Working on possible explanations of how the freeze-thaw Earth era ended, Martin Kennedy of the University of California, Riverside, and Nicholas Christie-Blick and Sohl of Columbia University published an exciting new hypothesis this year in Geology. They questioned the hypothesis that the cap carbonates deposited over the tillites resulted from the reaction of atmospheric carbon dioxide released from volcanoes with calcium and magnesium washed into the seas by weathering of the continents.
The rapid continental weathering required by this model should have rapidly increased the concentration in seawater of the isotope strontium 87, a signature isotope in continental rocks. But no evidence of elevated strontium 87 levels has been found in the cap carbonates, even though several studies have been conducted.
The Kennedy team has proposed instead that the cap carbonates are the result of destabilization of gas hydrates. Composed primarily of methane and water, gas hydrates are suspended in sediments as an icelike substance. These deposits are apparently so extensive that they are being seriously considered as a potential hydrocarbon energy source. Methane is produced from the breakdown of organic material buried in sediments and becomes concentrated near the sediment surface wherever temperature and pressure conditions are appropriate [see “The Ice That Burns,” The World & I , June 1999, p. 162]. Permafrost regions make some of the best reservoirs.
There must have been extensive permafrost regions toward the end of the Neoproterozoic: more abundant than at any other time due to the colder conditions. The Kennedy team has proposed that gas hydrates seeped to the surface during the later part of the Neoproterozoic, gradually releasing extensive amounts of methane into the atmosphere.
They contend that methane (a greenhouse gas that is more than 20–30 times as effective as carbon dioxide) warmed the planet as it increased in the atmosphere and brought on the melting of glaciers. The team believes that the carbon contained in methane is the ultimate source of carbon in the cap carbonates. (Marc J. Defant 2001)
The problem of greenhouse effect is global nowadays. The needs in industrial enterprises are constantly growing but the solution lies in the scientific approach to the problem. It is considered that cap carbonates resulted in the mutual reaction with atmospheric carbon dioxide got into World Ocean when the change of the climate happened many thousands years ago. The group of scientists of the Kennedy team, on the other hand, tends to think that this is the result of gas hydrates destabilization.
These substances infiltrate to the upside at the end of Neoproterozoic which in turn provoked emissions of methane into the atmosphere. It is exactly methane, as they think, caused the warmth of planet in spite of generally accepted theory that carbon dioxide caused it.
Egypt is an ancient country territory of which saw many changes in physical, social, and cultural as well as religious aspects of its development. The “calling card” and also one of the World Wonders are the pyramids which amaze with their geometrically, architecturally and mechanically rational forms.
One of the most popular pyramids is Great Pyramid at Giza. With regards to the geologic consistence of this masterpiece of architecture it is known that the main types of rocks used fall into “limestone of gray, hard, dense kind; gray, soft limestone; gray, shaley limestone; and yellow, limy, shaly sandstone (in order of decreasing resistance to weathering).” (Farouk El-Baz 306) This pyramid like everything on the planet is decayable and loses almost 0.01 per cent of its volume because of the materials it is made with. Therefore, Great Pyramid at Giza is supposed to retain its present shape for about 100,000 years more. (Farouk El-Baz 306)
Works Cited
Defant, Marc J. “Ice over Earth.” World and I. 200.
El-Baz, Farouk “The geology of Egypt: an annotated bibliography” Brill Archive, 1984.
Desautels, Paul E. “Treasures in the Smithsonian: the gem collection”, Smithsonian Institution Press, 1979.