▁gold ▁r ush . ▁Gu ests ▁were ▁able ▁to ▁clim b , ▁craw l , ▁sl ither , ▁slide , ▁and ▁rapp el ▁during ▁the ▁Lab yr inth ▁Tour . ▁ ▁References ▁ ▁http :// www . df g . ca . gov / bi oge od ata / c nd db / pdf s / in vert / A ra chn ids / B anks ula _ r ud ol phi _ etc . pdf ▁Thompson ▁$ ▁West , ▁ 1 8 8 1 , ▁History ▁of ▁Am ador ▁County ▁Led ger ▁Dis patch , ▁A pr . ▁ 3 0 , ▁ 1 9 7 4 , ▁Res cu ers ▁L ift ▁Man ▁From ▁Ca vern ▁S . ▁Far ley , ▁ 2 0 1 3 , ▁Manager ▁of ▁Black ▁Ch asm ▁ 1 9 9 9 - 2 0 1 6 ▁ ▁External ▁links ▁ ▁Ph otos ▁of ▁Black ▁Ch asm ▁hel ict ites ▁on ▁The ▁Virtual ▁C ave ▁" Black ▁Ch asm ▁C ave " ▁Y os em ite ▁Under ground ▁ ▁Category : C aves ▁of ▁California ▁Category : Land forms ▁of ▁Am ador ▁County , ▁California ▁Category : L im estone ▁c aves ▁Category : W ild ▁c aves ▁Category : National ▁Natural ▁Land marks ▁in ▁California ▁Category : T our ist ▁attra ctions ▁in ▁Am ador ▁County , ▁California <0x0A> </s> ▁The ▁Chinese ▁amb assador ▁in ▁Fre et own ▁is ▁the ▁official ▁representative ▁of ▁the ▁Government ▁in ▁Be ij ing ▁to ▁the ▁Government ▁of ▁Sierra ▁Le