890 resultados para Times and movements


Relevância:

100.00% 100.00%

Publicador:

Resumo:

During the summer of 2003, a ground-penetrating radar survey around the North Greenland Icecore Project (NorthGRIP) deep ice-core drilling site (75°06' N, 42°20' W; 2957 m a.s.l.) was carried out using a shielded 250 MHz radar system. The drill site is located on an ice divide, roughly 300 km north-northwest of the summit of the Greenland ice sheet. More than 430 km of profiles were measured, covering a 10 km by 10 km area, with a grid centered on the drilling location, and eight profiles extending beyond this grid. Seven internal horizons within the upper 120 m of the ice sheet were continuously tracked, containing the last 400 years of accumulation history. Based on the age-depth and density-depth distribution of the deep core, the internal layers have been dated and the regional and temporal distribution of accumulation rate in the vicinity of NorthGRIP has been derived. The distribution of accumulation shows a relatively smoothly increasing trend from east to west from 145 kg/m**2/a to 200 kg/m**2/a over a distance of 50 km across the ice divide. The general trend is overlain by small-scale variations on the order of 2.5 kg/m**2/a/km, i.e. around 1.5% of the accumulation mean. The temporal variations of the seven periods defined by the seven tracked isochrones are on the order of +-4% of the mean of the last 400 years, i.e. at NorthGRIP ±7 kg/m**2/a. If the regional accumulation pattern has been stable for the last several thousand years during the Holocene, and ice flow has been comparable to today, advective effects along the particle trajectory upstream of NorthGRIP do not have a significant effect on the interpretation of climatically induced changes in accumulation rates derived from the deep ice core over the last 10 kyr.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Knowledge of the long-term history of the perennial ice is an important issue that has eluded study because the Cenozoic core material needed has been unavailable until the recent Arctic Coring Expedition (ACEX). Detrital Fe oxide mineral grains analyzed by microprobe from the last 14 Ma (164 m) of the ACEX composite core on the Lomonosov Ridge were matched to circum-Arctic sources with the same mineral and 12-element composition. These precise source determinations and estimates of drift rates were used to determine that these sand grains could not be rafted to the ACEX core site in less than a year. Thus the perennial ice cover has existed since 14 Ma except for the unlikely rapid return to seasonal ice between the average sampling interval of about 0.17 Ma. Both North America and Russia contributed significant Fe grains to the ACEX core during the last 14 Ma.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Includes music.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Includes music.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

His Majesty King Ernestus Augustus of Hanover and the Iron Duke -- A page from the history of the Guelphs -- General Bosco -- Monseigneur Dupanloup -- The Empress Carlota's ride to Calvary -- Saxony saved by two yards of ribbon -- Thiers as Warwick of the second empire -- The Red Prince of Prussia and the white horse of Hanover -- General Gordon -- From Loanda to Zanzibar -- Bismarckiana -- "Rejected love" -- How to become a mistress of the robes -- A royal undertaker -- How to unhook a grand cordon -- Oscar -- Parisiana -- A well-deserved lesson -- Princess Metternich's madman.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Title vignette.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

"Chronological table": p. 365-367.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Includes bibliographical references and index.