▁based ▁on ▁whether ▁they ▁f ished ▁marine ▁life ▁or ▁h unted ▁in ▁loose ▁snow . ▁From ▁this , ▁he ▁the or ized ▁that ▁two ▁cult ures ▁developed ▁in ▁the ▁Ar ctic , ▁one ▁that ▁was ▁land - locked ▁and ▁another ▁that ▁was ▁coast al . ▁In ▁ 1 9 1 4 , ▁while ▁a ▁fellow ▁of ▁The ▁American - Sc and in av ian ▁Foundation , ▁he ▁studied ▁at ▁Columbia ▁University . ▁ ▁Career ▁In ▁ 1 9 1 9 , ▁H att ▁was ▁h ired ▁to ▁be ▁the ▁inspect or ▁at ▁the ▁National ▁Museum ▁of ▁Den mark ' s ▁Eth n ography ▁Department , ▁and ▁he ▁remained ▁at ▁this ▁civil ▁service ▁post ▁for ▁ten ▁years . ▁This ▁position ▁gave ▁him ▁the ▁opportunity ▁to ▁particip ate ▁in ▁arch ae ological ▁research ▁at ▁numerous ▁settlement ▁sites ▁in ▁central ▁and ▁western ▁J ut land . ▁Here , ▁he ▁was ▁among ▁the ▁first ▁in ▁Dan ish ▁arch ae ology ▁who ▁recognized ▁that ▁the ▁ancient ▁houses ▁were ▁not ▁destroyed ▁by ▁fire ▁which ▁he ▁recognized ▁after ▁exc av ating ▁the ▁areas ▁between ▁the ▁houses , ▁and ▁not ▁just ▁the ▁individual ▁house ▁sites , ▁which ▁was ▁previously ▁the ▁custom . ▁In ▁ 1 9 2 2 - 2 3 , ▁he ▁led ▁an ▁arch ae ological ▁expedition ▁to ▁the ▁Virgin ▁Islands ▁and ▁Santo ▁Dom ingo ▁in ▁the ▁Car ib bean . ▁From ▁ 1 9 2 3 , ▁H att ▁was ▁a ▁lect urer ▁in ▁cultural ▁ge ography ▁at ▁the ▁University ▁of ▁C open hagen , ▁becoming ▁a ▁full