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k 3-4 stresses greater than the tensile strength of the soil can result in cracking of the fill. Where irregularities exist in the foundation such as between Station 5400 and 7+00 (see Figure 3) differential settlment of the fill is likely. The magnitude of potential differential settle- ment in the alluvial soil could not be quantified due to the inability to obtain and test undisturbed samples. The coarse nature of the material should, however, preclude large differential settlement. This is supported by the lack of any observed cracks in samples taken in the fill. However, sufficient differential settlement could occur to cause small micro -cracks capable of increasing vertical permeabilities in the embankment fill. The potential exists for larger' cracks, especially considering the high grout takes in the base of the fill. Such cracking was, however, not observed. The bedrock beneath the alluvial soils consists of siltstone and sandstone of the Creede Formation. The upper 7 to 17 feet is mostly severely weathered and highly fractured. Frequent large grout takes in the upper portion (see Figure 3) indicate it has a number of open frac- Below the weathered and fractured zone the bedrock is relatively unweathered and unfractured providing an intact, tight foundation. It Is possible that a fault exists In the bedrock beneath the central portion the east side of the dam. Although the fault was not Identified In any borings, surface geologic features indicate the potential for such a fault. The differential flow condition in downstream areas at adjacent locations further support this potential. The fault is not, V" tures. These fractures are considered to be developed primarily from the weathering these flows natural of rocks, although seepage could feasibly have increased the aperture of the fractures and their perme- ability. Differential settlement in the rock is unlikely, unless the rock has been deteriorated by seepage. No evidence of significant deterioration was noted in cores obtained in the weathered rock. Below the weathered and fractured zone the bedrock is relatively unweathered and unfractured providing an intact, tight foundation. It Is possible that a fault exists In the bedrock beneath the central portion the east side of the dam. Although the fault was not Identified In any borings, surface geologic features indicate the potential for such a fault. The differential flow condition in downstream areas at adjacent locations further support this potential. The fault is not, V"