Question: The Cheakamus Valley basalts are part of what southwestern British Columbia formation?

full_context: Document 1: Axial Seamount: Axial Seamount (also Coaxial Seamount or Axial Volcano) is a seamount and submarine volcano located on the Juan de Fuca Ridge, approximately 480 km west of Cannon Beach, Oregon. Standing 1100 m high, Axial Seamount is the youngest volcano and current eruptive center of the Cobb-Eickelberg Seamount chain. Located at the center of both a geological hotspot and a mid-ocean ridge, the seamount is geologically complex, and its origins are still poorly understood. Axial Seamount is set on a long, low-lying plateau, with two large rift zones trending 50 km to the northeast and southwest of its center. The volcano features an unusual rectangular caldera, and its flanks are pockmarked by fissures, vents, sheet flows, and pit craters up to 100 m deep; its geology is further complicated by its intersection with several smaller seamounts surrounding it.
Document 2: Cheakamus River: The Cheakamus River (pron. CHEEK-a-mus) is a tributary of the Squamish River, beginning on the west slopes of Outlier Peak in Garibaldi Provincial Park upstream from Cheakamus Lake on the southeastern outskirts of the resort area of Whistler. The river flows into Cheakamus Lake before exiting it and flowing northwest until it turns south and enters Daisy Lake. Between the outlet of Daisy Lake and its mouth, much of its length is spent going through Cheakamus Canyon, where the river flows through swift rapids and even one good sized waterfall. The river flows south from the lake and through the canyon before joining the Squamish River at Cheekye, a few miles north of the town of Squamish. The river's name is an anglicization of the name of Chiyakmesh ("people of the fish weir"), a village of the Squamish people and a reserve of the Squamish Nation.
Document 3: Leech River Fault: The Leech River Fault extends across the southern tip of Vancouver Island in British Columbia, Canada, creating the distinctively straight, narrow, and steep-sided valley occupied by Loss Creek and two reservoirs that runs from Sombrio Point (southeast of Port Renfrew) due east to the Leech River, and then turns southeast to run past Victoria. It is a thrust fault that marks the northernmost exposure of the Crescent terrane (part of Siletzia), where basalt of the Metchosin Igneous Complex (correlative with the Crescent Formation on the Olympic Peninsula) is dragged under Vancouver Island by the subducting Juan de Fuca Plate. About ten kilometers north the nearly parallel "San Juan Fault" marks the southern limit of rock of the Wrangellia terrane, which underlies most of Vancouver Island. Between these two northeast-dipping thrust faults are the "Leech River Complex" and (near Port Renfrew, but also outcrops near Victoria) the "Pandora Peak Unit". These, along with the "Pacific Rim Complex" further up the coast, are remnants of the "Pacific Rim terrane" which was crushed between Wrangellia and Siletzia. The contact between the bottom of Wrangellia and the top of the subducted PRT continues northwest along the coast as the "West Coast Fault", and southeast towards Victoria as the "Survey Mountain Fault". The Leach River Fault (LRF) extends off-shore towards Cape Flattery, where the Crescent—Pacific Rim contact continues northwest as the "Tofino Fault" (TF).
Document 4: Pacific Northwest: The Pacific Northwest (in the United States, commonly abbreviated as PNW), sometimes referred to as Cascadia, is a geographic region in western North America bounded by the Pacific Ocean to the west and (loosely) by the Cascade Mountain Range on the east. Though no agreed boundary exists, a common conception includes the U.S. states of Oregon and Washington and the Canadian province of British Columbia. Broader conceptions reach north into Alaska and Yukon, south into northern California and east to the Continental Divide, thus including Idaho, Western Montana, and western Wyoming. Idaho, Wyoming, and Montana are more accurately termed the Inland Northwest (INW), as the climate, folia, fauna, and politics are different than in the Pacific Northwest, as well as a different time zone in all but North Idaho. Narrower conceptions may be limited to the northwestern US or to the coastal areas west of the Cascade and Coast mountains. The variety of definitions can be attributed to partially overlapping commonalities of the region's history, geography, society, and other factors.
Document 5: Latah Formation: The Latah Formation is a series of late Miocene lacustrine sedimentary deposits which outcrop in eastern Washington and northwestern Idaho. The lake beds are interbedded with igneous rock of the Columbia River Basalt Group. The formation was originally named from a site in Spokane, Washington by Dr. Kirk Bryan in 1923. Numerous fossil plants and insects have been recovered from the formation and described. When first described the formation was thought to have predated the deposition of the Columbia River Basalts, however further investigation showed them to be interbedded, being laid down in successive events. Potassium-argon dating of the formation returned an age range of 21.3 to 12.1 million years old, indicating an Early to Middle Miocene age range.
Document 6: Coast Mountains: The Coast Mountains are a major mountain range in the Pacific Coast Ranges of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia south to the Fraser River. The mountain range's name derives from its proximity to the sea coast, and it is often referred to as the Coast Range. The range includes volcanic and non-volcanic mountains and the extensive ice fields of the Pacific and Boundary Ranges, and the northern end of the volcanic system known as the Cascade Volcanoes. The Coast Mountains are part of a larger mountain system called the Pacific Coast Ranges or the Pacific Mountain System, which includes the Cascade Range, the Insular Mountains, the Olympic Mountains, the Oregon Coast Range, the California Coast Ranges, the Saint Elias Mountains and the Chugach Mountains. The Coast Mountains are also part of the American Cordilleraa Spanish term for an extensive chain of mountain rangesthat consists of an almost continuous sequence of mountain ranges that form the western backbone of North America, Central America, South America and Antarctica.
Document 7: Karmutsen Formation: The Karmutsen Formation is a Late Triassic volcanic sequence of tholeiitic pillow basalts and breccias on Vancouver Island, British Columbia, Canada. It is perhaps the thickest accreted section of an oceanic plateau worldwide, exposing up to 6000 m of basal sediment-sill complexes, basaltic to picritic pillow lavas, pillow breccia, and thick, massive basalt flows. The widespread succession of basalts and breccias are part of the Insular Mountains, a large volcanic mountain range that forms Vancouver Island and the Queen Charlotte Islands. In Strathcona Provincial Park, pillow basalts is the most abundant rock unit. About half the mountains, including the highest ones, are carved from these basalts, such as Golden Hinde, which is the highest peak on Vancouver Island.
Document 8: Yamsay Mountain: Yamsay Mountain is a large shield volcano in the Cascade Range of south-central Oregon, located about 35 mi east of Crater Lake on the border between Klamath County and Lake County. It is part of the Cascade Volcanic Arc but is located in a mountain range 30 to behind the main Cascade volcanic front. The best known members of this enigmatic arc are the massive shields of Newberry Volcano, about 55 mi farther north in Oregon, and Medicine Lake Volcano, about 80 mi south in Northern California. Yamsay is the highest volcano in the eastern arc, almost 300 ft higher than Newberry and Medicine Lake.
Document 9: Cascade Range: The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades. The small part of the range in British Columbia is referred to as the Canadian Cascades or, locally, as the Cascade Mountains. The latter term is also sometimes used by Washington residents to refer to the Washington section of the Cascades in addition to North Cascades, the more usual U.S. term, as in North Cascades National Park. The highest peak in the range is Mount Rainier in Washington at 14411 ft .
Document 10: Geology of the Lassen volcanic area: 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 (see Geology of the Pacific Northwest) and is also responsible for activities in the Lassen volcanic area.
Document 11: Columbia River: The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada. It flows northwest and then south into the US state of Washington, then turns west to form most of the border between Washington and the state of Oregon before emptying into the Pacific Ocean. The river is 1243 mi long, and its largest tributary is the Snake River. Its drainage basin is roughly the size of France and extends into seven US states and a Canadian province. The fourth-largest river in the United States by volume, the Columbia has the greatest flow of any North American river entering the Pacific.
Document 12: Eastern Cascades Slopes and Foothills (ecoregion): The Eastern Cascades Slopes and Foothills ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Oregon, Washington, and California. In the rain shadow of the Cascade Range, the eastern side of the mountains experiences greater temperature extremes and receives less precipitation than the west side. Open forests of ponderosa pine and some lodgepole pine distinguish this region from the Cascades ecoregion, where hemlock and fir forests are more common, and from the lower, drier ecoregions to the east, where shrubs and grasslands are predominant. The vegetation is adapted to the prevailing dry, continental climate and frequent wildfire. Volcanic cones and buttes are common in much of the region.
Document 13: Mount Baker: Mount Baker (Lummi: "Qwú’mə Kwəlshéːn "; Nooksack: "Kw’eq Smaenit" or "Kwelshán "), also known as Koma Kulshan or simply Kulshan, is an active glaciated andesitic stratovolcano in the Cascade Volcanic Arc and the North Cascades of Washington in the United States. Mount Baker has the second-most thermally active crater in the Cascade Range after Mount Saint Helens. About 31 mi due east of the city of Bellingham, Whatcom County, Mount Baker is the youngest volcano in the Mount Baker volcanic field. While volcanism has persisted here for some 1.5 million years, the current glaciated cone is likely no more than 140,000 years old, and possibly no older than 80–90,000 years. Older volcanic edifices have mostly eroded away due to glaciation.
Document 14: Cheakamus Valley basalts: The Cheakamus Valley basalts are a sequence of basaltic lava flows along the Cheakamus River in southwestern British Columbia, Canada. They are part of the Garibaldi section of the Cascade Volcanic Arc and were produced during an episode of volcanic eruptions from an unknown vent. The latest basaltic eruption deposited wood in lacustrine sediments under the lava flows that have been dated 34,200 ± 800 years old. These youngest lavas form isolated ridges above the older glaciated Cheakamus Valley basalts and were described as "esker-like" by Canadian volcanologist Bill Mathews.
Document 15: Cascade Volcanoes: The Cascade Volcanoes (also known as the Cascade Volcanic Arc or the Cascade Arc) are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 mi . The arc has formed due to subduction along the Cascadia subduction zone. Although taking its name from the Cascade Range, this term is a geologic grouping rather than a geographic one, and the Cascade Volcanoes extend north into the Coast Mountains, past the Fraser River which is the northward limit of the Cascade Range proper.
ground_truth: Cascade Volcanoes