Colossal forces active in Ontario nearly 2 billion years ago created a complex geologic structure and treasure chest that was initially more than twice the size of Rhode Island. On that much scientists agree. As an undergraduate, I was taught that catastrophic volcanic eruptions triggered the processes that resulted in Sudburys rich metallic ore deposits. Since then, geologists have found evidence that the Sudbury Structure may be an astrobleme, the eroded remnant of a meteoritic or cometary impact.
Astrobleme, according to the Glossary of Geology, comes from the Greek astron, star, and blema, wound from a thrown object such as a javelin or stone. If the impact theory is correct, that stone was a whopper, blasting a crater nearly 200 times the diameter of Meteor Crater in Arizona. The impact evidence includes a range of macroscopic and microscopic features such as shatter cones, unusual breccias, possible multiple-ring structures, and high-pressure mineral polymorphs. Multi-ringed basins of probable impact origin have been recognized on the moon, Venus, and one other place on Earth, around the Vredefort structure in South Africa. Also, NASA and University of California scientists reported in 1994 that the Sudbury crater contains the largest deposit of natural fullerenes (the rarest form of elemental carbon) of extraterrestrial origin found on Earth to date.
Whatever happened in the Sudbury region left it rich in metallic ores that miners have been extracting for 100 years. Underground mining operations at the 15 active mines of Inco Ltd. and Falconbridge Ltd. in Sudbury currently produce 51,000 tons of ore per day, and five other mines within 500 km of Sudbury produce another 50,000 tons per day. By-products of nickel-copper production include cobalt, platinum group metals, gold, silver, selenium, tellurium, sulfuric acid, liquid sulfur dioxide, and slag for road construction.
In the mid-1800s, during the building of the Canadian Pacific Railroad, a blacksmith working on the CPR discovered the first nickel-copper orebody known in the Sudbury area. The discovery fueled the growth and development of Sudbury, and the Canadian Copper Company mines started production in 1886. Although the ore was also rich in nickel, that metal was considered of little value. Demand for nickel was less than 1,000 tons per year worldwide in 1887, and it only became a marketable commodity early in this century.
As mining, stripping, sintering, and smelting operations increased with world demand for metals, Sudburys landscape began to look like a barren moonscape. The mining and processing of sulfide minerals released sulfur that contaminated and acidified soils. In the past 25 years, however, residents have restored and transformed the landscape. Today, Sudbury boasts the largest, most successful environmental restoration program in the world.
When restoration efforts began in 1969, germinating seeds died on contact with the contaminated soils, and thousands of tree seedlings planted in the first two years died within a year of planting. Residents decided to try a different approach. They applied lime to the soils to neutralize the acidity and planted grasses and clovers instead of trees. By 1974, a 3-hectare (7.4-acre) patch had a sparse grass cover. Nature took over then, and wildflowers, shrubs, and birches and poplars began to grow.
While citizens and students worked to restore the environment, the mining companies worked to reduce pollution and control wastewater quality. In 1972, Inco completed construction of a giant smokestack that reduced sulfur dioxide emissions. Inco completed a sulfur abatement program in 1994 that further reduced emissions to 10 percent, and planted the millionth tree seedling of its own land reclamation program. Falconbridge has planted 600,000 trees on its properties in the Sudbury area since 1955. The company opened a new smelter and acid plant in 1978 that reduced sulfur emissions and renovated the smelter in 1994 to reduce emissions further. Falconbridge recycles nearly half of the water it uses and treats wastewater to control acidity, heavy-metal content, and suspended solids. The treated water flows into a 299-hectare (494-acre) peat bog that over the last 15 years has been rejuvenated from an acidic wasteland to a productive wetland and transformed from a hostile environment into a wildlife sanctuary.
To date, more than 3,000 hectares (7,410 acres) of land have been restored and an additional 2 million trees planted through a joint program administered by the Regional Municipality of Sudbury and financed by job creation funding from government and industry. In recognition of it environmental transformation, Sudbury received the United Nations Local Government Honors Award at the 1992 Earth Summit in Rio de Janeiro.
I missed a geology field trip to Sudbury in its lunar-landscape days, and now Im glad I waited and have a second chance.
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