erc:
who: Geological Survey (U.S.)
what: Seven Heart Gap Northwest Quadrangle
when: 1973
where: https://texashistory.unt.edu/ark:/67531/metapth107590/
erc-support:
who: University of North Texas Libraries
what: Permanent: Stable Content:
when: 20081203
where: https://texashistory.unt.edu/ark:/67531/