Geomorphology of unique reefs on the western Canadian shelf: sponge reefs mapped by multibeam bathymetry     

Kim W. Conway  J. Vaughn Barrie  Manfred Krautter 《Geo-Marine Letters》2005,25(4):205-213

Multibeam imagery of siliceous sponge reefs (Hexactinellida, Hexactinosida) reveals the setting, form, and organization of five reef complexes on the western Canadian continental shelf. The reefs are built by framework skeleton sponges which trap clay-rich sediments resulting in a distinctive pattern of low intensity backscatter from the reefs that colonize more reflective glacial sediments of higher backscatter intensity. Bathymetry and backscatter maps show the distribution and form of reefs in two large complexes in the Queen Charlotte Basin (QCB) covering hundreds of km², and three smaller reef complexes in the Georgia Basin (GB). Ridges up to 7 km long and 21 m in height, together with diversely shaped, coalescing bioherms and biostromes form the principal reef shape in the QCB whereas chains of wave-form, streamlined mounds up to 14 m in height have developed in the GB. Reef initiation is dependent on the distribution of high backscatter-intensity relict glacial surfaces, and the variation in reef complex morphology is probably the result of tidally driven, near seabed currents.  相似文献   

Aliens like us?   总被引：1，自引：0，他引：1  

Simon Conway Morris 《Astronomy& Geophysics》2005,46(4):4.24-4.26

Simon Conway Morris explains that as and when (and indeed if) we meet the extraterrestrials, they will look eerily like us.  相似文献   

The global distribution of methane in the troposphere   总被引：6，自引：0，他引：6  

L. P. Steele  P. J. Fraser  R. A. Rasmussen  M. A. K. Khalil  T. J. Conway  A. J. Crawford  R. H. Gammon  K. A. Masarie  K. W. Thoning 《Journal of Atmospheric Chemistry》1987,5(2):125-171

Methane has been measured in air samples collected at approximately weekly intervals at 23 globally distributed sites in the NOAA/GMCC cooperative flask sampling network. Sites range in latitude from 90° S to 76° N, and at most of these we report 2 years of data beginning in early 1983. All measurements have been made by gas chromatography with a flame ionization detector at the NOAA/GMCC laboratory in Boulder, Colorado. All air samples have been referenced to a single secondary standard of methane-in-air, ensuring a high degree of internal consistency in the data. The precision of measurements is estimated from replicate determinations on each sample as 0.2%. The latitudinal distribution of methane and the seasonal variation of this distribution in the marine boundary layer has been defined in great detail, including a remarkable uniformity in background levels of methane in the Southern Hemisphere. We report for the first time the observation of a complete seasonal cycle of methane at the South Pole. A significant vertical gradient is observed between a sea level and a high altitude site in Hawaii. Globally averaged background concentrations in the marine boundary layer have been calculated for the 2 year-period May 1983–April 1985 inclusive, from which we find an average increase of 12.8 ppb per year, or 0.78% per year when referenced to the globally averaged concentration (1625 ppb) at the mid-point of this period. We present evidence that there has been a slowing down in the methane growth rate.Presented at the Conference on the Scientific Application of Baseline Observations of Atmospheric Composition (SABOAC), Aspendale, Australia, 7–9 November 1984.  相似文献   

Some limitations of the R_fφ technique of strain analysis — Reply     

Declan G. De Paor 《Tectonophysics》1981,72(1-2)

The analysis presented in the discussion is statistically invalid.  相似文献   

Elliptical markers and non-coaxial strain increments — discussion     

Declan G. De Paor 《Tectonophysics》1981,76(3-4)

Finite homogeneous strain may be deduced from the spatial distribution of initially uniformly oriented lines or planes in a rock, as recorded in a pole figure or petrofabric diagram. This paper presents a new analytic technique which is simple and rapid in practical application.  相似文献   

Spectral Line and Continuum Radiation Propagation in a Clumpy Medium     

John Conway  Moshe Elitzur  Rodrigo Parra 《Astrophysics and Space Science》2005,295(1-2):319-324

We discuss the propagation of spectral line and continuum radiation in a clumpy medium and give general expressions for the observed absorption or emission from a cloud population. We show that the affect of the medium clumpiness can usually be characterised by a single number multiplying the mean column opacity. Our result provides a simpler proof and generalization of the result of Martin et al. (1984). The formalism provides a simple way to understand the effects of clumping on molecular line profiles and ratios; for example, how clumping effects the interpretation of ¹³CO(1–0) to ¹²CO(1–0) line ratios. It also can be used as a propagation operator in physical models of clumpy media where the incident radiation effects the spectral line emissivity. We are working to extend the formalism to the propagation of masers in a clumpy medium, but in this case, there are special difficulties because formal expectation values are not characteristic of observations because they are biased by rare events.  相似文献   

Conodont palaeobiology: recent progress and unsolved problems     

S. Conway Morris 《地学学报》1989,1(2):135-150

The fossilized soft-parts of conodonts are extraordinarily rare; excluding dubious and refuted examples, only 10 specimens are known. Nine come from the Lower Carboniferous of Granton, Scotland, and represent at least two genera with complex polygnathacean apparatuses. The soft-parts include well-defined myotomal segmentation and a probable notochord, thus strongly suggesting affinity with the chordates. The tenth specimen, from the Lower Silurian of Waukesha, Wisconsin, bears a simpler apparatus of panderodontid conodont elements. The soft-parts are very poorly preserved, but appear to be unlike those of the Granton specimens. In both occurrences the conodont apparatus appears well adapted for grasping and biting, supporting earlier suggestions that conodont elements acted as teeth. Many conodonts were probably predators or scavengers, but other feeding modes are not necessarily excluded. Other aspects of conodont palaeobiology reviewed here include mode of life and possible migration, reproduction and genetics, and palaeopathology. All these topics rely almost exclusively on the study of conodont elements, and many problems of conodont palaeobiology await further research.  相似文献   

The final phases of the Viking mission to Mars     

Conway W. Snyder  Nancy Evans 《Icarus》1981,45(1):2-24

Of the four spacecraft that the Viking Project put into operation at Mars in the summer of 1976, one continues to acquire data periodically. The missions of the two orbiters were terminated by the depletion of their attitude-control gas: Orbiter 2 in July 1978 and Orbiter 1 in August 1980. Lander 2 was shut down in April 1980 because of degradation of its batteries. Lander 1 is programmed to continue acquiring a modest number of imaging, meteorology, and ranging data periodically until December 1994. During its final year Orbiter 1 continued to produce excellent data from its full complement of instruments—two cameras, two infrared instruments (thermal mapper and water vapor detector), and the radio subsystem. The major emphasis was on photography, with 10,000 images being acquired. These included two very large swaths of high-resolution contiguous coverage of the Martian surface and the completion of the moderate-resolution mapping of nearly the entire surface, as well as miscellaneous other observations. The majority of these images has not been processed and examined, but the others have revealed many previously unobserved features and have greatly enhanced the base for a geological understanding of the planet. The history of Viking mission operations is brought up to date.  相似文献   

1961-2004年宁夏极端气温变化趋势分析   总被引：4，自引：1，他引：3  

陈晓光  Declan Conway  郑广芬  陈晓娟 《气候变化研究进展》2008,4(2):73-077

 利用1961-2004年宁夏逐日最高、最低气温资料,分析了宁夏44 a来最高、最低气温的变化趋势。结果表明：宁夏的最高、最低气温表现出了明显的变化趋势,最高气温＜0℃的日数减少,＞30℃的日数增加;在年平均最低气温升高的同时,极冷日数也在增加,相对于1961-1990年的平均值,20世纪90年代和21世纪最初的4 a年极冷日数分别增加了1.1 d和0.7 d,距平百分率分别达350%和275%。  相似文献   

Probabilistic Approach to Evaluation of Metal(loid) Fate During Stormwater Aquifer Storage and Recovery          下载免费PDF全文

Joanne L. Vanderzalm  Declan W. Page  Karen E. Barry  Kathleen Scheiderich  Dennis Gonzalez  Peter J. Dillon 《洁净——土壤、空气、水》2016,44(12):1672-1684

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