1997-03-11_GENERAL DOCUMENTS - M1974004 (3)

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1 stone for the Colorado Front Range. The elevation of the property varies from 6250 feet on the east to 6970 feet on the west (see Figure 2). Bedrock in the quarry is overlain by relatively thin layers of residual overburden soils and weathered rock. The thickness of weathering across the property is variable. The bedrock in the quarry is a hard, relatively competent gneiss. The gneiss varies in color from tgreyish orange to dark grey and occurs across the quarry in a foliated anticlinal and synclinal pattern. The general orientation of the foliations is south-south east, and dips from 3549 degrees. Though no strength testing data is available, it is estimated that the unconfined compressive strength is in the range of 20,000 - 30,000 psi. The major discontinuities that were identified within the quarry consist of rock mass foliations, two faults, another suspected fault, numerous joints and several shear zones. Aerial photographs identified the near east-west trending fault that forms Jackson Gulch, and the near east-west trending fault that is evident on the east wall of the quarry. Another possible fault is exposed on the west wall of the quart'; however, the trace of feature was 1 not identifiable on the aerial photographs and may just be a fairly thick discontinuous shear 1 zone. Numerous joints and occasional shear zones are visible along the walls of the quarry. The joints are discontinuous over relatively short distances, varying in length from ' five feet to thirty feet. The shear zones are fairly well defined but are not traceable across the whole quarry. EXPLANATION OF ANALYSIS General 1 One of the most important aspects of rock slope analysis is the presentation of geologic data in such a manner that the results are easy to understand and interpret (Hoek & Bray, 1981). Following the completion of the geologic field mapping exercises, the data 5 I