Precambrian thermal event on the Canadian Shield that took place 1.7 billion years ago (± 1.5 million years). Rocks that produce dates in this time span are those in the Churchill Province, a large arcuate belt that includes most of Canada west of Hudson Bay, the exposed Precambrian rocks in northern Canada, the Arctic Islands and Baffin Land, most of northern Greenland, and part of Labrador; the Bear Province in the northwestern tip of the shield; and a broad area in the western United States. The Mazatzal orogeny in Arizona, the Black orogeny in South Dakota, and the Penokean orogeny in the southern part of the Lake Superior region may represent the Hudsonian event in the United States. Precambrian rocks in the Southern Province, which extends south-southwest of Lake Superior into the mid-continental United States, also are dated in the Hudsonian time span.