The Earth s Magnetic Field Its History

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Some of the earliest forms of scientific investigation, as we know them today, were studies of the earth's magnetic field.The Epistola de Magnete of 1259by Petrus Perigrinus is now regarded as the first scientific treatise ever written-and was about geomagnetism. Yet it was not until historical records of the geomagnetic field could be extended back in time, through the use of archaeomagnetism and palaeomagnetism, that great progress was made in our understanding of the history and origin of the earth's magnetic field. One of the most significant discoveries of palaeomagnetism has been that the geomagnetic field has changed its polarity many times in the past. This
discovery played a critical role in the development of the theory of plate tectonics and is a constraint on all models for the origin of the main field of the earth. However, the existence of two polarity states is not a powerful constraint on most magnetic fieldmodels. Indeed, the existence of two states of opposite polarity was compatible with theories for the origin of the earth's magnetic field that existed 30 years ago. Less startling observational results acquired subsequently appear likely to place far more powerful constraints on theories for the origin of the main field.
Over the past quarter of a century, scientific investigations of the geomagnetic field have been made on three broad fronts. There are the traditional aspects of geomagnetism relating to the present field and its secular variation. Also, palaeomagnetic and archaeomagnetic studies have been undertaken in many parts of the world. Often the geomagnetic aspects that arose from these studies were only secondary, the main thrust having been related to continental drift and plate tectonics. The third group of investigators have been theoreticians carrying out research into the origin of the main field and its secular variation. Unfortunately these three categories
Product Details
Paperback: 416 pages
Publisher: Academic Pr (January 1984)
Language: English
ISBN-10: 0124912427
ISBN-13: 978-0124912427
Product Dimensions: 8.9 x 5.9 x 0.8 inches

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