▁of ▁the ▁landscape ▁might ▁vary ▁in ▁rit ual ▁significance ▁( hill top s ▁very ▁likely ▁being ▁associated ▁with ▁rain - making ▁r ites ) ▁– ▁may ▁be ▁factors ▁more ▁germ ane ▁to ▁the ▁questions ▁of ▁vari ability ▁in ▁the ▁rock ▁art ▁of ▁the ▁region ▁than ▁appe als ▁primarily ▁to ▁eth nic ity ▁and ▁cultural ▁difference . ▁ ▁F ormal ▁protection ▁D rie k ops ▁E il and ▁was ▁declared ▁a ▁National ▁Monument ▁in ▁ 1 9 4 4 . ▁It ▁automatically ▁became ▁a ▁Gra de ▁ 2 ▁Provin cial ▁Heritage ▁Site ▁when ▁the ▁National ▁Heritage ▁Resources ▁Act ▁( Act ▁ 2 5 ▁of ▁ 1 9 9 9 ) ▁was ▁prom ul g ated . ▁ ▁Det r iment al ▁impact s ▁A ▁we ir ▁was ▁built ▁across ▁the ▁upper ▁part ▁of ▁the ▁site ▁in ▁ 1 9 4 2 , ▁causing ▁permanent ▁sub mer gence ▁of ▁an ▁estimated ▁ 1 5 0 ▁eng rav ings ▁above ▁the ▁we ir , ▁and ▁changing ▁flo od ▁dynamics ▁and ▁s ilt ▁accum ulation ▁patterns . ▁The ▁latter ▁triggered , ▁in ▁turn , ▁increased ▁re ed ▁growth ▁and ▁an ▁invasion ▁of ▁eu cal y pt us ▁sap lings ▁across ▁s ilt ed ▁parts ▁of ▁the ▁site ▁- ▁helped ▁along ▁by ▁increased ▁flow ▁after ▁a ▁canal ▁was ▁built ▁from ▁the ▁Orange ▁River ▁to ▁the ▁K alf onte in ▁Dam ▁( on ▁the ▁R iet ▁River ) ▁in ▁ 1 9 8 7 . ▁ ▁D rie k ops ▁E il and ▁in ▁art , ▁literature ▁and ▁film