▁in ▁his ▁journal : ▁at ▁this ▁place ▁there ▁is ▁a ▁large ▁rock ▁of ▁ 4 0 0 ▁feet ▁high ▁w [ h ] ich ▁stands ▁immediately ▁in ▁the ▁gap ▁which ▁the ▁miss ouri ▁makes ▁on ▁it ' s ▁passage ▁from ▁the ▁mountains ; ▁it ▁is ▁ins ulated ▁from ▁the ▁neighbour ing ▁mountains ▁by ▁a ▁hand some ▁little ▁plain ▁which ▁surr ounds ▁it [ s ] ▁base ▁on ▁ 3 ▁sides ▁and ▁the ▁Missouri ▁was hes ▁it ' s ▁base ▁on ▁the ▁other , ▁leaving ▁it ▁on ▁the ▁L ard . ▁as ▁it ▁dec ends . ▁this ▁rock ▁I ▁called ▁the ▁tower . ▁it ▁may ▁be ▁asc ended ▁with ▁some ▁difficulty ▁nearly ▁to ▁its ▁sum mit , ▁and ▁from ▁it ▁there ▁is ▁a ▁most ▁ple asing ▁view ▁of ▁the ▁country ▁we ▁are ▁now ▁about ▁to ▁leave . ▁from ▁it ▁I ▁saw ▁this ▁evening ▁imm ence ▁her ds ▁of ▁buff alo e ▁in ▁the ▁pla ins ▁below . ▁ ▁Tower ▁Rock ▁was ▁visited ▁by ▁a ▁member ▁of ▁the ▁expedition ▁again ▁in ▁ 1 8 0 6 . ▁The ▁expedition ▁remained ▁a ▁single ▁party ▁after ▁depart ing ▁Fort ▁Cl ats op ▁on ▁the ▁Pacific ▁Ocean . ▁Having ▁reached ▁Tra vel er ' s ▁Rest ▁( near ▁present - day ▁L olo , ▁Mont ana ), ▁Lewis ▁and ▁Clark ▁decided ▁to ▁split ▁the ▁expedition ▁in ▁two . ▁Lewis ▁took ▁nine ▁men ▁and ▁proceeded ▁due ▁east , ▁int ending ▁to ▁find ▁the ▁Mar ias ▁River ▁again . ▁Clark , ▁mean while , ▁proceeded ▁south - s out heast