The three classifications of magma are mainly identified using their silica composition. Basaltic magma has the lowest silica content of 45-55% by weight. This makes it the least viscous and least explosive. Andesitic magma has 55-65% , making it more explosive and viscous. Rhyolitic magma has 65-75% silica, and is the most viscous and catastrophic.
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<em>Ensuring a sustainable supply of food for the world's fast growing population is a major challenge. Food production is one of the key areas that require action, alongside issues of food consumption, nutrition and food security.
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It is estimated that by 2050 the world's population will reach 9.1 billion (34% higher than today). Food production will need to increase by 70% to feed the larger and most likely more urban population.1 More food will have to be produced using less land. In addition water and energy will become limiting factors.
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Added to the challenge is that sustainable food products need to be nutrient-dense to allow people to have a diverse diet that contains a balanced and adequate combination of energy and nutrients to support good health.</em>
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D. They both understood that if currently observable processes acted in the same manner in the distant past, those processes could then be scientifically tested
Explanation:
The scientists observed and analyzed different processes that have occurred. It was discovered that the processes could be linked together and there is the possibility of studying the processes experimental to prove their existence. In addition, they believed that the processes could be tested scientifically.
D. Losing some of its fertility because of overgrazing
