Canton, MI to Tobermory, ON

Most people think of Michigan in terms of cars.  If you get up to the Traverse City area, you may think of cherries and cherry pie.  I kind of think of it as sedimentary strata on top of  Precambrian rocks. (Yeah, right). There is this thing called the Michigan Basin.  It is a roughly circular formation that encompasses what is now Western Ontario, Lake Huron, the lower Michigan peninsula, Lake Michigan, and Eastern Wisconsin.  It is a basin because it subsided as shallow-sea sediments filled it.  In addition, barrier reefs formed around the edge of the basin.  As the shallow sea subsided (actually, rose and fell many, many times), the reefs caused the water in the basin to be trapped.  Over a long period of time, the water in the basin evaporated, leaving extensive salt deposits.  The largest underground salt mine in the world is currently being dug under Lake Huron from an entry point at Goderich, Ontario.  It currently extends more than five kilometers under the lake.  Unfortunately, Sifto, the operating company, doesn't appear to care for visitors and I could not find any informational exhibits about the phenomenon when I visited the town.  Sifto did donate some land overlooking the harbor for a very nice, rustic park that I very much enjoyed walking through.  Here is a picture of the Sifto facility in Goderich:

Sifto Salt Mine
Goderich, Ontario

Although the world may someday run out of oil, given the size just of the Michigan Basin, it is unlikely to ever run out of salt.

The next stop was Bruce Peninsula Canadian National Park, which juts between the main body of Lake Huron and Georgian Bay.  The primary feature of the park is that it is composed of part of the Niagara Escarpment, a geological formation from the Silurian Period (444 to 416 million years ago), which involved reef-building and the formation of a dolomite limestone capstone.  Dolomite is limestone in which magnesium has been chemically substituted  for some of the calcium.  Dolomite is usually harder than calcium-based limestone.  The most prominent feature of the Niagara Escarpment are the Niagara Falls, but a similar erosion-caused drop-off extends from Watertown, New York, westward roughly near the shore of Lake Ontario, then northerly across Ontario Province, then along the western shore of Georgian Bay up to Manitoulin Island, then westward along the Michigan upper peninsular and into Wisconsin, then following the western shore of Lake Michigan and ending northwest of Chicago.  Once the seas withdrew, the reef-building material started to erode, forming the escarpment, which appears as a ridge or drop-off.  The result in Bruce Peninsula National Park is stunning shoreline.  However, I apparently failed to take any pictures of it.

Example of Dolomite
That Composes the
Niagara Escarpment Capstone

Mileage: 324.  Cumulative mileage: 6,829.