 The resulting loaf-shaped haystacks can be up to 30 feet high, can weigh up to 20 tons, and can theoretically last up to five or six years.It was invented in the early 1900s and was first called the Beaverhead County Slide Stacker after its place of origin, the Big Hole Valley in Beaverhead County, Montana.The name was quickly shortened to "beaverslide."