Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous. Tuff composed of sandy volcanic material can be referred to as volcanic sandstone.
Goat Rocks is an extinct stratovolcano in the Cascade Range, located between Mount Rainier and Mount Adams in southern Washington, in the United States. Part of the Cascade Volcanoes, it was formed by the subduction of the Juan de Fuca Plate under the western edge of the North American Plate. The volcano was active from 3.2 million years ago until eruptions ceased between 1 and 0.5 million years ago. Throughout its complex eruptive history, volcanism shifted from silicic explosive eruptions to voluminous, mafic activity.
Silver Star Mountain is a recently uplifted ridge of older Western Cascades volcanic rock, underlain by a granitic pluton of similar Western Cascades age, located in the Cascade Range in the U.S. state of Washington. Consisting of late Eocene to Oligocene epoch rock, it lies within the Gifford Pinchot National Forest. Silver Star is composed of three lithologic units, including the large Silver Star Granodiorite unit.
Pelican Butte is a steep-sided shield volcano in the Cascade Range of southern Oregon. It is located 28 miles (45 km) due south of Crater Lake and 12 miles (19 km) northeast of Mount McLoughlin. Ice age glaciers carved a large cirque into the northeast flank of the mountain. Several proposals have been made over the last few decades for ski area development on the northeast flanks of the volcano, but there are no current plans to develop a ski area on the mountain.
The Mount Pleasant Caldera is a large eroded Late Devonian volcanic caldera complex, located in the northern Appalachian Mountains of southwestern New Brunswick, Canada. It is one of few noticeable pre-Cenozoic calderas, and its formation is associated to a period of crustal thinning that followed the Acadian orogeny in the northern Appalachian Mountains. It sits relatively near to the coastline.
The Siletz River Volcanics, located in the Oregon Coast Range, United States, are a sequence of basaltic pillow lavas that make up part of Siletzia. The basaltic pillow lavas originally came from submarine volcanoes that existed during the Eocene.
Trout Creek Hill is a small Pleistocene basaltic shield volcano in Washington, United States. Located in Skamania County, Trout Creek Hill rises to an elevation of 2,946 feet (898 m). It is part of the Cascade Volcanic Arc, located in the Marble Mountain-Trout Creek Hill volcanic field.
Tennena Cone, alternatively Icebridge Cone, is a small volcanic cone in Cassiar Land District of northwestern British Columbia, Canada. It has an elevation of 2,390 metres and lies on the western flank of Ice Peak, the prominent south peak of Mount Edziza. The cone is almost completely surrounded by glacial ice of Mount Edziza's ice cap which covers an area of around 70 square kilometres. Tennena Cone is 200 metres high, 1,200 metres long and up to 600 metres wide, its symmetrical structure resembling a black pyramid. The cone and the surrounding area are in Mount Edziza Provincial Park which also includes the Spectrum Range to the south.
The Canadian Cascade Arc, also called the Canadian Cascades, is the Canadian segment of the North American Cascade Volcanic Arc. Located entirely within the Canadian province of British Columbia, it extends from the Cascade Mountains in the south to the Coast Mountains in the north. Specifically, the southern end of the Canadian Cascades begin at the Canada–United States border. However, the specific boundaries of the northern end are not precisely known and the geology in this part of the volcanic arc is poorly understood. It is widely accepted by geologists that the Canadian Cascade Arc extends through the Pacific Ranges of the Coast Mountains. However, others have expressed concern that the volcanic arc possibly extends further north into the Kitimat Ranges, another subdivision of the Coast Mountains, and even as far north as Haida Gwaii.
The Cardenas Basalt, also known as either the Cardenas Lava or Cardenas Lavas, is a rock formation that outcrops over an area of about 310 km2 (120 mi2) in the eastern Grand Canyon, Coconino County, Arizona. The lower part of the Cardenas Basalt forms granular talus slopes. Its upper part forms nearly continuous low cliffs that are parallel to the general course of the Colorado River. The most complete, readily accessible, and easily studied exposure of the Cardenas Basalt lies in Basalt Canyon. This is also its type locality.
The Semilir eruption was a major volcanic event which took place in Indonesia during the Early Miocene. This eruption formed the Semilir Formation and Nglanngran Formation. These two geological formations are in the Southern Mountains of East Java. The eruption created two formations which consist of mostly pyroclastic rock. It has incredible thickness. In contrast, The Toba supereruption only formed 600 m (2,000 ft) ignimbrite. The estimated Semilir eruption age date by isotope method is 21 million years ago.
El Toro volcanic field is part of the Central Volcanic Zone of the Andes in the northern Puna of Argentina. Three of the cones in the volcanic field are located southwest of the town of El Toro and the fourth is found north. Part of a field of monogenetic volcanoes associated with subduction of the Nazca Plate beneath the South American Plate, it is constructed from three main cones and an additional lava flow. The field formed between six and two million years ago.
The island of Bonaire began to form as part of the Lesser Antilles island arc in the past 145 million years, beginning in the Cretaceous. The island has been submerged or partially submerged for much of its existence, forming large limestone and sedimentary rock formations, atop a thick basement of volcanic rocks.
The geology of Guam formed as a result of mafic, felsic and intermediate composition volcanic rocks erupting below the ocean, building up the base of the island in the Eocene, between 33.9 and 56 million years ago. The island emerged above the water in the Eocene, although the volcanic crater collapsed. A second volcanic crater formed on the south of the island in the Oligocene and Miocene. In the shallow water, numerous limestone formations took shape, with thick alternating layers of volcanic material. The second crater collapsed and Guam went through a period in which it was almost entirely submerged, resembling a swampy atoll, until structural deformation slowly uplifted different parts of the island to their present topography. The process of uplift led to widespread erosion and clay formation, as well as the deposition of different types of limestone, reflecting different water depths.
The geology of the Northern Mariana Islands began to form with undersea volcanic eruptions in the Eocene. Islands such as Saipan show a variety of rock types including volcanic rocks, breccia, tuff, conglomerate, sandstone, clay and extensive limestones.
The geology of Uzbekistan consists of two microcontinents and the remnants of oceanic crust, which fused together into a tectonically complex but resource rich land mass during the Paleozoic, before becoming draped in thick, primarily marine sedimentary units.
Volcaniclastics are geologic materials composed of broken fragments (clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it was deposited in, or whether nonvolcanic material is mingled with the volcanic clasts. The United States Geological Survey defines volcaniclastics somewhat more narrowly, to include only rock composed of volcanic rock fragments that have been transported some distance from their place of origin.
The Vasquez Formation (Tvz) is a geologic formation cropping out at the eponymous Vasquez Rocks in southern California. The formation dates to the Late Oligocene to Early Miocene.
The Newbury Volcanic Complex, also known as the Newbury Formation or the Newbury Volcanics, is a 16 km long, 3 km wide strip of volcanic materials and sediments in northeastern Massachusetts. The complex is made up of ten stratified members and is estimated to be between 3770 m 4400 m in thickness. Due to the fossils that have been found in this formation and with the help of radiometric dating, the Newbury Volcanic Complex has been determined to be Silurian in age, which provides useful information for interpreting the effects of the Acadian orogeny on the New England area.
The volcanic clastic Ohanapecosh Formation is an early state of cascade volcanism. It has been dated to the middle Oligocene [36 to 28 Ma]. The strata are as much as 3 kilometres (1.9 mi) thick, with exposures visible in more than 400 square kilometres of a total area exceeding 700 square kilometres. It is found throughout Mount Rainier National Park and the surroundings mountains. It is the foundation on which the Mt Rainier volcano was built. The formation has been identified in the Snoqualmie area to the north and as far south as the Columbia River Gorge including Mount St. Helens and Mount Adams. It extends from the west at Mt Rainier and Lake Tapps east to Little Naches River valley.
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