Landslide deposits as stratigraphical markers for a sequence‐based glacial stratigraphy: a case study of a Younger Dryas system in the Eastern Alps

Detailed ¹⁰Be and ¹⁴C dating and supporting pollen analysis of Alpine Lateglacial glacial and landslide deposits in the Hohen Tauern Mountains (Austria) constrain a sequence‐based stratigraphy comprising a major landslide (13.0±1.1 ka) overlain by till and termino‐lateral moraines of an advancing (12.6±1.0 ka) and retreating (11.3±0.8 ka) glacier in turn overlain by a minor landslide (10.8±1.1 ka). These results define glacier activity during the Younger Dryas age Egesen stadial bracketed by landslide activities during the Bølling‐Allerød interstadial and the Preboreal. In contrast to recent studies on Holocene glaciation in the Alps, no traces of any Holocene glacier advance bigger than during the Little Ice Age are documented. Furthermore, this study demonstrates the advantages of using an allostratigraphical approach based on unconformity‐bounded sedimentary units as a tool for glacial stratigraphy in formerly glaciated mountain regions, rather than a stratigraphy based on either isolated morphological features or lithostratigraphical characteristics.     

Cosmogenic Be and Al exposure ages of tors and erratics, Cairngorm Mountains, Scotland: Timescales for the development of a classic landscape of selective linear glacial erosion

The occurrence of tors within glaciated regions has been widely cited as evidence for the preservation of relic pre-Quaternary landscapes beneath protective covers of non-erosive dry-based ice. Here, we test for the preservation of pre-Quaternary landscapes with cosmogenic surface exposure dating of tors. Numerous granite tors are present on summit plateaus in the Cairngorm Mountains of Scotland where they were covered by local ice caps many times during the Pleistocene. Cosmogenic ¹⁰Be and ²⁶Al data together with geomorphic relationships reveal that these landforms are more dynamic and younger than previously suspected. Many Cairngorm tors have been bulldozed and toppled along horizontal joints by ice motion, leaving event surfaces on tor remnants and erratics that can be dated with cosmogenic nuclides. As the surfaces have been subject to episodic burial by ice, an exposure model based upon ice and marine sediment core proxies for local glacial cover is necessary to interpret the cosmogenic nuclide data. Exposure ages and weathering characteristics of tors are closely correlated. Glacially modified tors and boulder erratics with slightly weathered surfaces have ¹⁰Be exposure ages of about 15 to 43 ka. Nuclide inheritance is present in many of these surfaces. Correction for inheritance indicates that the eastern Cairngorms were deglaciated at 15.6 ± 0.9 ka. Glacially modified tors with moderate to advanced weathering features have ¹⁰Be exposure ages of 19 to 92 ka. These surfaces were only slightly modified during the last glacial cycle and gained much of their exposure during the interstadial of marine Oxygen Isotope Stage 5 or earlier. Tors lacking evidence of glacial modification and exhibiting advanced weathering have ¹⁰Be exposure ages between 52 and 297 ka. Nuclide concentrations in these surfaces are probably controlled by bedrock erosion rates instead of discrete glacial events. Maximum erosion rates estimated from ¹⁰Be range from 2.8 to 12.0 mm/ka, with an error weighted mean of 4.1 ± 0.2 mm/ka. Three of these surfaces yield model exposure-plus-burial ages of 295_− 71^+ 84, 520_− 141^+ 178, and 626_− 85^+ 102 ka. A vertical cosmogenic nuclide profile across the oldest sampled tor indicates a long-term emergence rate of 31 ± 2 mm/ka. These findings show that dry-based ice caps are capable of substantially eroding tors by entraining blocks previously detached by weathering processes. Bedrock surfaces and erratic boulders in such settings are likely to have nuclide inheritance and may yield erroneous (too old) exposure ages. While many Cairngorm tors have survived multiple glacial cycles, rates of regolith stripping and bedrock erosion are too high to permit the widespread preservation of pre-Quaternary rock surfaces.     

Along-strike shear-sense reversal in the Vals-Scaradra Shear Zone at the front of the Adula Nappe (Central Alps,Switzerland)

The Adula Nappe in the Central Alps comprises pre-Mesozoic basement and minor Mesozoic sediments, overprinted by Paleogene eclogite-facies metamorphism. Peak pressures increase southward from ca. 1.2 GPa to values over 3 GPa, which is interpreted to reflect exhumation from a south-dipping subduction zone. The over- and underlying nappes experienced much lower Alpine pressures. To the north, the Adula Nappe ends in a lobe surrounded by Mesozoic metasediments. The external shape of the lobe is simple but the internal structure highly complicated. The frontal boundary of the nappe represents a discontinuity in metamorphic peak temperatures, between higher T in the Adula Nappe and lower T outside. A shear zone with steeply dipping foliation and shallowly-plunging, WSW-ENE oriented, i.e. orogen-parallel stretching lineation overprinted the northernmost part of the Adula Nappe and the adjacent Mesozoic metasediments (Vals-Scaradra Shear Zone). It formed during the local Leis deformation phase. The shear sense in the Vals-Scaradra Shear Zone changes along strike; from sinistral in the W to dextral in the E. Quartz textures also vary along strike. In the W, they indicate sinistral shearing with a component of coaxial (flattening) strain. A texture from the middle part of the shear zone is symmetric and indicates coaxial flattening. Textures from the eastern part show strong, single c-axis maxima indicating dextral shearing. These relations reflect complex flow within the Adula Nappe during a late stage of its exhumation. The structures and reconstructed flow field indicate that the Adula basement protruded upward and northward into the surrounding metasediments, spread laterally, and expelled the metasediments in front towards west and east.     

Promoting a coupled human and natural systems approach to addressing conservation in complex mountainous landscapes of Central Asia

Global climate change, nonpoint source pollution, watershed and wildlife habitat destruction, and unsustainable development are damaging the natural world, threatening the socio-cultural integrity of communities, and jeopardizing the livelihood security of peoples worldwide. Despite the past 50 years of progress in addressing environmental damage in the United States and elsewhere, intractable problems have arisen that to date have eluded successful technological or policy responses. Solutions have been sought by recognizing that these problems are very complex and demand interdisciplinary approaches that require building effective partnerships among relevant academic institutions, governmental agencies, nongovernmental organizations, and private business, as well as levering various disciplines and traditional knowledge systems. Such thinking has evolved to now consider humans to be an integral part of nature, which is captured in the idea of the ‘human ecosystem’, where biophysical, socioeconomic, and cultural systems interact via a complex set of organizational, spatial, and temporal ‘couplings’. Within such a context, environmental problems can be viewed as coupled human and natural systems, which afford unique and novel approaches to their solutions. This paper discusses the development of the coupled systems approach as a scientific methodology, reviews its key characteristics and principles, provides an example of how it has been applied to assess conservation issues in alpine areas of Northwest Yunnan Province, China, and recommends how this scientific approach might be further developed for use in mountainous landscape regions of Central Asia and elsewhere.     

Duration and extent of lunar volcanism: Comparison of 3D convection models to mare basalt ages

It is widely accepted that lunar volcanism started before the emplacement of the mare fills ( b.p.) and lasted for probably more than 3.0 Ga. While the early volcanic activity is relatively easy to understand from a thermal point of view, the late stages of volcanism are harder to explain, because a relatively small body like the Earth's Moon is expected to cool rapidly and any molten layer in the interior should solidify rather quickly. We present several thermal evolution models, in which we varied the boundary conditions at the model surface in order to evaluate the influence on the extent and lifetime of a molten layer in the lunar interior. To investigate the influence of a top insulating layer we used a fully three-dimensional spherical shell convection code for the modelling of the lunar thermal history. In all our models, a partial melt zone formed nearly immediately after the simulation started (early in lunar history), consistent with the identification of lunar cryptomare and early mare basalt volcanism on the Moon. Due to the characteristic thickening of the Moon's lithosphere the melt zone solidified from above. This suggests that the source regions of volcanic rock material proceeded to increasing depth with time. The rapid growth of a massive lithosphere kept the Moon's interior warm and prevented the melt zone from fast freezing. The lifetimes of the melt zones derived from our models are consistent with basalt ages obtained from crater chronology. We conclude that an insulating megaregolith layer is sufficient to prevent the interior from fast cooling, allowing for the thermal regime necessary for the production and eruption of young lava flows in Oceanus Procellarum.     

Holocene Paleo‐Geographic Reconstructions of the Ramore Head Area,Northern Ireland,Using Geophysical and Geotechnical Data: Paleo‐Landscape Mapping and Archaeological Implications

We present early to Mid‐Holocene paleo‐geographic reconstructions for the Ramore Head area (Northern Ireland). This coastal area is characterized by Mesolithic occupation (c. 10–6 ka) and preserved early–Mid‐Holocene peats both on‐ and offshore. This paper improves on previous reconstructions by employing a backstripping methodology, which removes accumulated recent deposits from identified buried paleo‐landsurfaces instead of using modern topography as an analogue to the past landscape. Paleo‐landsurfaces are identified offshore from seismic profiles supplemented by cores, and onshore through legacy borehole records. The paleo‐landsurface can be traced offshore to depths of −2 to −19 m and is buried by <5 m of modern sediment. It extends onshore under the coastal town of Portrush and is buried <2.5–10 m below modern ground level. The identified paleo‐landsurface is combined with sea‐level curves from recent Glacio‐Isostatic‐Adjustment models to reconstruct marine transgression during the early–Mid‐Holocene. Comparison is also made with reconstructions based on modern topography. Together, the identified paleo‐landsurfaces and revised reconstructions can assist future site prospection on‐ and offshore and delimit high‐potential areas for heritage management. Revised reconstructions also allow placement of extant archaeology into a more accurate context of landscape change and help develop insights into local‐scale site location patterns.     

Learning Conservation: the role of conservation covenants in landscape redesign at Project Hindmarsh,Victoria

Biodiversity decline continues apace across the Australian landscape with a pressing need to redesign land use to address this situation. The significance of private land increasingly is recognised for the protection and enhancement of biodiversity as landholders inevitably make decisions that affect environmental quality. Biodiversity conservation is as much a social process as a physical one. Conservation covenants are perpetual agreements under which landholders choose to conserve land voluntarily, primarily for conservation purposes. The role covenants might play in landscape-scale conservation was investigated in north-western Victoria. In-depth interviews with a range of participants were undertaken, with an emphasis on the role covenantors might play as social learning and cultural change agents. Analysis of these interviews offers useful perspectives for understanding socio-cultural dimensions of landscape change and exploring the differing values of production farmers and nature conservation landholders. Consideration is then given to approaches to engaging local production farmers in nature covenants and promoting communication between this group and the largely non-production conservationists who currently form the mainstay of conservation covenants.     

Questioning community as a collective antidote to fear: Jean-Luc Nancy's 'singularity' and 'being singular plural'

Community has long been a key academic concept and lay narrative, especially in commentaries of rural as opposed to urban life. Although community is proffered as an antidote for a plethora of emotional, social and policy challenges in contemporary Western societies, we argue that it is problematic. Previously, we suggested that community is a device mobilised in response to fears surrounding finitude. In this paper, we again draw on Nancy's theorising of singularity and being-in-common, but also engage with his yet more fundamental conceptualisation of 'being singular plural' to suggest directions for new geographies of singular and collective life.     

Observations of the Hubble Deep Field South with the Infrared Space Observatory– I. Observations, data reduction and mid-infrared source counts

We present results from a deep mid-infrared survey of the Hubble Deep Field South (HDF-S) region performed at 6.7 and 15 μm with the ISOCAM instrument on board the Infrared Space Observatory ( ISO ). The final map in each band was constructed by the co-addition of four independent rasters, registered using bright sources securely detected in all rasters, with the absolute astrometry being defined by a radio source detected at both 6.7 and 15 μm. We sought detections of bright sources in a circular region of radius 2.5 arcmin at the centre of each map, in a manner that simulations indicated would produce highly reliable and complete source catalogues using simple selection criteria. Merging source lists in the two bands yielded a catalogue of 35 distinct sources, which we calibrated photometrically using photospheric models of late-type stars detected in our data. We present extragalactic source count results in both bands, and discuss the constraints that they impose on models of galaxy evolution, given the volume of space sampled by this galaxy population.