Quaternary evolution of Cedar Creek alluvial fan, montana   总被引：1，自引：0，他引：1  

J.B Ritter  J.R Miller  Y Enzel  S.D Howes  G Nadon  M.D Grubb  K.A Hoover  T Olsen  S.L Reneau  D Sack  C.L Summa  I Taylor  K.C.N Touysinhthiphonexay  E.G Yodis  N.P Schneider  D.F Ritter  S.G Wells 《Geomorphology》1993,8(4)

Cedar Creek alluvial fan is a textbook example of an alluvial fan because of its fan shape with smooth, concentric contours and excellent symmetry. Similar planimetric shapes have been used to infer uniform fan deposition; however, Cedar Creek alluvial fan is composed of four fan deposits of Quaternary age, Qf1 (oldest) to Qf4 (youngest), indicating that fan deposition was nonuniform in both time and space. Field studies indicate that deposition of Cedar Creek alluvial fan is related to glaciofluvial outwash activity during the Pleistocene and upper-fan entrenchment and lower-fan deposition during the Holocene.Qf1 and Qf2 deposits are sub-horizontally bedded, clast-supported sandy gravels uniformly imbricated upfan. Comparison of soil profiles developed in these deposits to radiogenically-dated chronosequences within the region indicates that Qf1 and Qf2 are correlative with Bull Lake and Pinedale-age deposits, respectively. These relationships are substantiated by physical correlation of Qf1 and Qf2 with Bull Lake and Pinedale moraines, respectively, in the Cedar Creek drainage basin. The sedimentology and timing of Qf1 and Qf2 indicate deposition in high-energy, proglacial, braided streams. Furthermore, the present morphology of Cedar Creek alluvial fan was established largely during aggradation of Qf1 and Qf2 when sediment supply to the fan was sufficient to activate 60% to greater than 90% of the total fan area. During Bull Lake glaciation, the apex of Qf1 deposition formed the apex of Cedar Creek alluvial fan as Qf1 covered more than 90% of the present fan area. During Pinedale glaciation, Qf2 deposition shifted downfan; Qf2 is inset into Qf1 above the intersection point, but below the intersection point it eroded and/or buried Qf1 as it activated as much as 60% of the fan area.Qf3 and Qf4, comprising 21% of the fan area, are inset into Qf2 in the lower fan area. Soil development in Qf3 and Qf4 deposits indicate episodic deposition and entrenchment beginning in early Holocene and continuing to present. A post-glacial decrease in sediment supply to Cedar Creek alluvial fan is indicated by sediment storage within the Cedar Creek drainage basin. Decreased sediment supply to the fan resulted in upper-fan entrenchment of Qf2 and deposition of Qf3 and Qf4 in the lower-fan area.  相似文献   

The politics of prevention     

Claudine Schneider 《Climatic change》1991,19(1-2):257-261

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Deposition of trace substances via cloud interception on a coniferous forest at Kleiner Feldberg     

S. Pahl  P. Winkler  T. Schneider  B. Arends  D. Schell  R. Maser  W. Wobrock 《Journal of Atmospheric Chemistry》1994,19(1-2):231-252

A resistance model to calculate the deposition of cloud droplets on a coniferous forest and some improved parameterizations of the indispensable input parameters are described. The deposition model is adapted to the coniferous forest at the Kleiner Feldberg site and verified by the data of a drip water monitoring station below the forest canopy. The measurements of liqud water content, wind speed and trace substance compounds in cloud water of the Ground-based Cloud Experiment (GCE) at Kleiner Feldberg in 1990 are used to calculate the cloud water deposition fluxes and the deposition of trace substances via cloud water interception. The calculated deposition of trace substances via cloud water interceptions is three to six times higher than via rain during the experiment. On a long term data basis the yearly amount of cloud water deposition is 180 mm year^–1 at Kleiner Feldberg site (840 m a.s.l.) while the precipitation amount is 1030 mm year^–1. Due to higher trace substance concentrations in cloud water compared to rain the ionic deposition via cloud water interception and via precipitation were assessed to be of comparable magnitude.  相似文献   

Editorial     

Stephen H. Schneider 《Climatic change》1985,7(4):365-366

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Loss of metals from pelites during regional metamorphism   总被引：3，自引：0，他引：3  

U. Haack  H. Heinrichs  M. Boneß  A. Schneider 《Contributions to Mineralogy and Petrology》1984,85(2):116-132

In aluminous metapelites the ratio H₂O⁺/K₂O decreases with increasing metamorphic grade and degree of reaction. This ratio is a very practical indicator for the progress of the mineral reconstitution during progressive metamorphism. With decreasing values of the ratio H₂O⁺/ K₂O the Cu concentration and the following element ratios also decrease either continuously or in stepwise fashion: Tl/K₂O, Ba/K₂O, Pb/K₂O, Bi/K₂O, Hg/K₂O, Sr/Na₂O, Zn/(Fe²⁺+Mg), Cd/(Fe²⁺+Mg); Rb/K₂O remains approximately constant. In the aluminous metapelites of the Damara Orogen in Namibia the following losses occur between the biotite isograd and anatexis: 61% Cu, 20% Tl, 34% Ba, 59% Pb, 86% Bi, 46% Hg, 30% Sr, 25% Zn, 31% Cd. Thus the potential of regional metamorphism to form hydrothermal deposits in the low grade environment should not be neglected.  相似文献   

Deforestation and climatic modification — an editorial     

Stephen A. Schneider 《Climatic change》1984,6(3):227-229

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‘Natural experiments’ and CO2-induced Climate Change: The controversy drags on — An editorial     

Stephen H. Schneider 《Climatic change》1984,6(4):317-321

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Editorial     

D. D. Klemm  Hans -J. Schneider 《Mineralium Deposita》1984,19(1):1-1

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Forecasting in the social and natural sciences: An overview and analysis of isomorphisms   总被引：1，自引：0，他引：1  

Kenneth C. Land  Stephen H. Schneider 《Climatic change》1987,11(1-2):7-31

This article identifies and analyzes several points of similarity in the structure and context of forecasting in the social and natural sciences. These include: the limits of identities or universal laws as a basis for forecasts; the corresponding need for simplifying parametric representations of one or more of the variables that enter into identities; various sources of uncertainty about parameterizations; intrinsic limitations on predictability or forecasting accuracy in large-scale systems; the need for sensitivity analyses of model responses to changes in exogenous variables and/or parametric structures; problems of model linkage; and the social (organizational and political) context of forecasts. Suggestions for future lines of inquiry are made in each case. Several of these are such that they can benefit from a sharing of experience and expertise across disciplinary lines.The research reported herein was supported in part by the IC² Institute, The University of Texas at Austin, and in part by National Science Foundation Grant Number SES-8411702. However, the opinions expressed in the paper are those of the authors and do not necessarily reflect those of the sponsoring organizations. We appreciate the advice and comments of Jesse H. Ausubel, Robert S. Chen, Judith Jacobsen, and Richard C. Rockwell on earlier versions of this paper.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

Editorial: Three essays of remembrance on the life of Helmut Landsberg     

Stephen H. Schneider 《Climatic change》1986,9(3):259-259

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