Answer:
The magma that melts in the upper mantle and erupts at the mid-ocean ridge has a different composition (higher in Ca, Mg, Fe and relatively lower in Si and Al) than the composition of the magma (more Si, Al, Na, K rich in relative terms) that built the continents. Melting different degrees (2%, 5%, 30%) of a rock with a mantle-like composition generates magma of different Al, Si contents. Continents grow at their edges by partial melting of oceanic crust that is being subducted, generating magmas of a somewhat more Si, Al-rich composition than the subducting slab itself. The chemistry and physics of melting a mixture of minerals rather than one homogeneous substance has the wonderful outcome of creating two distinct types of crust:
Régions particulièrement touchées. L'Arctique, l'Afrique, les petites îles et les mégadeltas asiatiques sont des régions susceptibles d'être particulièrement touchées par les futurs changements climatiques. Dans d'autres régions, certaines personnes sont particulièrement exposées aux futurs changements climatiques, comme les pauvres, les jeunes enfants et les personnes âgées.
Answer:
The process of desertification presents a serious impact on the well-being and health of the people living
in the areas affected by droughts and land degradation
on an unprecedented global scale. The worst situations
can be found in Africa, which is threatened because the
land degradation processes affect about 46 percent of
the whole continent and create a health risk to people
living in the regions far beyond the affected areas.
Explanation:
Inca ruins civilization in Peru country
I would think the erosion and wethering im just guesting since i dont know if theres any answer choices
