The Great Lakes Rock

The Great Lakes Rock

From the round surf-polished rocks of Lake Superior’s shore to the sand dunes of Lake Michigan, I have roamed and picked up stones: agates, pudding stones and some bearing copper or fossils.  And I hiked the alvars on the Door Peninsula and Ontario’s Bruce with their layered limestone shores bearing fossils of ancient salt seas.   Lake Huron’s green waters pour into Lake St. Clair and its silty marshes and then to Lake Erie teeming with birds and fish. The waters pick up speed in the Niagara River to take a tremendous plunge over Niagara Falls.  The rock underlying the falls will wear away in time I am told, but not in my life time.  Lake Ontario’s flat shores have good soil for vineyards and farm lands.  Sailors and sports fishers enjoy Lake Ontario’s riches and the lake flows out through the St. Lawrence River with a myriad rocky islands. 

pictured are layers of limestone on Wisconsin's Door Peninsula. This formation is called an alvar.

Flower Pot Island in Georgian Bay is named for the limestone feature pictured.  I enjoyed a boat trip where I saw many islands and I was so impressed that I painted this watercolor.  The color of the water is very beautiful and its clarity allows views of sunken ships from glass bottom boats.

I visited The Bruce Peninsula while researching my book, The Dynamic Great Lakes.

This painting is now on display in Grand Haven Michigan's Community Center Lakeland Artists Show.

My book is available at Barnes & Noble, Amazon.com and many other fine independent bookstores such as The Bookman in Grand Haven, MI.

The photo is the Bruce Peninsula in Lake Huron. I took this picture and liked it so much that I asked my publisher to use it on the cover of my book, The Dynamic Great Lakes. The Bruce Peninsula in Ontario is similar to the Door Peninsula in Wisconsin. Thousands of years ago, these limestone fingers of land were joined. They are part of the Niagara escarpment. Limestone underlies much of the Great Lakes basin. It was built during the time when much of North America was covered by saltwater seas.

The Bruce Peninsula is built of limestone and there are beautiful hiking trails where rare flowers may be found. I visited in fall and collected a basket full of mushrooms. I thought their shapes and colors were so beautiful that I took them home with me to paint. Unfortunately, the mushrooms didn't last very long, so I never did paint them. Sigh.

Pictured is a rock formation on Lake Huron called an alvar.

Lake Huron Georgian Bay

Georgian Bay on Lake Huron could almost be called another Great Lake since it is so large.  Pictured is an alvar, a limestone plain where rare plants may be found.  I used this photo for the cover of my book, The Dynamic Great Lakes.  In the Bruce Peninsula, Canada, I hiked the Bruce trail and saw plants found nowhere else.  The Bruce Peninsula is a finger of land that is part of the Niagara escarpment.  The Door Peninsula in Lake Michigan is also a part of this escarpment.

I cruised the waters of Georgian Bay in a glass bottom boat and saw shipwrecks beneath the green waters.  Many shipwrecks also lie under the waters around the Door Peninsula. Sailors used to call this Death's Door.

There are alvars on Wisconsin's Door Peninsula also. 

Books by Barbara Spring http://barbaraspring.yolasite.com/

Water Levels in the Great Lakes: NOAA Information

The information below is from the NOAA educational website.  The photo is on the cover of my book, The Dynamic Great Lakes.  The scene is an alvar on the Bruce Peninsula in Canada on Lake Huron.

"Water levels in the Great Lakes change because of meteorological effects, not tides.

Water levels in the Great Lakes have long-term, annual, and short-term variations. Long-term variations depend on precipitation and water storage over many years. Annual variations occur with the changing seasons. There is an annual high in the late spring and low in the winter. These changes occur at a rate that can be measured in feet per month.

True tides, changes in water level caused by the gravitational forces of the sun and moon, do occur in a semi-diurnal (twice daily) pattern on the Great Lakes. Studies indicate that the Great Lakes spring tide, the largest tides caused by the combined forces of the sun and moon, is less than five centimeters (two inches) in height. These minor variations are masked by the greater fluctuations in lake levels produced by wind and barometric pressure changes.

Consequently, the Great Lakes are considered to be essentially non-tidal.

For more information:

Center for Operational Oceanographic Products and Services

Great Lakes Water Level Data

Great Lakes Online

Tide Predictions and Data Frequently Asked Questions

Tides Tutorial, NOS Education

What are Tides? - Diving Deeper audio podcast "

The Bruce Peninsula on Flickr - Photo Sharing!

The Bruce Peninsula on Flickr - Photo Sharing!

The Bruce Peninsula in Canada is a fascinating place for boating, fishing or hiking. Wind and waves have eroded the sandstone into sentinals such as the one pictured. It is part of the Niagara escarpment. The Door Peninsula in Wisconsin is also.

The Bruce hiking trail is beautiful with many views of Georgian Bay.

There are glass bottomed boats that will reveal to you shipwrecks on the bottom of Georgian Bay.

Lake Huron Georgian Bay

Read about the Great Lakes in my book, The Dynamic Great Lakes

Alvar on the Bruce Peninsula

I took this photo on the Bruce Peninsula in Canada, a finger of land that juts into Lake Huron. Here and on the Door Peninsula in Wisconsin these peninsulas are of limestone and sometimes fossils may be found embedded in the rock. The tree pictured is a cedar. Many shipwrecks lie under the waters surrounding these peninsulas since the waters are trecherous. The Door Peninsula was so named because sailors called it "Death's Door."

I like this photo so well I asked my publisher to use it for the cover of my book, The Dynamic Great Lakes.