Several Quaternary and Holocene faults are located within a 60-mile radius of the site. 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). They have a low erosion hazard from water when bare and a moderate hazard from wind erosion. Includes Pike Creek Formation of Walker and Repenning (1965), originally identified as Pike Creek Volcanic Series by Fuller (1931), and unnamed volcanic and volcaniclastic rocks of southern Lake County, some of which have been correlated with the Miocene and Oligocene Cedarville Formation of northeastern California, Lava flows, breccia, volcaniclastic and epiclastic rocks mostly of andesitic and dacitic composition; includes minor amounts of altered basaltic rocks. A thrust fault, known as the Trinity or Bully Choop thrust, separates the Eastern Klamath Plate from the Central Metamorphic Plate. Modoc Plateau Flood Basalt Layers Earthcache (GC1X4B5) was created by PathfinderMark on 8/11/2009. 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. Their hazard for water and wind erosion is none to low when bare. The Modoc Plateau is a mile-high expansive prehistoric lava flow, with areas of sparse vegetation, rough broken lava rock, juniper trees, and sagebrush flats in a semi-arid region covering about a half-million acres. Gold appears in quartz veins that cut through slate, siltstone and shale originating in the Shasta Bally batholith. Most of the gold deposits date to the Cretaceous and formed in narrow belt around the Melones fault in quartz veins. Forest stand patterns on the landscape often reflect this complex fire history. It is lonely country out in the Modoc. Active subduction began in the Triassic during the Mesozoic, producing large granite intrusions and the beginning of the Nevadan Orogeny as well as more dryland conditions and the retreat of the ocean to the west. Flow in and out of the estuary has been controlled with a man-made structure since heavy silting in 1915. Borehole Conditions The vault is a horizontal tunnel, located beneath 5 meters of overburden to maintain thermal stability. 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. In places contains mollusks or vertebrate fossils indicating Pleistocene age; mostly deposits of late Pleistocene age, but locally includes some deposits of early Holocene age. Geologic guide to the Modoc Plateau and the Warner Mountains : annual field trip guidebook of the Geological Society of Sacramento, 1980. These soils contain a very deep profile and are somewhat poorly drained with moderately slow permeability. 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. Abstract. Without continuous dredging, San Diego Bay would fill with sediment and become dry land with deposition from the San Diego, Sweetwater and Otay rivers. Shasta, Lassen Peak, or Medicine Lake volcanic centers, all of which have had activity within the last 500years (CDMD, 1994). Large boulders have often eroded out of moraine deposits, coming to rest a few miles away. One potassium-argon age of about 28 Ma on porphyritic hornblende andesite from Sheep Creek, southwest corner of Union County, indicates in part coeval with unit Tsf. The Modoc National Forest has four obsidian mines in the Warner Mountains near Davis Creek, Calif. on the east side of the forest where it is legal to collect obsidian with a free permit available from the Forest Supervisor's office in Alturas. Andesite and dacite typically have plagioclase, hornblende, and clinopyroxene phenocrysts; some flows aphyric. The Peninsular Ranges were never glaciated during the Pleistocene. Similar rock formations and patterns are found throughout Ventura County, in the Topatopa Mountains and Pine Mountains. Except for being more saline, these latter soils have very similar characteristics as shown in TableVI-1 (NRCS, 2000). These disturbances could cause increased dust generation, siltation caused by placement of large aggregate on the waterside of levees, local soil compaction caused by equipment loads, and exposure of mineral soil surfaces to erosion. Source: US geologic names lexicon (USGS Bull. The plateaus block faulting is believed to be related to Basin and Range faulting in a terrain immersed by volcanic rocks (CDMG, 1966). These soils formed in basins of mixed alluvium and are moderately deep, poorly drained soils with slow permeability and a high shrink-swell potential (see TableVI-1). 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. Reference: Chorlton, L.B. 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. 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. Shasta, Lassen Peak, or Medicine Lake volcanic centers, all of which have experienced activity within the last 500 years (CDMG, 1994). Mostly nonmarine, but includes marine deposits near the coast. 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). Historically, 20 percent of the four million ounces of gold mined in California originated in the Klamath Mountains. The Peninsular Ranges are a group of mountain ranges that extend 900 miles (1,400km) from the Los Angeles basin and Transverse Ranges southward the entire length of Baja California. During the Jurassic, many sediments shed into the region from the rising proto-Sierra Nevada. 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. Tertiary pyroclastic and volcanic mudflow deposits. Sign In Skip to Main Content Listed on Feb 28, 2023 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. Two small islands to the north: North Island and South Island have been connected with fill to create the Naval Air Station. The rocks likely formed much further away from the Sierras and were relocated by the dramatic movements of faults. Policy SG-f - Shasta County shall pursue preparation of development standards based on topography and soil erosion potential in revising its land capability standards pursuant to Policy CO-h. Policy SG-g - Shasta County should comply with the requirements of the Seismic Hazards Mapping Act, when the Seismic Hazards Maps for the County are completed and made available by the State Geologist. Identify Priority Places: A Practitioner's Guide, Cumberlands and Southern Ridge and Valley, Willamette Valley-Puget Trough-Georgia Basin. The McArthur Swamp, Bowman Ditch, and the Ahjumawi Property are located within or adjacent to the McArthur Fault-Rupture Zone. It is also known for scores oflava-tubecaves and for well-preserved young volcanic features. Franciscan rocks have a complex geological structure. The ecoregion includes a large pumice zone in central Oregon, dominated by lodgepole pine (Pinus contorta), one of the very few places where the species is the climax tree (not replaced by other conifers if fire is suppressed). 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. Therefore, the volcano may be even larger than the estimated 600 km3(143 mi3, already the largest volcano by volume in the Cascade Range. Most intrusive igneous rocks are tonalite, granodiorite, quartz diorite or gabbro. 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. A few may date earlier, like the 400 million year old Mule Mountain. Glass in tuff and tuffaceous sedimentary rocks is commonly altered to zeolites, clay minerals, and small amounts of opal, chalcedony, orthoclase, and calcite. The Mojave Desert extends into areas of Basin and Range terrain and includes some of the oldest rocks exposed at the surface in California. Glacial till and moraines. Requires ability to work and study under rigorous conditions. The mountains are drained by the Russian, Eel, Mad and Klamath rivers which tend to follow faults and folds. Most precipitation accumulates from November through April. The oldest rocks are found in the San Jacinto and Santa Rosa mountains, with schist and gneiss that may be up to 22,000 feet thick. An official website of the United States government. Get this from a library! These different regions are called geological provinces. In Washington, much of the ecoregion is within the ceded lands and usual and accustomed fishing areas of tribes. [9]. 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. The Oldest Rocks: The Piedmont and Blue Ridge Fisher, once common in this ecoregion, now occurs only in the extreme southwestern portion of the East Cascades. The Fall River Valley and McArthur-Burney Fall Memorial State Park are located at the southern end of the Cascade Range within the Modoc Plateau Geomorphic province. The east side of the Warner Mountains in particular has exposed rock in the many canyons, including finds of petrified wood and assorted gemstones. The soils are moderately to strongly alkaline. 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. Lava lakes. Fountains. Lava Beds National Monument is on the Modoc Plateau in Modoc and Siskiyou Counties. Therefore, the transfer would not expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death. The water erosion hazard on these soils is low, while the wind erosion hazard is moderate, due to the high percentage of silt (refer to TableVI-1). Several potassium-argon ages ranging from about 4 to 7 Ma indicate unit is mostly of early Pliocene and late Miocene age. Therefore, a less-than-significant impact is expected. Unconsolidated to semiconsolidated lacustrine clay, silt, sand, and gravel; in places includes mudflow and fluvial deposits and discontinuous layers of peat. Gas was first consumed in Stockton in the 1850s and the massive Rio Vista gas field was discovered in 1936. Much of the remainder of the East Cascades to the north in Oregon is drained by the Deschutes River system, which includes a series of large lakes and reservoirs near its headwaters. flow of the Modoc Plateau exposed in a road cut about 4 miles northeast of Alturas on Highway 395.
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