Lanark County is a mostly forested and rocky county in the Ottawa Valley, about an hour west of the city of Ottawa.
In many ways, this county is a perfect example of the natural environment that extends throughout the entire Ottawa Valley.
It is a fine place for outdoor recreation, yet is often overlooked by hikers and naturalists who go instead to Gatineau Park or the Adirondacks.
Lanark County has Precambrian rock in the west, as you find in the upper Ottawa Valley (including Algonquin Provincial Park) as well as limestone in the east, as you find in the lower Ottawa Valley (including the City of Ottawa). There are also extensive areas of marble.
There are also thick clay deposits covering the county. These originated more than ten thousand years ago. The western side of Lanark County was flooded by an enormous glacial lake, so these clay areas originated under fresh water. The eastern side of the county was flooded by the Champlain Sea, so many of these deposits come from more saline conditions. The eastern clay plains extend from Lanark County all the way to Montreal. The old shoreline of the Champlain sea can still be found, and is mapped in my guide to the county.
When the first Europeans arrived, the area was mainly deciduous forest, but there were also fire barrens and pine ridges, as well as lakes and beaver ponds and extensive swamps. The history is also typical: indigenous peoples were replaced by Europeans, predominantly Scottish and Irish settlers, who logged the forests and cleared for farms. On deeper soils there are now prosperous communities, while on shallow and rocky soils, farming collapsed and the forests are recovering.
In spite of two centuries of human settlement, there are still important natural areas left. These include alvars, rock barrens, and wetlands. There are also distinctive southern species including five-lined skinks, gray rat snakes and southern flying squirrels. Shagbark hickories have crept as far north as some rocky south-facing hillsides, while a stand of hackberry trees clings to the limestone cliffs along the rapids in Carleton Place.
This page is intended to provide citizens with an introduction to the natural environment of the county, and to encourage the protection of important natural areas. It is also a guide for visitors who wish to explore the natural environment. Below are sources of information on on the ecology of Lanark County, including a guide to our priority natural areas, which I call the thirty Green Gems of Lanark County.
My Resources on Lanark County
Here is a recording of a public talk I gave about the natural environment of the county. If you teach biology or ecology in a local school, you may wish to share this with your class.
My self-published book Earth, Water, Fire: An Ecological Profile of Lanark County is a solid introduction to the natural heritage and human history of the area.
30 Green Gems
The thirty green gems of Lanark County: priority areas for protection.