There is a little island called the Isle of Pines about 40 miles south of New Caledonia. And on this little island are about 400 mounds of sand and gravel, each about 8 or 9 feet high and roughly 300 feet in diameter. A curious researcher named L. Chevalier of the Museum of New Caledonia, dug into four of these mounds in the early 1960s. Inside three of the mounds, Chevalier found a single upright pillar, and the fourth contained two pillars.
The pillars are about 40 to 100 inches high and range from 40 to 75 inches in diameter. The mortar, a lime-mortar compound, contained bits of shell which could be dated using radiocarbon techniques. Surprisingly, they were found to date between about 5120 BC and 10,950 BC.
There are several odd things about these cylinders. There are no other signs of human presence at the sites. Excavators found no bones, charcoal, or any other remains. Also, the use of mortar anywhere else in the world only dates back to a few hundred years BC.
Similar mounds have been found in the Paita district of southern New Caledonia. But New Caledonia is believed to have been settled by people arriving from Indonesia only around 4,000 years ago,long after the pillars were created. So who stopped by and left all the concrete cylinders?