The Canadian Shield, also called the Laurentian Shield or the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton, the ancient geologic core of the North American continent. Glaciation has left the area with only a thin layer of soil, through which exposures of igneous bedrock resulting from its long volcanic history are frequently visible. As a deep, common, joined bedrock region in eastern and central Canada, the shield stretches north from the Great Lakes to the Arctic Ocean, covering over half of Canada and most of Greenland; it also extends south into the northern reaches of the continental United States.
Siljan, in Dalarna in central Sweden, is Sweden's seventh largest lake. The cumulative area of Siljan and the adjacent, smaller lakes Orsasjön and Insjön is 354 km2 (137 sq mi). Siljan reaches a maximum depth of 134 m (440 ft), and its surface is situated 161 m (528 ft) above sea level. This renders the lowest point of the basin at 27 metres (89 ft) above sea level. The largest town on its shore is Mora.
The Sudbury Basin, also known as Sudbury Structure or the Sudbury Nickel Irruptive, is a major geological structure in Ontario, Canada. It is the third-largest known impact structure on Earth, as well as one of the oldest. The structure, the eroded remnant of an impact crater, was formed by the impact of an asteroid 1.849 billion years ago in the Paleoproterozoic era.
Cloud Creek crater is an impact crater in Wyoming, United States. The crater is located in Natrona County, about 48 miles (77 km) northwest of Casper, near the center of a geological feature known as the Casper Arch.
Keurusselkä is a lake in Central Finland between the towns of Keuruu to the north and Mänttä to the south. It covers an area of 117.3 km2 (45.3 sq mi). Its average depth is 6.4 m (21 ft) with a maximum depth of 40 m (130 ft). The surface lies at 105.4 m (346 ft) above sea level. The lake is 27 km (17 mi) long and is a part of the Kokemäenjoki water system. Keurusselkä gained international publicity in 2004 when a pair of amateur geologists discovered an ancient impact structure on the western shore of the lake.
Lake Temagami, formerly spelled as Lake Timagami, is a lake in Nipissing District in northeastern Ontario, Canada, situated approximately 80 km north of North Bay. The lake's name comes from dimii-agamiing "tih-MEE-uh-guh-MEENG", which means "it is deep water by the shore" in the Ojibwa language.
Bear Island is an island in Lake Temagami of Northeastern Ontario, Canada. With an area of 4.66 km2 (1.80 sq mi), it is the second largest island in Lake Temagami after Temagami Island. Much of Bear Island is in Joan Township, a geographic township that also includes the Joan Peninsula to the northwest.
Temagami, formerly spelled Timagami, is a municipality in northeastern Ontario, Canada, in the Nipissing District with Lake Temagami at its heart.
The Midcontinent Rift System (MRS) or Keweenawan Rift is a 2,000 km (1,200 mi) 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 possibly into Oklahoma.
In geophysics, a magnetic anomaly is a local variation in the Earth's magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying material. The magnetic variation in successive bands of ocean floor parallel with mid-ocean ridges was important evidence for seafloor spreading, a concept central to the theory of plate tectonics.
The Temagami Greenstone Belt (TGB) is a small 2.7 billion year old greenstone belt in the Temagami region of Northeastern Ontario, Canada. It represents a feature of the Superior craton, an ancient and stable part of the Earth's lithosphere that forms the core of the North American continent and Canadian Shield. The belt is composed of metamorphosed volcanic rocks that range in composition from basalt to rhyolite. These form the east-northeast trend of the belt and are overlain by metamorphosed sedimentary rocks. They were created during several volcanic episodes involving a variety of eruptive styles ranging from passive lava eruptions to viscous explosive eruptions.
The geology of Canada is a subject of regional geology and covers the country of Canada, which is the second-largest country in the world. Geologic units and processes are investigated on a large scale to reach a synthesized picture of the geological development of the country.
Beanland Mine, also known as Clenor Mine, is an abandoned surface and underground mine in Northeastern Ontario, Canada. It is located about 1 km (0.62 mi) west of Arsenic Lake and 4 km (2.5 mi) northwest of the town of Temagami in central Strathy Township. It is named after Sydney Beanland, who first claimed the mine site in the 1920s and was a director for the mine from 1937 to 1938.
Variations in the strength of gravity occur from place to place according to the density distribution of the rocks beneath the surface. Such gravity anomalies have been mapped across the British Isles and adjacent areas and they reveal aspects of these islands’ geological structure.
The Nipissing sills, also called the Nipissing diabase, is a large 2217– to 2210–million year old group of sills in the Superior craton of the Canadian Shield in Ontario, Canada, which intrude the Huronian Supergroup. Nipissing sills intrude all the Huronian sediments and older basement rocks in the northern margin of the Sudbury Basin; they were emplaced after the faulting and folding of Huronian rocks, and are hornblende gabbro of tholeiitic basalt composition. In the Sudbury–Elliot Lake area the Nipissing diabase is deformed; outcrops are parallel to the fold axes of the Huronian sedimentary rocks. Nipissing diabase intrusions are east-northeast trending and are no wider than 460 m (1,510 ft).
Big Dan Mine is an abandoned underground mine in Northeastern Ontario, Canada. It is located about 1 km (0.62 mi) southwest of Net Lake and just west of the Ontario Northland Railway in east-central Strathy Township. It is named after Dan O'Connor, who first claimed the site in the 1890s.
The Charity Shoal crater is a 1.2–1.4 kilometers (0.75–0.87 mi) in diameter circular feature that lies submerged beneath the northeast end of Lake Ontario about 12 kilometers (7.5 mi) southwest of Wolfe Island, and 25 kilometers (16 mi) south of Kingston, Ontario at about latitude 44° 02′ N and longitude 76° 29′ W. It is hypothesized to be a Middle Ordovician impact crater from about 460 million years ago.
O'Connor Mine, also known as Milestone Mine, is an abandoned surface mine in Northeastern Ontario, Canada. It is located about 1 km (0.62 mi) southwest of the town of Temagami near the Northeast Arm of Lake Temagami in northern Strathcona Township. It is named after John O'Connor who first developed the mine site.
The Bangui magnetic anomaly is a local variation in the Earth's magnetic field centered at Bangui, the capital of the Central African Republic. The magnetic anomaly is roughly elliptical, about 700 km × 1,000 km, and covers most of the country, making it one of the "largest and most intense crustal magnetic anomalies on the African continent". The anomaly was discovered in the late 1950s, explored in the 1970s, and named in 1982. Its origin remains unclear.
