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Environmental Scientists and Engineers, I.LC <br />sources. Both the sulfur dioxide and lead emissions are small. With the elimination of <br />lead from gasoline, it is no longer an air pollution problem in the region. <br />Air pollution measurement taken at the Hayden airport and local power plants as well as <br />surrounding mines show the air quality is within applicable standards for the area. PM 10 <br />measurements taken at the ColoWyo mine show background levels of 11 micrograms per <br />cubic meter for the annual average (Standard is 50) and 23 micrograms per cubic meter <br />for the 24 -hr average (Standard is 150). These on -site data show no exceeding of state air <br />quality standards over several years of monitoring. <br />There are no known special designation air sheds or non - attainment areas in the vicinity <br />that would be affected by the proposed action. <br />3.3 Geology and Minerals <br />3.3.1 Geology <br />The proposed Collom lease area is located north of the Danforth Hills in the Wyoming <br />Basin physiographic province, which is a high, arid plateau ringed by mountains (WMC <br />2005). General elevations range from 6,000 to 8,500 feet amsl. The region is composed <br />of a series of basins broken up by low ridges (Figure 4). Background information on the <br />geologic setting of the proposed Collom Mine was largely obtained from the "Geologic <br />Summary of the 2004 Collom Exploration and Evaluation Project," written by the <br />Collom Geologic Team (2005). <br />The ColoWyo Mine property lies within the Rocky Mountain foreland province, a region <br />characterized by deep- seated, basement faults that have undergone periodic episodes of <br />movement. These complex structures are overlain by younger sedimentary sequences that <br />reflect upward- diminishing deformation. Periodic movements have propagated these <br />deep - seated fault structures closer to the surface, causing warping in the overlying <br />sedimentary sequence. The ancestral Axial Fault located north of the Danforth Hills <br />Coalfield is believed to be such a fault structure. The latest movement along the fault was <br />during the Laramide Uplift, a Tertiary orogenic event which led to the uplift of the <br />modern Rocky Mountains. This episode of uplift was a compressional event that <br />eventually formed faults and major folds such as the Axial Basin Anticline north of <br />ColoWyo's property holdings. The axis of the Axial Basin Anticline occurs in the broad <br />valley just north of the ColoWyo study area. <br />Numerous large -scale anticlines, domes, and synclines formed in the region as a result of <br />this last compressive event. Superimposed on these larger -scale folds are smaller <br />secondary or accommodating folds, although some researchers suggest a different <br />episode of deformation formed them. This combination of structural features led to the <br />present geometry at the Collom study area. <br />P •PROJECFS 1:blolcyo.6188 CA final` BI 5I.%•E:\ Collom 08 01 is doc <br />18 <br />