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51.
ANNE KELLY KNOWLES 《Geographical review》2000,90(2):277-284
WISCONSIN'S PAST AND PRESENT: A Historical Atlas. By The Wisconsin Cartographers ' Guild , xv and 125 pp.; maps, ills. THE ATLAS OF ETHNIC DIVERSITY IN WISCONSIN. By Kazimierz J. Zaniewski and Carol J. Rosen CULTURAL MAP OF WISCONSIN: A Cartographic Portrait of the State. By David Woodward , Robert C. Ostergren , Onno Brouwer , Steven Hoelscher , and Joshua Hane . 相似文献
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ANNE E. BJUNE H. J. B. BIRKS HEIKKI SEPPÄ 《Boreas: An International Journal of Quaternary Research》2004,33(3):211-223
Changes in tree-line, mean July temperature (T jul ) and mean annual precipitation (P ann ) for the last 10 200 cal. yr BP are reconstructed on the basis of pollen and plant macrofossils preserved in lake sediments from two sites near the present-day tree-line in Troms, northern Norway. Quantitative climate reconstructions are performed using pollen-climate transfer functions based on WA-PLS regression. Early Holocene Betula pubescens forests were gradually replaced by Pinus sylvestris at Dalmutladdo (355 m a.s.l.) starting about 7000 cal. yr BP. The local presence of pine woodland at that time is supported by finds of stomata and plant macrofossils and by high pollen accumulation rates. Until about 4000 cal. yr BP the P. sylvestris tree-line was 250-300 m higher than today, suggesting T jul about 2.0°C higher than at present. The later part of the Holocene has a cooler and moister climate and an increasing development of mires and fern-rich vegetation, as shown by increases of Sphagnum and fern spores and the re-establishment of B. pubescens woodland. The reconstructed T jul from the two sites shows similar trends to previously published data, with T jul 1-2°C warmer between 9500 cal. yr BP and 2000 cal. yr BP T jul . Maximum T jul values occur between 8500 and 4500 cal. yr BP, after which there is a gradual decrease in T jul . 相似文献
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ANNE JENNINGS JAMES SYVITSKI LINDA GERSON KARL GRÖNVOLD ÁSLAUG GEIRSDÓTTIR JÓRUNN HARDARDÓTTIR JOHN ANDREWS SVEINUNG HAGEN 《Boreas: An International Journal of Quaternary Research》2000,29(3):163-183
Foraminifera, sedimentology, and tephra geochemistry in core 93030-006 LCF from the southwestern Iceland shelf were used to reconstruct paleoenvironments between 12.7 and 9.4 14 C ka BP. Seismic-reflection profiles place the core in glacial-marine and marine sediments within one meter of the underlying glacial till. Foraminifers in the earliest glacial-marine sediments provide a record of ice-distal conditions and immigration of slope species onto the shelf in association with warm Atlantic water. Meltwater increased during the Allerød under a weakened Atlantic water influence. Arctic conditions began by 11.14 14 C ka BP with an abrupt increase in meltwater and near exclusion of boreal fauna from the shelf. Meltwater diminished in the early Younger Dryas, coinciding with sea-surface cooling between 11.14 and 10.5 14 C ka BP. A slight warming recorded in the uppermost glacial-marine sediments was interrupted by an inferred jökulhlaup event emanating from glacier ice on the Western Volcanic Zone. Retreat of the ice margin from the sea sometime between c. 10.3 and 9.94 14 C ka BP coincided with this event. The onset of postglacial marine sedimentation occurred along with increasing evidence of Atlantic water c. 9.94 14 C ka BP and was interrupted by a short-lived Pre-boreal cooling of the Irminger Current c. 9.91 14 C ka BP. Conditions similar to those today were established by 9.7 14 C ka BP. 相似文献
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In a recent short communication,Miyashita et al.have commented on the weakness of the NIPALSalgorithm(equivalently the power method)for calculating the eigenvalues out of order.They offer adiagnostic to ascertain when this may have occurred and suggested a modification to the NIPALSalgorithm to avoid this situation.Further comments regarding the use of the power method andMiyashita's presentation of its weakness are warranted.The general inadequacies of methods fordecomposing a matrix with degenerate eigenvalues and their relationship to the orthogonal design ofexperiments are discussed. 相似文献
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