West Mojave Plan FEIR/S - Desert Managers Group

subtraction of transported ozone in determining attainment / nonattainment areas. However, thestate standards are much tighter. As a result, all of the West Mojave planning area outside ofInyo County is in nonattainment of the California ozone standards.Conformity Determination: The classification of an area as a federal nonattainmentarea brings an additional requirement for federal agencies. Section 176(c) of the Clean Air Act(CAA), as amended (42 U.S.C. 7401 et seq.), and regulations under 40 CFR, part 93,subpart W,state that “no department, agency or instrumentality of the Federal Government shall engage in,support in any way or provide financial assistance for, license or permit, or approve any activitywhich does not conform to an applicable implementation plan.” This means that under the CAA176(c) and 40 CFR, part 93, subpart W, (conformity rules), federal agencies must make adetermination that proposed actions in federal nonattainment areas conform to the applicableimplementation plan (SIP) before the action is taken.3.2.2 Geology and SoilsRegional Geologic Overview: The West Mojave planning area is mainly in the MojaveDesert geomorphic province (Mojave Block) of California. However, it takes in a substantialportion of the Basin and Range province to the north, and overlaps with the Sierra Nevadaprovince to the northwest and the Transverse Ranges to the southwest. The geomorphology ofthe province is dominated by broad basins filled with sediments shed from adjacent highlandsand mountains, burying the old topography. The region may once have been a part of the Basinand Range province until separated from it when the Garlock Fault became active in the early tomid Tertiary Period. Although Paleozoic and early Mesozoic-age rocks are present, the desertitself is a Cenozoic-age feature, formed as early as the Oligocene, presumably from movementsrelated to the San Andreas and the Garlock faults. During the Pleistocene (Ice Ages) this regionof California had a cooler average temperature and lesser evaporation rate than present. Whilenever a wet climate, it nonetheless once contained many small lakes, and the Mojave River stillhad water in it. The majority of the surface in the planning area is covered by Quaternary-ageunconsolidated surficial deposits. These deposits are comprised primarily of alluvial, fluvial,lacustrine and aeolian derived material.The Mojave Desert province can be divided into western and eastern portions. The“western Mojave” lies within the wedge where the San Andreas and Garlock faults meet, and isbounded on the east by the Mojave River and a line running northwest from Barstow to RedRock Canyon (Sharp, p.28). Uplifts along the two major fault systems include the El PasoMountains along the northwest side of the Garlock fault, and the San Gabriel and San BernardinoMountains along the southwest side of the San Andreas fault. The western Mojave consists ofgreat expanses of gentle surface with isolated knobs, buttes, ridges, and local hilly areas. The“eastern Mojave” consists of alluvial filled basins (downthrown blocks) between mountainranges separated by normal faults, but includes thrust-fault-emplacement basin and ranges. Inthe southern half, the mountain ranges have a general northwest trend, whereas in the northernhalf these features have no consistent orientation. For more detailed geology, the reader isreferred to the Geologic Map of California, San Bernardino Sheet (Bortugno and Spittler, 1986).Chapter 3 3-55