Geology | exploRVistas

July 22, 2020 – Leelanau County, Michigan

Written by Jim

One of the more interesting discoveries on our property in Leelanau County has been what lies just below the surface. Our land sits perched on a hill about a mile west of Grand Traverse Bay and four miles east of Lake Michigan. We are 150 feet above those bodies of water. Our soil is well drained, with a mix of topsoil, sand and lots of gravel. That gravel…and our hill…is courtesy of the Laurentide Ice Sheet that plowed its way southward from Canada 10,000 years ago. As it moved, it pushed whatever soil and stone it could dislodge in front of it. Much of that rock was sedimentary, having been laid down at the bottom of an ancient sea that once covered the central portion of North America. In our case, that sea was well to our north. Some of the gravel and stone is pink granite, which is found along the Canadian Shield on the north shore of Lake Superior…again, well to our north. In any case, sticking a shovel in the ground around here will bring up a multitude of surprises!

Mid June brought a project that required a bit of digging. We needed to run an electric line from our barn to our new RV sites, a distance of 100 feet. Rather than fight the rocky soil, we rented this beauty:

Four hours with this trencher goes for about $250, so we also cut a trench to the future cabin and put 2″ conduit in. That saved having to rent this again next year.

The trench to the RV sites was fairly easy, as the top portion was fill that the excavator brought in.

Not so on the other trench. This was all glacial till. Note how it is not a straight line, as the Ditch Witch was bouncing off of every boulder it encountered! Let’s just say that we were glad it finished the project in one piece. This particular slice required quite a bit of hand digging, as the machine couldn’t go deep enough because of the rock.

So what did we find?

This is an example of a Charlevoix stone, a cousin to the Petoskey stone. Both are some 350 million years old and are forms of coral from that ancient seabed I spoke of earlier.

Here is a Petoskey stone, which can be distinguished by its geometric shaped coral.

On occasion, I would toss a seemingly mundane gray rock onto the pile, only to have it split in two.

This one split and left not only the imprint of a shell on the right half, but the actual shell on the left half. Once again, that shell is millions of years old.

And check out this one. There is a lot going on in this beauty! This is not anything that would’ve lived on the bottom of freshwater Lake Michigan, but rather the shallow saltwater sea that was to our north and west. This was dredged up by the glaciers and transported here during the last ice age…high up on our hill.

Finding treasures like those makes doing work like this a lot more fun!

The rest of our project is coming along right on schedule.

We’ve been busy putting up fascia and soffit…

…and siding! We are just a few days from being done with that project. The back of the barn is built into the hill; that’s why the red portion looks so short. We should be able to get our final inspections within the next couple of weeks. Look for photos of the finished product in our next post.

The other excitement around here was when we discovered that a few of our large maples were hollow inside and were in danger of falling on our barn and future cabin. Had we noticed them before we built the barn, we could’ve cut them down ourselves. We chose to have a tree service come in and take them down for us.