Individual #petroleum_geology__petroleumgeology  the branch of economic geology that deals with the occurrence and exploitation of oil and gas fields
  >part of:  economic_geology  the branch of geology that deals with economically valuable geological materials
     >part of:  geology  a science that deals with the history of the earth as recorded in rocks
        >part of:  earth_science__earthscience  any of the sciences that deal with the earth or its parts

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