48 KINDLE 



Sand Ridge mine, at Aurora, great cracks similar in appearance to those 

 formed by earthquakes developed in the summer of 1900 as pumping 

 lowered the ground-water level. Near Carl Junction a section of rail- 

 way track at one time sank, presumably as the result of pumping, in this 

 instance some distance away." 



Another example of this kind of collapse is furnished by the fol- 

 lowing account 11 of a cave-in which occurred at Neck City, Mo., 

 early in January of this year. 



"A hole opened under the mill pond and a great elm tree was swallowed 

 into the earth, in a natural cave so large that nothing remained visible 

 of the tree when workmen arrived on the scene at 7 a.m. 



"Some time between the night before and 7 o'clock yesterday morning 

 the bottom of the pond went it, presumably as a result of water having 

 been pumped from beneath, though no mine drifts exist beneath the 

 cave. 



"A tape line set down into the cave to a distance of 84 feet failed to 

 touch bottom, though the nature of the hour-glass cave prevented a 

 close scrutiny from the top." 



From the cases cited above it will be seen that the caving of the 

 roofs of natural caverns is a rather familiar phenomenon in the zinc 

 region of Missouri where there appears to be no question regarding 

 its dependence upon extensive pumping. In the light of these anal- 

 ogous cases it is hardly possible to ignore the suggestiveness of the 

 fact that the caving at Staunton followed five days after the oper- 

 ation of the ico-gallon pump at the ice plant began. That the 

 pumping and caving bear the relation of cause and effect seems to 

 the writer most probable. 



The lowering of the water level in the cavern which resulted from 

 the operation of the ice plant pump it is believed not only removed 

 the buoyant support of the water from the beds forming the roof, 

 but probably initiated strong downward currents through subsur- 

 face channels, thus carrying downward soft beds which had partially 

 filled the interstices of the limestone roof and others above it, 

 and which would otherwise have remained undisturbed. The in- 

 tensified movement of downward trending waters through the 

 marl resulting from the drainage of the limestone cavern below 

 these beds may have developed fair-sized cavities in the marl 



11 Joplin (Mo.) News Herald, Jan. 15, 1911. 



