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Keweenaw Fault
The Keweenaw Fault is a reverse fault that bisects the Keweenaw Peninsula of the Upper Peninsula of Michigan. The fault thrusts lava flows of the Midcontinent Rift System onto sedimentary rocks of the Jacobsville Sandstone. The fault is part of the inversion of the Midcontinent Rift where a region that had previously undergone extension experienced significant contraction. This contraction occurred during the final stages of the Grenvillian orogeny. The Keweenaw Peninsula, itself, is the southeastern side of a large syncline beneath Lake Superior. The northwestern side forms Isle Royale. The fault is more than long and extends from the tip of the Keweenaw Peninsula in the northeast to a termination near the Michigan-Wisconsin border in the southeast. The fault is most likely younger than the Jacobsville Formation and the Devonian Period. A seismic event in 1906 claimed to be an earthquake has been attributed to a rock burst, as the area has been significantly mined. The Natural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Lake Superior
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences, including hydrology, and so is treated as one major aspect of integrated Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Earth's past climates. Geologists broadly study the properties and processes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reverse Fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keweenaw Peninsula
The Keweenaw Peninsula ( , sometimes locally ) is the northernmost part of Michigan's Upper Peninsula. It projects into Lake Superior and was the site of the first copper boom in the United States, leading to its moniker of "Copper Country." As of the 2000 census, its population was roughly 43,200. Its major industries are now logging and tourism, as well as jobs related to Michigan Technological University and Finlandia University. Geology The peninsula measures about 150 miles in length and about 50 miles in width at its base. The ancient lava flows of the Keweenaw Peninsula were produced during the Mesoproterozoic Era as a part of the Midcontinent Rift between 1.096 and 1.087 billion years ago. This volcanic activity produced the only strata on Earth where large-scale economically recoverable 97 percent pure native copper is found. Much of the native copper found in the Keweenaw comes in either the form of cavity fillings on lava flow surfaces, which has a ”lacy” cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Peninsula Of Michigan
The Upper Peninsula of Michigan – also known as Upper Michigan or colloquially the U.P. – is the northern and more elevated of the two major landmasses that make up the U.S. state of Michigan; it is separated from the Lower Peninsula by the Straits of Mackinac. It is bounded primarily by Lake Superior to the north, separated from the Canadian province of Ontario at the east end by the St. Marys River, and flanked by Lake Huron and Lake Michigan along much of its south. Although the peninsula extends as a geographic feature into the state of Wisconsin, the state boundary follows the Montreal and Menominee rivers and a line connecting them. First inhabited by Algonquian-speaking native American tribes, the area was explored by French colonists, then occupied by British forces, before being ceded to the newly established United States in the late 18th century. After being assigned to various territorial jurisdictions, it was granted to the newly formed state of Michigan as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Midcontinent Rift System
The Midcontinent Rift System (MRS) or Keweenawan Rift is a long geological rift in the center of the North American continent and south-central part of the North American plate. It formed when the continent's core, the North American craton, began to split apart during the Mesoproterozoic era of the Precambrian, about 1.1 billion years ago. The rift failed, leaving behind thick layers of igneous rock that are exposed in its northern reaches, but buried beneath later sedimentary formations along most of its western and eastern arms. Those arms meet at Lake Superior, which is contained within the rift valley. The lake's north shore in Ontario and Minnesota defines the northern arc of the rift. From the lake, the rift's eastern arm trends south to central lower Michigan, and possibly into Indiana, Ohio, Kentucky, Tennessee, and Alabama. The western arm runs from Lake Superior southwest through portions of Wisconsin, Minnesota, Iowa, and Nebraska to northeastern Kansas, and po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacobsville Sandstone
Jacobsville Sandstone is a red sandstone formation, marked with light-colored streaks and spots, primarily found in northern Upper Michigan, portions of Ontario, and under much of Lake Superior. Desired for its durability and aesthetics, the sandstone was used as an architectural building stone in both Canada and the United States. The stone was extracted by thirty-two quarries throughout the Upper Peninsula of Michigan approximately between 1870 and 1915. The sandstone has been variously called redstone, brownstone, Lake Superior Sandstone, and Eastern Sandstone. In 1907, the Jacobsville Formation was given its current classification and the name ''Jacobsville'', in honor of Jacobsville, Michigan, a town known for its production of the sandstone. The sandstone was deposited within terrestrial fluvial environments early in the Neoproterozoic Era. Geology Classification The earliest geologic studies of southern Lake Superior were made in the early 1800s. Many studies used th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grenvillian Orogeny
The Grenville orogeny was a long-lived Mesoproterozoic mountain-building event associated with the assembly of the supercontinent Rodinia. Its record is a prominent orogenic belt which spans a significant portion of the North American continent, from Labrador to Mexico, as well as to Scotland. Grenville orogenic crust of mid-late Mesoproterozoic age (c. 1250–980 Ma) is found worldwide, but generally only events which occurred on the southern and eastern margins of Laurentia are recognized under the "Grenville" name. These orogenic events are also known as the Kibaran orogeny in Africa and the Dalslandian orogeny in Western Europe. Timescale The problem of timing the Grenville orogeny is an area of some contention today. The timescale outlined by Toby Rivers in 2008 is derived from the well-preserved Grenville Province and represents one of the most detailed records of the orogeny. This classification considers the classical Grenville designation to cover two se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syncline
In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed smaller folds. Synclines are typically a downward fold (synform), termed a synformal syncline (i.e. a trough), but synclines that point upwards can be found when strata have been overturned and folded (an antiformal syncline). Characteristics On a geologic map, synclines are recognized as a sequence of rock layers, with the youngest at the fold's center or ''hinge'' and with a reverse sequence of the same rock layers on the opposite side of the hinge. If the fold pattern is circular or elongate, the structure is a basin. Folds typically form during crustal deformation as the result of compression that accompanies orogenic mountain building. Notable examples * Powder River Basin, Wyoming, US * Sideling Hill roadcut along Interstate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Superior
Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh water. The northern and westernmost of the Great Lakes of North America, it straddles the Canada–United States border with the province of Ontario to the north and east, and the states of Minnesota to the northwest and Wisconsin and Michigan to the south. It drains into Lake Huron via St. Marys River, then through the lower Great Lakes to the St. Lawrence River and the Atlantic Ocean. Name The Ojibwe name for the lake is ''gichi-gami'' (in syllabics: , pronounced ''gitchi-gami'' or ''kitchi-gami'' in different dialects), meaning "great sea". Henry Wadsworth Longfellow wrote this name as "Gitche Gumee" in the poem ''The Song of Hiawatha'', as did Gordon Lightfoot in his song " The Wreck of the ''Edmund Fitzgerald''". According to oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isle Royale
Isle Royale National Park is an American national park consisting of Isle Royale – known as Minong to the native Ojibwe – along with more than 400 small adjacent islands and the surrounding waters of Lake Superior, in the state of Michigan. Isle Royale is long and wide, with an area of , making it the fourth-largest lake island in the world. In addition, it is the largest natural island in Lake Superior, the second-largest island in the Great Lakes (after Manitoulin Island), the third-largest in the contiguous United States (after Long Island and Padre Island), and the 33rd-largest island in the United States. Isle Royale National Park was established on April 3, 1940, then additionally protected from development by wilderness area designation in 1976, declared a UNESCO International Biosphere Reserve in 1980, and added to the National Register of Historic Places in 2019 as the Minong Traditional Cultural Property. The park covers , with of land and of surroundin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Geological Survey
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization's work spans the disciplines of biology, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility. The agency was founded on March 3, 1879. The USGS is a bureau of the United States Department of the Interior; it is that department's sole scientific agency. The USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices near Lakewood, Colorado, at the Denver Federal Center, and Menlo Park, California. The current motto of the USGS, in use since August 1997, is "science for a changing world". The agency's previous slogan, adopted on the occasion of its hundredt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacobsville Formation
Jacobsville Sandstone is a red sandstone formation, marked with light-colored streaks and spots, primarily found in northern Upper Michigan, portions of Ontario, and under much of Lake Superior. Desired for its durability and aesthetics, the sandstone was used as an architectural building stone in both Canada and the United States. The stone was extracted by thirty-two quarries throughout the Upper Peninsula of Michigan approximately between 1870 and 1915. The sandstone has been variously called redstone, brownstone, Lake Superior Sandstone, and Eastern Sandstone. In 1907, the Jacobsville Formation was given its current classification and the name ''Jacobsville'', in honor of Jacobsville, Michigan, a town known for its production of the sandstone. The sandstone was deposited within terrestrial fluvial environments early in the Neoproterozoic Era. Geology Classification The earliest geologic studies of southern Lake Superior were made in the early 1800s. Many studies used the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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