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<br />i <br />'., <br /> <br />'1' ...1,...,.., <br />\.!. ~ ~ \j. <br /> <br />ANALYSIS OF SIGNIFICANCE <br /> <br />EVALUATION CRITERIA <br /> <br />The boundary study criteria contained in the National Park Service Management Policies <br />(Chapter 2:8), states that 'The National Park Service will conduct studies of potential <br />boundary adjustments and may recommend boundary revisions to include significant <br />resources or opportunities for public enjoyment related to the purposes of the park; <br />address operational and management issues such as access and boundary identification <br />by topographic or other natural features or roads; and protect park resources critical to <br />fulfilling the park's purposes. The latter two criteria are not applicable to this study since <br />there was not a situation where there was a related issue. Primary justification for <br />expanding the boundary woald be to include significant resources and opportunities for <br />public enjoyment related to the purpose of the park.' <br /> <br />The 'purpose' of BlCA is stated in Presidential Proclamation No. 2033 dated March 2, <br />1933, which established the area. This document cites the purpose as being ....for the <br />preservation of the spectacular gorges and additional features of scenic, scientific, and <br />educational interest. <br /> <br />Those resources and opportunities within the study area determined to be significant in <br />relation to the purpose of the monument and of scientific and public interest follow. <br /> <br />SIGNIFICANT FEATURES <br /> <br />Geological Values <br /> <br />Renowned geologist, Wallace R. Hansen, has thoroughly studied the lower gorge area <br />and offers the following comments on its character. 'This reach of the canyon shares <br />many of the attributes of the monument, but in many ways, it is much different, particularly <br />with respect to the sedimentary cap rocks, which are poorly exposed in the monument <br />but are exceptionally well exposed downstream. These rocks, Jurassic and Cretaceous <br />in age, add a scenic and geologic aspect to that part of the canyon that is essentially <br />nonexistent in the monument. <br /> <br />'Both sections ofthe canyon, however, are integral parts of one huge physiographic entity <br />and they complement one another rather than compete. Neither section alone tells the <br />whole story. The whole Black Canyon is truly a world-class gorge, among the best that <br />America has to offer the visiting public, and the geologic story is incomplete without <br />reference to its downstream section. <br /> <br />'One of the most significant geologic attributes of the downstream section of the canyon <br />is the extent and display of large-scale faulting and the relationship of faulting to the <br />geologic history of the Gunnison uplift and the canyon itself. This concept may at first <br /> <br />15 <br />