Investigations into an unknown organism on the martian meteorite Allan Hills 84001

Abstract— Examination of fracture surfaces near the fusion crust of the martian meteorite Allan Hills (ALH) 84001 have been conducted using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and has revealed structures strongly resembling mycelium. These structures were compared with similar structures found in Antarctic cryptoendolithic communities. On morphology alone, we conclude that these features are not only terrestrial in origin but probably belong to a member of the Actinomycetales, which we consider was introduced during the Antarctic residency of this meteorite. If true, this is the first documented account of terrestrial microbial activity within a meteorite from the Antarctic blue ice fields. These structures, however, do not bear any resemblance to those postulated to be martian biota, although they are a probable source of the organic contaminants previously reported in this meteorite.     

Occurrence of rhodolites in the tropical Pacific — a consequence of Mid-Miocene paleo-oceanographic change

Rhodolites occurring over wide areas of the tropical Pacific (Solomons, Loyalties, Vanuatu and Australes) are dated in many places by diagnostic larger foraminifera as of Middle Miocene age. They are preceded in Early Miocene and succeeded in Late Miocene by hermatypic coral deposits. The processes linking this facies change with time to paleo-oceanographic events documented in deep-sea sediments are identified as sea-level rise drowning the reefs, a slight drop of winter surface water temperature and an increase of the fertility of surface waters inhibiting compensatory growth of hermatypic corals until sea-level fall restored the earlier, original conditions of deposition.     

Distributed and integrated response of a geographic information system‐based hydrologic model in the eastern Palouse region,Idaho

Verification of distributed hydrologic models is rare owing to the lack of spatially detailed field measurements and a common mismatch between the scale at which soil hydraulic properties are measured and the scale of a single modelling unit. In this study, two of the most commonly calibrated parameters, i.e. soil depth and the vertical distribution of lateral saturated hydraulic conductivity K_s, were eliminated by a spatially detailed soil characterization and results of a hillslope‐scale field experiment. The soil moisture routing (SMR) model, a geographic information system‐based hydrologic model, was modified to represent the dominant hydrologic processes for the Palouse region of northern Idaho. Modifications included K_s as a double exponential function of depth in a single soil layer, a snow accumulation and melt algorithm, and a simple relationship between storage and perched water depth (PWD) using the drainable porosity. The model was applied to a 2 ha catchment without calibration to measured data. Distributed responses were compared with observed PWD over a 3‐year period on a 10 m × 15 m grid. Integrated responses were compared with observed surface runoff at the catchment outlet. The modified SMR model simulated the PWD fluctuations remarkably well, especially considering the shallow soils in this catchment: a 0·20 m error in PWD is equivalent to only a 1·6% error in predicted soil moisture content. Simulations also captured PWD fluctuations during a year with high spatial variability of snow accumulation and snowmelt rates at upslope, mid‐slope, and toe slope positions with errors as low as 0·09 m, 0·12 m, and 0·12 m respectively. Errors in distributed and integrated model simulations were attributed mostly to misrepresentation of rain events and snowmelt timing problems. In one location in the catchment, simulated PWD was consistently greater than observed PWD, indicating a localized recharge zone, which was not identified by the soil morphological survey. Copyright © 2006 John Wiley & Sons, Ltd.     

Test of independence by repeated matching of stratigraphic sections

Two stratigraphic sections of unequal length and uncertain relative position are usually tested for nonrandom similarities by calculating the coefficient of cross-association, using several of their possible mutual alignments. A rigorous statistical test of independence between the two sections is derived, utilizing results of such a procedure. Proper distinction is made between sections consisting of a record of lithological strata (consecutive repetition of the same rock type is allowed),and the situation when adjacent identical strata are merged into an lithological unit (a record of these must contain no contiguous replicates).The presented theory is first developed under assumption of prior knowledge of the exact probabilities of possible rock types, but is extended to accommodate the case of these being unavailable.