This accompanying picture is of a cave in marble known as “The Natural Land bridge”. It was first bought to my attention by Marcus Buck who had kayaked through it during the stream’s high flow.
Ontario’s marble caves are amongst the most beautiful natural formations in the region. As you will learn from my book “Rockwatching ; Adventures Above and Below Ontario”, the province is divided into a vast sedimentary plain in the south and the Canadian Shield in the north. The sedimentary plain consists of bands of limestone, dolostone and shale that increase in age as they move from the most south westerly areas of Ontario up toward the shield in the north.
The canadian Shield consists of granites, gneises and other metamorphic rocks in which it has been assumed up until recently that very few caves are found. There is a line that runs from Kingston up across the top of Bobcaygeon to either side of which these distinctive geological regions occur. As a general rule limestone solution caves will form in the more southerly areas and Marble caves will form in the canadian Shield.
Marble caves are known to have the cleanest and sharpest of features while limestone caves are generally larger and more rounded. I frequently travel into the shield area and explore the spectacular marble caves found there.
The first marble cave in Ontario that I had visited was about 15 years ago. My father, my son and I dropped down through a triangular hole into a dusty cavern. We proceeded to lower levels in marble shafts that were as clean and white as porcelain. Beneath these shafts we found ourselves in a sodden mire, surrounded on all sides by razor sharp shelves of rock. In shining my flashlight beneath the strata the whole plane “glowed like a burning ember”. Deeper into the system I found myself gazing down through a narrow crevice into a room below. In the middle of the room there was a huge chocolaty billow of mud and through it there was the solitary track of some previous explorer. It was kind of spooky, I could not find an entrance to that chamber and wonder how the explorer had found their way out. I wonder if during the spring flood the entrance had been silted over by the mud.