The New Madrid earthquakes broke up rock like this section of rock face, which was later filled with sand. This photo, from Mississippi County, Mo., was taken in 1904.
Credit M.L. Fuller (Image 362) / USGS
The earthquakes caused the Mississippi River to overflow its banks. The high water brought sand, which covered up several feet at the base of trees. The trees survived and grew roots into the new sand, which had been washed away by the time this picture was taken in 1904.
The magnitude-5.8 earthquake that rattled the eastern U.S. on Tuesday took everyone — even geologists — by surprise. But even when there are reasons to think an earthquake could be around the corner, scientists still can't make good predictions.