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Precambrian Shield
DCHP-2 (Oct 2016)
Spelling variants:Pre-Cambrian Shield
n. — Geography, Mining
an area of ancient rock (see Image 1) encircling Hudson Bay and extending from the Arctic to the Great Lakes; also Canadian Shield or Laurentian Shield.
Type: 4. Culturally Significant — The "Precambrian" supereon began 4.6 billion years ago, when the earth was formed, and ended with the emergence of multicellular organisms. The term "Cambrian" was first used in the 1830s to describe geological rock formations in Wales, known classically as Cambria (see OED-3, s.v. "Cambrian" (2)), and the term "Precambrian" derived from it (see OED-3, s.v. "Precambrian", the earliest attestations of which come 30 years after "Cambrian"). Although "Precambrian" was used earlier to describe various geological formations, Precambrian Shield is most frequent in Canada (see Chart 1), yet only by a slim margin compared with the US. The term bears cultural significance as it is one of the most important geological formations in Canada (see, e.g. the 1925 and 2013 quotations). The mineral richness of the Shield, for instance, has been a source of economic development since the early 20th century.
Quotations
1924
"An area which in my opinion, within the next few years, will develop into one of the world's richest gold-mining camps, is that section of the Canadian pre-Cambrian Shield known as the Rice Lake district, which extends from the Indian reserve at Hole River, on the east side of Lake Winnipeg, to the Ontario boundary."
1925
The title of Dr. Corless' address was "The Mineral Wealth of the Pre-Cambrian," and he spoke of the Pre-Cambrian Shield, so called, as the greatest physical and geological feature of Canada. It is about two million square miles in extent, covering more than nine-tenths of Quebec, three-quarters of Ontario, two-thirds of Manitoba, one-third of Saskatchewan and a portion of the north-east corner of Alberta.
1939
Only one-twentieth of Manitoba's land area has been brought under cultivation, after sixty-five years of trial and error. But three-fifths of Manitoba is the Pre-Cambrian shield in which precious and base metals occur. Production of gold and other metals in Canada last year is estimated at $322,000,000.
Taken together, the three facts suggest something of the opportunity that mining development holds for this province.
1942
A half-completed highway will carry as much material as no highway at all. Recall how long it has taken to forge the last link in the Trans-Canada highway. In the rock of new Ontario, construction slowed down to a snail's pace. Cordilleran rock is just as rugged as that of the Precambrian Shield. An easterly route avoids the main blocks of mountains, and most of it could be constructed with ordinary dirt-moving equipment. By avoiding rock work, an easterly route would economize on explosives.
1960
"For the first time in the history of mining on the Precambrian shield, free gold has been found underwater by this means," he says.
1978
At Key Lake, joint venture partners Uranerz Mining and Exploration Ltd., Saskatchewan Mining Development Corp., and Inexco Mining Co. have identified 100 million pounds of uranium oxide lying in a shallow fault that begins on the surface of the Precambrian Shield and runs underneath the adjacent sandstone of the Athabasca Basin.
1987
Strung over 20 kilometres of stable rock near the Arctic Circle, the array is one of only eight in the world sensitive enough to tell the difference between nuclear explosions and earthquakes.
Set on an old, relatively uniform geological structure called the Precambrian Shield, it is removed from sources of background noise such as oceans and cities.
More important, it is less than 10,000 kilometres from nuclear testing sites in the Soviet Union, China, French Polynesia and the Nevada desert.
1998
That would be a large, affluent crowd that embraces a sport-utility ethic, which goes something like this: I have a life, a vital life, an off-road life. I know work isn't everything; fun is important, too. And, even if I don't camp on the Precambrian Shield, I work hard enough to be able to buy transportation that makes it look like I do.
2013
"Masson, with his gay Gatineau landscapes; Jackson with the vast sweep of the Pre-Cambrian Shield; Bieler, with his crowded marketplace - these men are extroverts ... In a land of garish newness and bold statements, (Humphrey) is tentative, wistful and contemplative. Perhaps that is why many of us find his work so charming."
References
- OED-3
Images
Image 1: Stretch of land on the Precambrian Shield or Canadian Shield; area of the Flin Flon, Manitoba, with Big Island Lake in the background. (Source: Wikimedia Commons. Photo: Green slash)
