Earth interior

Earths interior is quite warm because of radioactive decay and gravitational pressures. In some areas, the heat comes relatively close to Earths surface. When this heat pokes through, we see it as lava from a volcano or steam from a geyser. This is geothermal energy, and it can be tapped for our benefit. Figure 19.22 shows some areas in the United States that have geothermal activity. 

Table 5.8. Noble gases produced in the Earth interior for 4.5 Ga...

Iron is the fourth most abundant element in the Earths crust. Iron is often found in the minerals hematite, magnetite, and mar-casite. Large deposits of iron-bearing minerals are found primarily in Australia, Canada, France, India, South Africa, and the United States. The iron used in industry comes from these mineral deposits. In addition, the interior of Earth—called the core—is believed to be composed primarily of iron. Earths interior is extremely hot—hot enough to melt iron into a molten state. 

Closer to home, but no less fascinating, are laboratory experiments that simulate the extremely high pressures of the Earths interior. These show a new phase of a magnesium silicate (MgSi03) that bonds in two directions rather than three. Such a phase of matter could indeed flow and help drive convection deep underground, and may, upon further investigation, explain minute changes in Earths rotation. 

Today, many hydrocarbons are obtained from a fossil fuel called petroleum. Petroleum formed from the remains of microorganisms that lived in Earths oceans millions of years ago. Over time, the remains formed thick layers of mudlike deposits on the ocean floor. Heat from Earths interior and the tremendous pressure of overlying sediments transformed this mud into oil-rich shale and natural gas. In certain kinds of geological formations, the petroleum ran out of the shale and collected in pools deep in Earths crust. Natural gas, which formed at the same time and in the same way as petroleum, is usually found with petroleum deposits. Natural gas is composed primarily of methane, but it also contains small amounts of other hydrocarbons that have from two to five carbon atoms. 

S common misconception is that ratlioactivit) is new in the environment, but it has been around loi r than the human mce. It is as much a pan of our environment as the siui and the tain. It has always txxuried in the soil we walk on and in the air we breathe, and it warms the interior of Hanh and makes it molten. The energ) released by ladioactive substances in Earths interior heats the water that spurts from a geyser and the water that wells up from a natural hot spring. 

Institute for Study of the Earth Interior, Okayama University, Yamada 827, Misasa, Tottori 682 0193, Japan... 

Filtration installations include wrapping the trench of a pavement-edge drain system to prevent contamination of the underdrain placement behind retaining walls and bridge abutments to prevent contamination of the sand blanket placed against the stmcture to allow dissipation of pore pressures in order to avoid failure of the stmcture as silt fences to allow surface mnoff from a site while retaining the soil suspended in the mnoff and on earth slopes beneath larger stone or other overlay materials to prevent erosion of the slope as water escapes from the interior of the slope. 

Rare-Earth Metals," ia Mineral Commodity Summaries 1991, U.S. Interior Bureau of Mines, Washington, D.C., 1991. 

Ahrens, T.J. and Petersen, C.F., Shock Wave Data and the Study of the Earth, in The Application of Modern Physics to the Earth and Planetary Interiors (edited by Runcorn, S.K.), Wiley, New York, 1969, pp. 449-461. 

Y. Syono, in Materials Science of the Earth s Interior, edited by I. Sunagawa (Terra, Tokyo, 1984), pp. 395-414. 

According to one theory, earth and the other planets were formed almost 5 billion years ago from the gas (the solar nebula) that trailed behind the sun as it rotated. Being remote from the sun s core, the matter in the nebula was cooler than that in the interior and therefore it contracted, accumulating heavier elements and becoming the series of planets that now circle the sun. 

Seismic observations furnish our only probe of the inner lithosphere. The shock waves initiated by an earthquake travel through the interior of the earth in paths that are bent in accordance with the elastic properties and density of the medium they penetrate. From these paths, seismologists have been able to determine the existence of zones within the lithosphere. The... 

In order to understand the impact of pollution on Earth, we must realize that the planet itself is not stagnant, but continually moving material around the system naturally. Any human (anthropogenic) redistribution in the elements is superimposed on these continuous natural events. Energy from the sun and radioactive decay from the Earth s interior drive these processes, which are often cyclic in nature. As a result, almost all of the rocks composing the continents have been processed at least once through a chemical and physical cycle involving... 

The constant transport of material within and through the geospheres is powered by the sun and by the heat of the Earth s interior. A simple diagram of these geospheric concepts and the energy that moves material within them is presented in Fig. 1-1. The result of the interactions shown in Plate 1 and Fig. 1-1 is an Earth system that is complex, coupled, and evolving. 

The composition of the Earth was determined both by the chemical composition of the solar nebula, from which the sun and planets formed, and by the nature of the physical processes that concentrated materials to form planets. The bulk elemental and isotopic composition of the nebula is believed, or usually assumed to be identical to that of the sun. The few exceptions to this include elements and isotopes such as lithium and deuterium that are destroyed in the bulk of the sun s interior by nuclear reactions. The composition of the sun as determined by optical spectroscopy is similar to the majority of stars in our galaxy, and accordingly the relative abundances of the elements in the sun are referred to as "cosmic abundances." Although the cosmic abundance pattern is commonly seen in other stars there are dramatic exceptions, such as stars composed of iron or solid nuclear matter, as in the case with neutron stars. The... 

Volume 1 Beno Gutenberg. Physics of the Earth s Interior. 1959 ... 

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