A harrowing obstacle for oregon trail pioneers, today this route up into the blues is pure delight, winding past rolling ranchlands, rocky peaks, wild rivers and. When the granitic magma cooled, various minerals formed along the contact zone with the older sedimentary rock and gold and silver collected in the granites quartz veins. Modified from miller, 2014, roadside geology of oregon, 2ed. A brief summary of oregon coast range geology, geomorphology. The highest peaks are the elkhorn mountains in oregon, which reach an elevation of 9,108 feet. The information desired has in part been published by the geological survey as sepa rate reports, the supply of nearly all of which has been exhausted. Geology faculty publications geology western washington. Geology of lode gold districts in the klamath mountains.
Geology of the blue mountains region of oregon, idaho, and washington. While the sheep rock unit has several trails for hiking, the highlight of our trip was the blue basin trail 3. Slightly less than a sixth of oregon s land area, the region occupies about 15,000 square miles. The town of greenhorn, at 6,300 feet in elevation, is oregons highest incorporated city. Its correlation with the northwestern boundaries of the klamath and blue mountain provinces suggests that these are continuous beneath the cascade volcanic. The terranes of the blue mountains formed in and around an ancient subduction zone. Housen pdf construction, emplacement, and geochemical evolution of deepcrustal intrusions.
Finally the blue mountains were pushed up and the coastal sediments sagged, creating the eastern escarpment of the blue mountains. Oregon geology by elizabeth and william orr is the real deal a geologic reference written for and by geologists. Crustal structure beneath the blue mountains terranes and. Ore bin oregon geology magazine journal oregon department. New evidence, based on mineral dating, suggests that rocks of the blue mountains, the oldest geological formation in oregon, may have been derived from. Paleomagnetism and rotation history of the blue mountains, oregon, usa, bernard a. Historically, most of the mapping in the blue mountains has been along the western margin. Accreted terranes form the foundation of both the blue.
Vallier 1995 petrology of pretertiary igneous rocks in the blue mountains region of oregon, idaho, and washington. The geology of the blue mountains records much of the early permian 295ma to middle triassic 240ma fig2 sedimentation on the stable, western margin of the sydney basin. Tenpeak and dirtyface plutons, north cascades, western north america, robert b. At several spots along the now busy, motorized thoroughfare of i84, travelers can stop and step in actual ruts left by the thousands of oregon trail wagon trains. The rocks and volcanoes were rafted toward the continental margin on a moving tectonic plate, and eventually accreted to the continental margin. This professional paper contains 14 chapters on the blue mountains region of oregon, idaho, and washington. The metamorphic petrology and structural geology of the serpentinite. It provides a diverse complex of mountain ranges, valleys, and plateaus that extend beyond oregon into the states of idaho and washington. The range has an area of about 15,000 square miles 38,850 km 2, stretching east and southeast of pendleton, oregon, to the snake river along the oregon idaho border.
Rivers slowly cut deep gorges through the sandstone, coal shale and lava rock layers, gradually washing away immense volumes of rock shown in brown on above diagram and producing the blue mountains landscape of today. The flat topped mesas of the table rocks, with their own. Hogenson, glenmore melvin, 1923 geology and ground water of the umatilla river basin, oregon. Geological history of the blue mountains comleroy road. Blue mountains geology 308 with miles at university of. A brief summary of oregon coast range geology, geomorphology, tectonics, and climate geology 4510. The range averages 1,500 feet in elevation and has a maximum elevation. Petrography of pretertiary rocks of the blue mountains. Geology of the blue mountains region of oregon, idaho, and washington u. Dissertations and theses department of earth sciences. Photos of the southern blue mountains this geology also led to the historical mining activity of the last 150 years. Geology of the blue mountains region of oregon, idaho, and. Most of the blue mountains are underlain by the columbia river basalt group crb lava flows, primarily the grande ronde basalt, which erupted around 16.
The blue mountains are a mountain range in the western united states, located largely in northeastern oregon and stretching into southeastern washington. Mar 17, 2018 located between john day and the elkhorn mountains, the greenhorn mountains are a low uplift within the blue mountains. Dec 29, 2014 5 years living in a 5ft bed toyota tacoma minimalist nomad micro home update duration. A forest service stream and riparian restoration network has been created to facilitate knowledge and technology transfer between forest service personnel throughout the agency. Regional gravity data clearly show a zone of southwestnortheast lineations across oregon that defines a major crustal lineament. The blue mountains, perhaps the most geologically diverse part of oregon, consist of a series of mountain ranges, rolling uplands, and valleys in the northeastern part of the state and extending into southeastern washington. Mesozoic collision and accretion of oceanic terranes in the blue mountains province of northeastern oregon. The blue mountains, perhaps the most geologically diverse part of. Geologic mapping in the klamath mountains is difficult due to the ruggedness of the terrain and limited access.
Sign up now to be included in the public distribution list, to connect with others who have duties that include a focus on stream and riparian restoration. Oregon department of transportation environmental section july 2000. Geology of the wallowa terrane, blue mountains province, in the northern part of hells canyon, idaho, washington, and oregon authors tracy l. Mineral ages show blue mountain rocks related to klamath.
The plutons are divided into an earlier series of probable permiantriassic age and a later intrusive series of probable late jurassic to middle cretaceous age. Nine small mesozoic plutons in tjmatilla county, northeast oregon, crop out within an area of 58 sq km in the blue mountains. The trail skirts the north side of the blue basin, then loops around and begins a steep ascent through a narrow canyon. Geology and ground water of the umatilla river basin oregon. The authors discuss petrology and tectonic evolution of an island arc that formed in the ancestral pacific ocean during the permian to cretaceous interval. Hotz the klamath mountains geologic province, in northwestern california and southwestern oregon, is divisible into four northtrending concentric arcuate lithologic belts which are convex to the west. Oregon department of geology and mineral industries.
New insights from the stratigraphic record rebecca j. The former also cuts far back into the region of the northern elkhorn range and heads in the great granodiorite area north of cable cove, near sumpter. Geology of the wallowa terrane, blue mountains province, in. May 12, 2020 final results of the oregon department of geology and mineral industries work on the statewide seismic needs assessment of oregon education and emergency services buildings, as directed by the 73rd legislative assembly senate bill 2, 2005. Oregon produces some of the best gemquality feldspar in the world.
The landforms of oregon are so varied and complex in origin that the authors have divided the book into a series of chapters each addressing a particular geologic province topographic expression. Its existence is supported by geologic and geophysical data. The blue mountains indeed look blue from a distance, a formidable range rising to more than 9,000 feet2,743 meters and stretching from the columbia river southeast to the snake river. The name oregon sunstone is used for gemquality feldspars from oregon, with and without aventurescence. They can be found in colors that range from clear through yellow, orange, pink, red, green, and blue. The southeast ern part of the blue mountains is drained by powder and burnt rivers. Geology of the wallowa terrane, blue mountains province. The gold belt of the blue mountains of oregon download pdf by. Geology of lode gold districts in the klamath mountains, california and oregon by preston e. Millers newly updated roadside geology of oregon provides everything you need to know about pulling over on road trips to gawk at feldspar and fossils. Field trip guide to the upper cretaceous hornbrook formation. Geologic features in the region range from the ancient klamathsiskiyou mountains to the geologically young high cascade mountains. The blue mountains terranes located west of the 87sr86sr 0.
The blue mountains ecoregion is a level iii ecoregion designated by the united states environmental protection agency epa in the pacific northwest, mainly in the state of oregon, with small areas over the state border in idaho and southeastern washington. The accompanying map eovers this area, but does not show quite the full extent toward the west, for gold placers are found on long creek and cottonwood creek, 18 miles west of susan ville, and isolated occurrences even farther westas, for instance, at. Stratigraphic and sedimentological analysis of sedimentary sequences from the wallowa terrane of northeastern oregon has provided a unique insight into the paleogeography and depositional history of the terrane, as well as establishing important constraints on its tectonic evolution and accretionary history. It is also contiguous with the world wildlife fund s blue mountain forests ecoregion. Oregon has some spectacular geology and for all the rockhounds out there, uo geologist marli b. Many emigrant journal accounts record their astonishment at the sight of 200foot tall trees and the view from the blue mountains pass of the high volcanic peaks of the cascade range.
Although a detailed survey of southwestern oregon has not yet been completed, enough has been done to warrant a preliminary report of. Geomorphic and hydraulic effects of large woody debris. Their highest point is vinegar hill, at 8,300 feet. Insights from springdominated streams in the oregon cascades dorsey. Tectonic geomorphology, university of oregon spanning 200 miles along the pacific, the oregon coast range is defined by a 3040 mile wide swath of moderately high mountains. Located in ne oregon, the blue mountains ecoregion is the largest ecoregion in the state. The geology of the blue mountains coxs road dreaming. Geology of southwest oregon southwest oregon has a rich, diverse, and complex geologic history. Concentrations on bedrock and in gravels extent of the placer deposits waldemar lindgren february 14, 1860 november 3, 1939 was a swedishamerican the gold belt of the blue mountains of oregon extract from the 22nd annual report 19001901 part 2. Mountains are drained by thegrande ronde and imnaha rivers, both flowing in sharply cut canyons. Dogami statewide seismic needs assessment home page.
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