Mining Geophysics: D.S. Parasnis,Elsevier, Amsterdam, 1973, 2nd ed., 395 pp., Dfl. 70.00     

John S. Sumner 《Sedimentary Geology》1974,12(4):297-298

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Surface‐climate attributes at Injisuthi Outpost,Drakensberg, and possible ramifications for weathering     

Paul D. Sumner  Werner Nel 《地球表面变化过程与地形》2006,31(11):1445-1451

Aerial and sub‐aerial climatic data were collected from a station at 1920 m a.s.l. in the Injisuthi region of the South African Drakensberg. Sensors monitored air temperature, soil surface and rock surface temperature, for two rock types, over the summer and winter of 2001/2002. Rainfall was measured from the summer of 2001 to January 2004. These are the first rock and soil surface‐climate data to be collected for an exposed site at this altitude in the area. Rainfall over the two calendar years 2002 and 2003 was found to be below estimates for the region, but patterns imply numerous rock wetting and drying cycles in summer. At the site, air, rock and soil temperatures differ considerably on a diurnal basis with respect to both absolute temperature and daily ranges. Mean rock daily ranges, as conducive to possible thermal fatigue, are found to be similar in the summer and winter periods. Of the two rock types monitored, the darker coloured basalt attained higher maximum and marginally lower minimum temperatures than the sandstone. Soil frost did not occur at 2·5 cm depth, but rock did reach below ?6 °C in winter. Both rock types maintain relatively high rock temperatures in winter (exceeding 25 °C), thus chemical weathering is probably only moisture restricted during this dry period. Findings highlight the importance of directly monitoring rock temperature when attempting to discern the rock weathering environment. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Economics of downscaled climate-induced changes in cropland,with projections to 2050: evidence from Yolo County California     

Hyunok Lee  Daniel A. Sumner 《Climatic change》2015,132(4):723-737

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Current‐aligned dewatering sheets and ‘enhanced’ primary current lineation in turbidite sandstones of the Marnoso‐arenacea Formation          下载免费PDF全文

Lawrence A. Amy  Peter J. Talling  Esther J. Sumner  Giuseppe Malgesini 《Sedimentology》2016,63(5):1260-1279

Turbidite sandstones of the Miocene Marnoso‐arenacea Formation (northern Apennines, Italy) display centimetre to decimetre long, straight to gently curved, 0·5 to 2·0 cm regularly spaced lineations on depositional (stratification) planes. Sometimes these lineations are the planform expression of sheet structures seen as millimetre to centimetre long vertical ‘pillars’ in profile. Both occur in the middle and upper parts of medium‐grained and fine‐grained sandstone beds composed of crude to well‐defined stratified facies (including corrugated, hummocky‐like, convolute, dish‐structured and dune stratification) and are aligned sub‐parallel to palaeoflow direction as determined from sole marks often in the same beds. Outcrops lack a tectonic‐related fabric and therefore these structures may be confidently interpreted to be sedimentary in origin. Lineations resemble primary current lineations formed by the action of turbulence during bedload transport under upper stage plane bed conditions. However, they typically display a larger spacing and micro‐topography compared to classic primary current lineations and are not associated with planar‐parallel, finely laminated sandstones. This type of ‘enhanced lineation’ is interpreted to develop by the same process as primary current lineations, but under relatively high near‐bed sediment concentrations and suspended load fallout rates, as supported by laboratory experiments and host facies characteristics. Sheets are interpreted to be dewatering structures and their alignment to palaeoflow (only noted in several other outcrops previously) inferred to be a function of vertical water‐escape following the primary depositional grain fabric. For the Marnoso‐arenacea beds, sheet orientation may be linked genetically to the enhanced primary current lineation structures. Current‐aligned lineation and sheet structures can be used as palaeoflow indicators, although the directional significance of sheets needs to be independently confirmed. These indicators also aid the interpretation of dewatered sandstones, suggesting sedimentation under a traction‐dominated depositional flow – with a discrete interface between the aggrading deposit and the flow – as opposed to under higher concentration grain or hindered‐settling dominated regimes.  相似文献   

Geomorphological characteristics of small debris flows on Junior's Kop,Marion Island,maritime sub ‐ Antarctic     

Jan Boelhouwers  Steve Holness  Paul Sumner 《地球表面变化过程与地形》2000,25(4):341-352

The geomorphological characteristics of small debris flows in a maritime sub‐Antarctic environment are described. The morphological and sedimentological characteristics of the debris flows are comparable to debris flows documented for other parts of the world; their initiation appears closely linked to the unusual environment in which they are found. Sediment supply is generated by diurnal frost heave of loamy sediment associated with Azorella selago. The debris flows are triggered by sediment mobilization upon saturation of the frost‐heaved surface gravel and overland flow over the low‐permeability and frost‐susceptible slope materials. Morphological effects of the flows are short‐lived due to obliteration by subsequent frost heave activity. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Experimental sandstone weathering using different wetting and drying moisture amplitudes   总被引：1，自引：0，他引：1  

P. D. Sumner  M. J. Loubser 《地球表面变化过程与地形》2008,33(6):985-990

Wetting and drying is an acknowledged yet still poorly understood rock weathering process. Previous experiments documented in the literature measure physical changes or mass loss in relation to moisture oscillations but only one study directly compares different moisture amplitudes by using different modes of moisture application. In this experimental study, four sets of sandstone tablets are subjected to 48 h wetting and drying cycles at set moisture content fluctuations of 29, 42, 56 and 63% respectively. A common moisture application, full immersion, is used for all four sets. Mass loss after 52 cycles averaged 0·27%, some three times more than that of the control samples. Average porosity of the samples increased, while water absorption capacities and the saturation coefficients of the samples decreased. No discernable difference in mass loss or change in physical properties was found between the different sample sets. When compared with previous studies, results suggest that the effect of moisture application type may be more of a controlling factor on the weathering effect than actual moisture content achieved. A need to move towards a more standardized approach in wetting and drying experimental studies is emphasized. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Rock weathering on the eastern mountains of southern Africa: Review and insights from case studies     

P.D. Sumner  K.J. Hall  J.L. van Rooy  K.I. Meiklejohn 《Journal of African Earth Sciences》2009,55(5):236-244

The mountains in the eastern region of southern Africa are of significant regional importance, providing for a diverse range of land use including conservation, tourism and subsistence agriculture. The higher regions are comprised of flood basalts and are immediately underlain by predominantly aeolian-origin sandstones. Our understanding of the weathering of these basalts and sandstones is reviewed here, with particular focus on the insights gained from the Lesotho Highlands Water Project and an ongoing study into the deterioration of rock art. While the chemical weathering attributes of the basalts have been substantially investigated, it is evident that the environmental surface conditions of rock moisture and temperature, as affecting weathering processes, remain largely unknown. Within the sandstones, studies pertaining to rock art deterioration present insights into the potential surface weathering processes and highlight the need for detailed field monitoring. Outside of these site-specific studies, however, little is understood of how weathering impacts on landscape development; notably absent, are detail on weathering rates, and potential effects of biological weathering. Some palaeoenvironmental inferences have also been made from weathering products, both within the basalts and the sandstones, but aspects of these remain controversial and further detailed research can still be undertaken.  相似文献   

USE OF REPLICATION AND SIGNAL-TO-NOISE RATIOS IN THE IDENTIFICATION AND ESTIMATION OF THE COMPOSITION OF LUBRICANT BASESTOCK MIXTURES USING ~(13)C NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY AND PROJECTION INTO PRINCIPAL COMPONENT/CANONICAL VARIATES SPACE     

JOHNM.DEANE  HALLIDAYJ.H.MacFIE  ALEXANDERG.KING 《地理学报(英文版)》1989,(1)

The theory of experimental error in analysis of mixture experiments by abstract factor analysis or targettransformation factor analysis is considered. The theoretical implications of using signal-to-noise ratios(as weights) or canonical variates analysis to reduce the level of imbedded error in the factor model areexamined. The approach is illustrated by application to ~(13)C NMR spectra of lubricant basestockmixtures.  相似文献   

Atmospheric circulation and daily precipitation in Wales     

M. Bonell  G. Sumner 《Theoretical and Applied Climatology》1992,46(1):3-25

Summary Daily precipitation affinity areas are established for Wales by means of S-mode Principal Components Analysis (PCA) and Cluster Analysis, using data for the autumn-winter (September-January) period, 1982–87, subset according to surface wind direction. Relatively strong PCA simple structures were found for five wind directions clockwise from south to north, using the OBLIMIN rotation for the first four (south to northwest) and the VARIMAX rotation for the last (north). Whilst interpretation of many of the most significant Prinicipal Components (PCs) was difficult in strictly meteorological or climatological terms, the precipitation areas produced by clustering based on the most important PCs, yielded a continuum of change in areal organisation with progressively changing wind direction. Only the far southwest and northwest of the country appear in every area map, although superficially, northeastern, English border and southeastern areas were present on most. The derived areas bear only small overall resemblance to currently used forecasting areas.With 9 Figures  相似文献   

Is the Arctic Surface Layer a Source and Sink of NOx in Winter/Spring?     

B. Ridley  J. Walega  D. Montzka  F. Grahek  E. Atlas  F. Flocke  V. Stroud  J. Deary  A. Gallant  H. Boudries  J. Bottenheim  K. Anlauf  D. Worthy  A. L. Sumner  B. Splawn  P. Shepson 《Journal of Atmospheric Chemistry》2000,36(1):1-22

Measurements of NO_x (NO +NO₂) and the sum of reactive nitrogenconstituents, NO_y, were made near the surface atAlert (82.5°N), Canada during March and April1998. In early March when solar insolation was absentor very low, NO_x mixing ratios were frequentlynear zero. After polar sunrise when the sun was abovethe horizon for much or all of the day a diurnalvariation in NO_x and NO_y was observed withamplitudes as large as 30–40 pptv. The source ofactive nitrogen is attributed to release from the snowsurface by a process that is apparently sensitized bysunlight. If the source from the snowpack is a largescale feature of the Arctic then the diurnal trendsalso require a competing process for removal to thesurface. From the diurnal change in the NO/NO₂ratio, mid-April mixing ratios for the sum of peroxyand halogen oxide radicals of 10 pptv werederived for periods when ozone mixing ratios were inthe normal range of 30–50 ppbv. Mid-day ozoneproduction and loss rates with the active nitrogensource were estimated to be 1–2 ppbv/day and in nearbalance. NO_y mixing ratios which averaged only295±66 pptv do not support a large accumulation inthe high Arctic surface layer in the winter and springof 1998. The small abundance of NO_y relative tothe elevated mixing ratios of other long-livedanthropogenic constituents requires that reactivenitrogen be removed to the surface during transport toor during residence within the high Arctic.  相似文献