Ottawa Gatineau Geoheritage

The Ottawa-Gatineau Geoheritage Project promotes greater public knowledge and appreciation of the geology and related landscapes in and around Canada's National Capital Region

22. Burnt Lands Alvar, Almonte

Barren limestone plain that hosts rare vegetation


Limestone, Burnt Lands Alvar, Almonte

North of March Rd., between Burnt Lands and Golden Line roads, Almonte, Ont.

Limestone plain, The Burnt Lands Alvar 

Photo by J. Aylsworth

An alvar, also known as a pavement barren, is a very special biological environment, with sparse vegetation and unusual species. Alvars occur only on limestone bedrock that is covered with little or no soil.

The Burnt Lands Alvar is a provincially significant Area of Natural and Scientific Interest (ANSI) to the east of Almonte, Ontario. Part is private land; part is a Nature Reserve Class provincial park; part is owned by City of Ottawa. The alvar contains a diversity of coniferous forest, dry and moist alvar meadows, and areas of open exposed bedrock. The most accessible part belongs to City of Ottawa and is the open land lying north of March Rd. and west of Burnt Lands Rd.

The Burnt Lands Alvar is a large, relatively flat area characterized by exposed 'pavements' of limestone belonging to the Gull River and Bobgaygeon formations. Chemical weathering of the limestone has pitted the rock surface and accentuated the joint patterns, which are deeply etched into the bedrock. Freeze-thaw weathering has also left a thin layer of shattered rock on the surface. The alvar vegetation is generally restricted to cracks and small low pockets in the rock where minimal soil has accumulated.

Please stay on the trails to protect the fragile ecosystem.


The Burnt Lands Alvar is the most extensive alvar east of the Frontenac Axis and is an outstanding example of this globally significant habitat. It supports some 82 breeding bird species, 48 butterfly species and 98 owlet moths. It is home to globally rare species such as the Ram's-head Lady's slipper and a new owlet moth discovered there by naturalist Dan Brunton. Many of its invertebrate species, such as the snail species Vertigo hannai, have likely been isolated and survived in such remnants of a prairie-like community that previously covered a wide area of North America. Although the alvar is not a prairie, many prairie species are present such as prairie sawflies and a thriving population of wingless prairie leafhoppers whose nearest other known population is in the Bruce Peninsula.