Ontario Rocks

The province of Ontario contains many sites of outstanding geological importance. Many are internationally well known and attract visitors from around the globe. Others no less important remain hidden in plain sight. During the last 3 billion years Ontario has been witness to giant tectonic collisions as North America collided in turn with South America and Africa creating huge mountains now long gone. Many of Ontario's northern rocks originated as magma on ancient ocean floors long before life flourished. The province has been dented by fiery meteorites, drifted across the equator, been flooded by tropical seas rich in marine life and scraped bare by ice sheets. Ontario's rich geologic history is illustrated here by short descriptions of more than 200 field sites ranging from Timmins in the north to Windsor in the south. These include the Sleeping Giant near Thunder Bay; Agawa Canyon; the Sudbury meteorite crater; Niagara Escarpment; the Falls and Gorge; numerous caves, the mineral-rich Bancroft area; and the high lakeshore cliffs at Scarborough Bluffs. Some sites are sacred to First Nations and are associated with spectacular rock art. Also included are sites from adjacent parts of Quebec such as the Monteregian Hills near Montreal, the Gatineau Hills at Ottawa and a few sites in New York State, all of which add to the story of the geological evolution of Ontario and all of which are all within easy driving distance from Ontario. Each site features a short summary of its significance and is depicted on a map with GPS coordinates. Take a drive through our geology and take a few moments to think of Ontario's long and varied history.

In its long and rocky past, the place we call Ontario has traveled across the equator, been peppered and pockmarked by meteorites, seen the rise and decline of towering mountains, and gave rise to some very strange and now extinct organisms. In fact, what seems like a changeless landscape was once covered by vast seas and huge, continent-wide ice sheets which measured 2 kilometres thick, leaving in their wake, the Great Lakes. Ontario Rocks tells this fascinating 3 billion year long story of Ontario's geological evolution, from its beginnings as part of an early landmass called Arctica, its incorporation into enormous supercontinents, through to the repeated ice ages and abrupt climatic changes of the last few thousand years. Merging Canadian geology with global evolution, this highly illustrated survey also touches on the development of Ontario's mining and oil industries, and the commercial use of rocks as building material. Ontario Rocks concludes with an exploration of the "artificial" urban landscape, and how geologists use their knowledge to safeguard groundwater and rivers, dispose of wastes and understand the hazards posed by earthquakes and erosion. Ontario Rocks is a highly accessible sourcebook, perfect for students and all those intrigued by the history and formation of the land under us.

Plutonic rocks of the Canadian Shield are being assessed as a potential host medium for the storage of radioactive waste. A study of the geological framework of three structural provinces (Superior, Southern, and grenville) within Ontario has resulted in an inventory of 1365 plutons which are identified on Map 1533A at a scale of 1:1,000,000. The plutons have been classified by rock type: granite (sensu lato) comprises 75% of the plutons, gabbro 15%, alkalic rocks 8%, and anorthosite 2%.