Title: The continent we live on
Identifier: continentweliveo00sandrich (find matches)
Year: 1961 (1960s)
Authors: Sanderson, Ivan Terence, 1911-1973
Subjects: Physical geography; Natural history
Publisher: New York : Random House
Contributing Library: New College of California
Digitizing Sponsor: Internet Archive

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The second-largest province on the continent, this province is over 2300 miles in length from the northwest, starting about the middle Peace River region in northern Alberta and extending to the east Gulf coast of Texas. It is on an average some 500 miles wide. It forms the core of North America and is commonly known as the Prairie Belt—which indeed it is, both technically and popularly. As a whole, it is an immense plateau that descends northward toward the shores of the Arctic Ocean, tilting gently in that direction from an elevation of some three thousand feet in the south. To the southeast it pitches over an abrupt bow-shaped escarpment which runs from the eastern edge of the Sacramento—Guadalupe Mountains, east and then northeast to the southern fringe of the Ouachita Mountains of the Interior Highlands. Beyond this escarpment it covers the coastal plain of east Texas to the Gulf: then, as a vegetational belt, it crosses the Gulf, frittges the Mississippi delta, and finally appears on the central third of the peninsula of Florida. The western edge of the prairies lies against the eastern face of the Rockies all the way from the Pecos River valley in the south to about Fort Nelson on the Yukon border in the north. On the north and northeast it marches with the boreal woodlands, from which it is separated by narrow belts of Parkland, North Temperate Broad-leafed Woodland, and the Transition Belt of hard and soft woods. There are long stretches where this change is abrupt and all these belts are compressed into a band only a few miles wide. At other places, the grasses meander into the forest in tongues or the forest breaks up into typical parklands with isolated trees. At still others, dense shrubbery intervenes, giving way to deciduous forests to the north. There are also isolated outliers of prairie deep in the boreal forest between Athabasca and Great Slave Lake. On the east, prairies once made a great sweep over the upper Mississippi into the Heartland area, hut this pocket has been considerably vegetated by agriculture. To the southeast, their border bows to the west around the Interior Highlands. This vast plateau varies from sandy plains and loess to steppes and flat prairies. Upon it stands quite a number of isolated low mountain blocks, and it is cut almost all over by fern-frond-shaped drainage systems, the meandering bottoms of which may be level and heavily vegetated with gallery forest and lush meadows. In other places, they form completely arid "badlands." There is much fertile land following the courses of all the larger rivers. In the past, these supported a different fauna from that of the plateau alongside, and they still do so in some valleys of the southeastern region. history of this earth. Prior to its appearance there had of course been herbivorous animals—and in large numbers—that fed on all manner of other green things, but it was not till the advent of grasses that vast herds of grazing herbivores could be devel- oped. In fact, the rise of the mammals coincided with the rise of the grasses, and the great herds of mammalian herbivores that flourished in Eocene times were definitely and primarily grass-eaters or grazers rather than browsers, as may be seen from the pattern of their teeth. Now, without the grasslands there would not have been all these kinds of animals; and without vast grasslands there could not have been the enormous numbers of them that we know from fossil evidence existed. And this was millions of years before the advent of man. Thus there must always have been grass belts from at least the end of the age of the dinosaurs. Grasslands must therefore be natural climax growths and must have been in existence long before man. The reasons for their position globally is the peculiar abil- ity of grass to grow in direct sunlight and withstand hot and cold aridity, combined with their inability to exist in deep shade or under a closed canopy. However, grasslands altogether unaided cannot hold their own against the encroachment of woody shrubs and trees if climatic changes take place. In the case of our Prairie Belt the chaparral of the Northern Scrub Belt would eventually have swamped the grass by moving in from the south, and then parkland and finally temperate woods would have done likewise from the north, had it not been for certain counterforces. These were animals, notably the bison and the prairie dogs. Before the arrival of Europeans, man in the form of the Amerindian did not influence the prairies except as just another predator. If he did not set fire to it, nature did so by lightning. The Plains Amerindians were hunters, not agriculturists, and they were nomadic, following the great bison herds. They shared their resources with the grizzly bears and a certain number of pumas. Bison ran by the millions, and along with them were large numbers of pronghorns and white-tailed deer, though the latter stayed mostly in the bottoms. Moreover, mastodons and mammoths were also present in considerable numbers—not nearly so long ago, it now appears, as was previously thought. It was these vast grazing hosts that maintained the grassfields, yet it was not they that held the scrub and the trees at bay. This was the work of certain lesser folk that made up for their small size by their incredible numbers. This lesser fauna was and is typical of and in many respects peculiar to these particular grass- lands, and unfortunately it has suffered as great a defeat at the hands of the invading white man as did the bigger game and the native Indian population. Its virtual disappearance has had even profounder effects. This fauna was originally dependent upon the delightful little animals known popularly as prairie dogs. I should not need to mention that these are not dogs at all, but there is still widespread confusion about their true identity. 150

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