Great Wall of China

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The newly mapped parts of the wall were also built during this period, but had been submerged over time by sandstorms that moved across the arid region, the study said.

Sandstorms continue to threaten the fortitude of the Great Wall. Chinese archaeologists say that the storms are reducing portions of the wall in Gansu province to "mounds of dirt" that may disappear entirely within 20 years, partly because some of these portions were constructed of packed earth, which proved less impervious to storms than the brick and stone used in much of