ISSN:
1573-1626
Source:
Springer Online Journal Archives 1860-2000
Topics:
Architecture, Civil Engineering, Surveying
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Geosciences
,
Physics
Notes:
Summary Apart from a brief account of the theories of the geomagnetic field and from suggestions of obtaining new data, the present work contains an analysis of the results of investigations into continental Quaternary sediments, which have become the object of close palaeomagnetic studies in Czechoslovakia in recent years. Besides sea sediments they represent one of the few possibilities of obtaining more complete data on the past of the geomagnetic field even though their investigation requires instruments of high sensitivity and exact processing technique. A brief geological description and chronological list of individual sedimentary cycles are presented and the results of their palaeomagnetic investigation on a number of samples (about 2 000) are given. The obtained results suggest that the geomagnetic field probably displayed successive changes in the position of its magnetic axis shifting from the region of the south pole to the region of the north pole over a period of approximately 2.5 millions of years in the form of oscillations caused by impulses recurring at periods of about 140 000 years. Three types of changes of the geomagnetic field with different periods can be identified (Fig. 2): not always expressive changes with the period of 2.5 × 10 4 years, quasisinusoidal changes with a period of about 1.4 × 10 5 years and long-term changes most likely also periodical with the period of about 2.5 × 10 6 years. The first and the second periods, particularly, are close to the precession constants as far as the magnitude is concerned. Thus it can be stated that the differences in the precession rates of the motion of the core and the mantle may markedly act together in the origin of the geomagnetic field.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01626584
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