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These soils have a Capability Class rating of III to IV, due to erosion hazards and are not considered to be Prime Farmland (NRCS, 2000). Since the active McArthur fault traverses the site, any displacement along this segment of the fault could result in potential fault rupture at the surface. These two locations are located approximately 30 miles east of the Park and less than a mile south of the Bowman Ditch and Ahjumawi Property. Eruptions relatively quiet, but spectacular. It is composed of layers of volcanic flows and periodic volcanic uplifts. Fisher, once common in this ecoregion, now occurs only in the extreme southwestern portion of the East Cascades. Dominant land uses are forestry, livestock grazing, recreation and conservation. Geologic guide to the Modoc Plateau and the Warner Mountains : annual field trip guidebook of the Geological Society of Sacramento, 1980. These basins steadily filled with sediment, with one famous example preserved as the Great Valley beds in the Coast Ranges. Like the Sierra Nevada, the Peninsular Ranges have gentle western slopes and steep eastern faces. Gold lodes upstream of the placers were found as well, the largest being French Gulch 15 miles west of Redding. Roadside Geology of Northern and Central California, "Second Edition", 2016, Alt/Hyndman Roadside Geology of Oregon, "Second Edition", 2016, Marli B. Miller Modoc Plateau - Wikipedia Alluvium, lake, playa, and terrace deposits; unconsolidated and semi-consolidated. [3], Forested areas of the plateau include Ponderosa Pine (Pinus ponderosa), as well as other tree species such as California Buckeye (Aesculus californica). Geology of Northern California Bulletin 190 CA Div of Mines - Etsy As discussed in Section1.0, Project Description, no development is proposed that would eventually be utilized for human occupancy. During the Pleistocene, the mountains had a large number of glaciers and cirques and glacially-carved U-shaped valleys are remaining features from that time period. The largest wild population in Washington occurs within the ecoregion in the Columbia River Gorge. A thrust fault, known as the Trinity or Bully Choop thrust, separates the Eastern Klamath Plate from the Central Metamorphic Plate. Geologic Regions of Georgia - New Georgia Encyclopedia The San Onofre Breccia also formed during this period with distinct glaucophane schist, gabbro, limestone and greenschist. Wetlands in the ecoregion are home to many birds including bald eagles, geese, ducks, herons, cranes, rails, and various songbirds. Modoc Plateau: Average elevation 1370 m (4500 feet) Predominant rocks: Late Cenozoic volcanics, especially basalts in the Modoc Plateau, andesites and dacites in the Cascades Plate tectonic setting: Andean-style volcanic arc in the Cascades, Basin and Range volcanoes in the Modoc Plateau Most recent eruptions: Lassen, 1914-1921 Before a development permit is granted for a site within a seismic hazard zone, a geotechnical investigation of the site has to be conducted and appropriate mitigation measures incorporated into the project design. The majority of the PG&E property is underlain by Quaternary Lake deposits comprising alluvial sediments derived from volcanic lands and water-lain ash deposits. These soils developed in basins from stratified alluvium of ash and lacustrine deposits. Additionally, each of the properties lie within or adjacent to an Alquist-Priolo Fault-Rupture Study Zone. [4]. Select Mineral List Type Most erosion of the Sierra Nevada was finished by the Eocene and faulting may have reactivated the roots of the mountains to create the current mountain range. Borehole Conditions The vault is a horizontal tunnel, located beneath 5 meters of overburden to maintain thermal stability. As with its flora, this diversity arises as a result of topography, unique climate, geology, and ecological isolation. Therefore, aside from naturally occurring erosional processes, no impact is anticipated. Pahoehoe vs. aa lavas. Gassaway soils occur approximately 30percent of the complex and have formed from eolian deposits in pockets of the broken Lava Flow lands. SP026: Traveling America's loneliest road: A geologic and natural history tour through Mercury was first discovered in Santa Barbara County in 1796. Includes Shumuray Ranch Basalt and Antelope Flat Basalt of Kittleman and others (1965), Grassy Mountain Basalt of Corcoran and others (1962), Drinkwater Basalt of Bowen and others (1963), basalt formerly assigned to Danforth Formation by Piper and others (1939) (see Walker, 1979), Hayes Butte Basalt of Hampton (1964), Pliocene and upper Miocene basalt flows capping and interstratified with the Madras (or Deschutes) Formation, and basalt flows interstratified in the Dalles Formation of Newcomb (1966; 1969). [16]. In the northeastern corner of California, lies a massive volcanic plain known as the Modoc Plateau. These soils have a Capability Class rating of III to IV and are considered Prime Farmland when irrigated (NRCS, 2000). Older alluvium, lake, playa, and terrace deposits. They are derived from lake sediments and alluvium, which formed from extrusive igneous rocks. "Modoc County has an area of 3823 square miles. Most intrusive igneous rocks are tonalite, granodiorite, quartz diorite or gabbro. [15] Areas along the northeastern shores of Big Lake are mapped as Recent Modoc basalt flows (CDMG, 1968). Soils of the Pittville Sandy Loam, 0 to 5 percent slopes mapping unit occur at the southern fringe of the site. The region surrounding the Modoc Plateau, encompassing parts of northeastern California, southern Oregon, and northwestern Nevada, lies at an intersection between two tectonic provinces; the Basin and Range province and the Cascade volcanic arc. In 1815, the Los Angeles River, which then drained to Long Beach, flooded so substantially that it changed course, joining Ballona Creek and flowing to Santa Monica Bay, before another flood in 1825 redirected it back to Long Beach. However, the Greenhorn Fault system is more active to the south, extending to the Tehachapi Mountains and causing more plateau-like landforms. The Santa Monica Mountains and the Channel Islands are different than the mountains to the north because they have granitic and metamorphic basement rocks more like the Sierra Nevada. Broad valleys occupy the lowlands between the mountain ridges. The color geologic road maps, based on the 2010 Geologic Map of California, are detailed and easy to read. Major uplift was going on in Pleistocene, with some marine terraces raised 1000 feet. Modoc Plateau. Some rocks in the Western Jurassic Plate seem to have been subducted, reaching blueschist grade metamorphism in the sequence of metamorphic facies in the South Fork Mountain schist. . Modoc County - Quarries and Beyond Home Locally a late Hemingfordian age indicated by mammalian fauna (Woodburn and Robinson, 1977). NGMDB Product Description Page These rocks date to the Cretaceous, with a lower sequence of conglomerate overlain by sandstone and shale, with huge ammonite fossils. Subsequently, sandstone and shale deposited while the region was still underwater. The Modoc Plateau is part of the larger Columbia Plateau which extends into eastern Oregon and Washington, southern Idaho, northern Nevada and western Wyoming. Miners extracted placer gold or dug up fossil placers in the Weaverville Formation and Hornbrook Formation. Furthermore, each of the properties would be subject to regional volcanic events originating from the previously discussed volcanoes. Most of the gold historically mined in California originated in the Mother Lode belt, located in the foothills of the western Sierras. Geologic units in Modoc county, California Additional scientific data in this geographic area Quaternary volcanic flow rocks, unit 1 (Cascade Volcanic Field) (Quaternary) at surface, covers 37 % of this area Quaternary volcanic flow rocks; minor pyroclastic deposits; in part Pliocene and Miocene. In all, 20 oil fields are located in the Santa Barbara Channel, with one of the largestthe Dos Cuadras fieldfound in 1968, although a major spill on January 18, 1969, hampered interest in the field. The eastern ranges, including the Santa Rosa Mountains are typically over 6,000 feet (1,800m) high, with San Jacinto Peak reaching 10,805 feet, whereas the western ranges like the Santa Ana, Agua Tibia and Laguna mountains are lower. It is mostly interchangeable with Qal, except that it implies some specifically younger Quaternary deposits. A thick sequence of mostly terrestrial sedimentary rocks including the Rosario, Ladd, Trabuco and Williams formations is exposed on the western slope of the Santa Ana Mountains and Santa Ana Canyon, stretching southward to Camp Pendleton, San Onofre, and smaller exposures in Encinitas, Leucadia, Point Loma and La Jolla. Click here to use the California geological interactive map Source: California Geological Survey Rhyolitic to dacitic varicolored bedded tuff, lapilli tuff, and fine- to medium-grained tuffaceous sedimentary rocks with interstratified welded and nonwelded ash-flow tuff and interbedded basalt and andesite flows. Virtually all of the islands in the bay are man-made from dredged sediments. The bulk of the plateau is composed of ancient lava flows and volcanic tuff dating back between 10 and 2 million years ago during the Tertiary period. US 97: Weed-Oregon 294. Roadside Geology of Northern and Central California Adherence to appropriate engineering, design, and construction practices, such as dust control, seasonal considerations, and rapid revegetation, would minimize impacts involving these improvements at the McArthur Swamp property, resulting in a less than significant impact. Major geologic changes began in the Cenozoic with continued continental shelf deposition of shale, sandstone and clay as well as near-shore tropical coal deposits. Should one of the local faults in the area experience displacement, the McArthur Swamp could potentially experience levee failures from ground lurching and/or lateral spreading. The three interconnected Suisun, San Pablo and San Francisco bays occupy a structural depression dating to the Pliocene which flooded several times due to Pleistocene glaciations. Both of these provinces have substantial geothermal resource base and resource potential. Shasta, Lassen Peak, or Medicine Lake volcanic centers, all of which have experienced activity within the last 500 years (CDMG, 1994). The services DOC provides are designed to balance today's needs with tomorrow's obligations by fostering the wise use and conservation of energy, land and mineral resources. The rocks likely formed much further away from the Sierras and were relocated by the dramatic movements of faults. This produced major crustal stretching, volcanism and displacement of up to 125 miles. Finally, the Modoc Plateau, a volcanic table ranging from 4,000 to 6,000 feet (1,200 to 1,800 m) in elevation, separates the Medicine Lake Highlands in the west from the Warner Mountains in the east, covering roughly 1,000,000 acres (400,000 ha) of the forest. Similar rock formations and patterns are found throughout Ventura County, in the Topatopa Mountains and Pine Mountains. [Age is early Tertiary (Eocene).] As described under item (a), while various areas of the project site do consist of unstable soils, there are no facilities proposed as part of the project which have the potential to be impacted by these soils, therefore this is a less than significant impact. The River | Fall River Conservancy Soils comprising the Burney-Arkright Complex, two to nine percent slopes mapping unit, occupy smaller areas in the eastern portion of the transfer property and are underlain by basaltic lava flows. The California Geotour: An Index to Online Geologic Field Trip Guides