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John Hamrick <br />January 16, 2001 <br />Page 4 <br />Structural and Stratigraphic Relationship Between the Mine Workings <br />and The Pack Rat Spring <br />Exploratory drill hole data, "box score" maps, and exploration cross sections were used <br />to prepare a structural contour map on the top of a prominent gray mudstone layer that <br />subdivides the "ore-bearing sandstone" (Figure 1), and two cross sections A-A' and B-B' <br />(Figures 3 and 4) through the mine area. <br />The "ore-bearing sandstone," in the vicinity of the Packrat/Hubbard Mines is 50- to <br />100-feet in thickness. A gray mudstone layer, 1-foot to 10-feet thick, divides the <br />sandstone body into two separate units (Figures 3 and 4). These mudstone layers have <br />a very low permeability and are known to act as a barrier to the downward migration of <br />ground water. Perched ground water is found above similar mudstones, throughout <br />the Salt Wash and Brushy Basin Members. <br />As indicated on cross sections AN and BB' the Pack Rat/Hubbard Mines are located <br />stratigraphically above the gray mudstone layer, whereas the Pack Rat Spring is located <br />stratigraphically below this layer and slightly above the red mudstone marking the base <br />of the "ore-bearing sandstone." Due to the structural and stratigraphic relationship <br />between the mine areas, the mudstone unit and the Pack Rat Spring, the low- <br />permeability mudstone layer will acts as a barrier to the downward flow of ground <br />water and keep it perched above the sandstone unit from which the Pack Rat Spring <br />issues. <br />Structural contours (Figure 1) on the top of the mudstone unit indicates that, in the <br />mine area, this unit dips to the west and northwest. Ground water perched on this <br />mudstone unit would be expected to flow perpendicular to the structural contours and <br />down dip, which would be away from the Pack Rat Spring toward the Lumsden fault, <br />located northwest of the mines. Once it reaches the fault it will migrate to the northeast <br />along or against the fault zone. <br />Comparison of Water Quality in the Pack Rat Mine and Pack Rat Spring <br />A number of water samples were collected from both the Pack Rat mine and Pack Rat <br />Spring and analyzed for various chemical constituents (Table 1 and Table 2). Stiff <br />diagrams (Figure 5) of the major ions of these waters show that both waters are a <br />sodium bicarbonate type. <br />The Pack Rat Mine was in production from the mid-1950's until the early 1980's. <br />During that time the mine was kept dry by pumping water from the mine sumps, <br />where it was collected, then pumped to the surface where it was discharged. When the <br />mine operations were shut down in the early 1980's the sumps began to fill and mine