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<br />i-" <br />Co\) <br />Ul <br />c:.;1 <br /> <br />CHAPTER II <br /> <br />PREVIOUS INVESTIGATIONS <br /> <br />Grand Valley and geologically similar regions in the Upper <br /> <br />Colorado River Basin have been studied for various purposes for <br /> <br />many years. Investigations have included the geomorphic de scrip- <br /> <br />tion of pediments, runoff and sediment yield from hillslopes, hill- <br /> <br />slope morphology, land use, and salinity. <br /> <br />Studies of pediments go back to Gilberts' (1877) study of the <br /> <br />Henry Mountains of Utah. He attributed pediment origin to lateral <br /> <br />swinging of the streams issuing from the mountains. Rich's (1935) <br /> <br />investigations along the Book Cliffs led to the conclusion that <br /> <br />weathering and sheetwash are the principal pediment-forming agents, <br /> <br />with stream capture causing the multiple surface levels. Hunt, et al. <br /> <br />(1953), after studying the Henry Mountains, concluded that pediments <br /> <br />are developed primarily by sheetwash and rill wash, and he also <br /> <br />elaborated on Rich's stream capture hypothesis. Godfrey (1968) and <br /> <br />Carter (1980) expanded on Hunt's conclusions and both observed that <br /> <br />former interstream divides are the sites most vulnerable to dissection <br /> <br />because the protective gravel cap is thinnest there. Carter (1980), <br /> <br />after studying pediments south of Price, Utah, proposed sudden <br /> <br />lowerings of the master stream's base level in order to account for <br /> <br />multiple surfaces. Sinnock (1981) investigated pediment genesis at <br /> <br />the base of Grand Mesa south of Grand Junction, Colorado. He con- <br /> <br />cluded that the gravel deposits mantling the Mancos Shale were <br /> <br />d <br />