Whenever I'm hiking in the woods, I'm always on the lookout for giant boulders sitting by themselves and looking quite out of place. This is no illusion: the boulders are often significantly different in composition than the local geological citizenry, and this difference is a reflection of the origins of the rock interlopers. These hunks of stone may have been carried here then left behind by glaciers, and sometimes the journey of the so-called "glacial erratics" can be measured in hundreds of miles. This one could have been plucked off a ravine face in the White Mountains of New Hampshire, and while I don't know its true former residence, I'm sure that it's not from around here. It's fun to point this out to people, but sometimes the statement gets surprisingly garbled, as during one trek I led in which I told the group about the erratic, only to have one of the kids with us tell his friend about seeing "glacial erotics." That would be an interesting, although probably very slow, movie.