North Shore Camping - Day 4

The title says 'North Shore Camping', but Day 4 found us almost sixty miles away from Lake Superior at the Trail's End campground at the end of the Gunflint Trail.  The plan for the morning was to accompany a group of Earth Science teachers and several geology professors on a couple of hikes to sites of geologic importance in the area.  The group of teachers were part of TIMES XIV, the TIMES Project is an intensive two-week long class teaching inquiry-based teaching methods and focusing them on Minnesota Earth Science.  As a past participant of TIMES (summer of 2009) and a member of the Minnesota Earth Science Teachers Association's Board of Directors, we were invited to go along on the days hikes.  My job would be to talk Earth Science with the teachers and get to know what they do in their classrooms, while giving them examples of what I do differently as a result of the TIMES Project.  Kieran and Luke's job for the day, just be themselves.

We met the group in the morning at the Magnetic Rock trailhead, the same place that we had hiked the day before, though we would not be repeating the entire hike this day.  The focus of the day were features found around the 1,878 million year old Gunflint Iron Formation.  A iron mine opened near here in the late 1800s, but failed rather quickly because the Mesabi Iron Range (located to the south) was already in operation and a financial panic scared investors in 1893.

We hiked approximately half way to Magnetic Rock to view stromatolites that are found along the trail.  Stromatolites are nearly circular algal mounds that can be several feet in diameter.  While alive, cyanobacteria (the living organism of the stromatolite) grow upward from the seafloor by trapping sediment on a sticky mat.  These organisms obtain energy by using the process of photosynthesis, essentially using carbon dioxide and releasing oxygen as a waste product.  Stromatolites are remarkable because they are the reason that we have the iron deposits around the world, before this period in Earth's history, the level of atmospheric oxygen was very low which allowed soluble iron to build in the world's oceans.  As the stromatolites began to release oxygen as a waste product, the iron in the world's oceans basically rusted (or precipitated) out of solution and was deposited on the ocean floor.  Stromatolites of this age are found around the world near most of the world's major iron formations.

The stromatolites are outlined in the pictures below.  Stromatolites are not unique to just this time period in Earth's history, they are found in many sedimentary rock sequences.  Much younger Ordovincian rocks of Southeastern Minnesota also have great examples of stromatolites.  They can even be found today in hypersaline waters, where predators are scarce, the best example being Shark Bay in Australia.

The next stop for the day was a short drive and short hike away that a catastrophic few hours in Earth's past.  Approximately 1,850 million years ago, a meteorite struck near Sudbury, Ontario, almost 450 miles away from Minnesota.  It is the second largest impact structure found and very few are older than this impact.  The outcrops showing evidence of the impact were found because a forest fire raged through the area in 2007 and removed most of the overlying vegetation, making it much easier to see the underlying rocks.

Essentially, the greater than 10 magnitude earthquakes fractured the iron formation and resulting tsunami would have re-worked or re-arranged the iron formation.  Near the base of the impact layer, angular fragments meters in length of the iron formation are cemented together in a green matrix.  Near the top of the formation, the size of the iron formation fragments are much smaller.  Iron ceased to be deposited worldwide after the impact.  For a much more detailed read on the formation of the impact layer and a history of the impact layer itself, read the document published by the Minnesota Geological Survey.

Many of the teachers we were accompanying were amazed that two boys, like Kieran and Luke, could go through some of these hikes.  A few were even surprised that they could camp in locations like these, this isn't a state park, there is no cell phone reception or any technology, and very few people.  Both boys did a great job doing there own thing, while dad got a few hours of adult inte
raction (a very rare thing for a week-long camping trip).  The boys even added to their rock collection, which of course, dad had to carry.

The picture below shows Kieran sitting on the burnt remains of a tree, just above the last outcrop that we would visit with the TIMES group, though they would continue on for at least one more stop before returning to the Twin Cities that evening.  It is located just a short hike down National Forest Service Road 1347 from the previous stop.

At this particular outcrop, you are able to stand near the uppermost portion of the Sudbury Impact Layer.  Deposited here are accretionary lapilli, essentially ash pellets that were thrown away from the impact site.  Using very high powered microscopes, shocked quartz (which is only found at impact sites) can be found in these centimeter pellets, commonly called ejecta, and the surrounding matix.  Look for the small circle structures in the pictures below.

After leaving the TIMES XIV group around 2:00 pm, we had a little bit of time to return to the campsite and relax.  Of course the boys have a different way of relaxing than I do, we had to explore the campsite.  Because of setting up the camp and cooking dinner under the threat of a thunderstorm the night before (though we only had thunder, no rain), we had not wandered the area properly.  Of course the boys through some rocks into the lake.

We later visited the Chik-Wauk Museum which Kieran really enjoyed the scavenger hunt that was available for kids.  The museum tells the history of the Gunflint Trail - biological, geological and human.  The ladies at the desk also gave us the directions to a sand swimming beach nearby, though when we got to the location given at nearly 5:00 pm it turned out to be a swamp.  The directions given were wrong or we went to the wrong location, either way the boys chose not to do any swimming.

On the drive back to the campsite from the swamp (a ten minute drive), the experiences of the last four days caught up with the boys as they fell asleep.  When we got back to camp, I carried them to their camp chairs because I didn't want them sleeping in the high temperatures of the van.  After a few minutes of sitting aimlessly in their chairs, I asked if they would like to lay on their sleeping bags in the tent, both immediately said yes (keep in mind this was about 5:30 pm).  Kieran woke up at 8:30 pm hungry, we made some hot dogs quick and he was back in the tent by 8:50.  Luke slept through the night until he woke up fairly hungry at 6:00 am.  I would say that they were exhausted...

This would be our last night at the Trail's End campground before we left for the North Shore again.  The campground is interesting because the forest fire burnt some areas of the campground to the ground and left others untouched.  The difference is extremely visible when walking around the area.  The areas that were completely burned have large outcrops of a whitish granite, the 2,689 million year old Saganaga Tonalite, where the areas that were not burned have basically an old growth forest ecosystem.

Day 5 would take us back to Lake Superior with several stops before reaching Tettegouche State Park.

To be continued...