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<br /> <br />Portland Limestone Quarries (M-1977-344) Permit Amendment-02 <br />Holcim US Inc, 3500 Highway 120, Florence, CO 81226 Revised pursuant to preliminary adequacy review November 20, 2023 <br />Phone (719) 288-1443 www.holcim.us 69 <br /> <br />2.4.2 Geologic Description <br />Limestone and sandstone will be extracted for use in cement production. The Fort Hays member and <br />translime layer are the limestone target deposits. The Codell member is the sandstone target deposit. <br />Sandstone will be extracted to a depth of 15 feet in open pits. Blue Hill and Fairport Chalky shales are <br />below the Codell as part of the Carlile formation. <br />Site geology is very similar to BCQ geology. The limestone formation lies relatively flat with the Codell <br />Sandstone quarry floor sloping about 14 feet per 1000 feet from NE to SW. The stratigraphic column (Fig <br />2.4.2-1) is similar to that of BCQ; however, the overburden is significantly less than that at BCQ. <br /> <br />Figure 2.4.2-1: Generalized stratigraphic section of the Bear Creek and Red Creek quarries <br />The following geology description was extracted from the 2002 BCQ amendment. <br />The Site is located in the Cañon City embayment created during a period of crustal deformation in late <br />Cretaceous and early Cenozoic time. Cretaceous marine sediments of the Florence -Cañon City area were <br />deposited in the sedimentary embayment that is now a structural basin with steeply dipping east and west <br />limbs and associated smaller fold structures. <br />Exposed strata at the Site include the Fort Hays Limestone and the more argillaceous Smoky Hill <br />Limestone, both members of the Niobrara Formation. Beneath the limestone lies the Codell Sandstone <br />Member of the Carlile Formation. Below the Codell Sandstone is the Blue Hill Shale Member of the Carlile <br />Formation (Figure 2.4.2-1).