Mapping the human record in the British early Palaeolithic: evidence from the Solent River system

The lithic record from the Solent River and its tributaries is re‐examined in the light of recent interpretations about the changing demography of Britain during the Lower and early Middle Palaeolithic. Existing models of the terrace stratigraphies in the Solent and its tributary areas are reviewed and the corresponding archaeological record (specifically handaxes) for each terrace is assessed to provide models for the relative changes in human occupation through time. The Bournemouth area is studied in detail to examine the effects of quarrying and urbanisation on collection history and on the biases it introduces to the record. In addition, the effects of reworking of artefacts from higher into lower terraces are assessed, and shown to be a significant problem. Although there is very little absolute dating available for the Solent area, a cautious interpretation of the results from these analyses would suggest a pre‐Marine Isotope Stage (MIS) 12 date for the first appearance of humans, a peak in population between MIS 12 and 10, and a decline in population during MIS 9 and 8. Owing to poor contextual data and small sample sizes, it is not clear when Levallois technology was introduced. This record is compared and contrasted to that from the Thames Valley. It is suggested that changes in the palaeogeography of Britain, in particular land connections to the continent, might have contributed to differences in the archaeological records from the Solent and Thames regions. Copyright © 2009 John Wiley & Sons, Ltd.     

Mapping the phases of Glacial Lake Algonquin in the upper Great Lakes region,Canada and USA,using a geostatistical isostatic rebound model

This study reviews Glacial Lake Algonquin, examines the Main and two “Upper Group” phases in northern Michigan and nearby Ontario, reports their spatial extents, and reassesses the lake history in light of isostatic rebound. Our paper presents the most accurate and detailed maps of Glacial Lake Algonquin in this region that have yet been published. Fieldwork was conducted at 243 ancient shoreline sites, which yielded position data that support geostatistical models that represent differentially upwarped water planes. Model parameters that describe water plane tilt are reported for the Main, Ardtrea and Upper Orillia phases. Geostatistical water plane models were used to adjust a digital contemporary elevation model, thereby creating a digital proglacial elevation model for each phase. Maps of these phases and the data that support them suggest (1) proto-Cockburn Island, Ontario existed as an islet in the lake that was deglaciated before the outlet at North Bay, Ontario was opened, (2) the Main and Ardtrea phases of the lake extended into the northern Lake Michigan basin, and (3) the Main and Ardtrea water planes intersect at places near Little Traverse Bay (by Lake Michigan) and Thunder Bay (by Lake Huron). Mapped isobases generally conform to those published in other works and suggest the regional pattern of isostatic adjustment has not changed substantially during the last 13,000 years.     

Magnetic fields,bremsstrahlung and synchrotron emission in the flare of 24 October 1969

An impulsive flare October 24, 1969 produced two bursts with virtually identical time profiles of 8800 MHz emission and X-rays above 48 keV. The two spikes of hard X-rays correspond in time to the times of sharp brightening and expansion in the H flare. The first burst was not observed at frequencies below 3000 MHz. This cut off is ascribed to plasma cutoff above the low-lying flare.A model of the flare based on H observations at Big Bear shows that the density of electrons with energy above 10 keV is 5 × 10⁷ if the field density is 10¹¹. The observed radio flux would be produced by this electron distribution with the observed field of 200 G. The H emission accompanying the hard electron acceleration is presumed due to excitation of the field atoms by the hard electrons.     

XMM–Newton observations of the Seyfert 1 AGN H 0557−385

We present XMM–Newton observations of the Seyfert 1 active galactic nucleus (AGN)  H 0557 − 385  . We have conducted a study into the warm absorber present in this source, and using high-resolution Reflection Grating Spectrometer (RGS) data we find that the absorption can be characterized by two phases: a phase with log ionization parameter ξ of 0.50 (where ξ is in units of erg cm s⁻¹) and a column of  0.2 × 10²¹ cm⁻²  , and a phase with log ξ of 1.62 and a column of  1.3 × 10²² cm⁻²  . An iron Kα line is detected. Neutral absorption is also present in the source, and we discuss possible origins for this. On the assumption that the ionized absorbers originate as an outflow from the inner edge of the torus, we use a new method for finding the volume filling factor. Both phases of  H 0557 − 385  have small volume filling factors (≤1 per cent). We also derive the volume filling factors for a sample of 23 AGN using this assumption and for the absorbers with  log ξ > 0.7  , we find reasonable agreement with the filling factors obtained through the alternative method of equating the momentum flow of the absorbers to the momentum loss of the radiation field. By comparing the filling factors obtained by the two methods, we infer that some absorbers with  log ξ < 0.7  occur at significantly larger distances from the nucleus than the inner edge of the torus.     

Lead in the Bolsa wetland of southern California, USA: Effect of flood control channelization

The distribution of lead in sediments of an estuary receiving flood control discharge has been examined. Relatively high concentrations of lead with a mean value of 64 ppm were found within the outer portion of Bolsa Bay which receives flood control runoff. Significantly lower concentrations of lead with a mean value of 9 ppm were found within the impounded inner portion of the bay which does not receive flood control discharge. On the basis of our findings we recommend that flood control runoff no longer be discharged directly into estuaries but that discharge be either rerouted to ocean outfalls or reclaimed and used for agricultural and industrial purposes.     

Experimental constraints on depths of fractionation of mildly alkalic basalts and associated felsic rocks: Pantelleria,Strait of Sicily

Pantelleria, Italy, is a continental rift volcano consisting of alkalic basalt, trachyte, and pantellerite. At 1 atm along the FMQ buffer, the least-evolved basalt (Mg #= 58.5% norm ne) yields olivine on the liquidus at 1,180° C, followed by plagioclase, then by clinopyroxene, and by titanomagnetite and ilmenite at 1,075°. After 70% crystallization, the residual liquid at 1,025° is still basaltic and also contains apatite and possibly kaersutite. A less alkalic basalt shows the same order of phase appearance. Glass compositions define an Fe-enrichment trend and a density maximum for anhydrous liquids that coincides with a minimum in Mg#.During the initial stages of crystallization at 1 atm, liquids remain near the critical plane of silica-undersaturation until, at lower temperatures, Fe-Ti oxide precipitation drives the composition toward silica saturation. Thus the qtz-normative trachytes and pantellerites typically associated with mildly ne-normative basalts in continental rifts could be produced by low-pressure fractional crystallization or by shallow-level partial melting of alkali gabbro. At 8 kbar, clinopyroxene is the liquidus phase at 1,170° C, followed by both olivine and plagioclase at 1,135°. Because clinopyroxene dominates the crystallizing assemblage and plagioclase is more albitic than at 1 atm, liquids at 8 kbar are driven toward increasingly ne-normative compositions, suggesting that higher-pressure fractionation favors production of phonolitic derivatives.Natural basaltic samples at Pantelleria are aphyric or contain 1–10% phenocrysts of plag olcpx or ol>cpx, with groundmass Fe-Ti oxides and apatite. The lack of phenocrystic plagioclase in two of the lavas suggests that crystallization at slightly higher PH₂O may have destabilized plagioclase relative to the 1-atm results, but there is no preserved evidence for significant fractionation at mantle depths as clinopyroxene is the least abundant phenocryst phase in all samples and contains only small amounts of octahedral Al. The liquid line and phenocryst compositions match more closely the 1-atm experimental results than those at 8 kbar.Although major-element trends in natural liquids and crytals reflect low-pressure fractionation, minor- and trace-element concentrations preserve evidence of multiple parental liquids. Scatter in variation diagrams exceeds that attributable to crystal accumulation in these phenocryst-poor rocks, and the large range in concentrations of P and Ti at high MgO contents cannot be produced by polybaric fractionation nor by mixing with coexisting felsic magmas. Sr and O isotope ratios rule out significant interaction with crystalline upper crust, Mesozoic shelf sediments, or Tertiary evaporites. Positive correlations of compatible and incompatible elements suggest that the basalts are not simply related to one another by closed-system fractional crystallization of a single parental magma. Increasing Ce/Yb with Ce suggests that these relations are not a product of mixing within a replenished magma chamber, nor of mixing with more felsic members of the suite, which have smaller Ce/Yb ratios. Low-pressure fractional crystallization of ol+cpx+ plag±oxides from slightly different parental magmas produced by varying degrees of melting of garnet-bearing peridotite is a possible scenario.Small and infrequently replenished magma reservoirs in this continental rift environment may account for the strongly differentiated nature of the Pantellerian basalts. There is no correlation between Mg# and eruptive frequency, in part because concentration of volatiles in residual liquids offsets the effect of Fe-enrichment on melt density, such that strong Fe-enrichment is no hindrance to eruption.     

New data on magmatic H2O contents of pantellerites,with implications for petrogenesis and eruptive dynamics at Pantelleria

Infrared spectroscopic analyses of melt inclusions in quartz phenocrysts from pantellerites erupted at Pantelleria, Italy, show that the magmas contained moderate pre-eruptive H₂O contents, ranging from 1.4 to 2.1 wt.%. Melt H₂O concentrations increase linearly with incompatible elements, demonstrating that H₂O contents were not buffered significantly during fractionation by any crystalline or vapor phase. The relatively low H₂O contents of pantellerites are consistent with an origin by partial melting of alkali gabbros rather than fractional crystallization of basalt. Preeruptive H₂O concentrations do not correlate with the volume or explosivity of pantellerite eruptions; decompression history is critical in determining the style of pantellerite (and other) eruptions.