Assertion: mammoth cave | /r/HasProperty | connected by survey
Facets:
value: to salts cave
type: LOCATION
value: in 1960
type: TEMPORAL
Source sentences:
text: Colossal Cave was connected by survey to Salts Cave in 1960 and in 1961 Colossal-Salts cave was similarly connected to Crystal-Unknown cave, creating a single cave system under much of Flint Ridge.