▁la vas ▁of ▁the ▁A uc an qu il cha ▁platform . ▁Cer ro ▁Pol an ' s ▁( 3 . 5 – 3 ▁my a ) ▁eastern ▁side ▁is ▁deeply ▁disse cted , ▁and ▁the ▁exposed ▁materials ▁are ▁heavily ▁alter ed ▁in ▁the ▁deeper ▁sections . ▁L ava ▁fields ▁to ▁Pol an ' s ▁west ▁and ▁south west ▁( 2 . 6 ▁my a ▁on ▁one ▁western ▁field ) ▁are ▁associated ▁with ▁it . ▁La ▁L una ▁( 2 . 9 7 – 2 . 5 7 ) ▁lies ▁just ▁east ▁of ▁Pol an ; ▁these ▁two ▁vol cano es ▁were ▁probably ▁one ▁vol cano ▁in ▁the ▁past . ▁La ▁L una ▁has ▁a ▁la va ▁d ome ▁surrounded ▁by ▁a ▁gla ci ated ▁but ▁un alter ed ▁la va ▁table . ▁Cer ro ▁T res ▁Mon os ▁( 3 . 4 – 2 . 7 8 ▁my a ) ▁forms ▁a ▁north bound ▁ ▁long ▁r idge ▁with ▁at ▁least ▁six ▁v ents . ▁H ydro ther mal ▁alter ation ▁has ▁affected ▁some ▁la vas ▁and ▁py ro cl ast ics ▁from ▁T res ▁Mon os , ▁and ▁the ▁western ▁side ▁has ▁later al ▁and ▁terminal ▁mor aines . ▁The ▁A uc an qu il cha ▁platform ▁( 3 . 6 – 2 . 7 ▁my a ) ▁s its ▁under ne ath ▁the ▁main ▁A uc an qu il cha ▁vol cano , ▁and ▁its ▁la va ▁mostly ▁flow ed ▁north . ▁Its ▁southern ▁side ▁is ▁a ▁ ▁table ▁with