▁and ▁adjacent ▁regions ▁ 1 0 , 0 0 0 ▁years ▁ago . ▁In ▁addition ▁to ▁the ▁project ile ▁points , ▁he ▁reported ▁finding ▁m amm oth ▁b ones . ▁A ▁later ▁investigation ▁of ▁the ▁ge ology ▁and ▁ge o arch ae ology ▁of ▁Ch init na ▁Bay ▁using ▁personal ▁notes , ▁photograph s , ▁and ▁directions ▁personally ▁supply ▁by ▁H ib ben ▁successfully ▁re located ▁the ▁locations ▁and ▁str ata ▁from ▁which ▁the ▁m amm oth ▁b ones , ▁Y uma - like ▁project ile ▁points , ▁and ▁project ile ▁point ▁" poss ibly ▁affili ated ▁with , ▁F ols om " ▁were ▁reported . ▁They ▁found ▁that ▁the ▁str ata ▁in ▁which ▁H ib ben ▁reported ▁finding ▁F ols om - ▁and ▁Y uma - like ▁project ile ▁points ▁and ▁m amm oth s ▁b ones ▁all ▁accum ulated ▁during ▁the ▁Late ▁Hol oc ene ▁in ▁" a ▁mud dy , ▁inter tid al ▁environment ". ▁As ▁result , ▁they ▁concluded ▁that ▁the ▁project ile ▁points ▁are ▁not ▁associated ▁with ▁any ▁Pale o - Ind ian ▁cult ures ▁and ▁the ▁identification ▁of ▁the ▁b ones ▁as ▁being ▁those ▁of ▁a ▁m amm oth ▁is ▁question able . ▁ ▁H ib ben ' s ▁research ▁on ▁later ▁cult ures ▁was ▁far ▁less ▁controvers ial . ▁While ▁a ▁gradu ate ▁student ▁he ▁exc av ated ▁and ▁reported ▁on ▁R iana ▁Ru in ▁in ▁the ▁Rio ▁Ch ama ▁d rain age . ▁His ▁Harvard ▁dis sert ation ▁was ▁based ▁on ▁extensive ▁field ▁studies ▁of