. ▁Professor ▁Thomas ▁Mac B ride ▁of ▁the ▁University ▁of ▁Iowa ▁published ▁the ▁first ▁description ▁of ▁the ▁site ▁in ▁ 1 8 9 3 . ▁There ▁were ▁believed ▁to ▁be ▁large ▁depos its ▁of ▁C ret ace ous ▁cy c ad ▁foss ils . ▁( C yc ads ▁are ▁plants ▁res emb ling ▁f ern s , ▁although ▁not ▁related ▁to ▁them . ▁The ▁ones ▁at ▁this ▁site ▁were ▁tree - s ized .) ▁ ▁In ▁ 1 9 2 0 , ▁Y ale ▁pale ob ot an ist ▁George ▁Re ber ▁Wiel and ▁obtained ▁the ▁foss il ▁cy c ad - rich ▁land ▁under ▁the ▁Hom est ead ▁Act ▁" in ▁order ▁that ▁the ▁cy c ads ▁might ▁not ▁fall ▁into ▁un worth y ▁hands ". ▁Two ▁years ▁later ▁he ▁offered ▁to ▁return ▁the ▁land ▁to ▁the ▁federal ▁government ▁if ▁a ▁national ▁monument ▁could ▁be ▁established ▁to ▁protect ▁the ▁foss ils . ▁ ▁Est ab lish ment ▁of ▁the ▁national ▁monument ▁The ▁original ▁monument ▁was ▁established ▁on ▁October ▁ 2 1 , ▁ 1 9 2 2 , ▁by ▁pro clam ation ▁of ▁President ▁Warren ▁G . ▁Hard ing . ▁It ▁en comp ass ed ▁ 1 . 3   km ² ▁( 3 2 0 ▁acres ) ▁at ▁the ▁south ▁entrance ▁to ▁the ▁Black ▁Hills ▁of ▁South ▁Dak ota . ▁It ▁was ▁said ▁to ▁be ▁" pro bably ▁one ▁of ▁the ▁most ▁interesting ▁foss il - plant ▁b eds ▁yet ▁discovered , ▁with ▁the ▁most ▁perfectly ▁preserved ▁spec im ens ,