This log was carved by Medieval farmers and connected to other such logs to transport water from a mountain lake to a lower alpine village in central Switzerland. The Aletsch Glacier advanced in 1240 AD and destroyed part of this aqueduct during the Little Ice Age cooling. Buildings and fences were also destroyed during the Little Ice Age glacier advance in the European Alps. There are beautiful paintings showing the glaciers stealthy encroaching on the alpine villages.
For more information, read the following articles, both by Wallace Broecker: