man-made [Adjective] + cavern [Noun]

Strength Strength Dispersion
A:
3
CHISQ:
441.26
AWT:
39,862,476
TTEST:
1.72
G2:
34.38
FAWT:
1.36
MI:
7.22
LOGLOG:
11.44
JD:
0.25
MI3:
10.39
DICE:
0.95
RANGE: