Other sites with remarkable construction tend to show a relatively short burst of creativity, followed by somewhat rapid collapse, as happened on Easter Island. The EI statues date from about 1250 AD to about 1500 AD, and it sez here that nearly half of them were never moved out of the quarry, which implies that the precipitous end to the statue-building phase — as recorded in their folklore — came about in a pretty short time frame near the end of that period.
The EI statues date from about 1250 AD to about 1500 AD
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The flaw in that theory is that many of the statues are buried 20 feet from the bottom to the surface. It takes more that a few centuries to have soil accumulate to that depth - more like thousands of years.