A radiometric age for the Cretaceous–Tertiary boundary based upon K–Ar, Rb–Sr, and U–Pb ages of bentonites from Alberta, Saskatchewan, and Montana

1988 ◽  
Vol 25 (7) ◽  
pp. 1088-1097 ◽  
Author(s):  
H. Baadsgaard ◽  
J. F. Lerbekmo ◽  
I. McDougall
Keyword(s):  
Standard Deviation ◽  
North American ◽  
Red Deer ◽  
Statistical Error ◽  
Systematic Errors ◽  
Stratigraphic Correlation ◽  
Coal Seams ◽  
Weighted Mean ◽  
The North ◽  
Iridium Anomaly

Bentonites associated with coal seams at the North American Cretaceous–Tertiary (K–T) boundary in the Red Deer Valley of Alberta, in the Frenchman Valley of Saskatchewan, and near Hell Creek, Montana, were dated by the K–Ar, Rb–Sr, and U–Pb methods. Based upon palynological stratigraphic correlation and the presence of a sharp iridium anomaly, the three sampled bentonite horizons all occur less than 1 m above the established K–T boundary. There is evidence of possible systematic errors giving dating results outside nominal statistical error values. Despite possible constant errors, the weighted mean of nine average dates is calculated as 64.3 ± 1.2 Ma (2σ standard deviation). An unweighted averaging produces a grand mean age of 64.4 ± 1.2 Ma.

scholarly journals Comparing Reanalyses Using Analysis Increment Statistics

2008 ◽  
Vol 9 (6) ◽  
pp. 1535-1545 ◽  
Author(s):  
Jean Fitzmaurice ◽  
Rafael L. Bras
Keyword(s):  
Standard Deviation ◽  
North American ◽  
Meridional Wind ◽  
Department Of Energy ◽  
Specific Humidity ◽  
South American ◽  
The South ◽  
The North ◽  
Uncertainty Estimates ◽  
Global Reanalysis

Abstract Reanalysis data are an important source of information for hydrometeorology applications, which use data assimilation to combine an imperfect atmospheric model with uncertain observations. However, uncertainty estimates are not normally provided with reanalyses. The model “first guess” (6-h forecast) is sometimes saved along with reanalysis estimates, which allows the calculation of the analysis increment (AI), defined as the analysis minus the model first guess. Analysis increment statistics could provide a quantitative index for comparing models in regions with sufficient observations. Monthly analysis increment statistics for the NCEP–NCAR Global Reanalysis 1 (NCEP-R1) and the NCEP/Department of Energy Global Reanalysis 2 (NCEP-R2) are computed for a North American and South American location for zonal and meridional wind and specific humidity at three atmospheric levels for 1998–2001. NCEP-R2 specific humidity was found to have a smaller mean monthly standard deviation of the analysis increment than NCEP-R1 at the North American location at the 300-mb level. The NCEP-R2 specific humidity monthly standard deviation at the South American location is much larger than NCEP-R1 for September–November 1998, which may be related to the transition to La Niña. For both zonal and meridional wind, the monthly AI standard deviations are similar for NCEP-R1 and NCEP-R2 at all atmospheric levels for the North American location. The South American location exhibits similar behavior for the wind AI statistics as for specific humidity: NCEP-R2 has a much larger monthly standard deviation of the AI for September–November 1998. The analysis increment statistics could be one method for quantitatively comparing reanalyses. First guess information should be available to the user in reanalysis archives.

American Geological Investigations and the French, 1750-1850

1990 ◽  
Vol 9 (2) ◽  
pp. 118-125 ◽  
Author(s):  
Kenneth Taylor
Keyword(s):  
Nineteenth Century ◽  
International Cooperation ◽  
North American ◽  
Historical Development ◽  
Scientific Activity ◽  
Stratigraphic Correlation ◽  
Early Maturity ◽  
The North ◽  
Geological Science ◽  
Geological Work

By the middle of the nineteenth century, leaders of the French geological community were taking a keen interest in North American geological phenomena and investigations. Most of this French attention to American geology developed during the first half of the nineteenth century. French geological preoccupations in America during that period tended to focus especially on issues of stratigraphic correlation and paleontology, with discernible concern also for the North American glacial (drift) phenomena, mineral ores, and meteorite observations. The growth of French regard for American geologists and for America as a geological resource, up to 1850, displays features of international cooperation and communication especially plain in such a location-specific science. Historical development of communal scientific activity is seen in travel accounts, and in exchanges of publications and specimens. The Société Géologique de France, founded in 1830, quickly became an important vehicle for commerce in geological knowledge between America and France. French respect for American geological work in the first part of the nineteenth century illustrates the comparatively early maturity of American geological science.

1588: The Bicalutamide Early Prostate Cancer Program: Findings of the North American Trial at 7.7 Years' Median Follow-Up

2006 ◽  
Vol 175 (4S) ◽  
pp. 511-512
Author(s):  
David G. McLeod ◽  
Ira Klimberg ◽  
Donald Gleason ◽  
Gerald Chodak ◽  
Thomas Morris ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
North American ◽  
Early Prostate Cancer ◽  
The North ◽  
Cancer Program
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