USGS Reference Samples Attapulgite ATT-1 and Bentonite CSB-1

The U.S. Geological Survey has prepared an attapulgite and a bentonite as reference samples because of their economic importance. The attapulgite (ATT-1) is from the Meigs-Attapulgite-Quincy fuller's earth district of Georgia and Florida, and the bentonite (CSB-1) is from the Northern Black Hills bentonite district of Wyoming, Montana, and South Dakota. The chemical and mineralogical properties of these two samples are quite different. Provisional values calculated from the few analytical data and the X-ray diffraction mineralogy are presented for those who wish to use the clays as reference samples.     

Three-dimensional elastic wave scattering and diffraction due to a rigid cylinder embedded in an elastic medium by a point source

The formal solutions of displacement field to the problem of elastic wave scattering and diffraction due to an infinitely long rigid cylinder embedded in an infinite elastic medium by an impulsive point source have been obtained in the integral form. The integrals for the reflected and the diffracted waves both in the shadow zone and in the illuminated zone are evaluated asymptotically for the early time motion by the Reisdue-Cagniard method and the Saddle-point-Cagniard method.Numerical results of the diffractedP, S andPS waves at a fixed circum-distance from the surface of the rigid cylinder show noticeably that (1) the energy partition for the diffractedS wave is small in comparison with that for the diffractedP wave, (2) the wave form of the diffractedS wave is broader and more diffused than that of the diffractedP wave, (3) the direction of the radial motions of the diffractedP andS waves varies as a function of the observational point, and (4) the energy partition for the diffractedP wave is much smaller than that for the direct or the reflectedP waves.This paper has been presented at the 46th Annual International Meeting of Society of Exploration Geophysicists in Houston, Texas, Oct. 28, 1976.     

A simultaneous interpretation,by wind speed and direction,of ambient air negative ion density in Athens,Greece

A recently developed data presentation technique, the rectangular wind frequency isopleth diagram, has been applied to examine the effect of wind speed and direction, acting simultaneously, on ambient air negative ion densities. The large negative ion concentration decreases in the majority of directions and wind speed intervals, while that of the small ions increases, as the wind speed increases. The local maxima and minima, occurring in some sectors, are properly discussed.     

A revised identification of the oldest sea-floor spreading anomalies between Australia and Antarctica

We propose that magnetic anomalies south of Australia and along the conjugate margin of Antarctica that were originally identified as anomalies 19 to 22 may be anomalies 20 to 34. The original anomaly identification has two troublesome aspects: (1) it does not account for an “extra” anomaly between anomalies 20 and 21, and (2) it provides no explanation for the rough topography comprising the Diamantina Zone. With our revised identification there is no “extra” anomaly and the Diamantina Zone is attributed to a period of very slow spreading (～4.5mm/yr half rate) between 90 and 43 m.y. The ages bounding the interval of slow spreading (90 and 43 m.y.) correspond to times of global plate reorganizations. Our revised identification opens up the possibility that part of the magnetic quiet zone south of Australia formed during the Cretaceous long normal polarity interval. Breakup of Australia and Antarctica probably occurred sometime between 110 and 90 m.y. B.P. The “breakup unconformity” identified by Falvey in the Otway Basin may correspond to a eustastic sea level change.     

Orthodoxy and creativity in theories of mountain building before 1922

In the 1870s, theories of mountain building emerged from little more than speculation to inference based on a growing body of observation and documentation. This coincided with abandonment of models stressing uplift, and their replacement, in the new orthodoxy, by models in which earth contraction led to lateral compression in its outer shell. Nevertheless, perceived weaknesses in this model gave impetus to new theories, some emphasizing primary vertical movement, and others continental displacement or subcrustal flow. The rebel theories added to the understanding of earth processes in important ways, by drawing attention to the weaknesses in the prevailing orthodoxy. But, in 1922, the complete answer remained out of reach.

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Zusammenfassung Die siebziger Jahre des vorigen Jahrhunderts brachten den Anfang von wissenschaftlich fundierten Theorien der Gebirgsbildung. Diese Zeit sah auch den Übergang von Erhebungstheorien zur neuen Lehrmeinung, nach welcher Erdkontraktion zu lateralen Drucken in der Außenhülle der Erde führte. Erkannte Schwächen dieses Modells führten jedoch zu neuen Gegentheorien, von denen einige primäre Vertikalbewegungen in den Vordergrund stellten, während andere Kontinentalverschiebung oder Unterströmungen als den Motor der Gebirgsbildung sahen. Diese Gegentheorien haben den Fortschritt der Erdwissenschaften gefördert, indem sie auf Schwächen der herrschenden Lehrmeinung aufmerksam machten. Aber selbst zu Argands Zeit war ein völlig befriedigendes Modell noch gar nicht erreichbar.

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Résumé C'est dans les années 1870–1880 que commençaient à s'établir les premières théories vraiment scientifiques de l'orogenèse. C'était la décade qui marqua l'abandon des théories à base de soulèvement et le début du règne de la nouvelle orthodoxie d'après laquelle la contraction de la terre mène à la compression latérale d'une pellicule extérieure. Néansmoins, certaines faiblesses du nouveau modèle servaient d'élan à des théories rebelles dont quelques-unes soulignaient l'importance des soulèvements primaires, tandisque d'autres cherchaient le moteur de l'orogenèse dans la dérive des continents ou dans des courants dans une masse quasi-fluide subcrustale. Ces théories rebelles ont avancé la science en soulignant les faiblesses de l'orthodoxie. En fin de compte, une solution complètement satisfaisante ne paraissait pas encore pouvoir être atteinte à l'époque d'Argand.

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The structure of two South Carolina estuarine tide pool fish assemblages

The fish assemblages of two South Carolina estuarine tide pools located in the North Edisto River were sampled from June to October 1977, and during June and July 1978, by haul seine, lift net and channel net. The nekton was dominated numerically byFundulus heteroclitus, Leiostomus xanthurus, Menidia menidia andAnchoa mitchilli. Oyster reef areas were dominated numerically byGobiosoma bosci andF. heteroclitus. The relative abundance of tide pool fishes differs from deep water areas of the North Edisto River as described from otter trawls, but is similar to that described by others for South Carolina tidal creeks.