Individual #petrology  the branch of geology that studies rocks: their origin and formation and composition
  >part of:  #geomorphology__morphology  the branch of geology that studies the characteristics and configuration and evolution of rocks and land forms
     >part of:  #geophysics__geophysical_science  geology that uses physical principles to study properties of the earth
        >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

No statement uses or specializes #petrology; click here to add one.