It is the only coastal mountain range in the USand potentially North Americawith rocks older than the Phanerozoic. The soils are moderately to strongly alkaline and have a very high shrink-swell potential (refer to TableVI-1). In Washington and the rapidly developing areas around Bend in Oregon, timber companies have recently begun to sell their lands in the mid-elevation forest and transition zones to developers. 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. Basaltandbasaltic andesitedominate the lower flanks, but higher on the volcano,basalticlavas are mostly absent,andesitedominates, and high-silicalavas are present. A thrust fault, known as the Trinity or Bully Choop thrust, separates the Eastern Klamath Plate from the Central Metamorphic Plate. Sign In Skip to Main Content . The southern portion of the ecoregion has extensive valleys and flatlands between the forested mountains and foothills, which include large marshes, irrigated meadows and pastures, and arid juniper and sagebrush steppes. 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. Recent (Holocene) volcanic flow rocks; minor pyroclastic deposits; in part Pleistocene. The area formed as a series of small island arcs, deep-ocean sediments and mafic oceanic crust accreted to the western edge of North America, producing a series of deep basins and high mountain ranges. Ash-flow tuff, lava flows, pumice-lapilli tuff, coarse pumicite, flow breccia, and domal complexes of rhyolitic, rhyodacitic, and dacitic composition; in places includes peralkaline rhyolite and some andesite and andesite breccia. See Answer. In the 19th century, a railroad pier was built out into the canyon to avoid waves closer in to shore when loading and unloading ships. These soils are classified as having a moderate shrink-swell potential[1] and are classified as having a Capability Class rating of IV, due to the high hazard of erosion and they are not considered Prime Farmland. These rocks were likely moved to their current location by the two major faults. Around Shasta Reservoir are other copper and zinc deposits in the Triassic-age Bully Hill rhyolite. The Lost River watershed drains the north part of the plateau, while southern watersheds either collect in basin reservoirs[clarification needed] or flow into the large Big Sage Reservoir, which sits in the center of Modoc County. the structural geology and tectonics of mid-ocean ridges and Icelandin 2011. Statutes such as Section 404 of the Clean Water Act and other federal and state regulations require an erosion and sedimentation control plan prior to major construction. It is the only state with all three types of plate boundaries, an extraordinary history of earthquakes and volcanoes, and it has many rocks and minerals found nowhere else. The Modoc Plateau is an undulating expanse of Miocene to Holocene basalt law flows at the southwest edge of the Columbia Plateau, covering 10,000 square miles. Therefore, the transfer would not expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death. [4] and Modoc Cypress (Cupressus bakeri).[5]. These soils are relatively deep (40 to 60 inches), well drained gravelly loams with moderately slow permeability. They have a high shrink-swell potential and have a low water erosion hazard and low wind erosion hazard when bare (see TableVI-1). Geothermal systems with evidence of magmatic heat, associated wi This is considered a less-than-significant impact. Historically, fires occurred at irregular intervals from under 10 years in the lowland foothills to 150 years or more at high elevations. The east side of the Warner Mountains in particular has exposed rock in the many canyons, including finds of petrified wood and assorted gemstones. [J Curtis Kramer; Geological Society of Sacramento. Thick Pliocene marine rocks up to 14,000 feet thick are found on the edges of the Santa Clara River Valley and parts of the San Fernando Valley, stretching to Fillmore. They have a moderate hazard for water and wind erosion when bare. These rocks date to the Cretaceous, with a lower sequence of conglomerate overlain by sandstone and shale, with huge ammonite fossils. The proposed project involves no earthwork at the Burney Falls, Bowman Ditch, and Ahjumawi Properties. Much more recent Pliocene terrestrial sedimentary rocks are also common in the northern Peninsular Ranges like the San Timoteo Canyon and Mount Eden conglomerate, sandstone and siltstone which are up to 7000 feet thick. Reference: Chorlton, L.B. There are no septic tanks or wastewater disposal systems proposed as part of this project, therefore this item is not applicable. The Great Valley Sequence is a 40,000 foot thick formation at the western edge of the Central Valley that formed between the Jurassic and Cretaceous, overlying the Franciscan Assemblage and granite rocks associated with the Sierra Nevada to the east. The Modoc Plateau has a diverse geography, with portions draining into closed basins such as Goose Lake and Surprise Valley, and most of the remainder draining into the Pitt River, a tributary of the Sacramento River. 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. 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. It is a succession of valleys, that in the past were inland lakes, and which follow one another through the county from north to south. However, the Greenhorn Fault system is more active to the south, extending to the Tehachapi Mountains and causing more plateau-like landforms. A machinist leased the property and used windmills to get small remaining amounts of oil out. Identify Priority Places: A Practitioner's Guide, Cumberlands and Southern Ridge and Valley, Willamette Valley-Puget Trough-Georgia Basin. The subsurface is well known from oil wells and oil fields are bounded in the east by the Kern Front fault. This 6"x9" paperback has 371 pages that are packed with detailed information about California Geology. The color geologic road maps, based on the 2010 Geologic Map of California, are detailed and easy to read. 0 Reviews. Gold lodes upstream of the placers were found as well, the largest being French Gulch 15 miles west of Redding. Reviews aren't verified, but Google checks for and removes fake content when it's identified. In spite of low rainfall, the numerous lava tubes and volcanic fractures in the plateau produce the Fall River Springs, one of the largest springs in the US. 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. 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. Comments: Columbia Plateau. The southern portion of the McArthur Swamp property is comprised of numerous soil mapping units, which include the Cupvar, Whipp, Pittville, Dugan, and Graven soil series. Large mammals are emblematic of the ecoregion, which supports populations of elk, blacktail deer, mule deer, bighorn sheep, mountain lions, and black bears. Henhill Silt Loams are classified as neutral to slightly alkaline and have moderate shrink-swell potential. Also includes minor rhyolite and dacite flows and domes. Policy SG-e - When soil tests reveal the presence of expansive soils, engineering design measures designed to eliminate or mitigate their impacts shall be employed. The threat of catastrophic wildfire and competition with barred owls (Strix varia) are concerns for the conservation of the spotted owl, a federally listed species that occurs within the ecoregion. The vast tableland between the Cascades and the Warners is referred to as the Modoc Plateau. Major Pierson Reading found gold in 1848 in the Trinity River near Douglas City. Because the mountain range is young only a very narrow coastal plain has developed around Santa Barbara. As indicated by PG&E in their PEA, wetland construction work will be completed under a USACOE Nationwide No. The movement of the San Andreas Fault and Garlock Fault helped to induce arid conditions during the Cenozoic. Alluvium, lake, playa, and terrace deposits; unconsolidated and semi-consolidated. High Cascades and the Modoc Plateau Road Guides 294. These soils have formed in dissected lacustrine terraces from alluvium derived from diatomite lacustrine deposits (NRCS, 2000). The Whipp-Cupvar Complex, 0 to 2 percent slope soils occupy the central, northern portion of the southern half of the site. Gold has been recovered along the eastern margin of the Great Valley, where it was derived from the Sierra Nevada. Isolated volcanic cones occupy steep mountain ridges, but tend to be smaller than those in the Western Cascades with the exception of Mount Adams. 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). [10], At the edge of the Los Angeles coastal plain and just west of the San Joaquin Hills, Newport Bay is a major hub of boating. The transfer property within the State Park is located on two constituent soil types. Partly coeval with the Saddle Mountains Basalt of the Columbia River Basalt Group (Swanson and others, 1979), Thin, commonly open-textured (diktytaxitic), subophitic to intergranular olivine basalt flows, intercalated with and grades laterally through palagonite breccia and tuff into tuffaceous sedimentary rocks (unit Ts). There are also several herds of wild horses on the plateau. These basins steadily filled with sediment, with one famous example preserved as the Great Valley beds in the Coast Ranges. Lake beds interbedded with volcanic ash are typical of the Cenozoic. Policy SG-d - Shasta County shall develop and maintain standards for erosion and sediment control plans for development. Includes deltaic gravel and sand and gravel bars, in pluvial lake basins in southeastern part of map area. Sur Series schist, quartzite, marble, gneiss and granulite in the Salinian block likely deposited in a marine shelf late in the Paleozoic. AmeriCorps Forestry Technicians will perform a wide variety of activities to support all stages of project work. 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). Movement along the Sierra Nevada fault helped to create the new Muir Crest and parts of the mountain range rose up to 10,000 feet over the last three million years, creating a steep face to the west of Owens Valley. 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. Platy flow-jointing common. The Marble Mountain Cambrian quartzite lies unconformably atop Proterozoic granites. Creating your LandScope profile is fast, free, and simple. 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. In the southern part of the range, between the Nacimiento and San Andreas fault zones, the metamorphic rocks and granite plutons of the Salinian block make up the basement rock. Joint surfaces and cavities commonly lined with hematite or montmorillonite clay, secondary silica minerals, zeolites, celadonite, or calcite. Very large earthquakes that occur closer to the Northern California coast could cause damaging levels of ground shaking here too. Both of these provinces have substantial geothermal resource base and resource potential. [8], The Modoc Plateau is an undulating expanse of Miocene to Holocene basalt law flows at the southwest edge of the Columbia Plateau, covering 10,000 square miles. The soils have a Capability Class rating of IV and are not considered Prime Farmland. Hill*s work, however, is of little value in understanding the areal . Modoc Plateau Flood Basalt Layers Earthcache (GC1X4B5) was created by PathfinderMark on 8/11/2009. In some places, ophiolite sequences preserve remnant oceanic crust rock on land, while other parts of the range are intruded with ultrabasic igneous rocks that have serpentinized to peridotite. Geologists group the plutons of the Peninsular Ranges as the Southern California batholith, which includes several large individual plutons like the San Marcos Gabbro, Woodson Mountain Granodiorite or Bonsall Tonalite. Cascades & Modoc Plateau Geology - YouTube Skip navigation Sign in 0:00 / 45:45 Cascades & Modoc Plateau Geology Kiersti Ford 541 subscribers Subscribe 6 Dislike Share 195 views Oct 7, 2021. They are small in area and are thought to represent a higher-grade metamorphic environment than the slate belt, and may have formed through subduction, when one plate slid beneath another. Polygons from the 1978 State map unit Qp were added where no playa was shown on the county maps. 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. Eruptions relatively quiet, but spectacular. The thick Galice formation slate and metamorphosed greywacke overlie the Josephine ophiolite and likely deposited in a deep ocean environment offshore of the island arc. Shasta, Lassen Peak, or Medicine Lake volcanic centers, all of which have had activity within the last 500years (CDMD, 1994). 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. Most of these wetlands have been drained and converted to agriculture. A lock () or https:// means youve safely connected to the .gov website. Before the end of the Oligocene, sea levels rose again leaving behind the Vaqueros Formation and then the Miocene deep water silt and clay of the Rincon Formation. By contrast, the Trinity ophiolite is found in the east, known for its numerous ultramafic rocks and being one of the most extensive ophiolites in the US. Drew earned a PhD. Similar rock formations and patterns are found throughout Ventura County, in the Topatopa Mountains and Pine Mountains. These sulfide minerals derive from the Copley Greenstone and or sea floor vents when the region was far offshore and formed as hot water "invaded" the Balaklala rhyolite. Second edition. Sign in with your username (email address) and password. It is exposed in the Smith River drainage to the north of US Highway 199 in Del Norte County. Plateau in the northeast corner of California, United States, List of plants on the Modoc National Forest, California Geologic Provinces, Note 36, page 2, https://en.wikipedia.org/w/index.php?title=Modoc_Plateau&oldid=1106243134, California placenames of Native American origin, Wikipedia articles needing clarification from May 2016, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 23 August 2022, at 20:13. May include some rocks of middle Miocene age in the area west and northwest of Lakeview. Rainbow (Oncorhynchus mykiss) and cutthroat trout are the common cold water inhabitants. As discussed in Section1.0, Project Description, no development is proposed that would eventually be utilized for human occupancy. [15] This property could potentially be subjected to ground motion from displacement along any of these local and regional faults. What people are saying - Write a review. Ships from Sacramento, CA. Groundwater quality in the 39,000-square-kilometer Cascade Range and Modoc Plateau (CAMP) study unit was investigated by the U.S. Geological Survey (USGS) from July through October 2010, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program's Priority Basin Project (PBP). The variety of habitat types in the East Cascades has led to a unique and diverse flora and fauna. Miners extracted placer gold or dug up fossil placers in the Weaverville Formation and Hornbrook Formation. 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. These deposited as part of a series of small island arcs, "rafted" against the coast of the proto-North American continent Laurentia. Deccan Traps in India. Serious flooding in 1862 created a three mile wide lake in the Santa Ana River, while serious flooding in 1938 inundated the San Fernando Valley and parts of the Los Angeles coastal plain, damaging 100 bridges and killing 43 people. CA 36: Red . 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. Bull trout occur within the ecoregion but their range has been significantly reduced. Most precipitation accumulates from November through April. Deep hydrothermal systems active in marine sedimentary rocks as they were being metamorphosed emplaced the gold. The largest wild population in Washington occurs within the ecoregion in the Columbia River Gorge. [16]. Potassium-argon ages on rocks from unit range from about 36 Ma (Swanson and Robinson, 1968) to about 20 Ma. Study with Quizlet and memorize flashcards containing terms like 11, Cascade Range, Great Valley, Transverse Range, Peninsular Range, Colorado Desert, Coast Ranges, Sierra Nevadas, Mojave Desert, Modoc Plateau, Klamath Mountains, Basin and Range, Mount Whitney, Sierra Nevadas and more. The San Onofre Breccia also formed during this period with distinct glaucophane schist, gabbro, limestone and greenschist. 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. In addition, the Bowman Ditch and surrounding area are located within an area that could be affected by regional volcanic events originating within the Mt. Substantially folding at the edge of the valley creates famous oil producing dome structures like Lost Hills and Kettleman Hills. Oil was first extracted in 1850 from the Pico Canyon field, close to Newhall with larger-scale production by 1875. In the northern end of the county are notable Goose Lake, Tule Lake, and the three lakes of Surprise Valley. There is a dramatic moisture gradient across the ecoregion as the precipitation diminishes from the cold, wet Cascade crest (up to 120 inches of precipitation per year) to the warm, dry eastern border with the Columbia Plateau and Great Basin (less than 20 inches per year). 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. This mapping unit is typically found at the base of toe slopes where alluvium from basalt has been deposited. [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. California has some of the most distinctive and unique geology in the United States. From inside the book . Copyright 2023 NatureServe. Shasta, Lassen Peak, or Medicine Lake volcanic centers, all of which have experienced activity within the last 500 years (CDMG, 1994). Columbia River / Modoc Plateau basalt. 27 Permit, which requires agreement with the USFWS and a water certification or waiver. The Rocky Ledge fault trends northwesterly about three miles to the south of the transfer property (CDMG, 1994). It is also known for scores oflava-tubecaves and for well-preserved young volcanic features. Their distribution and numbers are significantly reduced, particularly due to dams that restrict their passage through much of the ecoregion. Fast flowing rivers meant that the region has accumulated very little alluvium, except for a rare 400 foot thick deposit in Scott Valley, southwest of Yreka, California. Three remaining mapping units are located in a band along the southern portion of the property and include the Dugan-Graven Complex, Flooded, 0 to 5 percent slopes, Dugan-Graven Complex, 0 to 5percent slopes, and the Pittville Sandy Loam, 0 to 5 percent slopes occupy this area. As with its flora, this diversity arises as a result of topography, unique climate, geology, and ecological isolation. Over 40 different oil and gas fields are found in association with the Transverse Ranges and their surrounding basins. These soils also occupy smaller areas along Fall River in the southern half of the property. Modoc National Forest 800 West 12th Street Alturas, CA 96101 (530) 233-5811 Warner Mountain Ranger District PO Box 220 Cedarville, CA 96104 (530) 279-6116 Camping Warren Peak and Patterson Lake The nearest campground is available at Pepperdine Camp, near the trailhead. US 97: Weed-Oregon 294. Most of the Modoc National Forest is covered by basaltic lava flows. The rocks likely formed much further away from the Sierras and were relocated by the dramatic movements of faults. Pliocene and/or Pleistocene sandstone, shale, and gravel deposits; in part Miocene. Select Mineral List Type 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. The ditch was originally channeled out to increase flows to the Tule River for the Pit River Hydroelectric Project. The latest edition of this popular book explores the state s recent rumblings and tremulous past with the aid of full color illustrations. The McArthur Swamp and the Glenburn Dredge Site are located within the same regional geographical area and geomorphic province as the McArthur-Burney Falls Memorial Park. These flyers, referred to as Geo Gems Notes, address individual parks and describe the geological features they support, explain the geological processes demonstrated by the landforms at the site and their significance, and indicate where to find the sites in each park unit. The Modoc Plateau has both active volcanoes and faults. Quaternary volcanic flow rocks; minor pyroclastic deposits; in part Pliocene and Miocene. The western gray squirrel is at-risk within the ecoregion in Washington as it is restricted to two isolated populations, but populations in Oregon and California are more robust. Fisher, once common in this ecoregion, now occurs only in the extreme southwestern portion of the East Cascades. MOD - Modoc Plateau, CA, USA. Levee improvements and associated road maintenance necessary for delivery of imported fill would also cause temporary disturbances to the topsoil surfaces. In the 1960's, NASA astronauts trained for future moon landings in the pumice fields of the highlands. During the Miocene, the Coast Ranges were flooded again, with underwater volcanic eruptions in the southern part of the range and deposition of fossil-rich shales like the Monterey formation. In some areas, decades of fire suppression have resulted in large areas of dense, fire-prone forest. [1] It has cinder cones, juniper flats, pine forests, and seasonal lakes. Recent lava flows comprise approximately 60 percent of this complex and are characterized by sharp, jagged, broken blocks piled in tumbled heaps and have many crevices, sinkholes, and collapsed lava tubes. The Lava Flows-Gassaway Complex, 2 to 15 percent slopes map unit is found along the northeastern shoreline of Big Lake at the northeastern edge of the site. Mountain goats inhabit high elevations in the central and northern part of the ecoregion in Washington, but are largely absent from the southern portion of their range, and absent from Oregon. Unlike most of California, the Mojave region has numerous Precambrian Proterozoic rocks, such as granitic gneiss or marble intruded with porphyry in the Ord Mountains or schist in the Old Woman Mountains. False. 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. [17]. California s geology makes headlines when faults shift, volcanoes puff steam, and coastal bluffs fall into the sea. 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 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. With the exception of some metasedimentary and metavolcanic rocks, most rocks in the Peninsular Ranges are igneous and Jurassic in age, dating to the time of the Nevadan orogeny. Glacial till and moraines. Halemaumau, Mauna Loa One of the most important events was the advent of the San Andreas Fault around 29 million years ago in the Oligocene, when the region subducted a spreading center in the East Pacific Rise. The 7.6 magnitude 1952 Kern County earthquake was one of the most powerful in California in the 20th century. Britton Silt Loams, 30 to 50 percent slopes soils are characterized as being relatively shallow (10 to 20inches), and well drained with moderately slow permeability. 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 eastern portion of the property is underlain by Plio-Pleistocene olivine basalt flows such as those exposed by the falls on Burney Creek (CDMG, 1994). Large boulders have often eroded out of moraine deposits, coming to rest a few miles away. Lava lakes. 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. However some areas are virtually devoid of vegetation, due to deficient nutrient supplies (NRCS, 2000). The Modoc Plateau and surrounding area is a predominantly rural region of northeastern California, southern Oregon, and northwestern Nevada, centered on the Modoc Plateau physiographic province ().In general, the Modoc study area is characterized by elevated heat flow (Williams and DeAngelo, 2011) and some 30 known geothermal systems as identified by thermal springs and wells (Faulds et al . Geologists have struggled to define its structural geology with complex sequences of deep ocean crust, upper mantle rock and tectonic melanges. Adherence to standard grading practices as required by the grading permit would ensure that the impacts from erosion would be less-than-significant. The Modoc Plateau is part of the larger Columbia Plateau which extends into eastern Oregon and Washington, southern Idaho, northern Nevada and western Wyoming. Mercury was first discovered in Santa Barbara County in 1796. Some Great Valley rocks are exposed in the Coastal Ranges as well, like the Jurassic Knoxville Formation shale. [12] The Ventura Avenue field, north of Ventura is one of the largest fields in California, producing since 1903. In addition to gold, platinum is sometimes found with gold placers. 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. The Warner Basalt is the most common rock in the plateau, bordered by the Surprise Valley fault zone that first became active in the Miocene 15 million years ago. Based on faulting in recent alluvial material, the Surprise Valley fault zone is still active. In places includes talus and slope wash. During the Nevadan orogeny in the Jurassic, extensive folding and faulting altered the rocks and huge granite batholiths erupted. The West Shasta district has a long history of copper and zinc production out of chalcopyrite and sphalerite. Includes some Mesozoic rocks. GitHub export from English Wikipedia.