▁The ▁p ink ▁appearance ▁over ▁the ▁mid ▁and ▁upper ▁bas ins ▁( near ▁the ▁colour ▁of ▁a ▁rain bow ▁tr out ) ▁was ▁due ▁to ▁ant im ony ▁and ▁ar sen ic ▁sul f ides , ▁although ▁the ▁P ink ▁Terra ce ▁also ▁contained ▁gold ▁in ▁ore - grade ▁concentr ations . ▁ ▁Form ation ▁The ▁P ink ▁and ▁White ▁Terra ces ▁were ▁previously ▁thought ▁to ▁be ▁about ▁ 1 , 0 0 0 ▁years ▁old . ▁The ▁hydro ther mal ▁system ▁which ▁power ed ▁them ▁may ▁be ▁up ▁to ▁ 7 , 0 0 0 ▁years ▁old . ▁The ▁sil ica ▁precip itation ▁formed ▁many ▁po ols ▁and ▁steps ▁over ▁time . ▁P reci p itation ▁occurred ▁by ▁two ▁methods . ▁The ▁asc ending ▁foundation ▁over ▁time ▁formed ▁a ▁lip ▁which ▁would ▁trap ▁the ▁desc ending ▁flow ▁and ▁become ▁level ▁again . ▁This ▁process ▁formed ▁attract ive ▁sw imming ▁places , ▁both ▁for ▁the ▁shape ▁and ▁for ▁the ▁warm ▁water . ▁When ▁the ▁thermal ▁layers ▁s loped ▁in ▁the ▁other ▁direction ▁away ▁from ▁the ▁g ey ser , ▁then ▁sil ica ▁steps ▁formed ▁on ▁the ▁surface . ▁Both ▁types ▁of ▁formation ▁grew ▁as ▁sil ica - lad en ▁water ▁cas c aded ▁over ▁them , ▁and ▁the ▁water ▁also ▁en hanced ▁the ▁spect acle . ▁Ge ologist ▁Ferdinand ▁von ▁Hoch st etter ▁wrote ▁after ▁his ▁visit ▁in ▁ 1 8 5 9 ▁that ▁" d ou bt less ▁thousands ▁of ▁years ▁were ▁required " ▁for ▁their ▁formation . ▁ ▁The ▁White ▁Terra