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- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/07%3A_Cascade_Range_and_Modoc_Plateau/7.06%3A_Lassen_Volcanic_National_ParkPrior to the eruption of Mount Saint Helens in 1980, the 1915 Lassen Peak eruption was the most famous volcanic eruption in US History. Today, the park is known for a variety of volcanic features, no...Prior to the eruption of Mount Saint Helens in 1980, the 1915 Lassen Peak eruption was the most famous volcanic eruption in US History. Today, the park is known for a variety of volcanic features, not just for the evidence of the eruption. Four types of volcanoes can all be found in the park. The park also hosts hot springs and geysers that are the result of hydrothermal heating from the magma chamber at depth.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/10%3A_Klamath_Mountains/10.05%3A_Uplifting_a_Mountain_RangeThe Klamath Mountains province has not always been a mountain range. During the Cretaceous Period, the Klamath province was likely eroded to a flat continental shelf with a thick covering of marine se...The Klamath Mountains province has not always been a mountain range. During the Cretaceous Period, the Klamath province was likely eroded to a flat continental shelf with a thick covering of marine sediment. The Klamath Mountains were then uplifted during the Miocene Epoch and the marine sediments were nearly entirely eroded. The mountains that we see today were also heavily carved by Pleistocene glaciation.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/10%3A_Klamath_Mountains/10.04%3A_Plutons_of_the_Klamath_MountainsWhile terranes were being accreted in the Klamath Mountains province, arc volcanism also continued. At some times this volcanism produced island arcs (which became the terranes) and other times, it pr...While terranes were being accreted in the Klamath Mountains province, arc volcanism also continued. At some times this volcanism produced island arcs (which became the terranes) and other times, it produced continental arc mountain ranges. Though the volcanic ranges themselves are long gone, the magma chambers that fed them are still visible in the form of plutons. Castle Crags is perhaps the most famous of the plutonic rock formations in the Klamath Mountains, but there are many others.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/07%3A_Cascade_Range_and_Modoc_Plateau/7.04%3A_Volcanic_HazardsThere are a variety of volcanic Hazards in the California Cascades. Lava flows form when molten rock reaches the surface of the earth and flows across the ground or down the slopes of a volcano. Pyr...There are a variety of volcanic Hazards in the California Cascades. Lava flows form when molten rock reaches the surface of the earth and flows across the ground or down the slopes of a volcano. Pyroclastic flows are a mixture of gas, ash and other debris that flows along the ground surface. Lahars are water-based mudflows composed of volcanic material that can form with or without a volcanic eruption. Ash and tephra are ejected in the air and can rain down far from the volcano.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/10%3A_Klamath_MountainsThis page discusses the Klamath Mountains in Northwest California and Oregon, highlighting their rugged terrain, significant geological history involving terrane accretion, and diverse rock sequences....This page discusses the Klamath Mountains in Northwest California and Oregon, highlighting their rugged terrain, significant geological history involving terrane accretion, and diverse rock sequences. It mentions eleven wilderness areas and key geological features like the Josephine Ophiolite, which aid in understanding oceanic crust and continental formation. Current research focuses on the elevation of the mountains and detailed accretion processes.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/10%3A_Klamath_Mountains/10.06%3A_Chapter_SummaryA summary of the Klamath Mountains chapter.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/07%3A_Cascade_Range_and_Modoc_Plateau/7.05%3A_Mount_ShastaMount Shasta is California’s iconic composite volcano. The modern edifice has been built over the past 250,000 years, through four cone-building episodes. Mount Shasta is ranked fifth in the U.S. Geo...Mount Shasta is California’s iconic composite volcano. The modern edifice has been built over the past 250,000 years, through four cone-building episodes. Mount Shasta is ranked fifth in the U.S. Geological Survey’s National Volcanic Threat Assessment, meaning that there is a significant potential for a future eruption. There is also a risk of lahars or debris flows that are not associated with an eruption, as hot summer temperatures result in rapid melting of glaciers.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/10%3A_Klamath_Mountains/10.03%3A_The_Josephine_Ophiolite-_A_Little_Slice_of_the_MantleOceanic crust is the most common type of crust on earth, yet its structure is rarely seen in outcrops. A rare process called obduction emplaces oceanic lithosphere on or in continental lithosphere and...Oceanic crust is the most common type of crust on earth, yet its structure is rarely seen in outcrops. A rare process called obduction emplaces oceanic lithosphere on or in continental lithosphere and later uplift can expose this rock at the surface. The resulting rock formation is known as an ophiolite. The ophiolite sequence results from magmatic processes present at mid ocean ridges. The Josephine Ophiolite of Oregon and California makes a particularly good case-study ophiolite.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/10%3A_Klamath_Mountains/10.02%3A_The_McCloud_Limestone-_An_Ancient_Coral_ReefFossils in the Permian McCloud Limestone of the Eastern Klamath Terrane give paleontologists a glimpse of the coral reef communities that existed prior to Earth’s most devastating mass extinction. Com...Fossils in the Permian McCloud Limestone of the Eastern Klamath Terrane give paleontologists a glimpse of the coral reef communities that existed prior to Earth’s most devastating mass extinction. Comparison of the fossils found here to fossils found elsewhere in California provides evidence that these reefs formed far from the mainland continent.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/07%3A_Cascade_Range_and_Modoc_Plateau/7.09%3A_Chapter_SummaryA summary of the Cascade Range and Modoc Plateau chapter.
- https://geo.libretexts.org/Sandboxes/ajones124_at_sierracollege.edu/Geology_of_California_(DRAFT)/07%3A_Cascade_Range_and_Modoc_Plateau/7.08%3A_Glaciers_in_the_CascadesThere are not many glaciers still present in the California Cascades, as they make up the southernmost part of the Cascade Range. However, during the Pleistocene ice ages, glaciers were extensive. V...There are not many glaciers still present in the California Cascades, as they make up the southernmost part of the Cascade Range. However, during the Pleistocene ice ages, glaciers were extensive. Volcanic rock is often easily eroded by glaciers, and thus these glaciers significantly shaped the landscape of the Cascades. The only glaciers that remain in the California Cascades today are on Mount Shasta, but these too are threatened as the climate continues to warm.
