The Keweenaw Peninsula ( , sometimes locally ) is the northernmost part of Michigan's Upper Peninsula. It projects into Lake Superior and was the site of the first copper boom in the United States, leading to its moniker of "Copper Country." Its major industries are now logging and tourism, as well as jobs related to Michigan Technological University.
Geology
The peninsula measures about 150 miles in length and about 50 miles in width at its base.
The ancient lava flows of the Keweenaw Peninsula were produced during the Mesoproterozoic Era as a part of the Midcontinent Rift between 1.096 and 1.087 billion years ago. This volcanic activity produced the only strata on Earth where large-scale economically recoverable 97 percent pure native copper is found.
Much of the native copper found in the Keweenaw comes in either the form of cavity fillings on lava flow surfaces, which has a ”lacy” consistency, or as "float" copper, which is found as a solid mass. Copper ore may occur within conglomerate or breccia as void or interclast fillings. The conglomerate layers occur as interbedded units within the volcanic pile.
The Keweenaw Peninsula and Isle Royale, formed by the Midcontinent Rift System, are the only sites in the United States with evidence of prehistoric aboriginal mining of copper. Artifacts made from this copper by these ancient indigenous people were traded as far south as present-day Alabama. These areas are also the unique location where chlorastrolite, the state gem of Michigan, can be found.
The northern end of the peninsula is sometimes referred to as Copper Island (or "Kuparisaari" by Finnish immigrants), although this term is becoming less common. It is separated from the rest of the peninsula by the Keweenaw Waterway, a natural waterway which was dredged and expanded in the 1860s across the peninsula between the cities of Houghton (named for Douglass Houghton) on the south side and Hancock on the north.
A Keweenaw Water Trail has been established around Copper Island. The Water Trail stretches approximately and can be paddled in five to ten days, depending on weather and water conditions.
The Keweenaw Fault runs fairly lengthwise through both Keweenaw and neighboring Houghton counties. This ancient geological slip has given rise to cliffs. U.S. Highway 41 (US 41) and Brockway Mountain Drive, north of Calumet, were constructed along the cliff line.
Climate
Lake Superior significantly controls the climate of the Keweenaw Peninsula, keeping winters milder than those in surrounding areas. Spring is cool and brief, transitioning into a summer with highs near . Fall begins in September, with winter beginning in mid-November.
The peninsula receives copious amounts of lake-effect snow from Lake Superior. Official records are maintained close to the base of the peninsula in Hancock, Michigan, where the annual snowfall average is about . Farther north, in a community called Delaware, an unofficial average of about is maintained. At Delaware, the record snowfall for one season was in 1979. Averages over certainly occur in the higher elevations closer to the tip of the peninsula.
History
Beginning as early as seven thousand years ago and apparently peaking around 3000 B.C., Native Americans dug copper from the southern shore of Lake Superior. This development was possible in large part because, in this region, large deposits of copper were easily accessible in surface rock and from shallow diggings. Native copper could be found as large nuggets and wiry masses. Copper as a resource for functional tooling achieved popularity around 3000 B.C., during the Middle Archaic Stage. The focus of copper working seems to have gradually shifted from functional tools to ornamental objects by the Late Archaic Stage c. 1200 B.C. Native Americans would build a fire to heat the rock around and over a copper mass and, after heating, pour on cold water to crack the rock. The copper was then pounded out, using rock hammers and stone chisels.