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Geotechnical Stability Exhibit ��� <br /> Engineering Evaluation of Highwall Design for the South Quarry of the Morrison Quarry <br /> 2 Geologic Conditions <br /> General Geology <br /> The Morrison Quarry lies along the Colorado Front Range of the southern Rocky Mountains as <br /> part of the Colorado Physiographic Province. The front range forms the margin between the <br /> southern Rocky Mountains and the High Plains to the east. The region serves as the boundary <br /> between two major geological provinces of North America, the American Cordillera to the west, <br /> and the North American Craton to the east. <br /> The Front Range consists of metamorphic and crystalline Precambrian Age bedrock, that was <br /> accreted during the Proterozoic eon. The oldest rocks in the province are metasedimentary and <br /> metavolcanic, and were intruded by younger granitic units dating to roughly 1.7 to 1.4 Ga. The <br /> Precambrian units include north to northeast trending Proterozoic shear zones, several of which <br /> were reactivated during the Laramide Orogeny. In many areas along the Front Range, the <br /> Proterozoic crystalline bedrock is overlain by Paleozoic and Mesozoic sedimentary rocks. <br /> Deposited in shallow inland marine and deltaic conditions, they were uplifted along with the <br /> Precambrian formations during the Laramide Orogeny. Refer to Figure 3, below, for the <br /> Geologic Map of the area. <br /> May 2023 1 6 <br />