https://cdn.earthdata.nasa.gov/conduit/upload/5182/KeywordsCommunityGuide_Baseline_v1_SIGNED_FINAL.pdf 23.7 2026-04-15T10:53:30.610Z https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/sciencekeywords/d4ac49a1-9ba5-4a90-a033-2ef317028352 AGE DETERMINATIONS Date=2017-03-10 User Id=tstevens Entity=Definition Operation=UPDATE Field=reference System Note=update Definition New Value=USGS Date=2017-03-10 User Id=tstevens Entity=Definition Operation=UPDATE Field=text System Note=update Definition Old Value=Pertaining to the methods, results, and studies involved in determining the age of rock units found in and on the Earth's crust. New Value=Pertaining to the methods, results, and studies involved in determining the age of rock units found in and on the Earth's crust. Pertaining to the methods, results, and studies involved in determining the age of rock units found in and on the Earth's crust. 2017-03-10 10:57:05.0