THE NEW MADRID EARTHQUAKE 59 



the equilibrium, and when the great pressure of the artesian water 

 below would burst forth, causing the elastic clay roof to undulate, 

 with the resulting earth- waves and ejections of water, sand, and 

 lignite so vividly described by numbers of eyewitnesses of the catas- 

 trophe. The first disturbance, relieving, to a degree, the artesian 

 pressure, would be followed by a temporary equilibrium, which 

 would be succeeded by other periods of disturbance, as described. 



RECENT EARTHQUAKES 



This region has for many years been subject to slight earthquake 

 shocks. A year rarely passes without their occurrence, the last one 

 having as recent a date as September, 1904. In August, 1903, 

 houses were shaken and dishes rattled, the phenomena lasting about 

 ten minutes, and being accompanied by a roaring sound under- 

 neath. This earthquake was rather severe near Charleston, Mo., 

 where a pond 3 \ miles from the town was greatly enlarged by the 

 sinking of adjacent land. The disturbance was attended by the 

 throwing up of a considerable quantity of fine white sand. Mr. 

 W. M. Timbs, a railroad conductor, stated that on October 5, 1895, 

 quite a severe earthquake occurred in this region. At this time, 

 south of Belmont, the water flowed from the driven pumps in this 

 vicinity, and brought up sand and particles of coal, the pumps con- 

 tinuing to flow for a month. Numerous small cracks were formed 

 on the prairie, from which sand and particles of coal were ejected. 

 The writer's attention was called to the fact that one or more of these 

 earthquake shocks occur each fall, being more frequent at that season 

 of the year than at any other time. This might be accounted for 

 by the low water in swamps, streams, and ponds following the dry 

 season characteristic of the country — a condition which would give 

 decreased pressure at the surface and offer least resistance to the 

 artesian pressure below. Observers state that these shocks are 

 always accompanied by a roaring noise and a waving of the ground. 1 



Some of the intense local disturbances in the Charleston, S. C, 



1 Mr. W. S. Randall, of Poplar Bluff, Mo., informs the writer that in a well 

 sunk there to a depth of 700 feet, a number of years ago, the water rose to within 15 

 feet of the surface. A twelve-horse-power engine could lower it only about one 

 inch ; but after a severe earthquake shock, about three years ago, the well was 

 nearly ruined, and since then furnishes barely enough water to run a factory. 



