ced ▁and ▁the ▁de position ▁of ▁the ▁low - grade , ▁met ased iment ary ▁Ind a ▁Ad ▁sequence ▁occurred , ▁followed ▁by ▁more ▁de formation ▁and ▁regional ▁he ating . ▁▁ ▁The ▁sequence ▁of ▁events ▁in ▁Som al il and ▁in ▁the ▁Pro ter oz o ic ▁correl ates ▁with ▁the ▁Arab ian - N ub ian ▁Sh ield ▁to ▁the ▁north , ▁which ▁experienced ▁ igne ous ▁activity ▁related ▁to ▁sub du ction ▁and ▁witness ed ▁the ▁formation ▁of ▁marg inal ▁bas ins ▁and ▁island ▁ar cs . ▁ ▁Mes oz o ic ▁( 2 5 1 - 6 6 ▁million ▁years ▁ago ) ▁In ▁the ▁Early ▁Jur ass ic , ▁the ▁super cont inent ▁G ond w ana , ▁which ▁included ▁Africa , ▁began ▁to ▁break ▁apart . ▁The ▁marine ▁trans gression ▁of ▁the ▁T eth ys ▁Ocean ▁flo oded ▁large ▁parts ▁of ▁East ▁Africa ▁and ▁Arab ia ▁and ▁new ▁sed iment ary ▁rock ▁units ▁were ▁depos ited . ▁In ▁the ▁west ▁of ▁Som al il and , ▁the ▁C ret ace ous ▁at ▁the ▁end ▁of ▁the ▁Mes oz o ic ▁brought ▁cr ust al ▁up war ping , ▁which ▁is ▁preserved ▁in ▁the ▁Yes om ma ▁Sand stone . ▁▁ ▁Bas ins ▁formed ▁due ▁to ▁the ▁movements ▁of ▁India , ▁Mad agas car ▁and ▁East ▁Africa ▁and ▁the ▁opening ▁of ▁the ▁Indian ▁Ocean . ▁The ▁Late ▁Jur ass ic ▁through ▁the ▁C ret ace ous ▁left ▁mar l ▁and ▁am mon ite ▁foss ils , ▁from ▁an ▁open