388 SEE— THE CAUSE OF EARTHQUAKES. [October 19. 



mouth of the Ohio to that of the St. Francis River, the ground rose 

 and sank in great undulations ; trees had to be felled across the 

 fissures for the preservation of the inhabitants, and lakes were 

 formed and drained again, and many large streams changed their 

 channels and even their courses. Physical evidences of this terrible 

 convulsion are still seen near New Madrid, where the loose land 

 had settled so much as to form swamps, leaving great cypress and 

 other trees so deep in the water that they died (some were entirely 

 submerged), and in many places still remain to show where the 

 water rose in 181 1. Little Prairie, now called Caruthersville, 20 

 miles below New Madrid, was considered the center of greatest 

 violence. The first severe earthquake occurred on the night of De- 

 cember 16, 2:15 a. m., and shook severely the whole region of the 

 Ohio, Mississippi and Missouri rivers, as far north as the Lakes, as 

 far east as the Alleghanies, south to the gulf, and west to the 

 Rocky Mountains. 



One of the best accounts of this great earthquake, drawn from 

 contemporary sources of information, is that given by Professor G. 

 C. Broadhead, of the University of Missouri, in the American Geolo- 

 gist for August, 1902. The leading points may be summarized thus : 



1. After the first severe shock at 2:15 in the night, smaller 

 shocks followed, and at 7 a. m., December 16, 181 1, came a much 

 more severe shock ; then came lighter shocks daily or oftener, until 

 January 23, 1812, when an extremely severe shock was felt; con- 

 tinual agitations were felt till February 4, which brought another 

 severe shock, and four more followed next day; and on February 

 7, at 4 p. m., came one so much more violent than the preceding that 

 it was called " the hard shock." Hundreds and even thousands of 

 smaller after-shocks have continued at irregular intervals to the 

 present time. "Two series of the (original) concussions were par- 

 ticularly terrible." 



2. Thus there were at least eight very severe shocks, each of 

 which did great damage and spread devastation far and wide. 



3. The eye-witnesses generally agree that these severe shocks 

 were preceded by heavy subterranean thunder ; " a loud roaring 

 sound like steam escaping from a boiler " ; " distant rumbling sounds 

 succeeded by discharges as if a thousand pieces of artillery were 



