▁Dev onian ▁times . ▁The ▁land ▁was ▁gla ci ated ▁during ▁the ▁Ill ino ian ▁gla ci ation , ▁but ▁was ▁free ▁of ▁permanent ▁ice ▁during ▁the ▁Wis con son ian ▁gla ci ation . ▁Long sh ore ▁curr ents ▁have ▁depos ited ▁beach ▁rid ges ▁since ▁then ▁for ▁ 6 , 0 0 0 ▁years . ▁ ▁Arch ae ological ▁district ▁The ▁ar che ological ▁district ▁compr ises ▁ 1 1 4 ▁ancient ▁beach ▁rid ges ▁which ▁formed ▁approximately ▁ 6 0 ▁years ▁apart . ▁ ▁They ▁provide ▁a ▁sequ ential ▁look ▁at ▁over ▁ 5 0 0 0 ▁years ▁of ▁habit ation . ▁The ▁area ▁in ▁the ▁National ▁Historic ▁Land mark ▁is ▁vast , ▁making ▁this ▁one ▁of ▁the ▁largest ▁N HL s ▁in ▁the ▁U . S ., ▁along ▁with ▁the ▁Ad ir ond ack ▁Park . ▁The ▁national ▁historic ▁land mark ▁was ▁designated ▁on ▁November ▁ 7 , ▁ 1 9 7 3 . ▁ ▁The ▁beach ▁rid ges ▁are ▁the ▁primary ▁reason ▁for ▁the ▁area ' s ▁pres ervation , ▁which ▁serves ▁to ▁saf egu ard ▁evidence ▁of ▁ 5 , 0 0 0 ▁years ▁of ▁occupation ▁by ▁the ▁In up iat ▁people , ▁and ▁more ▁than ▁ 9 , 0 0 0 ▁years ▁of ▁human ▁occupation . ▁Initial ▁investig ations ▁by ▁arch ae ologist ▁J . ▁Louis ▁G idd ings ▁in ▁the ▁late ▁ 1 9 4 0 s ▁found ▁cam ps ites ▁on ▁the ▁c ape ▁as ▁much ▁as ▁ 4 , 0 0 0 ▁years