Geological evidence

Selection of the drill site is based largely on geological evidence indicating the possible accumula-... 

Now that we have reviewed some basic aspects of the chemical composition of the ocean we can turn to a more fundamental question. What processes determine the composition of the ocean Current evidence suggests that rivers are the most important contributors of dissolved substances to the ocean. Since there is geologic evidence that the concentration and composition of the ocean has been relatively constant over the last 1.5 billion years, we must conclude that the river input must be balanced by removal. 

MacKenzie and Carrels (1966) approached this problem by constructing a model based on a river balance. They first calculated the mass of ions added to the ocean by rivers over 10 years. This time period was chosen because geologic evidence suggests that the chemical composition of seawater has remained constant over that period. They assumed that the river input is balanced only by sediment removal. The results of this balance are shown in Table 10-13. 

Jurassic—Cretaceous Besshi-type and Mn-Fe strata-bound deposits are present in Hidaka, Hokkaido (Fig. 1.2). Geochemical data and geological evidence all point to a midoceanic ridge environment of ore formation. values of Shimokawa Besshi-type... 

The thin, newly formed Earth s crust, consisting of light silicates, swam on the surface of the sea of magma. It was often broken apart by collision with planetes-imals of various sizes. The formation of the crust was a complex process, many details of which are as yet not understood. This admission points to the fact that we do not have much geological evidence from this early phase of the Earth s formation. 

Except at very low pH values, the hexa-aqua ferric ion, Fe(H20)63+, would then undergo a series of hydrolysis and polymerization reactions, leading progressively to more and more insoluble ferric polynuclears which would precipitate to give the geologic evidence of atmospheric oxygenation by the presence around the... 

Considering that there is geologic evidence that the Ca concentration of the oceans change with time, it is necessary that Fvi,/Fsechanges with time. As noted by De La Rocha and DePaolo (2000), if the steady state equation for the sedimentary values is written as ... 

LaBerge GL, Rohhins El, Han TM (1987) A model for the biological precipitation of Precambrian iron-formations geological evidence. In The Precambrian Iron-Formations. Appel PWU, LaBerge GL(eds) Theophrastus Pub, Athens, p 69-96... 

After all, it takes only a single spark to persuade an entire forest to react with oxygen. The consequence in 1998-9 was a haze of smoke that covered Indonesia and altered the local climate. There is geological evidence for global wildfires in the distant past that make this one seem like a bonfire. 

There has been much speculation as to the sources whence the ancient Egyptians obtained the tin for their bronzes. No nearby sources have been discovered. Geologic evidence is to the effect that tin occurred in Persia, and it may have been from this region that the earliest supplies came. It is also possible that sources of tinstone from farther south on the African continent may have been drawn upon, but any evidence to that effect is also lacking. 

The Earth began forming about 4.6 billion years (Ga) ago. The first 600 to 800 million years (Ma) of Earth s existence have been erased by the constant early bombardment of asteroids and comets (Arrhenius and Lepland 2000 Delsemme 2001 Ehrenfreund and Men ten 2002 Wharton 2002). The earliest geologic evidence for life on Earth dates to 3.5 to 3.8 Ga (Schopf and Packer 1987 Mojzsis et al. 1996 Ehrenfreund and Menten 2002 Stetter 2002 Wharton 2002). Based on this evidence, it has been argued that life on Earth developed rapidly within about 200 to 300 Ma. During this interval, the Earth evolved from a hot dry rock to a cool wet world. Evidence suggests that the... 

EP, Wagner R, Williams KK (1999) Does Europa have a subsurface ocean Evaluation of the geological evidence. J Geophy Res 104 24,015-24,055... 

Some future day may yet arrive when all reasonable chemical experiments run to discover a probable origin for life have failed unequivocally. Further, new geological evidence may indicate a sudden appearance of life on the earth. Finally, we may have explored the universe and found no trace of life, or process leading to life, elsewhere. In such a case, some scientists might choose to turn to religion for an answer. Others, however, myself included, would attempt to sort out the surviving less probable scientific explanations in the hope of selecting one that was still more likely than the remainder.1... 

Rankama, K., 1955. Geologic evidence of chemical composition of the Precambrian atmosphere. Geol. Soc. Am., Spec. Pap., 62 651-664. 

Morner N.-A. (1979) The Fennoscandian uplift and Late Cenozoic geodynamics Geological evidence. Geojoumal 3, 287-318. 

Models of the early history of life come in two broad categories— models of the origin and first development of life itself and models of the environmental settings of that life. The geologist can contribute much more to the second class of model than to the first from the geological evidence it is possible to make reasonable models of the early planets, including their surface condition and the supply of chemicals and nutrients from the interior and from space. 

Figure 7 Model of the descent of life following the standard model of Woese (1987), as calibrated by the geological evidence (source Shen et al, 2001, and other evidence). See Figure 11 for alternative model.

Geological evidence for the early distribution of life is fragmentary. In the early Archean of... 

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