Physical History of the Platte River in Nebraska

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2.4.3 Bed- mat6rial size gradation and spatial distribution Eschner et al. (1983) provide some information in the form of pre - development observations of the characteristics of the bed of the Platte River. This information characterizes the bed as predominantly consisting of sand, with some mention on a few occasions of finer particles (mud) as well as coarser particles (gravel). A number of observers characterized the bed of the Platte River as quicksand as typified by the following quotes provided by Eschner. In 1812, Stuart (Rollins, 1935) wrote that the bed of the Platte River, near present day Gosper- Phelps County border, was composed "of such quicksand that it was diff cult for our horse to get over, though the water was in no place more than two feet [0.6m] deep. " Farther downstream near Fort Kearney, Taylor (Williams, 1969) in 1850 noted, "The bottom is composed of a fine quicksand * * *. " Fremont (1845) described the southern channel of the South Platte River near the confluence with the Platte River as being "generally quicksands. " 2.4.4 Bedform size, pattern, and movement Some early descriptions of the bedforms, patterns, and movement of the bed of the Platte River were presented by Eschner et al. (1983). The account o the Lon Expedition James 1823 stated o the Platte "its T o f g p () f bed is composed almost exclusively of sand, forming innumerable bars, which are continually changing their positions and moving downward [downstream] * * *. " In their travels, members of the Long Expedition observed on the flood plain "extremely numerous natural elevations of earth, of some considerable degree of regularity * * * of a more or less oval outline " with lengths of about 30 m and heights of 0.6 to 1.5 m. These elevations were presumed to have been former sandbars, "Their existence is doubtless due to the action of water. " Other observations presented by Eschner described the bed of the Platte River near Fort Kearney. In 1849, Pritchard (Mattes, 1969) noted the composition and character of the bed: "The bed of the river is composed of sand, and this is all the time shifting its position and fresh deposits are constantly being made. " Evans (Mattes, 1969) wrote in 1849 that the Platte was a wide sheet of water "running over a vast level bed of sand and mica * * * continually changing into short offsets like the shingled roof of a house Karlinger et al. (1983) presented additional information regarding macroforms. They describe Platte River macroforms, referring to Crowley (1981) as, "large bed forms proportional to the channel dimensions. " They go on to present more detailed information: I 20 1