2 - Heat Generation
Published online by Cambridge University Press: 10 May 2010
Summary
It is the surface of the earth which was heated, by combustion. It is composed in great part of metals, such as sodium and potassium, which catch fire by mere contact with air and water; this took place whenever rain fell, and as the water penetrated the cracks in the earth's crust, further combustion took place, causing explosions and eruptions.
A Journey to the Center of the Earth – Jules Verne, 1864.The physical properties of the Earth's deep interior are unavoidably obscure. Direct human observation is limited to mines in the top 3 km or less, while deep drilling has provided core samples and instrument access to maximum depths of around only 12 km (Kozlovsky, 1987). Deeper physical evidence, down to several hundred kilometres, is obtained from xenoliths and other volcanic products ejected onto the surface from the mid-crust to upper mantle, but this still represents a very small portion of the 6370 km radius of the Earth. The bulk of our knowledge of the Earth's interior composition and physical properties has been deduced by indirect means. Major internal boundaries and structural features (Figure 2.1) have been delineated using seismic methods and supported by density models deduced from gravity readings (e.g. Ringwood, 1969, 1979; Brown and Mussett, 1993).
One conclusion from velocity modelling is that the interior of the Earth is significantly hotter than the surface. The internal heat is derived both from primordial sources related to the formation of the globe and from secondary processes generating heat internally.
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- Crustal Heat FlowA Guide to Measurement and Modelling, pp. 23 - 44Publisher: Cambridge University PressPrint publication year: 2001
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