The western third of Michigan's Upper Peninsula, including the Keweenaw Peninsula, does not lie within the Michigan Basin. Rather, from a geophysical point of view, it is part of the Wisconsin Dome, which also includes much of northern Wisconsin and northeast Minnesota; in this region, which blends with the Canadian Shield, Precambrian rocks outcrop at the surface since overlying, younger sediments were either scraped away by the Pleistocene glaciers or eroded away in the distant past due to the general uplift of these ancient basement rocks.
We decided to give our legs a rest today and took a road trip to Copper Harbor, stopping at various lighthouses and beaches along the way. The highlight of the trip was the view from Brockway Mountain, just outside Copper Harbor; from this summit, one enjoys a panorama of Lake Superior and the northern Keweenaw Peninsula, including the shipping lanes, the rocky shoreline, inland lakes and colorful, forested ridges. Wherever we stopped, outcrops of Precambrian rock, volcanic or continental, dominated the scene; along portions of the coast, hogbacks and shoals of ancient basalt created a fascinating and scenic topography.
As I discussed yesterday, the Porcupine Mountains are volcanic in origin, as are some other ridges and uplifts across the Wisconsin Dome. Other ranges, such as the Huron Mountains east of Keweenaw Bay, have eroded from localized Precambrian domes (similar to the formation of the Black Hills and Adirondacks). Of course, the highlands across the Wisconsin Dome are among the oldest in North America (1-3 billion years old) and, over time, have eroded into hills and relatively low ridges. Just knowing you are walking on or amidst rock that pre-dates terrestrial life is an exhilarating experience.
Senin, 26 September 2011
Minggu, 25 September 2011
The Porcupine Mountains
About twenty miles west of the Keweenaw Peninsula, the Porcupine Mountains rise above the south shore of Lake Superior. Volcanic in origin, the "Porkies" formed 1 billion years ago along the Mid-Continent Rift; long quiescent, this rift extends southwestward into the Central Plains of the U.S. where, since buried by younger sediments, it remains a potential source for deep earthquakes.
Since their Precambrian birth, the Porcupine Mountains have been assaulted by the forces of erosion, especially during the Pleistocene Epoch when glaciers scoured the region. Today, an escarpment, capped by volcanic basalt, curves along the northern edge of the Porcupines, separated from the main uplift by the Big Carp Valley and its beautiful Lake of the Clouds; hikes along the escarpment are among the most scenic in the Park. Another popular hike is a short but steady climb to the top of Summit Mountain, 1958 feet (the highest point in the Porcupines), where a lookout tower offers a magnificent panorama of the Park and its surroundings, extending to Lake Superior; on a clear day, one can see the Apostle Islands (to the northwest) and Isle Royale, 80 miles to the north.
While the Porcupine Mountains formed 600 million years before life crawled from the sea, they now host a spectacular diversity of plant and animal residents. Among these are black bear, gray wolves, fishers and, of course, porcupines; so far, our mammal encounters have been limited to deer, squirrels, chipmunks and other humans. A Visitor Center, at the east entrance to this Michigan State Park, provides an excellent introduction to the region's natural and human history and access to this scenic refuge is provided by a well-engineered network of trails and boardwalks. Visitors should be aware that a Park passport fee is charged.
Since their Precambrian birth, the Porcupine Mountains have been assaulted by the forces of erosion, especially during the Pleistocene Epoch when glaciers scoured the region. Today, an escarpment, capped by volcanic basalt, curves along the northern edge of the Porcupines, separated from the main uplift by the Big Carp Valley and its beautiful Lake of the Clouds; hikes along the escarpment are among the most scenic in the Park. Another popular hike is a short but steady climb to the top of Summit Mountain, 1958 feet (the highest point in the Porcupines), where a lookout tower offers a magnificent panorama of the Park and its surroundings, extending to Lake Superior; on a clear day, one can see the Apostle Islands (to the northwest) and Isle Royale, 80 miles to the north.
While the Porcupine Mountains formed 600 million years before life crawled from the sea, they now host a spectacular diversity of plant and animal residents. Among these are black bear, gray wolves, fishers and, of course, porcupines; so far, our mammal encounters have been limited to deer, squirrels, chipmunks and other humans. A Visitor Center, at the east entrance to this Michigan State Park, provides an excellent introduction to the region's natural and human history and access to this scenic refuge is provided by a well-engineered network of trails and boardwalks. Visitors should be aware that a Park passport fee is charged.
Sabtu, 24 September 2011
Roughing It
We'll be roughing it for the next three nights; well, not exactly. We have rented a fully furnished cabin on the south shore of Lake Superior, just a few miles east of the Porcupine Mountains. While I am an avid naturalist and enjoy outdoor exploration during any season, I'm past the age when the proposition of sleeping in a tent and cooking over a campfire is an appealing opportunity; after a day of hiking, I enjoy a hot shower and a comfortable bed. Besides, it's difficult to watch college football in a tent!
After leaving Munising enveloped in fog and drizzle, we made a brief circuit through Marquette and then headed west across another stretch of Michigan moose country; despite the highway warning signs, we did not encounter any of those large herbivores but did see plenty of white-tailed deer. Based on a recommendation in our travel guide, we headed for an isolated point between Keweenaw and Huron Bays; though our adventure required a long drive on a graveled road on this chilly, gray, blustery day, two other couples also turned up at that scenic location during our visit, a reminder that solitude is becoming a rare gift on planet Earth.
If we manage to survive the night in our not-so-rustic cabin, we plan to head to the Porcupine Mountains for a day of hiking tomorrow. Here's hoping that the central heating system wards off that chilly breeze from Lake Superior!
After leaving Munising enveloped in fog and drizzle, we made a brief circuit through Marquette and then headed west across another stretch of Michigan moose country; despite the highway warning signs, we did not encounter any of those large herbivores but did see plenty of white-tailed deer. Based on a recommendation in our travel guide, we headed for an isolated point between Keweenaw and Huron Bays; though our adventure required a long drive on a graveled road on this chilly, gray, blustery day, two other couples also turned up at that scenic location during our visit, a reminder that solitude is becoming a rare gift on planet Earth.
If we manage to survive the night in our not-so-rustic cabin, we plan to head to the Porcupine Mountains for a day of hiking tomorrow. Here's hoping that the central heating system wards off that chilly breeze from Lake Superior!
Jumat, 23 September 2011
Pictured Rocks
The Pictured Rocks, which tower above Lake Superior east of Munising, are likely the most photographed natural feature of the Upper Peninsula of Michigan. These scenic cliffs anchor the west end of the Pictured Rocks National Lakeshore, which extends eastward to Grand Marias. Composed of Cambrian sandstone, deposited in a broad river delta about 550 million years ago, these rocks lie in the outermost band of the Michigan Basin and are some 400 million years older than the Jurassic sediments at the Basin's center.
This morning, my wife and I took a boat tour along the base of the Pictured Rocks; conducted by a private company in cooperation with the National Park Service, the tour provided a unique and up-close view of the spectacular cliffs that were exposed by Pleistocene glaciers and are now molded by the erosive forces of Lake Superior and the region's harsh northern climate. Rock falls are a common occurrence along this majestic wall, producing recessed caves, natural arches and varied rock formations that evoke images in the eyes of human visitors (hence the name of Pictured Rocks). The boat officers and an onboard Park ranger introduced us to both the natural and the human history of this region, including the story behind many of the shipwrecks that have occurred along this storm-ridden coast.
Later in the day, we hiked out to Chapel Rock, where a pine tree grows from the top of a rock pedestal, its roots dangling between the pedestal cap and the adjacent cliff; those roots formerly ran through the soil of a rock arch before the latter collapsed into the lake. On our loop hike to and from this popular site we passed through a karst landscape which included Chapel Falls and numerous sinkholes; this topography reflects the layer of Ordovician dolomite that overlies the Permian sandstone south and east of Pictured Rocks (i.e. toward the center of the Michigan Basin). Tomorrow, we'll head westward to the Keweenaw Peninsula and thence to the Porcupine Mountains.
This morning, my wife and I took a boat tour along the base of the Pictured Rocks; conducted by a private company in cooperation with the National Park Service, the tour provided a unique and up-close view of the spectacular cliffs that were exposed by Pleistocene glaciers and are now molded by the erosive forces of Lake Superior and the region's harsh northern climate. Rock falls are a common occurrence along this majestic wall, producing recessed caves, natural arches and varied rock formations that evoke images in the eyes of human visitors (hence the name of Pictured Rocks). The boat officers and an onboard Park ranger introduced us to both the natural and the human history of this region, including the story behind many of the shipwrecks that have occurred along this storm-ridden coast.
Later in the day, we hiked out to Chapel Rock, where a pine tree grows from the top of a rock pedestal, its roots dangling between the pedestal cap and the adjacent cliff; those roots formerly ran through the soil of a rock arch before the latter collapsed into the lake. On our loop hike to and from this popular site we passed through a karst landscape which included Chapel Falls and numerous sinkholes; this topography reflects the layer of Ordovician dolomite that overlies the Permian sandstone south and east of Pictured Rocks (i.e. toward the center of the Michigan Basin). Tomorrow, we'll head westward to the Keweenaw Peninsula and thence to the Porcupine Mountains.
Kamis, 22 September 2011
South of Superior
When we arrived at Whitefish Point this morning, a raw, northwest wind raised whitecaps on Lake Superior where an ore ship, similar to the Edmund Fitzgerald, was closing in on Whitefish Bay; backed by the rugged cliffs of the Ontario coast, the freighter was headed for the locks at Sault Ste. Marie. Noisy gulls cavorted in the cold, steady breeze, a flock of horned larks scurried across the barren, pebble-strewn beach and, out on the calmer bay, a lone red-throated grebe and a trio of common loons dove for their breakfast.
Once back in our warm car, we headed west, crossing the wooded bogs of Michigan's moose country. Along the way, we took side trips to the Lower and Upper Falls of the beautiful Tahquamenon River, where its pristine waters tumble over shelves of early Paleozoic sandstone and dolomite. Further west, we returned to the southern shore of Lake Superior, entering the Pictured Rocks National Lakeshore at Grand Marias; hikes to Sable Falls, the Grand Sable Dunes and the Au Sable Lighthouse rounded out our day. After a night in Munising, we'll return to the Pictured Rocks coast tomorrow morning.
It was fitting to end our day at the Au Sable Lighthouse, which commands a spectacular view of Lake Superior. Built in 1910 and restored during the past decade, the light is both a beacon of hope amidst the harsh conditions of this northern coast and a silent memorial to the many lives lost in the turbulent waters of this magnificent lake.
Once back in our warm car, we headed west, crossing the wooded bogs of Michigan's moose country. Along the way, we took side trips to the Lower and Upper Falls of the beautiful Tahquamenon River, where its pristine waters tumble over shelves of early Paleozoic sandstone and dolomite. Further west, we returned to the southern shore of Lake Superior, entering the Pictured Rocks National Lakeshore at Grand Marias; hikes to Sable Falls, the Grand Sable Dunes and the Au Sable Lighthouse rounded out our day. After a night in Munising, we'll return to the Pictured Rocks coast tomorrow morning.
It was fitting to end our day at the Au Sable Lighthouse, which commands a spectacular view of Lake Superior. Built in 1910 and restored during the past decade, the light is both a beacon of hope amidst the harsh conditions of this northern coast and a silent memorial to the many lives lost in the turbulent waters of this magnificent lake.
Rabu, 21 September 2011
Mackinac Island
Mackinac Island is an erosional remnant, carved from Devonian limestone by the forces of ice, wind and water. It sits in the Mackinac Strait, between Lakes Michigan and Huron, and is accessed by a twenty minute boat ride from the mainland; since no motorized vehicles are allowed on the island, all land transportation is by foot, bicycle or horse power.
Like all tourist resorts, Mackinac Island has its share of luxury hotels, brew-pubs, T-shirt shops and fudge kitchens. But most of the action and secondary tourist congestion is limited to the main downtown area and those with the energy and interest to bike or walk to other parts of the island are rewarded with broad shoreline vistas, woodland trails, peaceful lanes and a host of historic sites, including an 18th Century British Fort. Wave action and stream erosion along the coast has also produced a number of rock formations, including the famous Arch Rock.
Though it is a cloudy, damp day in northern Michigan, we enjoyed an 8.5 mile bike ride around the edge of the Island, taking in views of the Mackinac Bridge, Lake Huron and of the Island's scenic coast; among the birdlife were ring-billed and herring gulls, Canada geese, cormorants, red-breasted mergansers, a few common loons and an apparent flock of scoters, too distant to identify. Once the rain stops, we plan another journey through the center of Mackinac Island; by mid morning, we'll return to the mainland and head for the Upper Peninsula.
Like all tourist resorts, Mackinac Island has its share of luxury hotels, brew-pubs, T-shirt shops and fudge kitchens. But most of the action and secondary tourist congestion is limited to the main downtown area and those with the energy and interest to bike or walk to other parts of the island are rewarded with broad shoreline vistas, woodland trails, peaceful lanes and a host of historic sites, including an 18th Century British Fort. Wave action and stream erosion along the coast has also produced a number of rock formations, including the famous Arch Rock.
Though it is a cloudy, damp day in northern Michigan, we enjoyed an 8.5 mile bike ride around the edge of the Island, taking in views of the Mackinac Bridge, Lake Huron and of the Island's scenic coast; among the birdlife were ring-billed and herring gulls, Canada geese, cormorants, red-breasted mergansers, a few common loons and an apparent flock of scoters, too distant to identify. Once the rain stops, we plan another journey through the center of Mackinac Island; by mid morning, we'll return to the mainland and head for the Upper Peninsula.
Selasa, 20 September 2011
Sleeping Bear Dunes
Stretching along the northwest coast of Michigan's lower peninsula, massive sand dunes rise above Lake Michigan. Protected as a National Lakeshore since 1970, these dunes attest to both the erosive force of the Pleistocene glaciers and the powerful storms that have regularly lashed the region since those ice sheets retreated. While lakeshore "beach dunes" are modest in size, those atop the cliffs, known as "perched dunes" and composed of glacial sand, tower up to 450 feet above the waters of Lake Michigan and encompass a broad swath of shifting landscape. Bordered by a rich beech-maple forest, the dunes are temporarily stabilized by beach grasses, wildflowers, sand-tolerant shrubs and groves of cottonwood but, over time, are sculpted and advanced by the relentless wind, swallowing tracts of forest that lie in their path.
A Visitor Center, located in Empire, offers an introduction to the natural history of this fascinating ecosystem and provides an overview of the plants and animals that inhabit the dunes and adjacent forest. In addition, an auto tour road provides access to a host of overlooks, several of which yield spectacular views of the dunes, Lake Michigan and offshore islands. Those with the time and ability to do so are encouraged to hike at least one of the trails that lead into this beautiful yet harsh environment; trudging through the sand, especially when accompanied by intense sunshine and a strong wind, makes one appreciate the true nature of this unforgiving landscape.
Sleeping Bear Dunes National Lakeshore is located about 28 miles west of Traverse City, Michigan and is best reached via Michigan Highway 72. Its name is derived from a prominent dune that, topped by a clump of shrubs, resembled a sleeping bear in the eyes of Native American residents. While modern visitors might not appreciate that visual interpretation, they are sure to agree that this scenic coastline is one of the most spectacular sites in North America.
A Visitor Center, located in Empire, offers an introduction to the natural history of this fascinating ecosystem and provides an overview of the plants and animals that inhabit the dunes and adjacent forest. In addition, an auto tour road provides access to a host of overlooks, several of which yield spectacular views of the dunes, Lake Michigan and offshore islands. Those with the time and ability to do so are encouraged to hike at least one of the trails that lead into this beautiful yet harsh environment; trudging through the sand, especially when accompanied by intense sunshine and a strong wind, makes one appreciate the true nature of this unforgiving landscape.
Sleeping Bear Dunes National Lakeshore is located about 28 miles west of Traverse City, Michigan and is best reached via Michigan Highway 72. Its name is derived from a prominent dune that, topped by a clump of shrubs, resembled a sleeping bear in the eyes of Native American residents. While modern visitors might not appreciate that visual interpretation, they are sure to agree that this scenic coastline is one of the most spectacular sites in North America.
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