Although most Americans associate earthquakes with California, the tremors that shook the Mississippi valley in southeast Missouri from December 16, 1811, through February 7, 1812, are among the most violent quakes ever to hit the North American continent in recorded history. Collectively known as the New Madrid earthquakes, these quakes affected more than 1 million square miles. By comparison, the 1906 San Francisco earthquake affected only 60,000 square miles, less than one-sixteenth the area of the New Madrid earthquakes. Scientists believe that each of the three greatest tremors would have measured more than 8.0 on the Richter scale, had that measuing device been in place in 1811. Vibrations were felt from the Rocky Mountains to the Atlantic coast and from Mexico to Canada. The quake zone was in constant movement during this period. Five towns in three states disappeared, islands vanished in the Mississippi River, lakes formed where there had been none before, and the river flowed backward for a brief period. Providing eyewitness accounts from people both on the land and on the river, Bagnall captures the fears of the residents through their tales about the smells and dark vapors that filled the air, the cries of the people, the bawling of animals, and the constant roar of the river and its collapsing banks. ""On Shaky Ground"" also traces the history of the founding of New Madrid and considers the impact of the earthquakes on population and land in southeast Missouri. Predictions for future earthquakes along the New Madrid fault, as well as instructions on preparing for and surviving an earthquake, are also included. This informative text should be of interest to all general readers, especially those interested in earthquakes or Missouri history.