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Show One of the results 25 of the river exploration has been to determine the absolute limit of navigation , a question not settled by the ( ex- ex ) ploration of Ives , as a steamer ascended the river to a point ( Callville a short distance beyond the uppermost point reached by him in his boat . This limit is the foot of the Grand Canyon , or near the crossing oft1871 . It is certain that at no stage of water could steamers reach this point unless the channel . shall be improved by the removal of sunken ( rocks -rocks rocks ) ; but no unsurmountable obstacles of this nature exist . The ( farthest fartbest ) practical head of ( im- im ) proved navigation must remain permanently at the foot of Grand Canyon . ( Italics not in text . ) The exploration of the Colorado River may now be considered complete . Its course has been traced from its mouth ( to io ) the junction of the Green and Grand , and the positions of incoming tributaries noted . The greater ( part paTt ) of the basins of theGrand and Green have undergone quite thorough exploration and survey during the past ten years as well as much of the Great Colorado Plateau that borders the river in the vicinity of the great ( 1 ' ) canyons . 1 ( Report upon United States Geological Survey West of the One Hundredth Meridian , Capt . Geo . M . Wheeler , Washington , Government Printing Office , 1889 , Compl . Exhibit 73 . ) ( ( Freeman Freenian ) , Compl . Exhibit ( SI 81 ) , Chapter ( XI X1 ) , p . 252 ; ) ( Dcllenbangh , Compl . Exhibit 13 , Chapter XII , 294 ) p . . |
