Laserfiche WebLink
A notable geologic feature near the site is the Golden fault, which runs <br />approximately north-south and forms the eastern margin of the north-northwest <br />trending hogback immediately east of the quarry property. A mapped reverse <br />fault is located within the quarry property and constitutes the boundary between <br />the metamorphosed Precambrian bedrock (to the west) and the Pennsylvanian <br />sedimentary rocks (to the east) (Smith, 1964; Scott, 1972). The quarry property <br />straddles this boundary, with the majority of the processing plant and the entire <br />asphalt plant located east of the fault (Figure 3). The bedrock material east of <br />the fault is dominantly composed of upturned sandstones and shales of the <br />Fountain Formation (Scott, 1972). West of this fault, the material is typically <br />mapped as migmatitic, quartzo-felspathic gneiss with intrusions of granitic <br />pegmatite veins (Scott, 1972). In addition, mapped within the main pit of the <br />quarry are two approximately east-west trending faults that have been exposed <br />as the quarry has been excavated. One of the faults is located in Jackson <br />Gulch, and has been informally named the Jackson Gulch fault. The second <br />fault is unnamed and is exposed in the east wall and west wall of the main pit <br />and ranges between 20 to 50 feet wide. This fault was also mapped by Gable, <br />and strikes 260-270°, dips 80-85° to the south, and will continue to be exposed <br />as the pit deepens. <br />4.0 Data Collection <br />For the current (2004) geological structural review of the quarry, L&A geologists <br />and engineers have collected approximately 200 discontinuity measurements to <br />add to the existing structural geology database. Data collected for this <br />evaluation includes the measurement of strike and dip of the geologic <br />discontinuities from the exposed rock faces in the quarry, descriptions of the <br />character of the discontinuities, and data collection point descriptions relative to <br />general wall locations. Measurements were taken from the faces of advancing <br />benches in both the southern expansion area, and on the middle level of the <br />quarry. Due to minimal mining activity in the main pit and to the lack of <br />significant new rock exposures from the time of the 2002 report, no additional <br />data points were collected from the main pit for this study. Figure 2 indicates the <br />4- <br />