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Martin Marietta Materials <br />Spec -Agg 2013 Annual Report <br />3.0 LOCATION AND GEOLOGIC SETTING <br />The Spec -Agg Quarry is located to the north of Interstate 70 near Jackson Gulch on the east flank of the <br />Rocky Mountain Front Range, approximately 3 miles south of downtown Golden, Colorado (Figure 1). The <br />natural topography of the property increases significantly in elevation to the west, with elevations within the <br />planned mining pit area that vary from approximately EL 6,425 ft along the mine's eastern boundary to EL <br />7,110 ft on the western boundary (Figures 1 and 2). <br />This region of the Rocky Mountain Front Range was deformed during the Laramide orogeny in the late <br />Cretaceous and early Tertiary periods. The gneissic bedrock within the quarry is believed to have <br />undergone two to three episodes of deformation during Precambrian time (Gable, 1968). During this time, <br />the bedrock material was intruded by several distinct igneous bodies and dikes. The gneisses are mapped <br />as a series of folds, which are oriented roughly east -west and have been broken and displaced by faults <br />believed to range in age from Precambrian to Tertiary. <br />The bedrock within the mined portions of the quarry is mapped as migmatitic quartzo- felspathic gneiss with <br />intrusions of granitic pegmatite veins (Scott, 1972). The granitic gneiss found in the quarry is generally hard <br />and relatively competent. The gneiss varies in color from grayish orange to dark gray, with occasional <br />banding visible along the foliation of the rock. The term foliation refers to the realignment of minerals into a <br />parallel orientation as a result of the intense heat and /or pressure of metamorphism. The rock mass tends to <br />be weakest along the foliation planes, which ultimately results in a discontinuity set parallel to the orientation <br />of the foliation. The foliation orientation is the most prominent discontinuity set identified in the quarry. The <br />foliation undulates across rock exposures in some locations. The rock mass also exhibits several other joint <br />sets that are locally prominent. However, the joints are generally not as regular or as laterally continuous at <br />the foliation. <br />Two regional fault orientations, trending approximately east -west and north - south, have been mapped within <br />the property by others (Gable, 1968; Scott 1972), and multiple fault orientation measurements have been <br />recorded in our site visits over the years, as shown in Figure 3. <br />An approximately east -west trending fault is mapped by Gable (1968) across the northern margin of the <br />quarry. This fault is exposed in the northern portion of the main quarry pit (Figure 3). <br />A second approximately east -west trending fault was previously identified in Jackson Gulch (informally <br />named the Jackson Gulch fault). However, this fault is not mapped due to the uncertainty in the orientation of <br />the fault trace. The area has been extensively modified and fresh exposures were covered by backfill <br />material before measurements could be made. <br />In the Southern Expansion area, Gable (1968) mapped a third fault that also trends roughly east -west <br />(Figure 3). This fault was initially exposed during the 2006 investigation, and was noted by a distinct <br />pegmatite vein that was surrounded by decomposed weak biotite rich gneiss. The fault was exposed in <br />temporary excavation walls along the western margin of the expansion area during previous site visits. GPS <br />measurements taken along the margin of the fault exposure were registered in Google Earth to the existing <br />fault map yielding a good match with the previously mapped trace (Figure 3). At this location it was noted in <br />the 2012 report that the material to the south of the fault is more difficult to blast. <br />April 22, 2013 Page 4 Lachel & Associates, Inc. <br />Project 12361005.00 ©2013 All Rights Reserved <br />