▁areas . ▁ ▁There ▁was ▁little ▁fault ▁movement ▁during ▁the ▁T ert i ary , ▁but ▁differential ▁comp action ▁created ▁a ▁simple ▁ant ic line ▁d rap ed ▁over ▁the ▁underlying ▁C ret ace ous ▁structure . ▁At ▁bas ement ▁level , ▁Sar ir ▁C ▁is ▁less ▁pron ounced ▁than ▁structures ▁to ▁the ▁south ▁and ▁north west , ▁which ▁have ▁poor ▁sand ▁development , ▁in ▁that ▁Late ▁C ret ace ous ▁sh ales ▁rest ▁on ▁bas ement ▁without ▁the ▁interven ing ▁sand stone ▁res er voir ▁of ▁the ▁Sar ir ▁field . ▁ ▁The ▁fall ▁from ▁the ▁Sar ir ▁C ▁cr est ▁to ▁the ▁southern ▁low ▁is ▁ 1 0 0 0 ▁m , ▁occurr ing ▁over ▁a ▁ 2 2   km ▁distance ▁equivalent ▁to ▁an ▁overall ▁dip ▁of ▁ 2 . 5 ° . ▁The ▁ste ep est ▁dip ▁recorded ▁is ▁ 4 . 5 ° . ▁The ▁tri angular - sh aped ▁cr est ▁has ▁an ▁east - west ▁base ▁roughly ▁ 4 0   km ▁long ▁and ▁a ▁north - s outh ▁per pend icular ▁of ▁ 2 0   km . ▁Vert ical ▁closure ▁is ▁ 1 2 2 ▁m . ▁Sar ir ▁North ▁and ▁L - 6 5 ▁are ▁on ▁a ▁north west ▁extension ▁of ▁the ▁n ortheast ▁side ▁of ▁the ▁C ▁structure . ▁L - 6 5 , ▁has ▁a ▁tri angular ▁shape ▁with ▁a ▁south west - tr ending ▁fl ank . ▁Struct ural ▁evolution ▁was ▁marked ▁by ▁vertical ▁t ect onic ▁movement ▁with ▁little