</s> ▁Marine ▁Is ot ope ▁Stage ▁ 9 ▁( M IS ▁ 9 ) ▁is ▁a ▁Marine ▁Is ot ope ▁Stage ▁in ▁the ▁ge ological ▁record . ▁It ▁is ▁the ▁final ▁period ▁of ▁the ▁Lower ▁Pale ol ith ic , ▁and ▁last s ▁from ▁ 3 3 7 , 0 0 0 ▁to ▁ 3 0 0 , 0 0 0 ▁years ▁ago ▁according ▁to ▁Lis ieck i ▁and ▁Ray mo ' s ▁L R 0 4 ▁B enth ic ▁Stack , ▁which ▁has ▁been ▁adopted ▁by ▁the ▁Sub comm ission ▁on ▁Qu atern ary ▁Str at ig raph y ▁of ▁the ▁International ▁Commission ▁on ▁Str at ig raph y . ▁It ▁was ▁an ▁inter g la cial ▁( w arm ▁period ) ▁which ▁corresponds ▁to ▁the ▁Pur f le et ▁Inter g la cial ▁in ▁Britain , ▁and ▁falls ▁within ▁the ▁Pre - Ill ino ian ▁in ▁North ▁America . ▁Some ▁authorities ▁regard ▁it ▁as ▁corresponding ▁to ▁the ▁Hol stein ▁Inter g la cial ▁in ▁contin ental ▁Europe . ▁▁ ▁Europe ▁was ▁then ▁occupied ▁by ▁H omo ▁he idel berg ensis , ▁but ▁they ▁had ▁probably ▁retre ated ▁from ▁Britain ▁during ▁the ▁preceding ▁gla cial ▁period . ▁Pop ulations ▁returned ▁as ▁the ▁climate ▁war med ▁and ▁sea ▁levels ▁rose ▁around ▁ 3 3 0 , 0 0 0 ▁years ▁ago , ▁and ▁thousands ▁of ▁hand ▁axes ▁and ▁other ▁arte fact s ▁have ▁been ▁found ▁along ▁the ▁terra ces ▁of ▁the ▁Th ames ▁and ▁former ▁Sol ent ▁rivers . ▁In ▁Southern ▁England ,