AN EXCURSION ACROSS THE CONTINENTS¶
Contents
The tour from space now goes international, as in the next six pages we will look at scenes from five different continents to get a feel for the diversity of landscapes worldwide. On this page, Landsat images of parts of Canada will be examined.
AN EXCURSION ACROSS THE CONTINENTS
The many Landsat images spread over the next 6 pages that comprise Part 2 of this Section have mostly been selected from the master set used in developing the 1976 NASA publication Mission to Planet Earth: Landsat Views the World, produced by the writer and three colleagues, using imagery acquired by Landsat 1. Scenes made by other earth-observing satellites and as photos on the ground are also used in this excursion The description associated with each Landsat image is extracted from the captions in that book; consult it, NASA SP-360 (residing in many libraries), for more extensive descriptions of the scenes reproduced in the following Tutorial pages. Recall, too, that you have already seen a number of foreign images, e.g., specifically, London, Paris, Florence, Peking, Tokyo and other cities on page 4-4and the Game preceding this page in this Section.
Canada
Our trip to view examples of the Rest of the World begins in eastern Canada. The first scene covers some of the Eastern Townships in heavily forested (spruce; fir; pine; tamarack; birch; maple) hills in the Laurentian Lowlands of the Province of Quebec. The St. Lawrence River appears in the upper left and glacially-elongated lakes are scattered throughout the scene. The most striking feature throughout the image is a distinctive pattern of land-clearing by deforestation that stands out as elongate bars with jagged edges. Their lighter red color shows them to be grasslands. These long strips tend to be perpendicular to roads and small streams. They are a land use pattern brought over from France and adopted by the early French settlers (seigneurs) who colonized this region in the 1600s.
Moving northward into an area where eastern Quebec meets the western boundary of the Labrador subprovince of Newfoundland, we see next a segment of the Canadian Shield. This is the Labrador Fold Belt, made up of tightly folded sedimentary rocks wedged between two granite complexes. The structures represent an ancient (Precambrian) tectonic zone formed when one irregular continental mass collided with a sedimentary basin; the entire region has been much eroded to form “roots of mountains”. The present surface is strongly glaciated, leaving low hills and lakes. The high northern latitudes favor an arctic-like vegetation assemblage called tundra. This inhospitable landscape is very sparsely populated, with a few small towns build near iron mines.
Tundra again is typical of Canadian island surfaces well above the Arctic Circle. In this scene, the major land body is Melville Island, made up of Paleozoic sedimentary rocks and characterized by deep embayments that are valleys gouged out by continental glaciation of the Pleistocene, now occupied by the Arctic Sea which even in this July view is still completely frozen. Human life in this part of Canada�s Northwest Territories is limited to a few native villages (Eskimo types).
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Winter still remains in this March scene in the Province of Manitoba just north of North Dakota. Dominating the scene is Winnipeg, appearing black against the light snow because of snow removal and melting in that large city. In the countryside, dark lines (cleared farm roads) block out squares that are one-mile sections (part of the Township-Range system of surveying) similar to those so prevalent in the Great Plains (the lowlands here are an extension of that physiographic unit into Canada). Lakes Manitoba (left-center edge) and Winnipeg (top center) are remnants of a once larger lake system that covered wide areas of the plains at the end of the Pleistocene ice age. The dark areas that extend over the right third of the scene are the western edge of the Precambrian Canadian Shield. Pine and spruce are the prevalent trees in this part of the Shield.
Most of Canada’s cities lie in regions near the U.S-Canadian border. Its second largest city is Montreal, the capital of the Province of Quebec. Here is a Landsat image that shows Montreal and its surroundings. Note the elongated farms which follow the “long lot” style characteristic of France (and seen again around New Orleans).
This SPOT-4 panchromatic image shows much of the central part of Montreal.
The writer (NMS) spent a very satisfying summer in Canada’s capital, Ottawa (Ontario) visiting at the Dominion Observatory to work on shocked rock samples from the West Hawk Lake impact structure and other Canadian craters. Here is a Landsat 7 image of the western half of this city:
Walking on Carleton Road everyday the 3 miles to the Observatory, I passed the broad expanse of government experimental farms that stand out as red fields.
To close, a look at the border between the U.S. and Canada in eastern Montana. The borderline is sharply defined. Why? Not because of a fence but the result of different land use practices. The Americans have opened up the high plains to farming; the Canadians have left most of their side in its original state - grass-covered rolling swales.
