Yes, there certainly are ways to make similar ball-and-pillow structures. The most prominent is dewatering of sediments by overpressure (which is what these Ordovician features were previously attributed to). Another would be slumping of partially-consolidated muds. The main reason these Kentucky structures are now thought to be seismites is their widespread distribution in a tight time interval — they are virtually marker beds. That would be unlikely for dewatering or slumping, which would be more local and diachronous. (There are also contorted beds like these which may be associated with meteorite impacts. Wouldn’t that be cool?)

The structures you note at the base of the Mesa Verde Group sound like excellent subjects for undergraduate research. You and your students could follow them stratigraphically, although you probably don’t have the detailed biostratigraphic controls present in the highly fossiliferous Ordovician beds.

Good luck. Love to hear about what you find!

Are there ways to form ball-and-pillow structures (at about that scale) that aren’t related to earthquakes? I’m asking because we’ve got some very similar-looking sedimentary structures in Durango (near the bottom of the Cretaceous Mesa Verde Group), and I’ve never heard anyone interpret them as seismites before. Are there other things we could look for to test whether these ball-and-pillow structures are related to earthquakes? (I’m thinking that this might make an interesting undergraduate research project.)

Kim Hannula
Fort Lewis College