OCR Text |
Show 89 sections where one or the other predominates . . On the Green River above the ( mouth inouth ) of San Rafaelj the bars are gravel ( almost alniost ) without exception . . ( Be- Be ) low the ( moutli mouth ) of the San Rafael the river bed is in sand and silt without exception . On the Colorado River gravel bars occur in the short stretch ( bet-ween between ) Castle Creek and Nigger Bill Creek and frequently at the mouths of creeks , drains , and washes in the ( Glen G-leu Gleu ) Canyon section . ( Elsewhere ElseiNhere ) , excluding the Cataract Canyon section and the section where ( bed- bed ) rock is near the surface , the bed of the river is sand and sediment , As Howard points out ( Vol . 21 , page 3811 ) , there is a continuous change taking place in the beds of rivers having sandy beds . In the cataract section of the ( Colorado ColoTado ) velocities are apparently such that the only sediment in the river bed consists of large boulders . ( On Ou ) the ( San Sail ) ( Juan J-uan Juan ) River ( Exhibit 56 ) , where the gradient of the river is high , that is , exceeds 5 feet to the mile , at the mouth of tributaries and washes , the ( debris 6bris ) consists chiefly of heavy gravel and boulders . Elsewhere sand is prevalent ; some ( of oi ) ( which 'which which ) is in the form of exposed ( bars baTs ) which may rise above the water in islands or ( submerged subuierged ) from a fraction of an inch to greater depths . The profile prepared by ( Miser Niser ) ( Plate ( XKII XXII ) of Exhibit 56 ) shows that well over 90 per cent of the bed of the San Juan is in sand . |