Ancient Reefs in Our Great Lakes

Loreen Niewenhuis is an author, adventurer, and dynamic speaker. 

She has completed a trilogy of 1,000-mile adventures exploring the Great Lakes and has authored three books about these adventures: 

A 1,000-Mile Walk on the Beach  [A Heartland Indie Bestseller]

A 1,000-Mile Great Lakes Walk   [Winner of the Great Lakes Great Reads Award] 

A 1,000-Mile Great Lakes Island Adventure  [Long-listed for the Chautauqua Prize]

 

To learn more about her work, or to engage her as a speaker, go to http://www.laketrek.com/great-lakes-speaker/

Many people searching the lakeshore for petoskey stones are unaware that it is a fossilized coral. Vast coral reefs grew in the shallow sea covering the middle of this continent long before the glaciers gouged out the basins for our Great Lakes.

I recently visited a remote (and undisclosed) portion of the lakeshore to visit some giant pieces of that ancient reef:

Piece of reef with fossilized corals [size 11 foot included for scale]

Petoskey stones are abundant along some stretches of the lakeshore

Here's another piece of reef with fossilized corals

And I saw a new (to me) moth on this hike, 

the Leconte's Haploa Moth.

Can you find it here?

How about here?

Close-up of Leconte's Haploa Moth

Handfuls of Manitoulin Island

While on Manitoulin Island -- the largest island in the Great Lakes basin -- I found many fascinating fossils and stones:

Crinoid and quartz

This last one is a fossilized sponge

Manitoulin Island is the largest island in the 

Great Lakes. This is one of the many islands I explored for my upcoming book.

Tales from the Book Tour: 4 Events in 4 Days!

I traveled Michigan's midsection this week touring with my book. It's always fun to meet people who care about our Great Lakes!  I had events in Glen Arbor, Alpena, Big Rapids and East Tawas.

Alpena Public Library

I also had time to poke around the old Rockport Mine for fossils.

Rockhounding at Rockport Mine

Pier at Rockport Mine

I spoke to the Rock, Gem and Mineral Club in Big Rapids. They meet at Ferris State University.

Science building at Ferris State

Petoskey stone (in the rough)

Boots, Books, and ROCKS 

Lecture venue in East Tawas (sponsored by the Friends of the Library in East Tawas)

Thanks to everyone who came out to hear me read or give a talk about our Great Lakes!

I Ain't Nothin' but a Rock Hound!

It was torturous to hike and NOT pick up all the interesting rocks I came across.

Of course, already hiking with 30+ pounds on my back was a strong deterrent to rock-picking.

Still, when I came across these huge petoskey stones, I wanted to hoist them into my pack! 

Yep, that's a pretty big petoskey stone (ruler is 6")!

And another one!

All rocks in Sleeping Bear Dunes National Lakeshore are protected and must be left there. This includes both North and South Manitou Islands, so I took only photos there.

Not sure what this stone was, but it was beautiful (N. Manitou Island)

Rocks of Lake Michigan

Lake Michigan has a wonderful variety of stones.

My eye constantly scans  for the perfect composition.

Did You Know...

…the French explorer Jean Nicolet was the first European to travel the Great Lakes.

…the name Michigan is probably from the Ojibwa word michigami meaning “great water.”

...the Great Lakes are relatively young, geologically speaking, around 10,000 years old.

...the state fossil of Michigan -- the petoskey stone (in photo below) -- is a fossilized coral that thrived much earlier. They populated the inland sea that covered much of this region in the Devonian Period over 350 million years ago.

Rock Hound

Most people are familiar with the petoskey stone, a fossilized ancient corral, hexigonaria percarinata, found along the shoreline of NW Michigan (first photo). There are many other fossils to be found on the lake, though. Check out the second photo. I found all of these on my Lake Trek.

There is also a wide variety of rock types and colors in Lake Michigan. Photos 3&4 are of rocks from SW Michigan shoreline. Photo 5 is from the final stretch from Milwaukee to Chicago. One even looks like a fossilized tooth (photo 6).









































































The final handful are not natural stones at all. This is cast-off slag (the impurities separated out during the refining process) from a steel mill that has been tumbled by the lake for decades.

Around the city of Leland, Michigan, these are called 'Leland Blues.' Local artisans there make earrings and other crafts using these intriguing 'stones.'

The colors of tumbled slag range from turquoise to milky blue and all shades in between.