John and Diana are traveling around the country with a 37-foot RV and an 18-year-old cat. This is their story.
Friday, July 22, 2011
Natural History of Mackinac Island
The above picture was taken on Lake Shore Boulevard (M-185). The road is eight miles in circumference around Mackinaw Island, and is the only state road where cars are banned! The picturesque route took us past Arch Rock. John and I just could not pass up climbing the 700 foot elevation to see it!
I learned a new word while touring this island, and it is"brecciated". The rock formations on the island are brecciated, or composed of sharp-angled limestone fragments cemented in a fine matrix. The interpretive sign near the Arch Rock explained that at one time a solid mass arose 100 feet above the lake. Over many years the lake water dissolved the softer rock in the middle of the mass and the center of the formation crumbled, leaving a brecciated limestone arch. After lunch we traveled off the main road and took a path which went inland to Skull Cave, thought to be the oldest geological formation on the island.
Story has it that a fur trader in 1763 hid from Native Indians in this cave and found many human bones on the floor of the cave. It was a sacred Native American burial ground. Traveling back on the main road again we found Devil's Kitchen, another gouged-out breccia formation that eroded at a time when the lake levels where higher. That formation is pictured below. We also took a side trip to see another formation called Sugar Loaf.