Explore Geology
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Isle Royale

National Park


cover of park brochure

park geology subheading
moose swimming in the water at Isle Royale
Isle Royale National Park, Michigan

In Lake Superior's northwest corner sits a wilderness archipelago, a roadless land of wild creatures, unspoiled forests, refreshing lakes, and rugged, scenic shores-accessible only by boat or floatplane. Travel on and around the island is by foot, boat, or floatplane. There are 267 kilometers (166 miles) of foot trails on Isle Royale and the island boasts numerous inland lakes. And for more seaworthy craft there is, of course, Lake Superior itself.

Isle Royale exists as an island in many ways. It is an island of wilderness and home to wolves in a modern world. It is an island in time, a natural space in which you operate on natural time and experience the rhythms of light and dark. Days are measured by footsteps, possibly under a backpack. Walking the island you are struck by its striated layout, its elongated forested-rock and lake patterns that parallel its backbone, the Greenstone Ridge. The island, it seems, must have been forcibly combed from northeast to southwest. The surface scene you see from the island's heights is the product of 10,000 years of natural sculpting, soil-building, and plant-pioneering and succession. Back then- actually not long ago by nature's standards-the island appeared beneath glacial ice, rising as the lake level dropped. The island developed soil and was colonized by plants and animals. Its many inland lakes first formed in basins gouged out by glaciers, and then began to shrink, as lakes and ponds inevitably do.

Beneath the ponds, the forests, and the light soil covering, however, is a story which must be told not in increments of centuries, but by millions and billions of years. The "ridge-and-trough" pattern of the rocks is the work of millions of years, pre-dating even the formation of Lake Superior and its islands. The story begins some 1.2 billion years ago with a great rift in the earth's crust which may have extended from here southward all the way to the Gulf of Mexico. As this series of cracks poured forth molten lava covering thousands of square kilometers, the land along the rift zone sank to form the Superior Basin, which has shaped all subsequent geological events in the region. The rock record of this cataclysmic happening-the volcanics, sandstones, and conglomerates-forms Isle Royale's bedrock today. Clues to the island's past abound. Smoothed, rounded, and even groove rock belies the crushing power of the last major glaciation, know as the Wisconsinan. It ended here only a few thousand years ago.

On the southwestern part of the island, where this glacier paused in its retreat, are small linear hills made of its deposits. On the Stall Trail out toward Scoville Point you pass three small pits in the rock. These form another clue, a clue to the Indians who mined copper on the island. The Indians came to the island only in mild seasons, taking what resources they could, and leaving before winter. The Indians mined here by about 2000 B.C., continuing for 1,000 years, and Isle Royale and Superior area copper made its way by trade as far as New York, Illinois, and Indiana. Indians were probably most active here from 800 to 1600. By the 1840s, the only Indian encampments white miners encountered were a maple sugaring camp on Sugar Mountain and a seasonal fishing camp on Grace Island.

Isle Royale is indeed an island of superlatives for wilderness and beauty. Or how about this superlative?

Siskiwit Lake's Ryan Island is the largest island in the largest lake on the largest island in the largest freshwater lake in the world!

You will find your own superlatives here as you meet the island on its own terms: fishing, boating, hiking, backpacking, taking a guided interpretive walk or hike, or just relaxing, which are what vacations are for.

park maps subheading

The General park map handed out at the visitor center is available on the park's map webpage.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

photo album subheading

A geology photo album has not been prepared for this park.

Photo albums for park wildlife can be found here. Mammals, Amphibians

For information on other photo collections featuring National Park geology, please see the Image Sources page.

books, videos, cds subheading

Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.

geologic research subheading


For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.

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NPS Geology and Soils Partners

NRCS logoAssociation of American State Geologists
NRCS logoGeological Society of America
NRCS logoNatural Resource Conservation Service - Soils
USGS logo U.S. Geological Survey

teacher feature subheading

Currently, we do not have a listing for any park-specific geology education programs or activities.

General information about the park's education and intrepretive programs is available on the park's education webpage.

For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.
updated on 01/04/2005  I   http://nature.nps.gov/geology/parks/isro/index.cfm   I  Email: Webmaster
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