Copper Country Parks : Copper Country National Parks : Isle Royale National Park Email this article
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Isle Royale Geology and History

The Geological History of Isle Royale begins some 1.2 billion ago as measured in atomic time during the Precambrian and Cambrian Eras  or the Early Proterozoic  and Neo-Proterozoic Eras or about 3,700 - 3500 orbital years before Christ in dynamic time about the time of Noah up to the Great Flood.  During this period of time the internal heating of the earth increased causing sodium rich granites to be intruded near the surface, which resulted in some metamorphosed basement rocks, which formed the stable shield areas on the earth's surface. 

Within Michigan, the oldest Precambrian rocks have been subjected to at least three major periods of crustal deformation and mountain building and to at least three or four additional minor or local deformational episodes. In many cases these crustal crumplings were accompanied by the intrusion of molten masses of granitoid igneous rocks emplaced deep within the crust and subsequently unveiled by uplift and erosion. Periods of volcanism (at least four) produced lava and pyroclastic rocks, chiefly of basaltic composition and accompanied by dikes of diabase and gabbro. Metamorphism of varying degrees of intensity accompanied many of the disturbances and transformed sedimentary, intrusive igneous, and volcanic rocks into their metamorphic equivalents. Thus basalt became greenstone; granite became granitic gneiss; sandstone was converted to quartzite; limestone to marble; and shale became slate or mica schist. The youngest Precambrian rocks, such as those of the Keweenaw Period on the Keweenaw Peninsula, have not been metamorphosed and have remained largely unchanged as basalts, sandstones, and conglomerates. Even these nonmetamorphosed rocks, however, have been tilted, folded, and faulted. Because of the enormous length of Precambrian time and the complexity and multiplicity of its major geological events, the Precambrian rocks of the Northern Peninsula of Michigan are exceedingly diverse.

Titanic lava flows stretched 2000 kilometers from modern day Kansas northward all the way to the area occupied today by Lake Superior.  Pressures crinkled the lava flow downward in its middle and pushed it upward on its edges into the shape of a U.  As the U was pushed relentlessly from the side, its edges began to fracture into overlapping ridges that are still visible today on Isle Royale on the north (a satellite picture from space)

Isle Royale from Satelite

and on the Keweenaw Peninsula on the south.

Keweenaw Peninsula atop Brockway Mt

The above picture is taken on top of Brockway Mt. and is looking south.  This spectacular ridge (on the left) runs parallel to Lake Superior (on the right) throughout the Keweenaw Peninsula.  The ridge looses its unique distinctiveness as it moves into Houghton County, though it remains present all the way into Ontonagon County and into the Porcupine Mountains.

Volcanic activity eventually filled the cracks between the ridges with mineral deposits containing metals as copper. As the ice age was brought to a close by another impact event on earth that again changed the axis tilt from from than 28 degrees, back to the present 23.5 degrees, the climate and warmer conditions filled the Great Lakes with cool water.  This occurred about 10,000 atomic or geological years ago and took place during the time of Abraham or about 2300 orbital years before Christ. 

Presently Isle Royale National Park encompasses an archipelago of more than 200 islands, ranging from tiny islets nearly barren to the main island, which is about 45 miles long and 9 miles wide.

Human history connected with Isle Royale begins with Native American people advancing into the Great Lakes on the heels of the last receding glacier known as the Wisconsin.  On the Stoll Trail, by Scoville Point, you can find three small pits in the rock.  These form clues of the Native Americans who mined copper on the island.  These people came to the island during the mild seasons, taking what copper and other gems they found.     Estimates are that native people were most active on  Isle Royale between 800 AD to 1600 AD. 

Much has been written about prehistoric mining of native copper. Although Rickard (1932) believes the Indians used copper for purely ornamental purposes, copper spearheads, knives, and wedges are abundantly represented in collections of Indian artifacts. Ancient diggings are widespread. They are abundant on Isle Royale and were found locally in clusters at various places in the copper belt on the Keweenaw Peninsula, e.g., between Eagle Harbor and the Cliff Mine, northeast of Hancock, southwest of Houghton, and in Ontonagon County from the Fire Steel to beyond the Ontonagon Rivers. It has been estimated that 5000 pits are known on the Peninsula, some over 30 feet deep. Speculations have been made that the total mining effort might have involved 10,000 men who worked for 1000 years and removed 500,000,000 pounds of copper - bearing rock (Drier and Du Temple, 1961), but this "guesstimate" is probably excessive. 

Jacques Cartier, during his second voyage to Canada in 1535, was presented with a large copper knife which came from "Saguenay."By the 1840s, the only Indian camps the white miners discovered were a maple sugaring camp on Sugar Mountain and a seasonal fishing camp on Grace Island. The first printed mention of native copper near Lake Superior is in a book by Lagarde, published in 1636 in Paris, in which the mineral resources of the area are listed as including "copper, gold, rubies, steel, diamonds, iron, and limestone."

As the European fur traders moved into the region, the Ojibwa people traded for guns and superior weapons and thereby consolidated their westward expansion along Lake Superior, displacing other nations of native peoples. The French explorers named the majestic island in Lake Superior "Isle Royale."  The French quickly lost their political dominance though in the region and were replaced by the British at the end of the Seven Years War (1756-1763) in when they issued The Royal Proclamation of 1773 which in essence attempted to gain the mineral rights and steal the land from Native American people and to put them into bondage.  The Hudson Bay Company was a powerful arm of  Britain and sought to increase Britain's influence.  But Britain's influence ended  following the resolution of the British North American Colonial War in 1783, when Benjamin Franklin bargained Isle Royale into the United States territory because of its reputation for rich copper deposits. Originally during the treaty process the boundary line ran through the middle of Lakes Ontario, Erie, and Huron and their linking waterways.  Franklin, a member of the Boundary Commission, had heard of the mineral deposits of Lake Superior and shifted his pencil to mark a line somewhat north of the center line of Lake Superior.  Thus the Northern Peninsula and Isle Royale ended up as parts of the United States instead of Canada.

The United States Government then entered into various treaties during the 1840-50s with the Ojibwa Nation which negotiated lopsided arrangements with people who had very little understanding of what they are negotiating and giving up. Thus most ways of life known to the Ojibwa people came to a very abrupt and sad ending, with little concern for their well being.  Might and power of the United States left the Ojibwa people with little room to maneuver.  Today their rights as signed in the treaties remain a source of contention between the them and the United States Government.

The American Fur Company, owned by Jacob Astor, dominated the fur trade in the Lake Superior Region after the French lost Canada to the British.  But when the fur trade market began to collapse by the mid 1820s, the American Fur Trade attempted other ways to make money from their holdings.  Several geological surveys were sent to inventory the resources of Isle Royale and the surrounding areas.  Dr. Douglass Houghton, visited the copper country in 1831.  He initially believed that the presence of copper in the native form constituted an argument against its persistence in the veins in depth.  Up to the discovery of the Michigan native copper, the mineral was known only as a near-surface supergene species, formed under oxidizing conditions in the weathers parts of copper sulfide veins.  Later, after becoming familiar with the nature of the veins, he changed his belief.  With difficulty, Houghton persuaded the First Michigan Legislature to appropriate money for the first geological survey of the state.  Douglass began fieldwork in the Copper Country in 1839.  In 1941, in his report he discussed the economic potential of copper but only identified the copper vein at Copper Harbor. Douglass Houghton died prematurely on October 13, 1845, during a snowstorm and gale on Lake Superior hear Eagle River.  Houghton's boat was swamped as he hurried homeward after a late field season.  All members of the party, except for Houghton and one other man reached shore safely.  Houghton's body was recovered the following spring.

About twenty prospectors landed in Copper Harbor in 1843 and from then on prospectors were numerous.  In 1846, the permit system was replaced by government sale of mineral land at $5 per acre and shortly afterward at $1.25.  1846 marks the beginning of the copper mining industry in Michigan.

Three periods of mining operations on Isle Royale spanned the 1800s, with none of the 18 separate ventures taking significant quantities of ore, outside of the Sishowit Mining Company which took 95 tons of refined copper in a six year period starting in 1849.

The parts of the island not inhabited by the miners during the 1800s were habited by a number of people attracted to the banks of fish living in the coves and bays surrounding the island.  For the next 100 years several families commercially fished and lived on the island.  The last family was forced out of business by federal and state governments in the 1980s.

Isle Royale has claimed her share of shipwrecks.  Four lighthouses - Rock of Ages, Rock Harbor, Passage Island and at Isle Royale - were constructed to aide in navigation. 

(Some of the information above has come from the following sources: http://www.deq.state.mi.us/documents/deq-glm-rcim-geology-Mineralogy_Of_Michigan.Pdf
http://www.nyx.net/~sjhoward/Isle_Royale/
http://www.setterfield.org/report/report.html
and short notes from different brochures on Isle Royale published by the National Park Service)


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