A search for primordial atmospheric-like argon in an iron meteorite

He and Ar were extracted from the Weekeroo Station octahedrite in six heating steps. The Ar isotopic ratios were searched for any indication of an indigenous component with atmospheric-like values. Negative results were obtained.     

Environmental influences on the yield of spring Barley in England and Wales

Using data on crop yields and soil conditions derived from reports of the Soil Survey of England and Wales, and incorporating a variety of climatic and topographic data, relationships were identified between the yield of spring barley and edaphic and climatic conditions. Yields are highest on fine loamy and silty soils and on freely to imperfectly drained soils. Multiple regression analysis indicated that yields are related to sand contents, drainage conditions and available water capacity of the soil, potential summer soil moisture deficit and annual accumulated temperature.     

Development of longitudinal profiles of alluvial channels in response to base-level lowering

Degradation of alluvial channels in cohesive sediments was studied in 15 m and 20 m long flumes with a slope of 0°01 cm/cm. Degradation was initiated by lowering base level to a fixed position, and the development of the longitudinal profile of the channel is analysed through a model formulated as a heat (diffusion) equation. It is based on the equation of sediment continuity, combined with an assumption regarding sediment transport, namely that sediment discharge is linearly proportional to the channel slope. In accordance with the boundary and initial conditions imposed by the experimental setup and procedure, the basic equation is amenable to an analytical solution, which defines bed elevation at any distance and time, as a function of the amount of base-level lowering and a ‘diffusion’ coefficient. Additional problems arising from bank erosion and channel armouring are also treated successfully within the framework of the same model. The results show that in homogeneous alluvial sediments, not subject to armouring, the ultimate result of base-level lowering by a certain amount is degradation all along the channel by the same amount. The main impact of erosion is felt in the early stages after initiation of the process, and mainly near the mouth. The rate of degradation at any station along the channel reaches a peak and then slowly decreases with time, and the peak rate is attenuated with distance from the outlet. The model permits the prediction of intermediate stages of profile development at any distance from the outlet and at different times.     

In situ uptake of mercury by the intertidal mussel,Mytilus californianus

The in situ uptake of mercury in tissues of Mytilus californianus was studied by exposing control specimens to waters at four depths near a submarine wastewater discharge for a period of 24 weeks. The response patterns observed for digestive gland, adductor muscle and gonadal tissues were strikingly different. Digestive gland concentrations increased rapidly to the heightened levels found for indigenous specimens. On the other hand, changes in the mercury content of adductor muscle were not statistically significant, and gonadal tissues generally exhibited a low rate of increase. No correlation with depth was observed.     

A fast method for the solution of a system of simultaneous linear equations—A method adapted to a particular problem

Mathematical Geosciences - In mineral deposit evaluation, the estimation of block values can involve the solution of as many as 100,000 systems of linear equations. To minimize computing costs it...     

Quantitative taxonomy and biostratigraphy of Middle Cambrian trilobites from Montana and Wyoming

This study was made to revise the taxonomy and biostratigraphy of Middle Cambrian trilobites from Montana and Wyoming. Both numerical and conventional analyses were made of the taxonomic and biostratigraphic data. Numerical taxonomy was performed on a sample of 210 OTU's (Operational Taxonomic Units) using 66 characters which were determined on cranidia of Middle Cambrian ptychopariid trilobites. These characters consisted of linear measurements which were transformed to indices proportional to glabellar length, quantitative-qualitative shape or angle measurements, and multistate attributes. The similarity coefficients calculated were average taxonomic distances and Pearson's product-moment correlation coefficient. The matrices of similarity coefficients were clustered by single-linkage and unweighted pair-group algorithms. The coordinates of OTU's in a three-dimensional A-space defined by the first three principal axes also were calculated. A phenogram of the distance matrix clustered by UPGMA (which yielded the highest cophenetic correlation coefficient) and a three-dimensional pin-and-ball model were used to interpret the trilobite taxonomy. Insufficiently clear clustering in both representations of taxonomic structure necessitated also a conventional taxonomic study guided by the numerical phenetics. Numerical biostratigraphy was performed with 79 collections as OTU's and 43 trilobite genera as characters. Jaccard coefficients were used as similarity coefficients, and the results were clustered by UPGMA. The resultant phenogram was readily interpretable, and seven faunal assemblage zones (Albertella, Glossopleura, Ehmaniella, Bolaspis-Glyphaspis, Ehmania, Parehmania, and Bolaspidella)are defined for the Middle Cambrian in the study area. Two of the zones (Ehmaniellaand Parehmania)are new and replace part of the previously defined “Bathyuriscus-Elrathina”zone. Bolaspis-Glyphaspis, Ehmania,and Parehmaniazones may have only regional validity.     

Crustal structure and temporal velocity change in southern California

Summary About twenty blasts are used to determine crustal structure and to monitor temporal seismic velocity changes in southern California. The shot time is determined up to 10 msec by using a disposable pick-up placed directly on the explosive. About 17 permanent stations and 20 temporary stations are used for the recordings. With a fast paper speed (typically 1 cm/sec) and the WWVB radio signals superposed on the seismic trace, absolute timing accuracy of up to 10 msec is achieved. A representative structure thus determined consists of a 4 km thick 5.5 km/sec layer underlain successively by 23.4 km thick 6.3 km/sec layer, 5.0 km thick 6.8 km/sec layer and 7.8 km/sec half space. The details of the lower crust are somewhat uncertain. This structure can explain the travel time data, corrected for the station and source elevations and for the station delays, to ±0.15 sec. Small but systematic temporal velocity changes up to 3% have been found for some of the profiles. If the effect of the migration of the shot point is small enough, these changes are larger than experimental errors and represent real temporal change in the material property between the shot point and the stations.Contribution No. 2530, Division of Geological Sciences, California Institute of Technology, Pasadena, California.     

The Néel transition and magnetic properties of terrestrial,synthetic, and lunar ilmenites

The magnetic susceptibility of a terrestrial, synthetic and lunar ilmenite specimen has been measured from 4 to 300 K. All specimens had a single Néel temperature transition which ranged from 56 to 57.7 K. In one case the powdered specimen was partially aligned in the magnetic field prior to the susceptibility measurements and the Néel transition was observed to shift to 60 K indicating magnetic anisotropy. A study of several magnetic parameters calculated from the experimental data showed gross impurities in the terrestrial specimen, single-domain to multi-domain metallic iron in the synthetic specimen, and a small amount of superparamagnetic metallic iron in the lunar sample. No multidomain iron was observed in the lunar ilmenite. The results of electron spin resonance measurements were also in general agreement with these findings. Because of the absence of Fe³⁺ compared to most terrestrial samples it is suggested that the anisotropic magnetic parameters be determined on lunar ilmenite when a large enough single crystal becomes available.