It’s a long drive from the Gunflint Trail to Porcupine Mountains State Park in the Upper Peninsula of Michigan-316 miles. But in Wisconsin we picked up Route 2 again. It felt like home. And we saw some very interesting sights.
Once set up, we drove to the Visitors Center which has a very good display of mounted animals and birds native to the Porcupine Mountains, including a rare goshawk, a medium large bird of prey. After that we drove to the parking area and hiked to the beautiful Lake of the Clouds situated between two ridges.
The next day was cloudy with some rain. We drove on the South Boundary Road, stopping at the ruins of the Nonesuch Mining town, the Summit Peak, the Overlooked Falls and finally the Presque Isle side of the park. At Summit Peak one story board told the story of the great storm of 1953. On June 30, 1953 a storm moved across Lake Superior and hit the mountains with such force that it blew down many of the largest trees over 5,000 acres of forest. The only eyewitnesses to the event were two high school boys who had been camping and fishing on the Big Carp River. They reported that the winds started soon after daybreak and were so violent that they had to seek refuge in a ravine. From their shelter, they heard trees crashing around them for what they judged to be twenty minutes. The Summit Peak was especially hard hit. Park rangers at work clearing the trails after the storm recall seeing hardwood trees two-foot in diameter that had been twisted off at the base. The following winter, loggers were permitted to enter the park and salvage much of the downed timber.
The falls and rapids of the Presque Isle River have very strong currents and numerous deep holes. There is a great paved trail along the river with boardwalks and viewing platforms for breathtaking views of waterfalls and rapids. And it is possible to hike down to the shores of Lake Superior.
On the way back a goshawk flew across the road too quickly to take a picture. Later on we learned from a birder that it is rare to see one. In fact Hank, Richard’s high school friend that we visited in Harbor Springs, has been birding for years and he has never seen one.
Late in the afternoon the rain cleared and the sun came out so the Agate Hike was on. Ranger Bob explained the characteristics of the Lake Superior agate, a type of agate stained by iron and found on the shores of Lake Superior. Its wide distribution and iron-rich bands of color reflect the gemstone's geologic history in Minnesota, Wisconsin, and Michigan.
More than a billion years ago, the North American continent began to split apart along plate boundaries. Magma upwelled into iron-rich lava flows throughout the Midcontinent Rift System, including what is now the Minnesota Iron Range region. These flows are now exposed along the north and south shores of Lake Superior. The tectonic forces that attempted to pull the continent apart, and which left behind the lava flows, also created the Superior trough, a depressed region that became the basin of Lake Superior.
The lava flows formed the conditions for creation of Lake Superior agates. As the lava solidified, water vapor and carbon dioxide trapped within the solidified flows formed a vesicular texture (literally millions of small bubbles). Later, groundwater transported ferric iron, silica, and other dissolved minerals passed through the trapped gas vesicles. These quartz-rich groundwater solutions deposited concentric bands of fine-grained quartz called chalcedony, or embedded agates.
Over the next billion years, erosion exposed a number of the quartz-filled, banded vesicles—agates—were freed by running water and chemical disintegration of the lavas, since these vesicles were now harder than the lava rocks that contained them. The vast majority, however, remained lodged in the lava flows until the next major geologic event that changed them.
During the ensuing ice ages a lobe of glacial ice, the Superior lobe, moved into the Lake Superior area through the agate-filled Superior trough. The glacier picked up surface agates and transported them south. Its crushing action and cycle of freezing and thawing at its base also freed many agates from within the lava flows and transported them, too. The advancing glacier acted like an enormous rock tumbler, abrading, fracturing, and rough-polishing the agates.