natural philosopher · soft-earth geophysics
Postdoctoral Research Scholar, Los Alamos National Laboratory
Santa Fe, New Mexico
People have wondered for over a hundred years how soil moves downhill on slopes too gentle to slide.1 The standing explanation is disturbance: gophers, frost, rain, roots, all churning the ground. So we built a hillslope in the lab where we could switch the disturbances off. It crept anyway.2 It is still, as far as we can tell, creeping.
Fig. 1. A sandpile, left alone in a quiet lab, keeps creeping,
indefinitely, at rates much like real hillslopes. It slows as it settles.
A change in temperature or humidity wakes it up again. Shaking it, oddly,
does the opposite. |
Fig. 2. Different grains, different walls, rougher and
smoother. The creep didn't much care. The details did. |
Fig. 3. Twenty-seven authors and one question: what kind of
material is the ground? |