Biologists have recently stumbled upon an enormous beaver dam, over a half mile long, in a remote region of Wood Buffalo National Park in Alberta, Canada. The biologists believe it may have taken 20 years to complete, with several beaver families all helping to pile its wood, mud, and stone. It dwarfs a 1,956 foot dam in Montana previously thought to be the largest. The dam was able to reach such a massive size because multiple beaver families contributed to its construction, which required thousands of trees to produce. More info at Treehugger.MP3: Hot Tuna - How Long Blues