True. MODOC PLATEAU The Modoc Plateau is a volcanic table land (elevation 4,000- 6,000 feet above sea level) consisting of a thick accumulation of lava ows and tu beds along with many small volcanic cones. Site is located on private property in Modoc County, California, approximately 10 kilometers from the Oregon border and 20 kilometers from the Nevada border. Medicine Lake volcano lies in a strongly east-west extensionaltectonicenvironment slightly east of the main Cascade Range arc axis on the Modoc Plateau in northern California. Areas in the central portion of the northern half of the property contain the Henhill Silt Loam, partially drained, 0 to 2 percent slopes mapping unit. The rocks of eastern California formed a shallow continental shelf, with massive deposition of limestone during the Paleozoic, and sediments from this time are common in the Sierra Nevada, Klamath Mountains and eastern Transverse Range. Holocene faults such as the, McArthur, Mayfield, Pittville, Hat Creek, and Rocky Ledge faults are located within a 20-mile radius of the site. In addition to the web viewer, the GIS data can be downloaded for further use. It is the only coastal mountain range in the USand potentially North Americawith rocks older than the Phanerozoic. The actual distribution of these ten mapping units is complex, and therefore, will be described by bisecting the site into two northern quadrants and a southern half. The oldest rock in this part of the range is the Santa Monica Slate. In some areas, decades of fire suppression have resulted in large areas of dense, fire-prone forest. The river drains a 612-square mile area, but due to the porous volcanic nature of the region, most of the stream flow originates from springs within the valley. Furthermore, the McArthur Fault bisects the property and is designated as an Alquist-Priolo Fault-Rupture Study Zone. The latest edition of this popular book explores the state s recent rumblings and tremulous past with the aid of full color illustrations. The tribes manage tribally-owned lands on reservations and are also involved in monitoring and research activities on ceded lands. These are Jurassic and Cretaceous age greywacke, chert, basalt, ultrabasic rocks and serpentinite from modified oceanic crust. The Shasta County General Plan provides the following policies for properties outside of the FERCs jurisdiction as they relate to seismic and geologic hazards: Policy SG-c - Shasta County shall coordinate with state and federal agencies monitoring volcanic activity and shall periodically review and update the Shasta County Emergency Plan with respect to volcanic hazards. Major Pierson Reading found gold in 1848 in the Trinity River near Douglas City. Geologists have subdivided the four terranes in the mountain range, referring to them as "plates.". The Mojave Desert extends into areas of Basin and Range terrain and includes some of the oldest rocks exposed at the surface in California. Geology - 156 pages. The basement rocks of the Sierra Nevada date to the Paleozoic and include rocks in the Shoo Fly complex and Grizzly Formation. Contribute to chinapedia/wikipedia.en development by creating an account on GitHub. . Sandstone, shale, conglomerate, and fanglomerate; in part Pliocene and Oligocene. The mountains are drained by the Santa Margarita, San Luis Rey, San Diego and San Dieguito rivers, while San Felipe Creek in the east drains into the Salton Sea. Typical rock formations in the area include volcanic breccia, mud and ash flows, lava flows, lacustrine (lake) deposits, and cinder cone pyroclastic rocks. Recent (Holocene) volcanic flow rocks; minor pyroclastic deposits; in part Pleistocene. These soils developed in basins from stratified alluvium of ash and lacustrine deposits. Shasta, Lassen Peak, or Medicine Lake volcanic centers, all of which have experienced activity within the last 500 years (CDMG, 1994). They have a low shrink-swell potential, low to moderate water erosion hazard, and a low wind erosion hazard in bare areas (see TableVI-1). North of the San Joaquin River, the mountains have a tilted-block pattern caused the Sierra Nevada fault, which is interpreted as being similar to the more common Basin and Range terrain to the east. The low shield shape, central caldera, and dominance ofmaficlavas are similar to Newberry Volcano of central Oregon, also located in anextensionaltectonicenvironment east of the Cascade arc axis. 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. This area is currently inundated due to the lack of maintenance of the levee along the southern boundary of the property. As deep basins up to one mile deep formed in the Miocene and filled with thick sediments, volcanic eruptions related to the San Andreas Fault led to rhyolite and basalt eruptions. It is also known for scores of lava-tube caves and for well-preserved young volcanic features. Includes deltaic gravel and sand and gravel bars, in pluvial lake basins in southeastern part of map area. Better run fast! Major uplift was going on in Pleistocene, with some marine terraces raised 1000 feet. The McArthur fault is mapped as trending in a northwesterly direction about three miles northeast of the site between Big Lake and Horr Pond (CDMG, 1994). As discussed under the Bowman Ditch subheading, numerous faults are located in the immediate vicinity of the McArthur Swamp. The Coast Range is at even higher risk for damaging landslides than other parts of coastal California due to sheared serpentinite in Franciscan basement rocks. Shrub-steppe vegetation composed of big sagebrush (Artemesia tridentata) or antelope bitterbrush (Purshia tridentata) and native bunchgrasses occurs along the foothills and higher south-facing slopes. These soils have a Capability Class rating of III to IV and are considered Prime Farmland when irrigated (NRCS, 2000). Large boulders have often eroded out of moraine deposits, coming to rest a few miles away. The Modoc Plateau has both active volcanoes and faults. Glass in tuff and tuffaceous sedimentary rocks is commonly altered to zeolites, clay minerals, and small amounts of opal, chalcedony, orthoclase, and calcite. Twenty-five thousand feet of Jurassic marine sediments in the Sacramento Valley do not necessarily correspond exactly to the height of the mountains, but fist-sized cobbles in conglomerates from the Cretaceous suggest steep conditions and potentially higher altitudes than today. Andesite and dacite typically have plagioclase, hornblende, and clinopyroxene phenocrysts; some flows aphyric. LavaBeds National Monument encompasses about 188 km2(73 mi2) on the northern flank of Medicine Lake volcano and displays mostlybasalticand someandesiticlavas. In places includes flows of platy olivine andesite or basaltic andesite. At mid elevations, there are areas of Douglas-fir and grand fir (Abies grandis) forests to the north, and white fir and Douglas-fir forests to the south. Fossils are common in the marine rocks of the Pacific Beach and Mission Bay formation around San Diego. A small andesitic dome near Marysville is the only example of volcanic rocks in the valley exposed near the surface. Most areas are vegetated by such plants as western juniper, ponderosa pine, antelope bitterbrush, manzanita, and Modoc cypress. 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 High Cascades and the Modoc Plateau Road Guides 294. Most of the Modoc National Forest is covered by basaltic lava flows. 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. Soils of the Cupvar Silty Clay, 0 to 2 percent slopes mapping unit are located in the central portion of the southern half of the site. Older alluvium, lake, playa, and terrace deposits. Below the bays, is the Merced Formation, with 45000 feet of marine rocks overlain by 500 feet of terrestrial sedimentary rocks and capped with more modern sediments from the Sacramento River. We'll be adding other personal features soon. A lock () or https:// means youve safely connected to the .gov website. Listed on Feb 28, 2023 These mapped faults include the McArthur, Mayfield, Pittville, Hat Creek, and Rocky Ledge faults; whereby the McArthur fault trends northwesterly through the site between Big Lake and Horr Pond (CDMG, 1994). The transfer property within the State Park is located on two constituent soil types. This act requires the State Geologist to delineate various seismic hazard zones and requires cities, counties, and other local permitting agencies to regulate certain development projects within these zones. Contribute to chinapedia/wikipedia.en development by creating an account on GitHub. The movement of the San Andreas Fault and Garlock Fault helped to induce arid conditions during the Cenozoic. It is also known for scores oflava-tubecaves and for well-preserved young volcanic features. This region of the mountains was likely underthrusted by the adjoining plates, producing multiple schists around 380 to 400 million years ago in the Ordovician. Gold lodes upstream of the placers were found as well, the largest being French Gulch 15 miles west of Redding. Fountains. In the northeastern corner of California, lies a massive volcanic plain known as the Modoc Plateau. 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. [4]. A .gov website belongs to an official government organization in the United States. The Santa Ynez Mountains extend up the coast of Santa Barbara County and contain Franciscan basement rocks (also referred to as the Franciscan basement complex) like the Coast Ranges. Even moderate shaking . Large mammals are emblematic of the ecoregion, which supports populations of elk, blacktail deer, mule deer, bighorn sheep, mountain lions, and black bears. An exception is the broad Teays Valley which was created by a large, preglacial river. In the nineteenth century, mining began in the vicinity of Julian, extracting nickel and gold, in the Julian Schist. Second edition. The Poway Formation has rounded metavolcanic pebbles with no known source nearby, suggesting an original source somewhere in Sonora before a major offset to the north by faults. Surface fault rupture is not necessarily restricted to the area within an Alquist-Priolo Zone. They are very deep, poorly drained soils with slow permeability and a high shrink-swell potential (see TableVI-1). Condado de Modoc, California, Estados Unidos The northeastern-most county in California with a total area of 4,203.37 square miles, but with a population under 10,000. This project could not have been undertaken without the financial support of The Nature Conservancy's Oregon, Washington and California offices, and the Washington Department of Fish and Wildlife (WDFW). The Alquist-Priolo Earthquake Fault Zoning Act (formerly the Alquist-Priolo Special Studies Zone Act), signed into law December 1972, requires the delineation of zones along active faults in California. In the Modoc Plateau, Douglas-fir becomes less important, western white pine (Pinus monticola) woodlands dominate many areas, and Jeffrey pine (Pinus jeffreyi) and Washo pine (Pinus washoensis) occur with or replace ponderosa pine. Columbia River / Modoc Plateau basalt. "Modoc County has an area of 3823 square miles. Most of the gold deposits date to the Cretaceous and formed in narrow belt around the Melones fault in quartz veins. Non-seismic hazards addressed in the document include volcanoes, erosion, and expansive soils. 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. This ecoregion has one of the most extensive Ponderosa pine forests in the western U.S., occurring in all parts of the ecoregion, from Wenatchee to Mount Lassen. The ditch was originally channeled out to increase flows to the Tule River for the Pit River Hydroelectric Project. In some places they are interbedded with shale, limestone and radiolarian chert. The California Coast Ranges extend from the Oregon line southward 600 miles to the Santa Ynez River. Roadside Geology of Northern and Central California, "Second Edition", 2016, Alt/Hyndman Roadside Geology of Oregon, "Second Edition", 2016, Marli B. Miller In places includes talus and slope wash. The plateau consists of a thick accumulation of lava flows and tuff beds along with many small volcanic cones. [1], During the Cenozoic, the volcanic and deep water sedimentary Franciscan rocks were accreted to the edge of California and vast areas of marine sedimentary rocks deposited in the Central Valley and what would become the Transverse and Coast Ranges. The Pastolla Muck, drained, 0 to 2 percent slopes and Pastolla muck, 0 to 1 percent slopes occupy a large portion of the area of the northern quadrants along the Tule River. The bay system was the second place in the US to be mapped in 1826 by Edward Belcher and Alex Collie, a surveyor and surgeon respectively on the British vessel HMS Blossom. Also includes isolated masses of dacitic and rhyodacitic flows, breccia, and ash-flow tuff along eastern slope of Cascade Range that are lapped by flows and sediments of the Madras (or Deschutes) Formation. Includes older alluvium and related deposits of Piper (1942), Willamette Silt (Allison, 1953; Wells and Peck, 1961), alluvial silt, sand, and gravel that form terrace deposits of Wells and others (1983), and Gresham and Estacada Formations of Trimble (1963). They have a low erosion hazard from water when bare and a moderate hazard from wind erosion. Geodetic monitoring of transient deformation along the Pacific-North American plate boundary This page integrates daily GPS measurements from ~1500 stations along the Pacific/North American plate boundary, ranging from Alaska to the U.S-Mexico border (click on figure to right). They are associated with the Whipp-Cupvar Complex, slightly saline, 0 to 2percent slopes mapping unit which occupies a flanking position to the south. The Western Jurassic Plate stretches for 220 miles on the western edge of the mountains. Initially, hydraulic mining was used to get at placer deposits, but it destroyed the landscape and choked rivers with sediments, ultimately being banned the California government in 1884. California's Geomorphic Regions Modoc Plateau Location: located east of Cascade Range and adjacent to the Basin & Range Region The Modoc Plateau is the California part of the greater Colombian Volcanic Plateau that extends into Oregon, Washington & Canada Mountains California's Geomorphic Regions:

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