The Long Deep History of Parry Sound, Pt. 1

The Long Deep History of Parry Sound is a two-part series telling the geological history of our area.

The first white settlers came to this region in the 1850s – but history is more than just what is recorded by people. To some people, the unrecorded past can be just as interesting; but the reading of that history is often difficult as it requires special knowledge. I have a bit of the special knowledge, and so I want to tell you a bit of the hidden history of Parry Sound.

Everyone who lives around here knows that the area is old. We live in the Precambrian Shield, but for most people that is all they know. I would tell you that saying we live in the Precambrian Shield is like saying, “Parry Sound is in North America.” One hundred percent correct, but not very specific. I think that is a shame, because Parry Sound is located in a very interesting place.

Read more about Parry Sound's geological history after the jump...


People think that the rocks around here are mainly granite, and this is not true. As the late Charlie Farquharson used to say on CFRB in Toronto many years ago: Orrville (his hometown) was not built on granite, but on a load of schist. Granite is an igneous rock made of cooled magma. Schist is metamorphic shale, a sedimentary rock made from clay. There is granite in the area, but for the most part, Charlie was right – the rock is schist.

Schist, and the other common rock in the area, gneiss (pronounced like nice), make the area much more interesting. As I said before, schist and gneiss are metamorphic shale, and shale is made from layers of compressed clay. When I think of this, I think of lakes or rivers holding fine grains, which settle out onto the lake bed or the ocean floor when the waters are calm. They are packed together by time and pressure to make many layers of clay. Shale forms when the clay hardens into rock.

There is another commonly known fact that will set the stage for the wonder I hold for these rocks: the Canadian Shield, another name for the Precambrian Shield, is over a billion years old. That means that the rocks that you see all over the region were formed from mud and clay laid down 1-2 billion years ago. If I stopped there, that would be quite a story to think about, but there is more.

Shale becomes schist and gneiss when it is forced to go through one of the most extraordinary processes that occur on this planet: mountain building. About 1 billion years ago, two landmasses came together; the same way that India and Asia came together millions of years ago and created the Himalaya Mountains. They pushed the shale together to form mountains as tall as or taller than Mount Everest. The heat caused by the compression and twisting of the rock as it was thrust into these mountains turned the shale into schist and gneiss.

When I look out at the rock in the area, I find it difficult to imagine that they are the last roots of mountains like those in the Himalayas. But that is what they are. It took hundreds of millions of years for these mountains to be worn down and weathered to their roots – to the form that they are now. From when the mountains hit their peak and to when they were worn down low to where they are now, life evolved from proto-bacteria into many of the forms that we see today.


– by Aubrey Jackson