) and all containing archaeological and paleontological finds. The structure, caused by diverse resistance of the local lithology and tectonic activity, is assigned to the Benot Ya'aqov Formation. The material culture is assigned to the Acaheulian Industrial Complex and is indicative of a continuous occupation of the Benot Ya'aqov embayment during Middle Pleistocene times.     

The ‘old red sandstone’ of county mayo,Northwest Ireland

The distribution and stratigraphic relations of the Old Red Sandstone of the Clew Bay area. County Mayo are described. They comprise two groups both dominated by conglomerates, one Lower Devonian and one Middle Devonian, which have differing clast contents and which are separated by faults. The sediments are described in terms of five facies which are all interpreted as alluvial fan deposits. Provenance data from palaeocurrents and clast composition suggest transport predominantly to the west-northwest but one formation shows an opposite sense of transport. The rocks are folded about northeast-southwest axial traces and are affected by numerous faults. Structures are more complex than those of the Lower Carboniferous rocks which unconformably overlie the Devonian. A similar tectonosedimentary setting to the Old Red Sandstone of parts of the Scottish Caledonides is indicated.     

Up to 400‐year‐old Rhododendron shrubs on the southeastern Tibetan Plateau: prospects for shrub‐based dendrochronology

In harsh and treeless environments, shrubs constitute the dominant growth form of woody plants, thus offering the opportunity to extend dendrochronological networks beyond the uppermost and northernmost distribution limits of trees. However, shrub‐based dendrochronology has so far resulted in only a few long and climate‐responsive ring‐width chronologies at such stressful sites, particularly above the alpine tree line. A previous study on an alpine Rhododendron shrub species resulted in <80‐year‐long ring‐width chronologies. Here, we collected Rhododendron aganniphum var. schizopeplum stems from elevations between 4000 and 4500 m a.s.l. on the SE Tibetan Plateau and built six tree‐ring width chronologies. One of them is 401 years long and well replicated from AD 1670 to 2011 (EPS>0.85), thus representing the longest shrub chronology available to date. A principal component analysis (PCA) converted the total variability of all six site chronologies into PCs. Then, the six site chronologies and the PC1, accounting for 65.9% of the total variance of the tree‐ring width, were correlated with time series of monthly climate data. Based on this, the year‐to‐year variability of the ring‐width indices was positively correlated with July temperature, which thus turned out to be the dominant factor controlling growth. Accordingly, such long shrub‐ring chronologies may act as climatic and ecological proxies in treeless environments of the Tibetan Plateau.     

Neoproterozoic ‘anomalous’ kimberlites of Guaniamo, Venezuela: Mica kimberlites of ‘isotopic transitional’ type

In Venezuela, kimberlites have so far only been found in the Guaniamo region, where they occur as high diamond grade sheets in massive to steeply foliated Paleoproterozoic granitoid rocks. The emplacement age of the Guaniamo kimberlites is 712±6 Ma, i.e., Neoproterozoic. The Guaniamo kimberlites contain a high abundance of mantle minerals, with greater than 30% olivine macrocrysts. The principal kimberlite indicator minerals found are pyrope garnet and chromian spinel, with the overwhelming majority of the garnets being of the peridotite association. Chrome-diopside is rare, and picroilmenite is uncommon. Chemically, the Guaniamo kimberlites are characterized by high MgO contents, with low Al₂O₃ and TiO₂ contents and higher than average FeO and K₂O contents. These rocks have above average Ni, Cr, Co, Th, Nb, Ta, Sr and LREE concentrations and very low P, Y and, particularly, Zr and Hf contents. The Nb/Zr ratio is very distinctive and is similar to that of the Aries, Australia kimberlite. The Guaniamo kimberlites are similar in petrography, mineralogy and mantle mineral content to ilmenite-free Group 2 mica kimberlites of South Africa. The Nd-Sr isotopic characteristics of Guaniamo kimberlites are distinct from both kimberlite Group 1 and Group 2, being more similar to transitional type kimberlites, and in particular to diamondiferous kimberlites of the Arkhangelsk Diamond Province, Russia. The Guaniamo kimberlites form part of a compositional spectrum between other standard kimberlite reference groups. They formed from metasomatised subcontinental lithospheric mantle and it is likely that subduction of oceanic crust was the source of this metasomatised material, and also of the eclogitic component, which is dominant in Guaniamo diamonds.     

The ‘Polish Solnhofen’: a long‐awaited alternative?

Here we briefly report on the discovery of a new Fossil‐Lagerstätte locality, Owadów‐Brzezinki quarry (central Poland), which exposes Late Jurassic (Late Tithonian) carbonate sediments with an extremely fossiliferous horizon of lithographic‐type limestones. Numerous specimens of horseshoe crabs were found in association with an enormously rich assemblage of the soft‐shelled bivalves Corbulomima obscura and Mesosaccella sp., the remains of various fishes and marine reptiles, rare ammonites, crustaceans, land insects and pterosaurs. The uniqueness of this new locality lies in its very close stratigraphical relationship to one of the most famous Fossil‐Lagerstätte localities in the world—Solnhofen, in southern Germany, with approximately 2 Ma separating them. Marine and terrestrial creatures lived and died during the Late Jurassic both at Solnhofen (Hybonotum Zone) and in another area (Owadów‐Brzezinki quarry, Zarajskensis Subzone), under closely related environmental conditions. The small palaeogeographical distance separating these two locations enables, for the first time, an effective palaeobiological test of the pace of evolutionary speciation amongst different groups of organisms.     

Geographies of generosity: Beyond the ‘moral turn’

This paper questions Geographers debates about ‘caring at a distance’ and the ‘geographies of responsibility’, focussing on the treatment of the theme of partiality in ethics and justice. Debates in Geography often present partial commitments as morally or politically problematic on the grounds that they prioritize self-interest, exclusionary, and geographically restricted ways of relating to others. We outline how debates about caring at a distance and the geographies of responsibility frame partiality as a problem to be overcome. We argue that Geography’s engagements with moral philosophy are premised on faulty assumptions about the sorts of influences people are liable to act upon (one’s that privilege causal knowledge as the primary motivating force), and also flawed assumptions about the sorts of problems that academic reasoning about normative issues is meant to address (the assumption that people are too egoistical and not altruistic enough). We use the theme of generosity as an entry point to argue that partiality and finitude might be the conditions for any ethical–political project that de-centres the motivation of practical action away from the sovereign self towards responsive and attentive relations of encounter with the needs of others. Understanding generosity as a modality of power suggests a revised programme for geographical investigations of the intersection between ethics, morality and politics: one which looks at how opportunities to address normative demands in multiple registers are organized and transformed; at the ways in which dispositions to respond and to be receptive to others are worked up; and how opportunities for acting responsively on these dispositions are organized.     

Concerning the notion of ‘sub-region’: the French case

At least in France the sub-region is a living spatial entity. It is partly the heir of structures established in the pre-industrial epoch, receiving from the ancient ‘pays’ and old administrative structures the sense of belonging to a certain social cadre held by a population. For a long period the weak development of an hierarchy of urban services made most towns of equal standing, limiting the growth of commercial relationships and the dimensions of functional spaces. With the growth of an hierarchy of urban services, and improvement in accessibility the functional units have enlarged, breaking unequally the former cadres, and creating polarisations of various scales. Where the metropolises have not become dominant the sub-regions remain sufficiently autonomous, around a town of medium size. More often, in every case where local polarisations have been progressively effaced, and economic spaces have enlarged immeasurably and where the administrative region is seeking identity, the sub-region is reasserted as a social functional space in the pattern of customary life-style, and appears acceptable as a level in the operation of spatial management.     

Late‐Quaternary history of ‘great lakes’ on the Tibetan Plateau and palaeoclimatic implications – A review

Geomorphic evidence suggests that shorelines of 100–200 m above the modern lake levels were common across the Tibetan Plateau during late Marine Isotope Stage (MIS) 3. The timing of this lake‐level highstand is mainly based on radiocarbon ages. Problems surrounding the ages of lacustrine sediments at or beyond the limit of the radiocarbon‐dating method have created a need for alternative geochronometers. Chronological advances during the last decade have renewed interest in the timing of events beyond the limit of radiocarbon dating. Here, we synthesize published data for elevated lacustrine landforms of 48 lakes on the Tibetan Plateau, in order to provide a thorough perspective on the timing and pattern of lake‐level changes in this alpine area during the late Quaternary. The ages of these elevated shore features reveal a long‐term trend of relative lake‐level fall from at least MIS 5, instead of a peak in MIS 3, as previously thought. Dating lacustrine terrace sequences reveals that the rate of lake‐level fall ranged from ~1 to 3 mm a^?1, comparable with that of related river downcutting across the plateau. Palaeoclimatic proxy records point to a sustained drying since the Last Interglacial, suggesting that long‐term aridification might be the culprit for this widespread and progressive lake‐level fall.     

On the non-linear ‘squeezing’ effects around circular tunnels

An analysis is presented of the non-linear creep effects around a deep circular tunnel driven in ‘squeezing’ ground. The time-dependent behaviour of the geotechnical medium is described by means of a simple viscoplastic rheological model capable of approximating primary, secondary and tertiary creep behaviours. It is shown that tertiary creep can be allowed for by providing a suitable law governing the variation of some material parameters (such as viscosity) with stresses and strains. The basic operations of the ‘evolutive’ procedure adopted for time integration are outlined. Along each time integration step, quadratic variations of the stress and strain fields and linear variations of the material parameters are assumed. The results of various finite element analyses are presented concerning both lined and unlined cases. For the lined cases, the influence of the liner stiffness and of the time elapsed between the end of excavation and the liner installation is considered.     

FxJj43: A window into a 1.5‐million‐year‐old palaeolandscape in the Okote Member of the Koobi Fora Formation,northern Kenya

FxJj43 differs from most other archaeological sites preserved in the Okote Member of the Koobi Fora Formation in ways that make it especially suited to the problem of clarifying the behavioral information encapsulated in fine time‐lines. At this site in northern Kenya, a continuous strip of outcrops, preserving a set of interlocking landforms, can be traced around the modern erosion front for more than half a kilometer. The characteristics and three‐dimensional geometries of the beds making up these outcrops show that they have preserved the southern bank, levee, and floodplain of a westerly flowing sandy channel. Both stone tools and animal bones are strewn across the eroding surfaces of these outcrops, and excavations show that they are derived from a narrow stratigraphic horizon immediately overlying the volcanic ash at the base of the sequence. The blue tuff, and the archaeological horizon that overlies it, have been dated using the ⁴⁰Ar‐³⁹Ar method on single crystals of alkali feldspar. Although there is no direct measure of how long it took the archaeological horizon to accumulate, it probably accumulated over a time span of 10²–10³ years. Thus the locality may be used to test the proposition that the analysis of archaeological debris from fine‐time lines will help to resolve ambiguities in the interpretation of early Pleistocene archaeological assemblages. © 2002 Wiley Periodicals, Inc.     

Evidence of multiple thermokarst lake generations from an 11 800‐year‐old permafrost core on the northern Seward Peninsula,Alaska

Permafrost degradation influences the morphology, biogeochemical cycling and hydrology of Arctic landscapes over a range of time scales. To reconstruct temporal patterns of early to late Holocene permafrost and thermokarst dynamics, site‐specific palaeo‐records are needed. Here we present a multi‐proxy study of a 350‐cm‐long permafrost core from a drained lake basin on the northern Seward Peninsula, Alaska, revealing Lateglacial to Holocene thermokarst lake dynamics in a central location of Beringia. Use of radiocarbon dating, micropalaeontology (ostracods and testaceans), sedimentology (grain‐size analyses, magnetic susceptibility, tephra analyses), geochemistry (total nitrogen and carbon, total organic carbon, δ¹³C_org) and stable water isotopes (δ¹⁸O, δD, d excess) of ground ice allowed the reconstruction of several distinct thermokarst lake phases. These include a pre‐lacustrine environment at the base of the core characterized by the Devil Mountain Maar tephra (22 800±280 cal. a BP, Unit A), which has vertically subsided in places due to subsequent development of a deep thermokarst lake that initiated around 11 800 cal. a BP (Unit B). At about 9000 cal. a BP this lake transitioned from a stable depositional environment to a very dynamic lake system (Unit C) characterized by fluctuating lake levels, potentially intermediate wetland development, and expansion and erosion of shore deposits. Complete drainage of this lake occurred at 1060 cal. a BP, including post‐drainage sediment freezing from the top down to 154 cm and gradual accumulation of terrestrial peat (Unit D), as well as uniform upward talik refreezing. This core‐based reconstruction of multiple thermokarst lake generations since 11 800 cal. a BP improves our understanding of the temporal scales of thermokarst lake development from initiation to drainage, demonstrates complex landscape evolution in the ice‐rich permafrost regions of Central Beringia during the Lateglacial and Holocene, and enhances our understanding of biogeochemical cycles in thermokarst‐affected regions of the Arctic.