utes ▁the ▁Earth . ▁The ▁field ▁of ▁ge ology ▁en comp ass es ▁the ▁study ▁of ▁the ▁composition , ▁structure , ▁physical ▁properties , ▁dynamics , ▁and ▁history ▁of ▁Earth ▁materials , ▁and ▁the ▁processes ▁by ▁which ▁they ▁are ▁formed , ▁moved , ▁and ▁changed . ▁The ▁field ▁is ▁a ▁major ▁academic ▁discipline , ▁and ▁is ▁also ▁important ▁for ▁min eral ▁and ▁hydro car bon ▁extra ction , ▁knowledge ▁about ▁and ▁mit ig ation ▁of ▁natural ▁ha z ards , ▁some ▁Ge ote chn ical ▁engineering ▁fields , ▁and ▁understanding ▁past ▁clim ates ▁and ▁environments . ▁ ▁Ge ological ▁evolution ▁ ▁The ▁ge ology ▁of ▁an ▁area ▁evol ves ▁through ▁time ▁as ▁rock ▁units ▁are ▁depos ited ▁and ▁inserted ▁and ▁de form ational ▁processes ▁change ▁their ▁shapes ▁and ▁locations . ▁ ▁Rock ▁units ▁are ▁first ▁emp la ced ▁either ▁by ▁de position ▁onto ▁the ▁surface ▁or ▁intr ude ▁into ▁the ▁over lying ▁rock . ▁De position ▁can ▁occur ▁when ▁sed iments ▁sett le ▁onto ▁the ▁surface ▁of ▁the ▁Earth ▁and ▁later ▁l ith ify ▁into ▁sed iment ary ▁rock , ▁or ▁when ▁as ▁vol can ic ▁material ▁such ▁as ▁vol can ic ▁ash ▁or ▁la va ▁flows , ▁blank et ▁the ▁surface . ▁Ig ne ous ▁intr us ions ▁such ▁as ▁b athol ith s , ▁la cc ol ith s , ▁d ikes , ▁and ▁s ills , ▁push ▁up wards ▁into ▁the ▁over lying ▁rock , ▁and ▁cry st all ize ▁as ▁they ▁intr ude . ▁ ▁After ▁the ▁initial ▁sequence