No. 80: Mar-Apr 1992
While on the subject of ancient hydrological engineering, it is appropriate to mention a remarkable wooden well found in northwest Germany. Over 200 oaken planks have been discovered so far. These are up to 15 centimeters thick and 50 wide. Fairly large oaks had been cut and split with stone axes and then worked into planks. Mortises were cut in some way so that the planks could be joined. It is quite clear that the Neolithic peoples of the region were skilled carpenters. The size of the well, too, is impressive: it was more than 15 meters deep. The tree rings on the planks permitted very accurate dating: 5303 BC -- well over 7000 years ago.
(Bahn, Paul G.; "The Great Wooden Well of Kuckhoven," Nature, 354:269, 1991.)