GEOLOGICAL HISTORY

The Pinhey Sand Dune system in Canada’s Capital is an end product of thousands of years of geological change. 

 

In the Northern Hemisphere, thick continental ice sheets have grown and retreated over the past 2.6 million years forming glacial periods. The last glacial period was between 120,000 and 11,500 years ago. The massive Laurentide ice sheet covered most of Canada. The movement of this 2-kilometre thick ice sheet gouged the earth and its colossal pressure formed deep depressions.

As the Laurentide ice sheet retreated 20,000 years ago, these gouges and depressions filled with water either from the melting glacier or from the ocean where levels were high. This is how the Great Lakes and Champlain Sea was formed. This sea covered part of Ontario, Quebec, New York, and Vermont in brackish waters. The Champlain sea was a mix of ocean water due to its connection to the Atlantic ocean and fresh water runoff from the glacier. This sea lasted from about approximately 13,000 to 10,000 years ago and had a maximum depth of approximately 200 meters.

9,500 years ago, without the pressure of the glacier, the land started to rebound and rise to above sea level bringing the Champlain Sea to its end.  As the water receded, fine grains of sand previously on the sea floor were exposed. This sand was formed by the action of the water (from the sea) and ice (from the glacier) on rocks over thousands and even millions of years. 

 

From approximately 8,500 to 8,000 years ago this sea floor sand formed the Pinhey Sand Dunes. During the growing seasons of this period, southwesterly winds slowly picked up the fine sand grains and deposited them in this area of Ottawa. The original Pinhey Sand Dunes system was extensive and covered over 1.5 million square metres.

This is a unique habitat in Ottawa and has been home to many species for thousands of years however, more modern human actions have put them at risk. 

 

In the early 1950s, tree planting programs planted species of trees that were not natural to the dunes, including red pines. Over time, these plants took up more and more space, and the organic matter they deposited on the sand turned the dunes into a pine forest.

In 2011 Biodiversity Conservancy International in collaboration with the National Capital Commission (NCC) took on the restoration and reclamation of the Pinhey Sand Dunes. Since then, 4 sites have been cleared and we continue to restore and maintain the dunes.  This involves protecting the plants and animals that rely on the unique dunes’ habitat for their survival.

Information was sourced from: Canadian Encyclopedia, Nation Capital Commission, NOAA National Centers for Environmental Information