Each year, a cement block is placed on a wooden trestle in the middle of Joe's Pond. When the ice melts in the spring, the 40-pound concrete block breaks through the ice and sinks. The block is attached to a rope which, when the block falls through the ice, pulls an electrical cord out of a plug on the shore. The cord is connected to an electric clock which stops when its power is cut.

Joe's Pond is located just outside the town of Danville, in Vermont's Northeast Kingdom. For more than 80 years, hundreds of people have been placing wagers at the local general store for when the cement block falls through the ice.

Although no pattern can be seen over the past 15 years, climate change could affect the date in this indicator.