Rocks On A Roll, As Seen In March's National Geographic Magazine (PHOTOS)

The following is an excerpt from the March issue of National Geographic magazine:

The journeys of erratics, carried by glaciers during a succession of ice ages, were long, sometimes hundreds of miles. Their name comes from the Latin errare, to wander, which makes sense because they have been carried by ice from their original locations to where we find them today, deposited over the northern U.S. On prairies the anomalous stones fracture the horizon. Early stone carvers gave them buffalo ribs and hoofprints; later fans painted them, carved initials, honored them with plaques. In forests they are enigmatic giants penned in by trees. On mountaintops they perch as though balanced by impish fingers.

How did the rocks arrive in such unlikely places? Did a primordial volcano cough them out? Did the Arctic Ocean flood so violently that it swept boulders onto mountains? Did a stutter in Earth's orbit cause uphill avalanches?

Also, check out NatGeo's weird rap ode to rocks below .

All photos courtesy of Fritz Hoffman/National Geographic.