Little Ice Age glaciers and climate in the Mediterranean mountains: In parts of Turkey some glaciers were several kilometres longer than they are today, whilst in the Pyrenees glaciers were up to several hundred metres longer. In the wettest Mediterranean mountains, such as the Dinaric Alps, many small glaciers and perennial snow patches would have been present. Even in driest and most southerly mountains, such as the High Atlas, small glaciers and perennial snowfields were present. This paper examines the evidence from these two contrasting regions the western and southern Balkans and the High Atlas and the climatic significance of glaciers in these areas during the Little Ice Age. Particular focus is given on the climatological controls on glacier mass balance in different climatic conditions. Glaciers in cold and dry climates exhibit different sensitivity to regional climate change compared with glaciers in cold and wet climates. In addition, the factors controlling ablation of glaciers in different climatic regimes can differ considerably, especially the relative contributions and effects of melting and sublimation. All Mediterranean mountain glaciers were strongly controlled by local topoclimatic factors.
In high and mid-latitudes, boulder fields are thought to form and be active during glacial periods; however, few quantitative data support this assertion. Here, we use in situ cosmogenic 10Be and 26Al to quantify the near-surface history of 52 samples in and around the largest boulder field in North America, Hickory Run, in central Pennsylvania, USA. Cosmogenic nuclide data demonstrate that Hickory Run, and likely other boulder fields, are dynamic features that persist through multiple glacial-interglacial cycles because of boulder resistance to weathering and erosion.
Long and complex boulder histories suggest that climatic interpretations based on the presence of these rocky landforms are likely oversimplifications.
Schmidt hammer (SH) R-values are reported for surface clasts from numerically dated Holocene and Pleistocene fluvial terraces in the South Island of New Zealand. The R -values are combined with previously obtained weathering rind, radiocarbon, terrestrial cosmogenic nuclide and luminescence terrace ages to derive SH R -value chronofunctions for.
Landforms 31, — DOI: The exfoliation rate was obtained using a simple model in which the sheeting joints experience intermittent denudation, i. The analysis is useful for understanding the evolution of granite sheeting structures on this dome in Korea. From this it is possible to infer the erosion rates of bare bedrock surfaces. The available data are spatially limited or are from only certain environments. For example, the erosion rates of exposed rock surface on granitic and quartz-bearing sedimentary and volcanic rock has been estimated to be in the range of metres to tens of metres per million years Nishiizumi et al.
Measurement of 10Be in a bedrock tor, specifically an outcropping tower of granite exposed along the escarpment characteristic of the southeastern coast of Australia, suggests sequential exposure from a lowering soil mantle at c. Similar slow rates of erosion have been inferred from 10Be and 36Cl measurements on tors in the arid, granitic Alabama Hills of southern California and the semi-arid Llano uplift of central Texas, USA Bierman and Turner,
Hide All Ballantyne, C. Winter-talus, nivation ridges, and pro-talus ramparts. Journal of Glaciology, 33, — Some observations on the morphology and sedimentology of two active protalus ramparts, Lyngen, northern Norway. Arctic and Alpine Research, 19, —
Their barrel aged and schmidt-hammer exposure-age dating shd is a calibrated-age dating shd as a calibrated-age dating shd and terrestrial cosmogenic nuclide dating. Mochaabarbie – foot worship deep throat, eric david harris, suggest that can be used for mutual testing.
Early views were that its dating role was limited to distinguishing recently exposed from much older. Typically, either a few sites of possibly different ages or occasional older surfaces amongst many young sites were studied. More recently, calibration curves based on individual R-value means from small numbers 2—4 of sites of known ages have been used to estimate the ages of undated sites.
Only two outlying sites in the two younger age categories have overlapping confidence intervals, demonstrating remarkable robustness in differentiating early- and late-Holocene surfaces. Second, we examine the feasibility and desirability of controlling non-age-related factors, including some previously considered critical instrument wear, operator bias, initial rock surface texture , which emerge either as less important than previously argued or as relatively unimportant, together with others previously unreported e.
Third, we investigate the potential for calibrated-age dating by applying exploratory, linear rates of R-value decline to selected combinations of sites. This improved dating capability, however, will require adequate numbers of site means not only for each age category used to define these curves but also for each set of test surfaces of the same ages.
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We present two highly resolved intertidal and nearshore food webs for the Sanak Archipelago in the eastern Aleutian Islands and use them to compare trophic roles of prehistoric humans to other species. We find that the native Aleut people played distinctive roles as super-generalist and highly-omnivorous consumers closely connected to other species.
Although the human population was positioned to have strong effects, arrival and presence of Aleut people in the Sanak Archipelago does not appear associated with long-term extinctions. We simulated food web dynamics to explore to what degree introducing a species with trophic roles like those of an Aleut forager, and allowing for variable strong feeding to reflect use of hunting technology, is likely to trigger extinctions.
Potential extinctions decreased when an invading omnivorous super-generalist consumer focused strong feeding on decreasing fractions of its possible resources. This study presents the first assessment of the structural roles of humans as consumers within complex ecological networks, and potential impacts of those roles and feeding behavior on associated extinctions.
Most studies of the relationships of humans and ecosystems are presented in terms of human impacts on ecosystems 1,2. However, our ability to understand and mitigate human impacts depends on research that elucidates the roles humans play in ecosystems including how they interact with other species 3. In modern marine ecosystems, humans are depleting many commercial fisheries, causing major disruptions to ecosystem function and the persistence of species 1,4—7. As a result, regulators have curtailed fisheries and excluded local peoples from traditional harvesting territories 2.
This is a critical problem for the Aleut peoples of the western Gulf of Alaska, who depend strongly on biotic resources from the marine communities 8— This central dependence on marine resources stretches back throughout the nearly 10, year prehistory of human presence in the North Pacific, raising the questions of what kinds of impacts humans have had on marine species and ecosystems in this area and how should future impacts be managed.
Blockgletscher in Zentral- und Ostösterreich: Verbreitung – Alter – Genese
In-situ produced 10 Be in moraine boulders, glacially trans- formed bedrock surfaces and rockfall accumulations constrains the timing of the Last Glacial Maximum LGM glacier expansion and provides chronological evidence for the post-LGM decay of one of the largest paleoglaciers in the range. The uncertainty-weighted mean age of The timing of these advances is broadly synchronous within the High Tatra Mts.
Surface exposure dating of four rockfall accumulations produced uncertainty-weighted mean ages of
Schmidt-hammer exposure-age dating (SHD) was applied to a variety of late Quaternary periglacial and paraglacial landforms composed of coarse rock debris on Muckish Mountain, northwest Ireland.
Although these faults have undergone numerous paleoseismological investigations, quantitative data remain crucially lacking for a large number of fault segments. Because such data are essential to understanding how these faults have ruptured and interacted in the past and how they might behave in the future, we investigated the Holocene seismic history of the Pizzalto normal fault, a 13 km long fault segment belonging to the Pizzalto-Rotella-Aremogna fault system in the Apennines.
We collected 44 samples from the Pizzalto fault plane exhumed during the Holocene and analyzed the 36 Cl and rare earth element REE contents. Together, the 36 Cl and REE concentrations show that at least six events have exhumed 4. No major events have been detected over the last 1 kyr. The Rotella-Aremogna-Pizzalto fault system has a clustered earthquake behavior with a mean recurrence time of 1. The measurements of 51 samples both lacustrine and floodplain , ranging from
Dating in exposed and surface contexts
Tayloring of mineral separation techniques for different rock types commonly used for exposure dating translated from Norwegian. The use of cuttings material from exploration wells for studies of Quaternary erosion translated from Norwegian. Vertical extent of glacially transported material on Gaustatoppen translated from Norwegian.
Schmidt Hammer exposure dating (SHED): Calibration procedures, new exposure age data and an online calculator Author links open overlay panel Matt D. Tomkins a Jonny J. Huck a Jason M. Dortch a Philip D. Hughes a Martin P. Kirbride b Iestyn D. Barr c.
Earth Surface Processes and Landforms in press. Schmidt-hammer exposure ages from periglacial patterned ground sorted circles in Jotunheimen, Norway, and their interpretative problems. Geografiska Annaler A in press. A rock-surface microweathering index from Schmidt hammer R-values and its preliminary application to some common rock types in southern Norway. Catena , 35 — Modelling of future mass balance changes of Norwegian glaciers by application of a dynamical-statistical model.
Climate Dynamics 46, — Earth Surface Processes and Landforms, Das Eis der Erde. Morpho-Memory — a geomorphological outreach ressource. Journal of Hydrology NZ 53, — Comparison of electronic and mechanical Schmidt hammers in the context of exposure-age dating: