The Long Deep History of Parry Sound, Pt. 2

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

The mountains that formed were not just in Parry Sound, but in the whole local region — thousands and thousands of square kilometers. A second story occurred in the same place, but deep in underground.

Perhaps before or during the great mountain building period, a hole formed deep in the crust and filled with liquid rock, called magma. Had it burst through to the surface, the lake of magma would have spewed hot lava as a terrific volcano; but it did not breach the surface. The mountain sized lake of magma cooled slowly beneath the ground. This deep landform is called a batholith, and it only becomes exposed when the rock covering it is worn away. Today, the quarry chips away at the deep formed granite, and chunks reside outside the Earth Sciences Centre at the University of Toronto.

Read more about Parry Sound's varied lands after the jump...


Back to the mountains. About 400-500 million years ago, when the mountains were worn down to their roots (possibly exposing the tip of the batholith) all of southern Ontario was flooded by a shallow inland sea — and it was teeming with life. Over many millions of years the dead sea creatures and sediment built up many tens of metres of sediment, which covered the region with deep limestone rock.

Today, you can see one of the upper layers of this rock as the Niagara Escarpment. A lower, older layer just off the shore from Parry Sound (known as the Limestone Islands) dates almost as far back as the Cambrian Explosion.

Deep holes in the Canadian Shield also harbour some remains of that ancient sea in the area, but most have weathered and worn away over the last few hundred million years.

It is hard to imagine this area covered in sea; almost as hard as it is to imagine it covered in tall, picturesque mountains. It is equally as difficult to imagine Parry Sound covered with deep, rich soil, and many strong, tall trees. But until about 4 million years ago, it was just like that. The entire area was covered in rolling hills of trees and very few lakes, just like the forests of southern Ontario.

4 million years ago, until just the last 20 thousand years, most of the Northern Hemisphere (including Canada) was covered with glaciers. The glaciers pushed and carried the surface soil away — ice flowed over a cushion of water that eroded the soil from the rock, scouring most of the soil from the surface of the area. In a few places, sand was left. In a few other places, clay was deposited at the bottom of large lakes, and it remained after the lakes drained away. But for the most part the region was bare rock.

Slowly, over the last few thousand years, mosses and ferns recolonized the land; slowly building up the soil. Slowly the soil built up, until it would support trees like white pine and red oak, hemlock and maple.

Over the last several hundred years, native people began using these forests as a source of food and shelter. Not semi-permanent natives like the Iroquois, and not nomadic natives like the Plains Indians — the semi-nomadic people moving about in search of game during the winters, and settling during the summers to fish in Georgian Bay and the Seguin River.

There were at least three separate tribes that settled here in the past five hundred years: The Catfish People; after them the Mississauga, who moved down south after 1670; and the present day Wasauksing, who were moved to Parry Island in 1850 to make way for the people who would build our town.

I hope that when you look at the land around, you see it with different eyes. This land that was under water twice, and was once treacherous, snow-topped mountains too.


— by Aubrey Jackson