Jason Idzerda
Underwater Escarpment
Along the south eastern shoreline of Flowerpot Island there are very noticeable drop offs just beneath the waters surface. This underwater cliff is part of the Niagara Escarpment and drops around 100 feet and up to 300 feet in some places before meeting the Flowerpot Beach (an old beach at the bottom of these cliffs). There was an ancient waterfall similar in size to Niagara Falls just north of the island that is now entirely underwater. I held on tight to my camera gear while walking along the edge wondering what creatures live at the bottom of the cliff I was standing on. It is an erie feeling walking along the top of such a massive cliff and my mind could not help but wonder what kind of photo opportunities this area presented 450 million years ago.
The Niagara Escarpment extends 700 Kms. from Niagara Falls to Tobermory, where the 200 foot cliffs plunge into the depths of Georgian Bay, only to reappear as islands such as Flowerpot and Manitoulin. This formation is part of an extensive geological phenomenon known as Barrier Reefs. Formed mainly by colonial tabulate coral during the Silurian Period (438 and 408 million years ago), the barrier reef structures completely enclosed the Michigan basin region of North America. While present in the subsurface of Ohio, Indiana, Wisconsin and Michigan, barrier reef limestone formed cliffs all along the Niagara Escarpment. The thickness of the main reef limestone varies between 100 and 500 meters. On the Bruce Peninsula, the cliff forming limestone is generally named the Cabot Head Formation.
It is worth knowing that during the Silurian Period, the North American continent was smaller than today, and was situated with a different geographical orientation. What is now north was then east. While the Bruce Peninsula is now at 45 degrees north of the equator, it was then 10 degrees south of the equator. The barrier reefs were thriving in warm, shallow, tropical seas. On the tectonic scene, the Northern Appalachian Mountains were being built by Taconic Orogeny as Baltica (Scandinavia and western Russia) collided with ancestral North America, closing the lapetus Ocean (the pre-Atlantic Ocean). Therefore the sea was warm and marine life such as coral flourished. `Rooted' in the quiet waters behind these coral were plant like animals called crinoids that waved in an effort to filter feed. More active cephalopods (uncoiled relatives of today's nautilus) swam freely in this sea.
As the animals died their remains settled and became part of the mud of the sea bottom. Tissue decomposed but the skeletons of calcium carbonate remained and accumulated. As the weight of the sediment built up, the lower layers hardened into limestone (calcium- carbonate). Magnesium bearing fluids concentrated and changed the limestone into dolomite (magnesium-calcium-carbonate), the rock we see on the surface today. Many of the fossils were destroyed by this recrystallization. Long periods or erosion and weathering have since exposed and sculpted the rock. The cliffs of the escarpment were formed as the more layered underlying rock was eroded away leaving the dolomite caprock unsupported. Eventually the caprock fell and the characteristic cliff face remained. Actually, the cliff face was at one time near Sudbury and has since eroded to here.
Copyright © 2012, Jason Idzerda
Underwater Escarpment
Along the south eastern shoreline of Flowerpot Island there are very noticeable drop offs just beneath the waters surface. This underwater cliff is part of the Niagara Escarpment and drops around 100 feet and up to 300 feet in some places before meeting the Flowerpot Beach (an old beach at the bottom of these cliffs). There was an ancient waterfall similar in size to Niagara Falls just north of the island that is now entirely underwater. I held on tight to my camera gear while walking along the edge wondering what creatures live at the bottom of the cliff I was standing on. It is an erie feeling walking along the top of such a massive cliff and my mind could not help but wonder what kind of photo opportunities this area presented 450 million years ago.
The Niagara Escarpment extends 700 Kms. from Niagara Falls to Tobermory, where the 200 foot cliffs plunge into the depths of Georgian Bay, only to reappear as islands such as Flowerpot and Manitoulin. This formation is part of an extensive geological phenomenon known as Barrier Reefs. Formed mainly by colonial tabulate coral during the Silurian Period (438 and 408 million years ago), the barrier reef structures completely enclosed the Michigan basin region of North America. While present in the subsurface of Ohio, Indiana, Wisconsin and Michigan, barrier reef limestone formed cliffs all along the Niagara Escarpment. The thickness of the main reef limestone varies between 100 and 500 meters. On the Bruce Peninsula, the cliff forming limestone is generally named the Cabot Head Formation.
It is worth knowing that during the Silurian Period, the North American continent was smaller than today, and was situated with a different geographical orientation. What is now north was then east. While the Bruce Peninsula is now at 45 degrees north of the equator, it was then 10 degrees south of the equator. The barrier reefs were thriving in warm, shallow, tropical seas. On the tectonic scene, the Northern Appalachian Mountains were being built by Taconic Orogeny as Baltica (Scandinavia and western Russia) collided with ancestral North America, closing the lapetus Ocean (the pre-Atlantic Ocean). Therefore the sea was warm and marine life such as coral flourished. `Rooted' in the quiet waters behind these coral were plant like animals called crinoids that waved in an effort to filter feed. More active cephalopods (uncoiled relatives of today's nautilus) swam freely in this sea.
As the animals died their remains settled and became part of the mud of the sea bottom. Tissue decomposed but the skeletons of calcium carbonate remained and accumulated. As the weight of the sediment built up, the lower layers hardened into limestone (calcium- carbonate). Magnesium bearing fluids concentrated and changed the limestone into dolomite (magnesium-calcium-carbonate), the rock we see on the surface today. Many of the fossils were destroyed by this recrystallization. Long periods or erosion and weathering have since exposed and sculpted the rock. The cliffs of the escarpment were formed as the more layered underlying rock was eroded away leaving the dolomite caprock unsupported. Eventually the caprock fell and the characteristic cliff face remained. Actually, the cliff face was at one time near Sudbury and has since eroded to here.
Copyright © 2012, Jason Idzerda