Sum of sinkhole area for sinkholes with minimum depth of 3m
based on Sutherland's digital analysis.
Click on cell for quadname and cumulative area (100*km2).
Based on 3x3 cells over a topo quad.
TN topo is about 60 sq miles, so each cell is about 6.7 sq miles
Each sinkhole is represented as a point (centroid) in determining
the containing cell.