A surprising abundance of karst features in what was otherwise belived to be a cave desert.
As of late Jeff Mirza, Jeff Collins, myself and my regular caving partner have all been investigating off the caving radar in Southern Ontario – an area that is not generally recognized as “primo” caving ground.
The rock in Southern Ontario is layed out in concentric rings from a central point over the Michigan peninsula. The most recently deposited rock in this vast amphitheatre is at the center of this huge layer cake – a feature known to geologists as “The Michigan Basin”.
The basin was once an inland sea and as it evaporated the shores moved further and further toward the modern day Michigan Peninsula. Deposition obviously occured along the lines of understood sedimentary principles, the oldest layers being along the bottom of the layer cake and the fresher layers being atop that.
Imagine an enormous geological bowl where the water is evaporating toward the center of the bowl and around the outer edges of the bowl the deposition is exposed in concentric rings, each ring further toward the center being of a younger age.
The geological deposits out at the furthest point from the center of the bowl are the oldest – those of the Ordovician age – shales and limestones that form some of the best caving environments in the province. Closer in there are the Silurian Age dolostones of the Niagara Escarpment and lastly, as close as you can get to Michigan and still be in Ontario, the Devonian Age limestones and shales.
The Devonian Age rocks are the youngest sedimentary rocks in Ontario and, as generally believed – disguised well beneath a thick mantle of glacial till – hence little opportunity for karst development – or so you might imagine. Studies that I have read suggest quite the opposite. Where there is some amount of till above and as you might expect – vegetation, there is a greater opportunity for the development of carbonic acid and so increased action from the tunnel forming acids in the ground water.
Rumours of caves and sinkholes in Devonian Age rocks abound and we were encouraged to investigate the area by the overwhelming bombardment of “D’s” ariel photo observations.
A recent trip down to the shores of Lake Erie seemed encouraging. We had already heard of the many abandoned gypsum mines and alongside a dry river bed we located this stinking sulfur spring. Jeff C. pointed out a crack that he had slithered into and said that at its end he had cleared debris in the top of what appeared to be – possibly a bell shaped shaft.
Thus began the investigation into the possibilities of Ontario’s Devonian Age rock.