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Ancient Egypt Brought down by Famine
Even ancient Egypt’s mighty pyramid (金字塔) builders were powerless in the face of the famine (饥荒)that helped bring down their civilization around 2180 B.C.. Now evidence collected from mud deposited by the River Nile suggests that a shift in climate thousands of kilometers to the south was ultimately to blame and the same or worse could happen today.
The ancient Egyptians depended on the Nile’s annual floods to irrigate their crops. But any change in climate that pushed the African monsoons (季风) southwards out of Ethiopia would have reduced these floods.
Declining rains in the Ethiopian highlands would have meant fewer plants to stabilize the soil. When rain did fall it would have washed large amounts of soil into the Blue Nile and into Egypt, along with sediment (沉积) from the White Nile.
Blue Nile mud has a different isotope (同位素) signature from that of the white Nile, so by analyzing is
A. Because they once worked miracles.
B. Because they were well-built.
C. Because they were actually very weak.
D. Because even they were unable to rescue their civilization.