No abstract

An event stratigraphy of dune stability/instability phases has been reconstructed, using 22 radiocarbon and 13 luminescence dates, for six dunefields along the north coast of Northern Ireland. There is no evidence for dune development prior to ċ. 7000 cal. years BP, during the early-Holocene rapid rise in RSL, and only limited evidence for sand accumulation in association with the RSL maximum. Dunefield dates correspond to either the subsequent regressive phase or, later, the gradual transgressive phase of RSL history in the mid-and late Holocene. At these times accommodation space for dune development and sediment supply were maximized. Episodes of climatic deterioration, particularly at 3100–2400 cal. years BP and 650–50 cal. years BP (the‘Little Ice Age’) were marked by widespread dune instability. A similar coincidence in timing has been recorded for dune systems elsewhere in northwestern Europe and is generally attributed to an increased frequency of storms and storm surges associated with the climatic downturns. However, between-site inconsistencies in the event stratigraphy suggest that site-specific factors (e.g., sediment availability) had a modulating influence on dune regional controls.

The recent environmental history of coastal dune systems in Northumberland, northeast England, has been examined using geomorphological, stratigraphical and sedimentological techniques linked to radiocarbon and infrared-stimulated luminescence (IRSL) dating. Stratigraphies were determined from 22 vibracores and three sections, and dune chronology was based on 28 14 C dates, from peat and soil organic horizons, and 26 IRSL dates on K-feldspar grains from within sand layers. Almost all dune systems are associated with regressive shorelines consequent upon a fall in relative sea level (RSL) from its Holocene peak, and indicate RSL functioned as a macroscale control on dune development. Where dunes are anchored on terrestrial sediment, dune expansion may have been either transgressive or regressive in nature. Where near-shore marine sediments form the dune substrate, a regressive (prograding) dune model seems most likely. Most dune building occurred during the ‘Little Ice Age’ (LIA), probably in association with specific climatic and morphosedimentary conditions, principally periods of easterly circulation, a greater frequency of severe North Sea storms, RSL fall, and sediment and accommodation space availability. Dune development in Holocene cool intervals earlier than the LIA was of limited spatial extent, suggesting some differences in prevailing conditions at those times.

Quark nuggets are theoretical objects composed of approximately equal numbers of up, down, and strange quarks and are also called strangelets and nuclearites. They have been proposed as a candidate for dark matter, which constitutes ~85% of the universe’s mass and which has been a mystery for decades. Previous efforts to detect quark nuggets assumed that the nuclear-density core interacts directly with the surrounding matter so the stopping power is minimal. Tatsumi found that quark nuggets could well exist as a ferromagnetic liquid with a ~1012-T magnetic field. We find that the magnetic field produces a magnetopause with surrounding plasma, as the earth’s magnetic field produces a magnetopause with the solar wind, and substantially increases their energy deposition rate in matter. We use the magnetopause model to compute the energy deposition as a function of quark-nugget mass and to analyze testing the quark-nugget hypothesis for dark matter by observations in air, water, and land. We conclude the water option is most promising.

2014. Age and origin of ice-cored moraines In Jotunheimen and Breheimen, Southern Norway: insights from Schmidt-Hammer exposure-age dating.ABSTRACT. High-precision Schmidt-hammer exposureage dating (SHD) is applied to ice-cored moraine-ridge complexes at three high-alpine glaciers in Jotunheimen and Breheimen, southern Norway. Local calibration curves were established using moraine ridges dating from the last 50 years and bedrock surfaces deglaciated ∼9700 years ago. SHD ages, with 95% statistical confidence intervals, ranged from 3920 ± 790 years to a negative (futuristic) age of -890 ± 580 years at Gråsubreen, 420 ± 700 to 260 ± 710 years at Vesle-Juvbreen and 2250 ± 450 to 1605 ± 410 years at Østre Tundradalskyrkjabreen. Negatively skewed R-value distributions were interpreted as the result of weathered boulders from reworked surfaces. This leads to the interpretation of these SHD ages as maximum estimates of moraine-ridge age. Østrem's hypothesis (that the proximal ridges are the oldest and survived being overridden many times) is rejected on the basis of our SHD ages. Although ice-cored moraine ridges resemble the flow structures of rock glaciers, Barsch's hypothesis (that these icecored moraine complexes are rock glaciers) is also rejected. Instead, the ice-cored moraine-ridge complexes are considered to be glaciotectonic structures produced by the interaction of polythermal glaciers and alpine permafrost over the late Holocene. All the individual ridges were essentially formed during the 'Little Ice Age' glacier advance from material deposited earlier by multiple neoglacial events. The considerable size of the moraine complexes is attributed not only to the accumulation of material from these different events over a long period of time but also to their survival in the landscape during phases of glacier retreat when ice cores do not melt and fluvial and other destructive processes remain ineffective in the permafrost environment.