Assertion: aquifer | /r/HasProperty | conducted by the u.s. geological survey
Facets:
value: recently
type: TEMPORAL
Source sentences:
text: The potentiometric surfaces and altitudes of the tops of the Minnelusa and Madison aquifers were contoured at the same scale (1:100,000) as studies of the aquifers recently conducted by the U.S. Geological Survey (USGS) in the Black Hills area within South Dakota (Carter and Redden, 1999a, 1999b; Strobel and others, 2000a, 2000b).