264 
place in the St. Louis series of rocks than the sinkhole channels, but un- 
like them they are never inundated with floods of muddy water. Their 
exemption from overflows is due to the fact that the water-bearing chan- 
nels terminate as artesian springs soon after they pass beyond the sink- 
hole plateau and under the Paoli limestone and foothills of the Kaskaskia 
sandstone. The artesian springs are found east of the Crawford County 
caves, and, if this was not the case, the deep valley of Blue River as it 
runs south on the eastern boundary of the county, would terminate the 
westward trend of the underground drainage system of Harrison County. 
The entrance to the Wyandotte cave is 150 feet above Blue River; and 
none of the cave entrances of this class are below or on a level with the 
creeks of the surrounding country, as they are where sinkholes are com- 
mon. Where the Mitchell limestone is well protected by the overlying 
Paoli limestone and Kaskaskia strata, caves of any kind are rare, but 
when they do occur they are very interesting and should be thoroughly 
explored. 
In Missouri, it is said that when the coal measures strata rest immedi- 
ately on the St. Louis limestone, deep borings pass through cavernous 
openings,* which is explained by the theory that the St. Louis was for a 
time dry land and more or less tunneled before the coal strata were depos- 
ited. There is very little data to show that the Indiana St. Louis is cay- 
ernous for any great distance beyond the surface sinks. As the sinks are 
only common where the Paoli limestone has been removed it is reasonable 
to suppose they do not occur under other conditions, and this view is con- 
firmed by what has before been stated. Two deep wells have been drilled 
at Paoli and no caverns noted. At Orleans, in one out of three wells, the 
drill passed through a cave at one hundred feet below the surface; but the 
latter town is located on the cavernous limestone and the former is not. 
In comparing the caves of Indiana with those of Kentucky it is well 
to remember that in the immediate vicinity of Mammoth Cave, according 
to competent authority, the Kaskaskia group strata are wanting, and the 
capping stone of the St. Louis is one of the sandstone members of the 
lower coal measures. Some of the Kentucky caves are said to reach up 
to the sandstone, but if the same is true of the Indiana caves the fact has 
not been noted, nor is it probable that such will be found to be the case. 
*Keyes’ Mo. Geol Sur. XI, p. 252. 
+ Keyes’ Mo. Geol. Sur. IV, p. 73, 
