The Globe and Mail, Saturday, June 20, 1998, Science, Section D5
BY MICHAEL JUDGE
Special to The Globe and Mail, Winnipeg

Toronto was once higher than the Himalayas, Newfoundland, a neighbour to Africa. Fleshing out this geological tumult is the mission of the mammoth LITHOPROBE project, which uses deep-diving echos to detect Canada's ancient faults and future prospects.

Canada's ancient roots include billion-year-old rock on the northern shore of Georgian Bay.

A 25-tonne truck with oversized balloon tires is parked on the shoulder of a country road. The truck's wheels are hoisted up so all its weight is bearing down on a giant steel pad that is vibrating against the ground, kicking up dust and scattering stones. Nearby, Ron Clowes sits in another vehicle, where computers click and whir. It might not look like it, but Dr. Clowes is operating a time machine.

The quavering truck is part of an elaborate echo technique that peers down through a hundred kilometres of solid stone and back billions of years into the past. Dr. Clowes, the time traveller, is a professor of geophysics at the University of British Columbia as well as the director of LITHOPROBE, a mammoth Canadian earth sciences research venture. "This is definitely the biggest Canadian geoscience project ever," he says. "Our aim is to piece together the jigsaw puzzle represented by Canada's geography and geology."

Results from LITHOPROBE paint a picture of Canada's origins stretching back a mind-boggling four billion years. It's hard to imagine, but there were times when Toronto perched atop a mountain range that dwarfed the Himalayas, Newfoundland bumped up against Africa, and Manitoba was under an ocean the size of the Pacific.

Canada's ancient roots include billion-year-old rock on the northern shore of Georgian Bay.

LITHOPROBE began in 1984 with the energy of a group of ambitious geoscientists and financing from the Geological Survey of Canada and the Natural Sciences and Engineering Research Council. It was only natural that the most comprehensive project of its kind in the world should take place here: Canada lays claim to some of the oldest - and youngest - exposed rocks on Earth. In fact, the oldest rocks found on the planet sit about 300 kilometres north of Yellowknife. They are four billion years old - very respectable when you consider that the Earth itself is only 4.6 billion years old.

Fourteen years after its inception, LITHOPROBE has involved the efforts of more than 700 scientists, mapped out enormous areas of Canada and produced spinoff benefits for the mining and oil industries. "This project has been an inspiration around the world," says George Thompson, a professor of geophysics at California Stanford University. "This has given us unique information we wouldn't have received any other way. The results will be exploited for many decades to come."

LITHOPROBE scientists are looking at the stuff of which Canada is made - our portion of the lithosphere. "The lithosphere is the relatively rigid outer part of the Earth," Dr. Clowes says. If the Earth were an orange, the lithosphere would be its peel. It's not an exact analogy, however, because the lithosphere is broken up into interlocking tectonic plates, with thicknesses ranging from 50 to 300 kilometres. And the plates are constantly moving - at imperceptible speed but with sufficient power to cause most of the world's earthquakes.

One of the team of vibration-generating dancing elephants that the LITHOPROBE project uses to discern what's beneath the surface of the earth.

An important component of LITHOPROBE's results come from a technique called seismic reflection. Huge trucks carrying mechanical vibration units - such as the one operated by Dr. Clowes - are parked on the surface and pump sound waves into the ground over a range of frequencies. Four or five of the "dancing elephants" will work simultaneously, sending sounds down into the rock, where they will echo back from various underground structures, such as interfaces between different types of rocks or an ancient faults. An array of 5,000 sensors on the ground picks up the returning echoes, and computers crunch the numbers into cross-sectional pictures going down as far as 100 kilometres.

Used expertly, this is a relatively inexpensive way to get a good picture of what is underfoot. Seismic reflection has been used in the past, but only to relatively shallow depths and primarily for oil exploration. One of the accomplishments of LITHOPROBE, working together with other groups around the world, has been to improve this technology so that it can see 10 times deeper than before, with better resolution.

One of the team of vibration-generating dancing elephants that the LITHOPROBE project uses to discern what's beneath the surface of the earth.

These two-dimensional pictures are fleshed out by looking at variations in the earth's gravitational and magnetic fields and its electrical conductivity at various depths. Another tool is seismic refraction, which measures the speed of sound waves from an underground explosion.

The age of the rocks, which supplies the important fourth dimension to the map, is usually determined from isotopic analysis. This is possible because many rocks contain radioactive elements that decay into other elements on a precise schedule. Uranium, for example, will be half changed to lead after 4.5 billion years. This is on the order of the Earth's time scale, so geologists measure the relative amounts of the two elements in rocks to get a good idea of when the rocks formed.

When information from LITHOPROBE is added to what we already know about our continent, the cosmic drama of Canada's prehistoric birth unfolds. To see it from the beginning requires getting into a time machine. Destination: four billion years ago.

Over eons, the first microcontinents formed and then crunched together to form large continental blocks. Then, almost two billion years ago, there was a global fender bender. Three enormous, ancient blocks smashed into one another, welded together and parked themselves in the vicinity of where Canada sits today. "This is the glue that has held together the main part of our continent" Dr. Clowes says. One of the most prominent blocks is technically called the Superior Province, but we know it better as the Canadian Shield.

In this early period, between the Shield to the east and the Hearne-Rae Province to the west, sat the Pacific-sized Manikewan Ocean. Its eastern shore was near where Thompson, Man., is today. Fortunately for Prairie farmers, this ocean was eventually squeezed shut as the two provinces converged like a pair of titanic bulldozers and were then broadsided by yet other block.

Moving ahead about a billion years, the protocontinent Laurentia collided with a gigantic land mass on its southeast coast, probably the biggest collision in Earth's history. The force of this impact pushed up the largest mountain range that has existed on this planet, higher than Everest. Southern Ontario once greatly resembled present-day Tibet.

Nothing lasts forever, though, and these mighty peaks eventually crumbled under erosion by wind and water. The remnants of the mountain belt are scattered as far away as the Arctic Islands, although some remain closer to home, in the form of rocks dotting the shores of Georgian Bay. At about the same time, in a prehistoric commentary on Canadian politics, Laurentia was trying to split in two. A 35-kilometre-deep rift developed through the Great Lakes region, almost slicing the continent in half.

Continents continued to form and rub shoulders until, by 200 million years ago, the super-continent Pangaea formed, uniting almost all of Earth's continental crust. Then Pangaea split, with the southern continents separating first and then breaking apart in turn to form the South Atlantic.

More recently, about 120 million years ago, the continents that would go on to become Europe and Asia split away from North America, forming the North Atlantic. The traces of this departure remain: The Appalachians, which run from the southern United States up into Newfoundland, have a twin range in Europe. As that split proceeded, packages of crust accumulated on the West Coast from somewhere in the early Pacific Ocean, adding the finishing touches to British Columbia. Our country was complete.

Of course, Canada hasn't stopped moving just because people are standing on it now. The Atlantic is still expanding, we continue to move apart from Europe. And, on the B.C. coast, our continent is moving westward and grinding over the offshore Juan de Fuca plate, which is slipping underneath us at the leisurely rate of about four centimetres a year. It is the potential of these two overlapping plates to grab and then release suddenly that leads to earthquakes.

Unfortunately, although LITHOPROBE's scientists have contributed to a better understanding of the processes at work, even they can't predict exactly when or where the next big earthquake will strike.

LITHOPROBE isn't only about the past, though. It is giving Canadian industry some very up-to-date tools. Mining and oil companies have contributed millions of dollars to the project and have received many benefits in return. Black gold, for example. "LITHOPROBE has contributed to the reinitiation of petroleum probing on the west coast of Newfoundland," Dr. Clowes says. "This has indicated potential petroleum reserves. Even if we contributed only 5 to 10 per cent to this discovery, its value would more than pay back the entire cost of the LITHOPROBE project."

LITHOPROBE has surveyed many other regions of Canada in cooperation with natural resource industries. Often the approach has been to investigate sites where an expensive mining infrastructure has already been built. Because LITHOPROBE can look so much deeper than conventional mining probes, it ran help find deposits that haven't yet been touched.

LITHOPROBE is due to wrap up in 2003, although it will take many more years before all the information it gathers is fully interpreted and published. Mapping out almost four billion years of geological history in two decades is a Herculean task, but, after all, this is important stuff. "This ties into the part of the Earth where the energy and materials that drive much of modern civilization are found," notes Stanford's Dr. Thompson. It's exciting to watch space missions blasting off, but it could turn out that it's more important for us to explore our inner space.

Michael Judge is a science writer based in Winnipeg.