The Canadian Shield—also called the Laurentian Plateau, or Bouclier Canadien (French)—is a massive geological shield covered by a thin layer of soil that forms the nucleus of the North American or Laurentia craton. It is an area mainly covered by igneous rock which relates to its long volcanic history.
Lake Agassiz was an immense glacial lake located in the center of North America. Fed by glacial runoff at the end of the last glacial period, its area was larger than all of the modern Great Lakes combined, and it held more water than contained by all lakes in the world today.
The Mesabi Iron Range is a vast deposit of iron ore and the largest of four major iron ranges in the region collectively known as the Iron Range of Minnesota. Discovered in 1866, it is the chief deposit of iron ore in the United States. The deposit is located in northeast Minnesota, largely in Itasca and St. Louis counties. It was extensively worked in the earlier part of the 20th century. Extraction operations declined throughout the mid-1970s but rebounded in 2005.
The St. Peter Sandstone is an Ordovician formation in the Chazyan stage of the Champlainian series. This sandstone originated as a sheet of sand in clear, shallow water near the shore of a Paleozoic sea and consists of fine-to-medium-size, well-rounded quartz grains with frosted surfaces. The extent of the formation spans north-south from Minnesota to Missouri and east-west from Illinois into Nebraska and South Dakota. The type locality for the formation is St. Peter, Minnesota.
Gouverneur Kemble Warren (January 8, 1830 – August 8, 1882) was a civil engineer and prominent general in the Union Army during the American Civil War. He is best remembered for arranging the last-minute defense of Little Round Top during the Battle of Gettysburg and is often referred to as the "Hero of Little Round Top.
The Driftless Area or Paleozoic Plateau is a region in the American Midwest noted mainly for its deeply carved river valleys. While primarily in southwest Wisconsin, it includes areas of southeast Minnesota, northeast Iowa and northwest Illinois (see map at right). This region includes elevations ranging from 603 to 1,719 feet (184 to 524 m) and covers an area of 16,203 square miles (41,986 km²). This region's peculiar terrain is due to its having escaped glaciation in the last glacial period.
The Vermilion Range exists between Tower and Ely, Minnesota, and contains significant deposits of iron ore. The Vermilion, along with the Mesabi and Cuyuna Ranges, constitute the Iron Ranges of northern Minnesota. While the Mesabi Range had iron ore close enough to the surface to enable pit mining, mines on the Vermilion and Cuyuna ranges tended to be deep underground. The Soudan mine was nearly 1/2 mile underground and required blasting of Precambrian sedimentary bedrock.
The Gunflint Range is an iron ore deposit in northern Minnesota in the United States and Northwestern Ontario, Canada. The range extends from the extreme northern portion of Cook County, Minnesota into Canada. The Gunflint is a continuation of the Mesabi Range to the southwest. The two have been separated by the intrusion of the Duluth Gabbro complex. The iron deposit is a banded iron formation of the Early Proterozoic Animikie Group.
The Cuyuna Range is an iron range to the southwest of the Mesabi Range, largely within Crow Wing County, Minnesota. It lies along a line between Brainerd and Aitkin, although those communities are not mining towns. The range was discovered by Cuyler Adams, a surveyor who discovered traces of magnetic ore in 1895 while doing land surveys. The word "Cuyuna" was coined by Adams' wife, who combined the first three letters of Cuyler's name with "Una", the name of their dog.
The Gunflint chert is a sequence of banded iron formation rocks that are exposed in the Gunflint Range of northern Minnesota and western Ontario along the north shore of Lake Superior. The black layers in the sequence contain microfossils that are 1.9 to 2.3 billion years in age. Stromatolite colonies of cyanobacteria that have been converted to jasper are found in Ontario.
The Penokean orogeny was a mountain-building episode that occurred in the early Proterozoic about 1.85 to 1.84 billion years ago, in the area of North America that would eventually become Minnesota, Wisconsin, Michigan and Ontario. It was a major event in the formation of the North American continent, and happened during a worldwide period of mountain building and continent formation.
Glacial Lake Duluth was a proglacial lake that formed in the Lake Superior drainage basin as the Laurentian Glacier retreated. The oldest existing shorelines were formed after retreat from the Greatlakean advance, sometime around 11,000 years B.P. Lake Duluth formed at the western end of the Lake Superior basin. Lake Duluth overflowed south through outlets in Minnesota and Wisconsin at an elevation of around 331 m ASL. The drawing on this page is accurate but uses the obsolete term, "Valders".
Glacial Lake Minong was a proglacial lake that formed in the Lake Superior basin during the Wisconsin glaciation around 10,000 B.P.. This was the last glacial advance that entered Michigan and covered only part of the upper peninsula. Lake Minong occurred in the eastern corner of the Lake Superior basin while Lake Duluth was in the western end. The lakes became separated when the glacier reached the upper peninsula. Lake Minong expanded to the north as the ice retreated after 9,800 B.P.
Kasota limestone or simply, 'Kasota stone,' is a dolomitic limestone found in southern Minnesota. This sedimentary rock is part of the Oneota Dolostone Formation of southern Minnesota and is approximately 450 million years old. This particular limestone is rich in dolomite and magnesium, making it resistant to weathering, and it is thus widely used as a building material.
The geology of Minnesota is the study of the rock, minerals, and soils of the U.S. state of Minnesota, including their formation, development, distribution, and condition. The state's geologic history can be divided into three periods. The first period was a lengthy period of geologic instability from the origin of the planet until roughly 1,100 million years ago.
The Hull-Rust-Mahoning Mine in Hibbing, Minnesota, is the largest open pit iron mine in the world. The mine, located in the Mesabi Range, supplied as much as one-fourth of all the iron ore mined in the United States during its peak production years of World War I and World War II. This area of the Mesabi Range was explored in 1893–1894, shortly after the Mountain Iron mine was established in 1892.
The Midcontinent Rift System (MRS) or Keweenawan Rift is a 2,000 km (1,243 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.
Palisade Head is a large rock formation on the North Shore of Lake Superior in the U.S. state of Minnesota. It is within Tettegouche State Park but not contiguous with the rest of that park. Palisade Head is located at milepost 57 on scenic Minnesota State Highway 61 approximately 54 miles (86 km) northeast of Duluth and three miles (five km) east of Silver Bay.
The glacial history of Minnesota is most defined since the onset of the last glacial period, which ended some 10,000 years ago. Within the last million years, most of the Midwestern United States and much of Canada were covered at one time or another with an ice sheet. This continental glacier had a profound effect on the surface features of the area over which it moved.
The Duluth Complex, the related Beaver Bay Complex (often treated as part of the Duluth Complex), and the associated North Shore Volcanic Group are rock formations which comprise much of the basement bedrock of the of the U.S. state of Minnesota. The Duluth and Beaver Bay complexes are intrusive rocks formed during the formation of the Midcontinental Rift system; they adjoin and are interspersed with the extrusive rocks of the North Shore Volcanic Group produced during the same geologic event.
The Dakota Formation is a geologic formation composed of sedimentary rocks deposited on the western side of the Late Cretaceous Western Interior Seaway. F.B. Meek and F.V. Hayden named it for exposures along the Missouri River near Dakota City, Nebraska. The strata lie unconformably atop Paleozoic and Precambrian rocks, and are the oldest Cretaceous rocks in the northern Great Plains, including Kansas, Nebraska, Iowa, Minnesota, and Wisconsin.
The Traverse Gap is an ancient river channel occupied by Lake Traverse and Big Stone Lake and the valley connecting them at Browns Valley, Minnesota. It is located on the border of the U.S. states of Minnesota and South Dakota. Traverse Gap has an unusual distinction for a valley: it is crossed by a continental divide, and in some floods water has flowed across that divide from one drainage basin to the other.
Glacial River Warren or River Warren was a prehistoric river that drained Lake Agassiz in central North America between 11,700 and 9,400 years ago. The enormous outflow from this lake carved a mighty valley now occupied by the much-smaller Minnesota River and the Upper Mississippi River.
The proglacial lakes of Minnesota were lakes created in what is now the U.S. state of Minnesota in central North America in the waning years of the last glacial period. As the Laurentide ice sheet decayed at the end of the Wisconsin glaciation, lakes were created in depressions or behind moraines left by the glaciers. Evidence for these lakes is provided by topography and sedimentary deposits characteristic of lakebeds, referred to as lacustrine deposits on glaciolacustrine landscapes.
The discovery of Mountain Iron Mine in Mountain Iron, Minnesota in 1890 represents the beginning of the exploitation of the Mesabi Range iron ore in the Iron Range of northeast Minnesota. The Mesabi Range and nearby Vermilion Range led Minnesota to become the nation's largest producer of iron ore and the United States to lead the world in steel production. This capacity is considered to have been a major factor in America's ability to contribute to World War II.