Crayfish chimney from the Spiro archaeological site in eastern Oklahoma - the mud was ejected as a burrow was formed. I have seen crayfish burrows extend more than 2 meters deep at archaeological sites. I once read that crayfish feed mostly at night and crawl into burrows in the morning, and that they use the first empty crayfish burrow they find, only digging a new one if they have to. Musical burrows!

Armadillo dig from Northwest Arkansas. Armadillos dig into the soil with their front claws to get at grubs and other bugs. These diggings aren't usually very deep, but can be numerous in an area with lots of armadillos. They also use their snouts to "plow" through leaf layers looking for bugs to eat, and I've seen them waddling backwards scooping up leaves in their arms to take back to their dens.

This is a tiny path in the desert soil of Buckeye Hills Recreation Area south of Tempe, Arizona. Notice that the pebbles have all been cleared and the path itself is composed mostly of sand. These little paths criss-crossed much of the desert, running from one bush to the next. I'm not sure what made them - probably a rodent, or maybe lizards?

 

Killdeer are ground-nesting birds that dig small depressions and line them with twigs and stones. In this case, the nest is lined with artifacts from a prehistoric archaeological site - including scrapers (stone tools used in processing wood and hides), and flakes (chips left over from stone-tool making). This photo was taken by Adam Newman of the Iowa Office of the State Archaeologist in Missouri near I-70.

 

Bill Whittaker is an archaeologist with the Iowa Office of the State Archaeologist. Here he has his leg in a hollow tree stump, on top of a prehistoric mound at Effigy Mounds National Monument. When the stump rots away completely, it may look like a looter's hole in the mound. Bill Whittaker and Glen Story wrote a publication on factors that can create false mounds or cause depressions in mounds (listed on the technical articles page here).

Frost pillars pushing up particles of soil. The pillars are tiny (about 3 cm tall), but over time they can significantly alter the top layer of soil. This picture was taken near West Fork, Arkansas, where it doesn't frost very often. The hill slopes have lots of exposed soil, though, so frost pillars are able to move soil more easily than in areas with thick vegetation.

 

This is a prehistoric spear point I found on an archaeological survey along the Alaska Peninsula just north of Kodiak Island. Bears dig into the tundra to get at roots and berries, and we found them to be very useful for looking beneath the moss of the tundra without further disturbing the vegetation.

A somewhat unusual form of bioturbation: sailfin catfish burrowing several meters into the shoreline in south Florida. Story from "Off the beaten path" compilation by Trey Reid, Arkansas Democrat Gazette, Sept. 27, 2001.

This is a gravestone in Evergreen Cemetery in Fayetteville, Arkansas. It was set flush with the ground in 1982 or later, and by the time this picture was taken (2004), it had already been partially buried through bioturbation.

 

Another gravestone from Evergreen Cemetery, this one dating to the 1870s. It is broken, and the lower portions had been completely buried through bioturbation. A footstone to a different burial was buried too, about 30 centimeters beneath the ground surface. The "sinking" of older monuments is a common problem at many cemeteries.

Tree throw at Fort Harrison State Park, Indianapolis Indiana. Trees can move a great deal of soil when they fall over, bringing material up with their roots and leaving a deep pit below. This creates 'pit and mound' topography in many forested areas. It can mix artifacts in the upper portion of the soil, and create features that mimic prehistoric storage pits.

Saguaro cactus throw in Arizona. The dynamics of cactus throws are similar to tree throws, but the amount of soil moved is much smaller. Notice also that there is a ring of larger stones right at the base of the cactus - these appear to have been pushed out of the way as the cactus grew. Will this look like a fire ring when the remains of the cactus are completely gone?

Strips of cleared forest floor at Fort Harrison State Park, Indianapolis Indiana. Tree falls, burrowing mammals, and other factors are evident in the irregular surface of the bare soil. High School students cleared all forest debris from the soil as part of a large surface collection in Martin University's Next Step Education Through Archaeology Program (NSEAP).