The U.S. has more than 87,000 dams greater than six feet high (and two million overall). While many dams continue to provide benefits such as flood control, irrigation, and water supply, for other dams the cost of maintenance or the negative effects on communities, fish, and tribes justifies their removal.
Dam owners and regulators decide whether to remove a dam by weighing many factors including: the cost of removal and the ability to replace any lost power generation against avoided long-term maintenance; safety concerns; benefits to endangered fish populations; increased recreational and commercial fishing; and restoration of cultural values of nearby tribes.
By 2020, roughly 70% of dams will be more than 50 years old, inviting us to reconsider the value to the public of long-term investments in this infrastructure.
The country that would be the best source of chromium for specialty steel production within the United States is South Africa.
This is because South Africa is known to have the highest deposits of chromium, with about 17,000,000 out of the 40,000,000 worldwide.
Also, South Africa was known to have supported the likes of the United States during the Cold War.
Options B and C are wrong because Brazil and Zimbabwe have no chromium deposits.
Option D is wrong because India stylishly supported the Soviet Union during the cold war; hence, they wouldn't have supplied the United States with the Chromium needed.
Also, option E is wrong because Russia forms the larger part of the Soviet Union, and till today they are still not on the same side in most political issues.
Hence, in this case, it is concluded that the correct answer is option A." South Africa."
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Answer:
Q. 41. Basaltic Lava, Q.43. Basaltic magma Q.44. False
Explanation:
Basalt is a mafic extrusive igneous rock, formed by the rapid cooling of Mg and Fe rich lava, exposed at or near the surface of the earth. Thus forming about 90% of the surface lava on earth.
Shield Volcanoes emit lava or magma in the form of viscous basaltic lava. Highly explosive.
Greenland and Antarctica together constitute the 99% of the earth ice caps so, Greenland has about 80% cover as compared to antarctic 98% and both are depleting fast.
