Caribou Island is an uninhabited island in the eastern end of

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 wa ...

, south of

Michipicoten Island Michipicoten Island is an island in Ontario, Canada, in the northeastern part of Lake Superior, about northwest of Sault Ste. Marie and southwest of Wawa, Ontario. At its closest point to mainland Ontario, the island is located about from t ...

. It lies entirely within the territorial waters of

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

although only about five kilometres from the international border between Canada and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. It is approximately long and wide, and in area. The interior is low scrub and bog with small lakes, Little Italy, Hambone, and Deer Lake among many unnamed ones. Several of the lakes are maintained by

beaver Beavers are large, semiaquatic rodents in the genus ''Castor'' native to the temperate Northern Hemisphere. There are two extant species: the North American beaver (''Castor canadensis'') and the Eurasian beaver (''C. fiber''). Beavers ar ...

s and all are several feet above

History

Canadians first went to Caribou Island around 1820 when nearly 400 acres of the islands 1,600 acres were found to have large deposits of bird

guano Guano (Spanish from qu, wanu) is the accumulated excrement of seabirds or bats. As a manure, guano is a highly effective fertilizer due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. G ...

. At the time this was an important part in making

gunpowder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). ...

and would be for nearly five years a primary source of

saltpeter Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitrat ...

for the

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

powder works in 1852.The

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

around Caribou island made travel difficult for many merchants and harvesters moving from

. Caribou Island was considered for an emergency landing airport (YCI) during World War II but it was never built because of the proximity of the twin cities of

Sault Ste. Marie, Michigan Sault Ste. Marie ( ') is the only city in, and county seat of, Chippewa County, Michigan, Chippewa County in the U.S. state of Michigan. With a population of 13,337 at the 2020 United States census, 2020 census, it is the second-most populated ...

, and

Sault Ste. Marie, Ontario Sault Ste. Marie ( ) is a city in Ontario, Canada. It is at the St. Mary's River on the Canada–US border. It is the third largest city in Northern Ontario, after Sudbury and Thunder Bay. The Ojibwe, the indigenous Anishinaabe inhabitants of ...

, only about 80–90 miles SE. However an interior lake, Deer Lake on the center East side of the island, was used as an Amphibian base with a dock and ramp built by the last private owners of the island because of the unpredictable water/wave condition of

. A small three room cabin was built on the east shore of

adjacent to Deer Lake and the Amphibian base.Carter, J.L. 1979. ''A trip to lonely Caribou-island outpost of the lakes (in two parts).'' Inland Seas. 35, pp. 4-12, 95-103. The island was privately held by a group of hunters and stocked with caribou in the late 1800s. It was considered a private hunting preserve through the early 1900s. The caribou were very aggressive, treeing the lighthouse keeper for hours on several occasions. It is rumored that the light house keepers poached caribou and beaver. One winter, in the 1920s, the caribou walked off the island when the lake froze over. Because of the Great Depression, the island was not restocked and the island was more or less abandoned by the approximately 15 owners-in-common. The island was acquired completely by the Roys A. Ellis family in the 1960s and was transferred to the Mellon Conservancy Trust of the

Andrew W. Mellon Foundation The Andrew W. Mellon Foundation of New York City in the United States, simply known as Mellon Foundation, is a private foundation with five core areas of interest, and endowed with wealth accumulated by Andrew Mellon of the Mellon family of Pitts ...

in the early 1980s to never be developed. In 2018 6 caribou were moved to Caribou Island from

to the north, due to pressure from Michipicoten First Nation.

Geology

According to the available information, Caribou Island consists of a mixture of

glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...

s and

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

. Caribou Island is part of a large glacial moraine that accumulated south of

.Dell, C.I., 1976. ''Sediment distribution and bottom topography of southeastern Lake Superior.'' Journal of Great Lakes Research, 2(1), pp.164-176. In addition, exposures of gently dipping, friable Jacobsville Sandstone, have been reported from Caribou Island.Halls, H.C. and West, G.F., 1971. ''A seismic refraction survey in Lake Superior.'' Canadian Journal of Earth Sciences, 8(6), pp. 610-630. The

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 sand ...

is the uppermost and youngest layer comprising about of sandstone and conglomerate that underlies Lake Superior and fills the upper part of the Lake Superior segment of the

Midcontinent Rift The Midcontinent Rift System (MRS) or Keweenawan Rift is a long geological rift in the center of the North America, North American continent and south-central part of the North American plate. It formed when the continent's core, the North Amer ...

. These sedimentary strata overlie an additional of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...

and

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s that fill the remainder of the Midcontinental Rift.Cannon, W.F., Green, A.G., Hutchinson, D.R., Lee, M., Milkereit, B., Behrendt, J.C., Halls, H.C., Green, J.C., Dickas, A.B., Morey, G.B. and Sutcliffe, R., 1989. ''The North American Midcontinent rift beneath Lake Superior from GLIMPCE seismic reflection profiling.'' Tectonics, 8(2), pp. 305-332.Hinze, W.J., Allen, D.J., Fox, A.J., Sunwood, D., Woelk, T. and Green, A.G., 1992. ''Geophysical investigations and crustal structure of the North American Midcontinent Rift system.'' Tectonophysics, 213(1-2), pp. 17-32.

Navigation hazards

A dangerous

known as "Six Fathom Shoal" stretches more than north of the north point of the island, and is rumored to be the one the

SS Edmund Fitzgerald SS ''Edmund Fitzgerald'' was an American Great Lakes freighter that sank in Lake Superior during a storm on November 10, 1975, with the loss of the entire crew of 29 men. When launched on June 7, 1958, she was the largest ship on North America ...

shoal In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It ...

ed on prior to sinking. A shallow reef to the southwest of

Caribou Island Lighthouse Caribou Island Lighthouse sits on the uninhabited Caribou Island in the eastern end of Lake Superior, south of Michipicoten Island. It lies entirely within the territorial waters of Canada although only about three miles from the international bo ...

lies only below the lake's surface. The now unmanned lighthouse which is owned by the

Canadian Coast Guard The Canadian Coast Guard (CCG; french: links=no, Garde côtière canadienne, GCC) is the coast guard of Canada. Formed in 1962, the coast guard is tasked with marine search and rescue (SAR), communication, navigation, and transportation issues in ...

is located on a tiny adjacent island called Lighthouse Island a few hundred feet across and positioned west of the southern tip of the island. When originally built, it was visible for and operated on a 30-second revolving cycle. These reefs are not

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

s. Instead they consist of bedrock ridges and interfluves that lie between northerly trending bedrock valleys, which are known as ''

tunnel valley A tunnel valley is a U-shaped valley originally cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and formerly covering portions of all continents during past glacial ages. They can be as lo ...

s.'' These tunnel valleys were excavated by subglacial meltwater at the base of the

Laurentide Ice Sheet The Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glacial epochs, from 2.58 million years a ...

along pre-existing fractures and joints that exist within the bedrock floor of Lake Superior.Laidly, W.T., 1961. ''Submarine Valleys in Lake Superior.'' Geographical Review, 51(2), pp. 277-283.Regis, R.S., Patterson, C.J., Wattrus, N., and Rausch, D., 2003. ''Relationship of deep troughs in the eastern Lake Superior basin and large-scale glaciofluvial landforms in the central Upper Peninsula of Michigan.'' North Central Geological Society of America Abstracts with Program, Paper 19–10. Samples dredged from a shoal northwest of Caribou Island and close to one of these valleys resemble Jacobsville Sandstone. The lateral continuity and consistent and parallel direction of the tunnel valleys indicated that they are carved from friable sandstones that underlies the floor of most of eastern Lake Superior.Wold, R.J., Hutchinson, D.R. and Johnson, T.C., 1982. ''14: Topography and surficial structure of Lake Superior bedrock as based on seismic reflection profiles.'' Geological Society of America Memoirs, 156, pp. 257-272.

References

External links

Weather conditions on Caribou Island
{{Authority control Uninhabited islands of Ontario Islands of Lake Superior in Ontario Lake Superior