Activity for Hyden‭

Type	On...	Excerpt	Status	Date
Answer	—	A: Expanding occupied underground habitations safely? According to Wikipedia: "A cave-in is a collapse of a geologic formation, mine or structure which may occur during mining or tunneling. Geologic structures prone to spontaneous cave-ins include alvar, tsingy and other limestone formations" You can safely assume that you don't want to dig throug... (more)	—	about 9 years ago