The Intermontane Plateaus of the Western United States is one of eight U.S. Physiographic regions (divisions) of the physical geography of the contiguous United States. The region is composed of intermontane plateaus and mountain ranges. It is subdivided into physiographic provinces, which are each subdivided into physiographic sections.
The geology of the Lassen volcanic area presents a record of sedimentation and volcanic activity in the area in and around Lassen Volcanic National Park in Northern California, U.S. The park is located in the southernmost part of the Cascade Mountain Range in the Pacific Northwest region of the United States. Pacific Oceanic tectonic plates have plunged below the North American Plate in this part of North America for hundreds of millions of years. Heat from these subducting plates has fed scores of volcanoes in California, Oregon, Washington and British Columbia over at least the past 30 million years and is also responsible for activities in the Lassen volcanic area.
The richly textured landscape of the United States is a product of the dueling forces of plate tectonics, weathering and erosion. Over the 4.5 billion-year history of our Earth, tectonic upheavals and colliding plates have raised great mountain ranges while the forces of erosion and weathering worked to tear them down. Even after many millions of years, records of Earth's great upheavals remain imprinted as textural variations and surface patterns that define distinctive landscapes or provinces.
The Faroe Islands lie on the Eurasian plate between Scotland, Norway and Iceland. The islands are of volcanic origin and are made up of three layers of basalt, with the top and bottom layers resembling each other. The age of this rock is between 54 and 58 million years, with the oldest material at the bottom.
The Columbia River Basalt Group is a large igneous province that lies across parts of the Western United States. It is found in the U.S. states of Washington, Oregon, Idaho, Nevada, and California. The Basalt group includes the Steen and Picture Gorge basalt formations.
Level Mountain is a massive complex volcano in the Northern Interior of British Columbia, Canada. It is located 50 km (31 mi) north-northwest of Telegraph Creek and 60 km (37 mi) west of Dease Lake on the Nahlin Plateau. With a maximum elevation of 2,166 m (7,106 ft), it is the third highest of five large complexes in an extensive north-south trending volcanic zone. Much of the mountain is gently-sloping; when measured from its base, Level Mountain is about 1,100 m (3,600 ft) tall, slightly taller than its neighbour to the northwest, Heart Peaks. The lower broader half of Level Mountain consists of a shield-like edifice while its upper half has a more steep, jagged profile. Its large summit is dominated by the Level Mountain Range, a small mountain range with prominent peaks cut by deep valleys. These valleys serve as a radial drainage for several small streams that flow from the volcano. Meszah Peak is the only named peak in the Level Mountain Range.
Volcanology of Canada includes lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes, and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds. It has a very complex volcanological history spanning from the Precambrian eon at least 3.11 billion years ago when this part of the North American continent began to form.
The geology of the Pacific Northwest includes the composition, structure, physical properties and the processes that shape the Pacific Northwest region of the United States and Canada. The region is part of the Ring of Fire: the subduction of the Pacific and Farallon Plates under the North American Plate is responsible for many of the area's scenic features as well as some of its hazards, such as volcanoes, earthquakes, and landslides.
The Western Cascades is a region of the U.S. state of Oregon between the Willamette Valley and the High Cascades. The range contains many extinct shield volcanoes, cinder cones and lava flows. The range is highly eroded and heavily forested.
Horeke is a settlement in the upper reaches of the Hokianga Harbour in Northland, New Zealand. Kohukohu is just across the harbour. The Horeke basalts are located near the town, and can be viewed on an easy stroll through the Wairere Boulders, a commercial park.
Maitland Volcano is a heavily eroded shield volcano in the Northern Interior of British Columbia, Canada. It is 83 km (52 mi) southeast of the small community of Telegraph Creek in what is now the Klappan Range of the northern Skeena Mountains. This multi-vent volcano covered a remarkably large area and was topped by a younger volcanic edifice. Little remains of Maitland Volcano today, limited only to eroded lava flows and distinctive upstanding landforms created when magma hardened within the vents of the volcano.
Boulder Park National Natural Landmark, along with the nearby McNeil Canyon Haystack Rocks and Sims Corner Eskers and Kames natural landmarks, illustrate well-preserved examples of classic Pleistocene ice stagnation landforms that are found in Washington. These landforms include numerous glacial erratics and haystack rocks that occur near and on the Withrow Moraine, which is the terminal moraine of the Okanogan ice lobe.
The Flume Gorge is a natural gorge extending 800 feet (240 m) horizontally at the base of Mount Liberty in Franconia Notch State Park, New Hampshire, United States. Cut by the Flume Brook, the gorge features walls of Conway granite that rise to a height of 70 to 90 feet and are 12 to 20 feet apart. Discovered in 1808 by 93-year-old "Aunt" Jess Guernsey, the Flume is now a paid attraction that allows visitors to walk through the gorge.
The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern British Columbia, central Yukon and the U.S. state of easternmost Alaska. The volcanic activity lies in the northern part of the Western Cordillera of the Pacific Northwest region of North America. Extensional cracking of the North American Plate in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of volcanoes throughout the Northern Cordilleran Volcanic Province over at least the past 20 million years and occasionally continued into geologically recent times.
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 Ngaoundéré Plateau is a highland area in the Adamawa Region of Cameroon. It contains Tchabal Nganha, a large volcano, and many other recent volcanic structures.
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.
Loriu Plateau is an elevated Precambrian bedrock exposure at the southwest margin of Lake Turkana in Kenya. The plateau is only seasonally habitable due to aridity and was once home to fauna otherwise rare in Turkana. Loriu is west of and adjacent to the Barrier Volcano at the southernmost portion of Lake Turkana.
The geology of Saint Helena resulted from the long-running volcanic activity of the Saint Helena hotspot. Most of the island was formed beginning 14 million years ago. Volcanism on the island ceased seven million years ago, leading to long-running erosion and the formation of deep, v-shaped valleys along with steep coastal cliffs. Some geochemists have observed significant trace element variations between South Atlantic islands and proposed that deep-ocean sediments may have mixed into the magma which formed Saint Helena.
