Stratigraphic Trapping of Spilled Jet Fuel Beneath the Water Table

Environmental conditions and the initial attempt to recover JP-4 jet fuel from a shallow aquifer at a tank farm in Hanahan, South Carolina, in 1975. allowed the jet fuel to become stratigraphically trapped below the water table. The trapped jet fuel remained an undetected source of dissolved hydrocarbon contamination in shallow ground water in the area for 17 years. The trapped jet fuel was located when a variety of chemical, hydrologic. geologic, and historical evidence led investigators to install and sample deeper wells. These findings emphasize the need to use an integrated approach lo evaluating the data when determining the extent of contamination and planning fuel recovery operations in a lithologically heterogeneous aquifer.     

Glacial and Fluvial Deposits in the Aragón Valley,Central‐Western Pyrenees: Chronology of the Pyrenean Late Pleistocene Glaciers

The Aragón Valley glacier (Central Western Pyrenees) has been studied since the late nineteenth century and has become one of the best areas in the Pyrenees to study the occurrence of Pleistocene glaciations and the relationships between moraines and fluvial terraces. New morphological studies and absolute ages for moraines and fluvial terraces in the Aragón Valley allow a correlation with other Pyrenean glaciers and provide solid chronologies about the asynchroneity between global last glacial maximum (LGM) and the maximum ice extent (MIE). Six frontal arcs and three lateral morainic ridges were identified in the Villanúa basin terminal glacial complex. The main moraines (M1 and M2) correspond to two glacial stages (oxygen isotopic stages MIS 6 and MIS 4), dated at 171 ± 22 ka and 68 ± 7 ka, respectively. From a topographical point of view, moraine M1 appears to be linked to the 60 m fluvioglacial terrace, dated in a tributary of the Aragón River at 263 ± 21 ka. The difference in age between M1 moraine and the 60 m fluvioglacial terrace suggests that the latter belongs to an earlier glacial stage (MIS 8). Moraine M2 was clearly linked to the fluvioglacial 20 m terrace. Other minor internal moraines were related to the 7–8 m terrace. The dates obtained for the last glacial cycle (20–18 ka) are similar to other chronologies for Mediterranean mountains, and confirm the occurrence of an early MIE in the Central Pyrenees that does not coincide with the global LGM.     

Shrinking ‘Smart’?: Urban Redevelopment and Shrinkage in Youngstown,Ohio

Abstract

This article analyzes the impact of the much-heralded Youngstown 2010 Plan and the enacting of a program of “controlled” or “managed” shrinkage. It is argued that while the program of redevelopment has had an impact on Youngstown and its national image, it represents an exclusionary project that has centered on redeveloping downtown areas and neglected many city neighborhoods which continue to experience high levels of unemployment, vacancy, and crime. The analysis is situated in relation to the contemporary literature on “shrinking cities.” Youngstown's experience raises critical questions regarding the nature of the challenges facing shrinking cities, the constraints on actions available to them due to state and federal funding, and the coherence of the concept of “smart shrinkage.”     

Varying Constants in Brane World Scenarios

Higher-dimensional theories imply that some constants, such as the gravitational constant and the strength of the gauge-couplings, are not fundamental constants. Instead they are related to the sizes of the extra-dimensional space, which are moduli fields in the four-dimensional effective theory. We study the cosmological evolution of the moduli fields appearing in brane world scenarios and discuss the implications for varying constants. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Impact of the Degree of Aquifer Confinement and Anisotropy on Tidal Pulse Propagation

Oceanic tidal fluctuations which propagate long distances up coastal rivers can be exploited to constrain hydraulic properties of riverbank aquifers. These estimates, however, may be sensitive to degree of aquifer confinement and aquifer anisotropy. We analyzed the hydraulic properties of a tidally influenced aquifer along the Meghna River in Bangladesh using: (1) slug tests combined with drilling logs and surface resistivity to estimate Transmissivity (T); (2) a pumping test to estimate T and Storativity (S) and thus Aquifer Diffusivity (D_PT); and (3) the observed reduction in the amplitude and velocity of a tidal pulse to calculate D using the Jacob‐Ferris analytical solution. Average Hydraulic Conductivity (K) and T estimated with slug tests and borehole lithology were 27.3 m/d and 564 m²/d, respectively. Values of T and S determined from the pumping test ranged from 400 to 500 m²/d and 1 to 5 × 10^?4, respectively with D_PT ranging from 9 to 40 × 10⁵ m²/d. In contrast, D estimated from the Jacob‐Ferris model ranged from 0.5 to 9 × 10⁴ m²/d. We hypothesized this error resulted from deviations of the real aquifer conditions from those assumed by the Jacob‐Ferris model. Using a 2D numerical model tidal pulses were simulated across a range of conditions and D was calculated with the Jacob‐Ferris model. Moderately confined (K_top/K_aquifer < 0.01) or anisotropic aquifers (K_x/K_z > 10) yield D within a factor of 2 of the actual value. The order of magnitude difference in D between pumping test and Jacob‐Ferris model at our site argues for little confinement or anisotropy.     

A full-glacial biota from southeastern Iowa,USA

Wisconsinan full-glacial silts filling a swale exposed in Conklin Quarry, Johnson Co., Iowa, contain a large and diverse biota that includes pollen, bryophytes, vascular-plant macrofossils, small mammals, molluscs, and insects. Radiocarbon dates on wood from the top, middle and bottom of the swale fill respectively were 16710 ± 270, 17 170 ± 205, and 18090 ± 190 yr BP. The pollen diagram is dominated by Picea (spruce), Pinus (pine), and Cyperaceae (sedge), and it records low pollen accumulation rates. Plant macrofossils include a number of tundra species along with Picea and Larix (larch) needles and small pieces of wood. The insect fauna contains many species now confined to the forest-tundra transition zone of northwestern Yukon and Alaska. Small mammals include the tundra indicators Dicrostonyx (collared lemming), and probably Microtus miurus (singing vole) together with boreal forest taxa. The molluscs include extinct and relict species and show the widest range in present geographic distribution, but Rocky Mountain and especially northern elements predominate in the swale fill. All these lines of evidence lead to consistent palaeoclimato-logical interpretation and palaeoecological reconstruction. The dominant habitats represented by the biota and sedimentary environment collectively included open calcareous silty to sandy or gravelly upland sites, minerotrophic fens (wetlands), pond- or stream-side clayey to sandy shores, and shallow (possibly ephemeral), cold, clear-water ponds. Mean July temperatures were probably 11° to 13°C cooler than at present. The biota indicates that a Picea-Larix krummholz with extensive tundra openings was present in southeastern Iowa between 18090 and 16710 yr BP.     

Tropical stone lines and podzolized sand plains as paleoclimatic indicators for weathered cratons

Stone lines and podzolized (white) sand plains are characteristic features of the regolith in many low-latitude cratonic landscapes, but nevertheless often seem to be out of phase with the present pedogenic and geomorphic regimes of the humid tropics and subtropics. Consideration of contemporary environments where the genetic processes related to these features can be observed, implies several conditions for prior events in landscape evolution: (1) tropical stone lines may be interpreted as winnowed mudflows or lag deposits that reflect morphoclimatic events of brief duration (torrential rains) within an arid or semi-arid phase of pronounced global cooling; (2) within the present zone of the prevailing westerlies, stone lines may reflect periglacial activity during brief interstade fluctuations; (3) in lower latitudes the principal stone line, which commonly truncates saprolites, appears to be late Wisconsinan (Würmian) in age coinciding more or less with the pleniglacial phase; (4) the podzolized sands represent leached residuals and, accordingly, reflect extended intervals of leaching during the Pleistocene; and (5) the nature and distribution of podzolized sand plains indicates a pedogenic history of considerable variety and no brief episodicity as implied with stone lines.     

Geology and tectonic setting of the Mule Creek caldera,New Mexico,U.S.A.

The 10-km diameter Mule Creek caldera is the youngest felsic eruptive center in the Mogollon-Datil volcanic field of southwestern New Mexico. The caldera forms a topographic basin surrounded by a raised rim. The caldera wall is well displayed on the south and west sides of the structure where it dips 20–30 degrees toward the center of the basin. Mudflow breccia fills the caldera and is banked up against the caldera wall. Post-caldera porphyritic quartz latite domes and flows crop out along the ring-fracture zone. The caldera is superimposed upon an older volcanic complex of flow-banded rhyolite and porphyritic andesite lava. The Mule Creek caldera probably originated by explosive eruption of about 10 km³ of pumice and ash, in part preserved in the matrix of the mudflow breccia. Periods of explosive volcanism during the deposition of mudflow breccia are documented by tuffaceous beds interbedded with the breccia. A thin rhyolite ash-flow sheet originated in the caldera and overlies the mudflow breccia. The youngest felsic rocks around the caldera are (1) domes and flows of crystal-rich porphyritic quartz latite of variable mineralogy, interpreted as a defluidized magma, and (2) widespread crystal-poor, flow-banded rhyolite, dated at 18.6 m.y., which is not directly related to the caldera sequence. The Mule Creek caldera and other volcanic features farther south represent the only documented overlap of felsic volcanism with early stages of Basin-Range tectonism in the Mogollon-Datil field.     

The chemical composition of soil from the Apollo 16 and Luna 20 sites

The concentrations of the rare earth elements (REE), K, Rb, Sr, Ba, U, Zr and Cr for the Luna 20 soil and four different Apollo 16 soils are reported. These trace element abundances imply: (1) that the lunar highlands consist of a mixture of rocks rich in large ion lithophile (LIL) elements and LIL-element impoverished anorthosites; or (2) that the bulk of the aluminum-rich crust did not originate by upward segregation of plagioclase in a primitive liquid shell. The Luna 20 soil is distinguished from the Apollo 16 soil by lower aluminum and LIL element abundances.