Photograph of a small waterfall in the Old Man's Cave area of Hocking Hills State Park, southeastern Ohio. The photo shows a small waterfall in a channel carved between two low rock cliffs. The archway of a stone bridge crosses above the waterfall. The waterfall drops into a small pool at the base of the rock cliffs.

Geologic History of the Midwestern United States

Page snapshot: Introduction to the geologic history of the midwestern U.S. from the Precambrian to the Quaternary Period.

Topics covered on this page: Hadean to Proterozoic; Canadian Shield; Banded iron formations; Penokean Mountains; Midcontinent Rift System (Keweenawan Rift); Paleozoic; Cambrian to Ordovician; Silurian to Mississippian; Pennsylvanian to Permian; Mesozoic; Quaternary; Resources.

Credits: Most of the text of this page is derived from "Geologic history of the Midwestern US" by Richard A. Kissel and Alex F. Wall, chapter 1 in The Teacher-Friendly Guide to the Geology of the Midwestern USedited by Mark D. Lucas, Robert M. Ross, and Andrielle N. Swaby (published in 2014 by the Paleontological Research Institution; currently out of print). The book was adapted for the web by Elizabeth J. Hermsen and Jonathan R. Hendricks in 2022. Changes include formatting and revisions to the text and images. Credits for individual images are given in figure captions.

Updates: Page last updated September 28, 2022.

Image above: Waterfall, Old Man's Cave area, Hocking Hills State Park, southeastern Ohio. Photo by amanderson2 (flickr, Creative Commons Attribution 2.0 Generic license, image resized).

Hadean to Proterozoic (4.6 billion to 541 million years ago)

Canadian Shield

The shape and position of North America has changed dramatically over the last few billion years, and geologic processes continue these changes today. The Earth is estimated to be approximately 4.6 billion years old. The oldest rocks known are located in northern Quebec and date to 4.3 billion years ago. Rocks dating to 4 billion years old are found on almost every continent. In North America they are found exposed at the surface in parts of Canada, composing the Canadian Shield, the stable core of the North American continental landmass.

The Canadian Shield is the original core, or craton, of the North American continent. It includes much of Greenland, more than half of Canada, and it extends into the Adirondack Mountains of New York and the Superior Upland region of the Midwest. It is an accumulation of smaller plates and terranes that formed over a period of hundreds of millions of years, between 2.5 and 1.25 billion years ago. The shield was the first section of the North American continent to emerge above sea level, and it remains the largest exposure of Precambrian-aged rock in the world.

Map of Precambrian rocks in the midwestern region. The map shows the Midwestern states with the borders of states outlined in black. Most of the region is white, indicating Paleozoic and younger rocks. Keweenawan sedimentary and mafic igneous rocks are shaded dark blue and occur in northeastern Minnesota, northwestern Wisconsin, and the western Upper Peninsula of Michigan. Older Precambrian rocks and shaded light blue and occur in northern Minnesota, Northern Wisconsin, the western Upper Peninsula of Michigan. A few isolated outcrops also occur in the southwestern Minnesota and northwestern Iowa in the Minnesota River Valley and the Sioux Range, as well as in southwestern Wisconsin in the Baraboo Range.

Precambrian outcrops in the Midwest. Adapted in a figure from W.I. Anderson, Iowa's Geological Past: Three Billion Years of Change.

Seven distinct provinces compose the nucleus that is the Canadian Shield. The Superior Province formed about 2.7 billion years ago. It is found in south central Canada, and it extends into northeastern Minnesota, northern Wisconsin, and the western part of the Upper Peninsula of Michigan. Metamorphic gneisses exposed in the Upper Peninsula of Michigan and within the Minnesota River Valley in southern Minnesota represent the oldest rocks found in the Midwest, dating back more than 3.5 billion years. The oldest rocks from Wisconsin are represented by 2.8-billion-year-old gneiss, while Precambrian outcrops in a small area of northwestern Iowa—the Sioux Quartzite in Gitchie Manitou State Preserve—date to 1.7 billion years ago. No Precambrian rocks are exposed in Indiana, Illinois, or Ohio.

Close-up photograph of Archean Morton Gneiss from Morton, Minnesota. The photo shows a rock with irregular vertical bands of alternating pink and gray rock.

Detail of Archean (about 3.52 billion-year-old) Morton Gneiss from Morton, Minnesota. Photo by James St. John (flickr, Creative Commons Attribution 2.0 Generic license, image cropped and resized).

Photograph of a sample of Archean Watersmeet Gneiss from Watersmeet, Michigan. The photo shows a mottled dark gray and pinkish beige rock.

Detail of Archean (about 3.56 billion-year-old) Watersmeet Gneiss from Watersmeet, Michigan. Photo by James St. John (flickr, Creative Commons Attribution 2.0 Generic license, image cropped and resized).

Banded iron formations

The late Archean to Proterozoic of the Midwest was characterized by the deposition and presence of banded iron formations. With the evolution of photosynthetic organisms (still single-celled at this time), their waste product, oxygen, was released into the oceans and ultimately the atmosphere. The oxygen reacted and combined with dissolved iron particles to produce bands of iron oxides such as hematite and magnetite.

Photograph of a banded iron formation from the Archean of Minnesota.

Banded iron formation (jaspilite) from the Soudan Iron-Formation, Minnesota, about 2.7 billion years old. Excerpt from original caption: "The light-colored layers are chert (= microcrystalline to cryptocrystalline quartzose sedimentary rock), the red layers are 'jasper' (= hematite-rich chert), and the silvery-gray layers are magnetite-chert." Information from and photo by James St. John (flickr, Creative Commons Attribution 2.0 Generic license, image cropped and resized).

Penokean Mountains

Between 1.8 and 1.9 billion years ago, an orogenic event produced the Penokean Mountains, which extended from Minnesota into northern Wisconsin and Michigan. The Penokean Orogeny occurred as the Pembine-Wausau island arc and Marshfield terrane collided from the south, increasing the size of the Superior landmass. Erosion of the Penokean Mountains led to deposits of sandstone along the margin of a shallow sea. Around 1.7 billion years ago, after millions of years of heat and pressure, this sandstone produced the metamorphic Sioux Quartzite of Minnesota and Iowa. The Baraboo Quartzite of the Devil’s Lake area in central Wisconsin also dates to this time.

Map of Precambrian provinces and terranes in the midwestern region. The map shows part of the Midwest and southern Canada with the borders of states and provinces outlined in black. The Superior Province is shaded gray. It extends across the north of the map, including southern Saskatchewan, Manitoba, and Quebec and a little of Ontario, as well as the eastern Dakotas, most of Minnesota, and northern Wisconsin, and part of the Upper Peninsula of Michigan. The Penokean Province is shaded blue and extends across part of central Minnesota, northern Wisconsin, the eastern Upper Peninsula of Michigan, and the northern tip fo the Lower Peninsula of Michigan. The Marshfield Terrace is located south of the Penokean Provicne in eastern Minnesota and western Wisconsin.

The accretion of the Pembine-Wausau island arc and the Marshfield terrane led to the Penokean Orogeny of the Proterozoic. Adapted from a figure in S.J. Whitmeyer and K. Karlstrom (2007) Geosphere 3(4): 220-259.

Photograph of Sioux quartzite in Minnesota. The quartzite is pink and shows cross-bedding in one layer. A person is pointing at the cross-bedding.

Sioux quartzite in Blue Mounds State Park, Minnesota. Photo by Awickert/Andrew Wickert (Wikimedia CommonsCreative Commons Attribution-ShareAlike 3.0 Unported license, image cropped and resized).

Close-up photograph of Baraboo Quartzite from Devil's Lake, Wisconsin. The photo shows a pinkish rock with cross-bedding.

Baraboo Quartzite, Devil's Lake State Park, Wisconsin. Photo by James St. John (flickrCreative Commons Attribution 2.0 Generic license, image resized).

Midcontinent Rift System (Keweenawan Rift)

Around 1.1 billion years ago, a rift valley called the Midcontinent Rift System (Keweenawan Rift) began to split North America apart. The Midcontinent Rift System extended from the eastern edge of modern-day Lake Superior to Kansas. Intense volcanism occurred along the rift, producing igneous deposits with a thickness of some 7.6 kilometers (25,000 feet). The spreading occurred for 20 million years, after which the rift zone began to sink and was gradually filled with sediment.

Two-panel image of the Midcontinent Rift System. Panel 1: Map of a portion of the Midwestern U.S. with the boundaries of the rift indicated by a black line. Sedimentary, metaphoric, and igneous rocks are mapped. Panel 2: Photo of Precambrian rhyolite forming a cliff on the edge of Lake Superior in Minnesota. The rhyolite has a pinkish color.

The Midcontinent Rift System. Left: Map showing the boundary of the Midcontinent Rift (black line) and the rocks types in it. Green = sedimentary rock; blue = metamorphic rock; purple = volcanic rock; pink = intrusive igneous rock. Map from USGS "Mineral Deposits of the Midcontinent Rift System" (U.S. government work/no other use policy found). Right: Palisade rhyolite (an extrusive igneous or volcanic rock), about 1.1 billion years old, shore of Lake Superior, northeastern Minnesota. Photo by James St. John (flickrCreative Commons Attribution 2.0 Generic license, image cropped and resized).

Paleozoic (541 to 252 million years ago)

Overlying the older rock of the Canadian Shield, much of the remaining geologic history of the Midwest records the presence of shallow seas, the formation of the supercontinent Pangaea, and—most recently—the modern ice age.

Cambrian and Ordovician (541 to 444 million years ago)

Cambrian deposits are recorded in Wisconsin, Illinois, Minnesota, and Iowa. During this time, shallow seas covered much of the Midwest, with several transgression and regression episodes recorded as well. Nearly all of what would become North America (a continent called Laurentia) was located just south of the equator at the dawn of the Cambrian, and it drifted within the tropics for most of its existence.

The globe (Earth) about 565 million years ago, near the end of the Precambrian. Laurentia is turned about 90 degrees clockwise from North America's present position and much of the present-day eastern and western US are underwater.

Earth at the end of the Precambrian, 565 million years ago. Laurentia is the name given to "proto-North America"; Baltica consists of modern northern European countries; Amazonia, which was part of Gondwana, includes much of modern Brazil. All of these continents were positioned south of the equator 565 million years ago. Reconstruction created using basemap from the PALEOMAP PaleoAtlas for GPlates and the PaleoData Plotter Program, PALEOMAP Project by C. R. Scotese (2016); map annotations by Jonathan R. Hendricks for PRI's Earth@Home project (CC BY-NC-SA 4.0 license).

Photograph of the pygidium of the trilobite Dikelocephalus from the Cambrian of Minnesota. The photo shows a the fossil preserved as an impression on dark brown rock. 

Trilobite pygidium (Dikelocephalus minnesotensis), Cambrian Trempealeau Formation, Washington County, Minnesota. Photo of USNM PAL 17863 by Department of Paleobiology (National Museum of Natural History, Smithsonian Institution, CC0/public domain).

During the middle of the Ordovician period, about 470 million years ago, the Iapetus Ocean began to close as Baltica (proto-Europe) approached the North American plate from the southeast. The intense pressure of the colliding plates and islands smashing into the side of North America caused its edge to crumple, crushing and folding it into mountains. This mountain-building event is called the Taconic Orogeny, and the resulting Taconic Mountains stretched from Newfoundland to Georgia, sharing roughly the same location and orientation of the Appalachian Mountains today, but with towering peaks in eastern Canada and New England.

Illustration of the Earth near the Cambrian-Ordovician boundary, about 485 million years ago.

Earth 485 million years ago, at the beginning of the Ordovician Period. Laurentia is the name given to "proto-North America"; Baltica consists of modern northern European countries. Reconstruction created using basemap from the PALEOMAP PaleoAtlas for GPlates and the PaleoData Plotter Program, PALEOMAP Project by C. R. Scotese (2016); map annotations by Jonathan R. Hendricks for PRI's Earth@Home project (CC BY-NC-SA 4.0 license).

This folding propagated far to the west, forming waves parallel to the Taconic Mountains themselves that ran roughly southwest to northeast. Nearest the mountains, the crust warped downwards from central New York to central North Carolina, creating the Appalachian Basin. From western Ohio to Alabama, it was warped up into the Cincinnati Arch, and then down again further inland, creating the Michigan and Illinois basins. These formations are prominent features of Midwestern geology. The inland basins were flooded by the ocean for nearly all of their existence.


Volcanic islands formed where the plates were forced together as the Iapetus Ocean closed. The compression crumpled the crust to form the Taconic Mountains and a shallow inland sea farther to the west. Image modified from original by J. Houghton first published in The Teacher-Friendly Guide to the Earth Science of the Southeastern US, 2nd ed., edited by Andrielle N. Swaby, Mark D. Lucas, and Robert M. Ross (published by the Paleontological Research Institution) (CC BY-NC-SA 4.0 license).

Photograph of brachiopods from the Ordovician of Oho. The photograph shows a dense aggregation of brachiopods preserved on the surface of a gray rock. Some have radiating ridges and some are relatively smooth.

Brachiopods, Ordovician Waynesville Formation, Warren County, Ohio. Photo by James St. John (flickrCreative Commons Attribution 2.0 Generic license, image resized).

Photograph of crinoids from the Ordovician of Ohio. The photo shows a group of crinoids exposed on the surface of a beige rock. One crinoid has much of its stalk, calyx, and arms preserved. The other crinoids consist mostly of parts of the calyx and/or arms. The arms on this species of crinoid bifurcate repeatedly.

Crinoids (Iocrinus subcrassus) from the Ordovician McMillan Formation, Hamilton County, Ohio. Photo of USNM PAL 33475 by Bruce Martin (National Museum of Natural History, Smithsonian Institution, CC0/public domain).

Silurian to Mississippi (444 to 323 million years ago)

The mountain building ceased around the beginning of the Silurian, but the Taconic Mountains still played a major role in the formation of the Midwest. As sediment was eroded from the western side of the Taconic Mountains, deposits spread away, through the Northeast and Midwest, as far west as Wisconsin. Thousands of feet of this sediment built up on the floors of the seas that filled the Midwestern basins, and this sediment, along with the millions of generations of marine organisms that lived there, formed the Silurian and Devonian bedrock of much of the area.

Photograph of a branching bryozoan from the Silurian of Illinois. The photo shows a heavily branched, gray structure that his completely weathered out of the rock matrix. The surface of the bryozoan is bumpy.

A bryozoan (Fistulipora neglecta), Silurian, Illinois. Photo by James St. John (flickrCreative Commons 2.0 Generic license, image resized).

Photograph of the colonial rugose coral Hexagonaria from the Devonian of Michigan. The photo shows part of a curved gray rock covered with a series of shallow circular pits. 

The colonial rugose coral Hexagonaria, Devonian, Michigan. Photo by James St. John (flickrCreative Commons 2.0 Generic license, image resized).

For about 60 million years, the eastern margin of North America was relatively quiet. The subduction of the oceanic Iapetus plate caused volcanic eruptions that occasionally spread ash over the Midwest, but for the most part, the Taconics were slowly eroding. Finally, Baltica collided with North America near the end of the Devonian period, around 380 million years ago, and mountain-building began again, creating the Acadian Mountains. The Acadian Mountains effectively replaced the Taconics, creating a massive range that was similar in location and extent.

Paleogeographic map showing the positions of Earth continents during the Silurian Period.

Earth 430 million years ago, during the middle of the Silurian period. The Iapetus Ocean was closing as Baltica, Avalonia, and Ganderia neared the margin of Laurentia. Laurentia is the name given to "proto-North America"; Baltica consists of modern northern European countries. Reconstruction created using basemap from the PALEOMAP PaleoAtlas for GPlates and the PaleoData Plotter Program, PALEOMAP Project by C. R. Scotese (2016); map annotations by Elizabeth J. Hermsen for PRI's Earth@Home project (CC BY-NC-SA 4.0 license).


North America and Baltica finished colliding in the mid-Devonian, crumpling the crust to form the Acadian Mountains. Sediments that was eroded from the highlands formed the Catskill Delta. Image modified from original by J. Houghton first published in The Teacher-Friendly Guide to the Geology of the Northeastern U.S. by Jane Ansley (published by the Paleontological Research Institution) (CC BY-NC-SA 4.0 license).

Just as in the Taconic mountain-building period, compression from the Acadian continental collision warped the crust downward, reinforcing the inland seas. Sediments eroding from the mountains formed the Catskill Delta, creating a new wedge of sediments stretching into a shallow inland sea; the Devonian and Mississippian rocks of Ohio are evidence of this event.

At the time of the Acadian mountain building and subsequent erosion during the Devonian, the Midwest was located at the Equator and experienced a tropical climate. Baltica and North America were united as one larger landmass. Africa, South America, India, Australia, Antarctica, and Florida formed a second continent—Gondwana—in the southern hemisphere.

Photograph of a slab of trilobites from the Devonian of Ohio. The photo shows a group of dark brown trilobites exposed on the surface of a light gray rock. More than 20 trilobites are preserved. The trilobites have no spines or other ornamentation.
Photograph of the Devonian shark Cladoselache from Ohio. The shark is preserved on the surface of a gray rock, with the viewer looking at its back (dorsal side). The photo shows an elongated animal with two large pectoral fins behind its head. The tail is not preserved.

An ancient shark (Cladoselache fyleri) Devonian Ohio Shale, Cuyahoga County, Ohio. Photo by James St. John (flickrCreative Commons Attribution 2.0 Generic license, image resized).

Pennsylvanian to Permian (323 to 252 million years ago)

During the Carboniferous, the collision of North America with Gondwana was the genesis of Pangaea. This event also resulted in the formation of both the Appalachian Mountains and, in Arkansas and Oklahoma, the Ouachita Mountains.

During the Pennsylvanian to Permian, sea levels began to fluctuate and ultimately fall. Regression of the sea was caused by a combination of glaciation at the South Pole and the forces of mountain building. Along the margins of the retreating sea, enormous coastal swamps formed. These swamps extended from modern Pennsylvania to Alabama and inland as far as Ohio, Indiana, Illinois, and Kansas. They were dominated by strange trees related to modern clubmosses and horsetails. When the vegetation in the swamps died, it fell into stagnant, oxygen-poor water. The lack of oxygen in the water slowed decomposition, forming huge deposits of peat. Sediment covered these deposits, compressing and ultimately metamorphosing them into some of the largest coal beds in the world. The extensive coal beds in North America and western Europe give the Carboniferous period its name.

The burial of so much carbon lowered the amount of carbon dioxide (CO2) in the Earth's atmosphere, and the abundant plant life raised global oxygen levels. Global temperatures continued to fall, accelerating glaciation in the southern hemisphere and lowering sea level worldwide. Ultimately, the interior seaways regressed from the Midwest, which is why there is no marine sediment younger than Pennsylvanian in age across this area of North America until the development of the Western Interior Seaway in the Cretaceous.

2-panel image showing bark of scale trees (order Lepidodendrales) from the Carboniferous of the Midwest. Panel 1: Photo of a piece of Lepidodendron bark showing diamond-shaped leaf cushions. Panel 2: Photo of a piece of Sigillaria bark showing hexagon-shaped leaf cushions. 

Scale trees (Lepidodendrales), an extinct group of lycophytes, Carboniferous. The "scales" forming the patterns on the trunks and branches of these trees are actually leaf cushions, scars left behind after leaves were shed. Left: Lepidodendron (YPM PB 035396), Orange County, Indiana. Right: Sigillaria elegans (YPM PB 035538), Summit County, Ohio. Photos by Robert Swerling (Yale Peabody Museum of Natural History/YPM on, CC0 1.0 Universal/public domain dedication).

Photograph of a strip mine in Fulton County, Illinois, 1972. The photo shows a bucket wheel excavator in a trench. On the back of the excavator, a wheel with bucket spokes digs into a bank. On the front of the excavator, a conveyer empties sediment at the other edge of the trench. 
Reconstruction of Earth 300 million years ago showing Gondwana glaciation and Central Pangean Mountains.

Earth 300 million years ago, during the end of the Carboniferous Period (Pennsylvanian). Pangaea was completed when North America finally collided with Gondwana. "Laurussia" is the landmass including ancient North America, and the Central Pangean Mountains are, in part, the ancestral Appalachian Mountains. Reconstruction created using basemap from the PALEOMAP PaleoAtlas for GPlates and the PaleoData Plotter Program, PALEOMAP Project by C. R. Scotese (2016); map annotations by Jonathan R. Hendricks & Elizabeth J. Hermsen for PRI's Earth@Home project (CC BY-NC-SA 4.0 license).

Mesozoic (252 to 66 million years ago)

In the Midwest, Mesozoic-aged rocks are preserved primarily in Minnesota, Iowa, and, to a lesser extent, in Illinois. For the remainder of the Midwest, the Mesozoic was a time of erosion and very little deposition.

The rocks that do exist were deposited mainly during the Cretaceous. At that time, North America was roughly divided into thirds: a western portion, an eastern portion, and a vast seaway inundating the center. This seaway stretched from Utah to the western edge of the Midwest and connected the Gulf of Mexico to the Arctic Ocean. Deposits in western Minnesota and Iowa contain a variety of Cretaceous creatures that lived near the shores of the Western Interior Seaway. The early Cretaceous was the first time during the Phanerozoic that the Midwest was north of the tropics, approaching its current position.

Map of the Western Interior Seaway. The map showing the seaway extending across North America from the Gulf of Mexico to the Arctic Ocean. Laramidia occurs to the west of the seaway and Appalachia to the east. The Hudson Seaway branches off the Western Interior Seaway to the northeast, covering modern-day Manitoba and Hudson Bay.

Extent of the Western Interior Seaway during the Cretaceous Period. Image from Cretaceous Atlas of Ancient Life: Western Interior Seaway (Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license).

Photograph of Late Cretaceous shark tooth from the Mesabi Iron Range, Minnesota. The photo shows a roughly triangular shark tooth missing its root. The tooth is orange in color with serrated edges.

Crow shark tooth (Squalicorax), Late Cretaceous Coleraine Formation, Calumet, Minnesota. Photo by Rylan Bachman (Wikimedia CommonsCreative Commons Attribution 4.0 International license, image resized).

Quaternary (2.6 million years ago to present)

At the start of the Quaternary period, about 2.6 million years ago, continental ice sheets began to form in northernmost Canada. Throughout this period, the northern half of North America has been periodically covered by continental glaciers.

The Quaternary period is divided into two epochs: the Pleistocene and Holocene. During the Pleistocene, the ice sheets advanced south and retreated north several dozen times. The Holocene Epoch is the most recent (and current) period of retreat, called an interglacial interval. The most recent glacial advance in North America reached its maximum extent 21,000–18,000 years ago, while the beginning of the Holocene is considered to be 11,700 years ago, or about 9,700 BCE.

The landscape of the Midwest has been heavily influenced and shaped by the advance and retreat of these glaciers, with the surface of every state shaped by the forces of the moving ice that scraped loose rock, gouged the bedrock beneath, and deposited sediment and water as the ice advanced and retreated.

Map showing the positions of major North American ice sheets during the Last Glacial Maximum.

Extent of glaciation over North America at the Last Glacial Maximum. Image adapted from map by the USGS (public domain).

Map showing Pleistocene glaciations in the Midwest. The map shows the midwestern states with their borders outlined in black. Three phases of glaciation are various shades of blue, from pre-Illinoian (light blue) to Illinoian (medium blue) to Wisconsinian (dark blue). The pre-Illinoian gets into Iowa and areas to the south and west of Iowa. The Illinoian covers much of Illinois, part of southern Indiana, and a little of Ohio and Wisconsin. The Wisconsinian, which is the most recent, covers much of Minnesota, part of north-western Iowa, northern and eastern Wisconsin, northeastern Illinois, all of Michigan, northern Indiana, and northern Ohio.

Map of the midwestern states showing Pleistocene glaciations. Each glacial advance differed slightly and left different sets of deposits. Adapted from figures by C.L. Matsch and USGS.

The Great Lakes of the Midwest and Northeast were formed during the last great glacial advance some 18,000 years ago. The broad, deep basins of the Great Lakes were flooded as the glaciers receded. Glacial meltwater poured into these basins, and the ice blocked the drainage that would eventually flow to the northeast via the St. Lawrence River. Once this path was available, the lakes gradually dropped to their current levels.

The ice age continues today, but the Earth is in an interglacial stage, since the ice sheets have retreated for now. The glacial-interglacial cycling of ice ages predicts that the world will return to a glacial stage in the future, but the impacts of human-induced climate change might radically shift the direction of these natural cycles.

Photograph of the landscape in near the Glacial Ridge Trail, Minnesota. The photo shows a landscape of gently rolling hills covered by grass with patches of trees. The grass is yellow and the trees have green  to yellow leaves, indicating that it is fall. A road can be seen crossing the photo horizontally behind a low hill in the foreground. The sky is overcast.

Landscape along the Glacial Ridge Trail, Minnesota, 2017. The landscape in this region is shaped by deposits of the Alexandria Glacial Moraine Complex, and includes eskers, kettles, and kames. Photo by Greg Gjerdingen (flickrCreative Commons Attribution 2.0 Generic license).

Satellite photograph of the Great Lakes in the midwestern and northeastern United States. The photo shows the five Great Lakes, from west to east, Superior, Michigan, Huron, Erie, and Ontario. The lakes are dark blue and surrounded by green landscape. The green generally becomes darker to the north, indicating more forest cover.

Satellite image of the Great Lakes region of North America. Photo by Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC (NASA Visible Earth, used following NASA's image use policy).