▁vic inity ▁of ▁E bb et ts ▁Pass ▁in ▁April ▁ 1 8 5 1 . ▁ ▁He ▁believed ▁the ▁pass ▁he ▁had ▁used ▁would ▁be ▁suitable ▁for ▁the ▁trans cont inental ▁rail road , ▁as ▁he ▁noted ▁little ▁snow ▁at ▁the ▁time . ▁He ▁later ▁survey ed ▁near ▁the ▁pass ▁for ▁a ▁possible ▁rail road ▁route , ▁but ▁found ▁it ▁un su itable . ▁He ▁intended ▁to ▁return ▁to ▁the ▁pass ▁itself ▁to ▁survey ▁it ▁for ▁a ▁road ▁but ▁was ▁killed ▁in ▁the ▁explos ion ▁of ▁the ▁steam bo at ▁Secretary ▁on ▁San ▁Pablo ▁Bay ▁in ▁ 1 8 5 4 ▁before ▁he ▁could ▁do ▁so . ▁While ▁the ▁pass ▁was ▁referred ▁to ▁by ▁his ▁name ▁earlier , ▁it ▁was ▁not ▁until ▁ 1 8 9 3 , ▁when ▁the ▁U . S . ▁Ge ological ▁Survey ▁survey ed ▁the ▁Mark lee ville ▁quad rangle , ▁that ▁the ▁pass ▁was ▁officially ▁named ▁after ▁him . ▁ ▁The ▁route ▁was ▁used ▁only ▁occasionally ▁until ▁silver ▁was ▁discovered ▁east ▁of ▁the ▁Sierra , ▁and ▁mer ch ants ▁in ▁Mur phys ▁had ▁a ▁road ▁constructed ▁to ▁Mark lee ville ▁to ▁more ▁easily ▁transport ▁supplies ▁over ▁the ▁pass ▁to ▁the ▁min ers . ▁This ▁became ▁a ▁to ll ▁road ▁in ▁ 1 8 6 2 . ▁From ▁Mark lee ville , ▁travel ▁further ▁east ward ▁was ▁taken ▁along ▁established ▁routes . ▁ ▁It ▁was ▁not ▁until ▁the ▁early ▁ 1 9 5 0 s ▁that ▁the ▁road ▁over ▁Mon itor ▁Pass ▁to ▁U . S .