OCR Text |
Show 148 this stretch twice , testified to always looking each rapid over before running it the second time , , since there is often a rearrangement of the boulders and rocks in the rapids . No one person had made a ( suffi- suffi ) cient number of trips or observations in Cataract Canyon to be in a position to testify conclusively that changes of great magnitude occur in the cataract section . Glen Canyon Section ( Exceptions 60 , 62 , 63 , 64 , 65 ) . ( -The The ) most exact information relative to the shifting character of the bed of Colorado River in the Glen Canyon section , except at those sections where gravel bars or bedrock occur , is contained on Plate ( II-A IIA ) and Plate ( III-A IIIA ) of Compl . Exhibit 82A . These cross sections are based on actual ( obser- obser ) vations of depth made by engineers of the U . S . ( Geo- Geo ) logical Survey in connection with their determination of daily discharge . They show conclusively that scour and fill amounting to as much as 17 feet has occurred in the river bed and that the average scour and fill across the entire cross section has amounted to 12 feet . Plate ( III-A IIIA ) especially shows the rapidity withwhich the river has scoured as shown by a change of 5 feet in two days . Col . Dent , Loper , Rust , Stanton , and others have also described the sand waves on the Colorado River especially below the mouth of the San Juan River ( M . . R . , p . . 141 , Exception 59 ) . Their ( descrip- descrip ) tion by Stanton following observation made below |