Prairie. Candace Savage

volcanoes. From there, it is on to the broad, terraced valleys of the Colorado Piedmont, literally “foot of the mountains,” where the waters of the Arkansas and South Platte rivers have, over millions of years, stripped away layer after layer from the original High Plains surface. (This dramatic, if localized, lowering of the surface explains, for example, why the road heading east out of Denver tracks steadily upward for the first half hour or so, as it climbs out of the South Platte floodplain and onto the surrounding High Plains benches.) The effects of water erosion can also be seen on the rugged Missouri Plateau and the deeply dissected valleys of the Plains Border region.

      If water has cut into these landscapes, wind has smoothed them out. For example, the southeastern edge of the Platte River valley is softened by a broad belt of curving, undulating sand dunes that were deposited by dust storms sometime during the Ice Age. Similar formations, shaped by similar forces, are also to be found strewn up and down the drier, western side of the Great Plains, from the Great Sand Hills of southwestern Saskatchewan in the north to the Mescalero Dunes of the Pecos Valley. And right in the middle of the map lies one of the prairies’ little-known natural wonders—the Nebraska Sand Hills, a region of whale-backed, grassy rises and prairie wetlands that, at an area of 24,000 square miles (62,000 square kilometers), ranks as the largest field of sand dunes in the Western Hemisphere. These sandscapes were put in place by the relentless northwest winds that have been coursing across the landscape for millions of years.

      With so few barriers to stand in their way, these same winds have had the run of the entire Great Plains region. Although their influence can be seen in many parts of the country—for example, as ridges of windblown silt along both the South Saskatchewan and upper Missouri rivers—their touch is most obvious in the eastern and southern regions of the Great Plains. These include not only areas of the Colorado Piedmont and the High Plains but also the “low plains” to the east, notably the rolling hills of the Plains Border country, the Osage Plains, and the Glaciated Central Lowlands. Much of this sweep of country is blanketed in deep, contoured drifts of fine silt, or loess—pronounced “luss”—another gritty, wind-borne by-product of glaciation. The result is a gently undulating landscape of soft, rolling hills and, in places, extraordinary bluffs, like the delightfully eroded and unexpected Loess Hills of western Iowa.

      The northern plains region, by contrast—north and east of the Missouri River, from Alberta to Manitoba and south through the Dakotas—is less apt to be buried in loess, but it nonetheless bears the imprint of the Ice Age. Here the terrain is an unmade bed of glacial rubble, or till, lying exactly where it dropped when the ice sheets retreated from the landscape ten thousand years ago. And protruding above this jumble of knobs and kettles is an assortment of sprawling, flat-topped uplands, including Turtle Mountain, Wood Mountain, and the Cypress Hills, which straddle the boundary between past and present. Like miniature versions of the High Plains, they are the last surviving remnants of an ancient, preglacial landscape that has otherwise been lost to erosion.

      Finally, and most surprising of all, are the honest-to-goodness mountains that jut up out of the northern plains, particularly on the unglaciated reach of country south and east of the Missouri River. From the glowering Black Hills to the jagged Crazy Mountains, they stand as a peak experience (if you’ll forgive the pun) for anyone who has been led to believe that the prairies are monotonous.

       > THE MOST TREMENDOUS ROARING

      The Corps of Discovery led by Captains Meriwether Lewis and William Clark spent the winter of 1804–5 in the villages of the Mandans and Hidatasa, in what is now central North Dakota. It was likely there that they first heard stories about the ferocious “great white bears,” or plains grizzlies, that had spilled the blood of so many warriors. But when the Corps members met their first bear, at the confluence of the Missouri and Yellowstone rivers the following spring, the kill was surprisingly easy.

      “The Indians may well fear this animal equipped as they generally are with their bows and arrows,” Captain Lewis mused in his journal, “but in the hand of skillful rifle men they are by no means as formidable or dangerous as they have been represented.”

      That was April 29, 1805. Six days later, Lewis’s partner, Captain Clark, was singing a different tune. “The river rising & current Strong & in the evening we saw a Brown or Grizzly beare on a sand beech,” he wrote. “I went out with one man Geo Drewyer & killed the bear, which was verry large and a turrible looking animal, which we found very hard to kill we Shot ten Balls into him before we killed him, & 5 of those Balls through his lights. This animal is the largest of the carnivorous kind I ever saw.”

      Plains grizzly bear

      Lewis described the same encounter in greater detail: “It was the most tremendious looking anamal, and extreemly hard to kill notwithstanding he had five balls through his lungs and five others in various parts he swam more than half the distance across the river to a sandbar, & it was at least twenty minutes before he died; he did not attempt to attack, but fled and made the most tremendous roaring from the moment he was shot . . . . Capt. Clark thought he would weigh 500 lbs. for my part I think the estimate too small by 100 lbs. he measured 8 Feet 7½ inches from the nose to the extremety of the hind feet, 5 F. 10½ Ins. arround the breast.”

      Once widely distributed across the Great Plains, grizzlies may have been most common in the major river valleys. They were extirpated from the region by the 1890s or early 1900s.

       Then and Now

      It is one thing to send our minds running across the contours of the Great Plains grasslands and their unexpectedly varied landforms. It is quite another to bring these spaces to life, to try to perceive them in their full, natural vitality and splendor. What would it have been like to step out onto the round bowl of the southern grasslands with Coronado in 1541, aware that at any moment our progress might be blocked by a dusty, pawing, milling herd of bison? Or, precisely 150 years later, in 1691, to have traveled with Henry Kelsey and his Cree and Assiniboine guides from Hudson Bay through the northern forest and onto the prairies of the Saskatchewan River country? What emotion would have seized us when a blocky, hunched shadow gradually resolved into the form of a massive and potentially lethal grizzly bear? Or what if we could slip back in time to 1805–6 (a mere two hundred years ago) and join Lewis and Clark on their famous expedition up the Missouri River?

      Imagine: Bison beyond counting. (“I do not think I exaggerate,” Lewis wrote as he crossed the Dakota plains in 1804, “when I estimate the number of Buffaloe which could be compre[hend]ed at one view to amount to 3000.”) Flights of pronghorns at every turn. Elk coming up out of misty valleys to graze on the prairie at dawn. Bighorn sheep perched on the steep, crumbling walls of the Little Missouri Badlands. Wolves threading across the prairies, trailing the herds.

      Two hundred years isn’t very long on the geologic timescales of planet Earth. These memories lie at the very threshold of the present, so close that we half expect to be able to walk into a fold in the landscape and encounter them. And something like this still occasionally happens when we stumble across a physical trace of the past, whether it’s a flaked stone tool that once belonged to a bison hunter or a shallow, saucer-shaped hollow that was worn into the dirt by generations of rolling, grunting bison. The animals have vanished, but the imprint of their flesh and blood is still on the land. It is all so mind-bogglingly recent.

      There are not many places where the wild is as close at hand as it is on the Great Plains. In the Old World of Europe and Asia, no one can quite remember what “natural” looked like, because the land has been successively shaped and reshaped to meet human needs for hundreds or thousand of years. But in the New World of the prairies—right up to the moment when the settlement boom began— humans had lived off the natural productivity of this vast, sun-swept expanse of grass. From the beginning, the First Peoples had drawn their sustenance from the native animals and plants, experiencing both feast and famine as hunters and gatherers. This is not to say that they sat back passively and let nature take its course. They were active participants in the ecosystem, ready and willing to use whatever technologies they could