Geology of Johnson County. 411 
The following diagram will illustrate this description :— 
Pothole number four: This is the largest and deepest of any yet 
Pothole No. 3. aa, coal seam. 
observed, having a depth of slightly upward of fourteen feet. 
Although much of the rock in which this pothole was formed has 
aa, coal seam; the lower part shaly and containing fish teeth; bb, ‘ash-colored 
and greenish underclay ; ce, coarse sandstone in curved lamine, 
been removed by quarrying, yet enough of the excavation itself 
remains to demonstrate the fact that it was formed by the enlarge- 
