In late prehistoric times in the Northern Rockies, grizzly bears came out of caves in the high country in late winter, ravenous and searching the lower slopes for winter-killed carrion. In early spring, sunflowers bloomed on the south slopes of foothills and later in the spring the Bitterroot’s bright fuchsia blossoms adorned the valleys. In mid summer, huckleberries ripened on mountains slopes in the mottled light under Ponderosa stands that were kept thinned by regular fires. As summer days waned, antelope gathered into large herds, posting sentries and grazing on the golden grass, and as the air became cold, bull elk became belligerent and reckless, descending from high ridges, bellowing challenges.
Some of what we think is based on what we know of peoples in the recent past. The Salish moved in family groups to different areas in different seasons based on their knowledge of plants and animals. From time to time, small groups of Salish gathered together into larger groups at places where food was abundant, such as the camas fields that made spring meadows look like blue lakes. At such gatherings, they greeted relatives and old friends, shared hunting information, got married, and danced and prayed together.
Such lifeways are similar in important ways to many peoples throughout the world, and so we draw on them in making educated guesses about deep time. Salish oral traditions say they have been in western Montana since time immemorial and this is true, in the sense that we have no memory of a time when they were not here. Oral traditions preserve an important kind of knowledge, passing on cultural understandings that help people decide who they might to be.
People digging in the earth for knowledge are generally preoccupied with insight of a different order. Archaeologists study the past by looking carefully at material evidence such as tools, bones, shelters, clothing and jewelry.
In the summer of 1927, Carl Schwachheim found something that he knew was going to create a stir. In Wild Horse Gulch, eight miles west of Folsom, New Mexico, about eight and a half feet beneath the surface, the amateur naturalist found a spear point lying amid the ribs of a bison. What was especially strange was that the bison was of a species that had been extinct for millennia. Most professional archaeologists believed that humans had not been in the Northern Hemisphere until thousands of years after those ancient beasts had vanished.1
When he knew for sure what he had found, he stopped digging. He got his camera and photographed the spear point where it lay with the bones. That picture is somewhat famous in archaeological circles. It changed our understanding of deep time.
Schwachheim next sent a telegram to professional archaeologists, asking them to come examine the site before he disturbed it any more. If the spear point had once been embedded in the bison’s flesh, it was clear that humans had hunted these beasts.
The place where he was digging had been known to the rancher who owned the land for eighteen years, but most professional archaeologists did not take reports of what had been found there seriously. Because Schwachheim left the point where he found it, the archaeologists who came in 1927 were convinced. Further excavations helped them piece together more of the story.
We now know that on a fall day 11,000 years ago (we know it was fall by the developmental stage of fetal remains), a group of hunters trapped a herd of buffalo (Bison antiquus) in that southwestern arroyo. Using stone-tipped spears, they killed about thirty animals and butchered them where they lay.
In further study at the site, archaeologists found over twenty of the distinctive spear points embedded in the bison skeletons. Many points of the same style—now called Folsom points—have since been found at other sites. They are usually about two inches long with grooves, or flutes, for the spear shaft cut into each side, and they are extremely sharp, with 100 or 150 sharpening flakes removed from their edges.
They are examples of high-quality stone age technology. With these elegant weapons, hunters killed bison that are much larger than modern buffalo.
The Folsom discovery quickly changed our understanding of the distant past. It was clear that humans had been in America far longer than most scientists had thought. Researchers began searching for evidence—which they found—that people had been here during the Ice Age more than 10,000 years ago, at the same time as saber-tooth tigers, dire wolves, giant ground sloths, wooly mammoths, mastodons and the other dramatic giants—the so-called megafauna of the Pleistocene (“Pleistocene” means “most recent,” and it refers to the last ice age).
Small discoveries can change our understanding of the distant past in large ways, partly because so little is known that any new fact can make a big difference. This is because a lot of what we suppose is based more on logic and reasoning than on physical evidence. Since there are many more possibilities than we can imagine, merely logical theories are likely to be based on mistakes. This is why scientists do not think far without hankering for observations.
But how can we observe events that occurred twenty or thirty or a hundred centuries ago? Faced with that challenge, archaeologists, geologists, and other scientists interested in deep time have come up with hundreds of clever strategies, some of which I’ll talk about. They figure out these strategies by playing around with ideas—using their imaginations and speculating on what might have happened. This is normal for young sciences such as archaeology. The speculations help researchers form plans for systematic observations. Then their findings and their reasoning are published so other people can check them out. These other people agree sometimes and add more information. But they also disagree sometimes, pointing out flaws in the research methods or suggesting different explanations.
How Do We Know?
The world of the distant past doesn’t give up its stories easily. You can’t run simple experiments or interview witnesses to learn about the way things were thousands of years ago. But careful examination of what survives from the past allows us to make sense of what has happened. In 1797, Englishman John Frere discovered a collection of what he thought were probably hand axes made of chipped flint buried twelve feet deep in a layer of gravel. Above them in a layer of sand he had found the bones of extinct animals.2
Frere realized that if the layers of sediment had accumulated
naturally through time, the deeper layers would be older than the
higher levels. When students turn in their textbooks at the end of
the year, each one might set his or her book on a pile beside the
teacher’s desk. If someone came in after all the books were returned
and tried to guess which book was turned in first, he could
reasonably assume it would be the one on the bottom of the pile.
Nature works in a similar way. As leaves fall and dust settles,
older layers are buried by later layers. If you dig down a few feet,
you’ll see the various layers or what scientists call strata. The
deepest strata are the oldest.
In a typical excavation pit, you can see the differences in color and texture of the soil in every stratum as well as the different kinds of artifacts or features found at each level. Artifacts are the material objects; features are the evidence of cultural activity, such as the way shelters are arranged in relation to each other. The patterns found at sites can provide insight into how people lived or worked. How many buildings or tents are there in one settlement? What were they used for? Why are they where they are? Where are the middens (garbage piles) and what do they contain? If debris left from manufacturing tools is outside rather than inside stone circles that were once shelters, it might indicate that the place was used in warm weather.3 The floor of a small hut in South America, where people lived nearly 13,000 years ago was littered with many plants that we know have medicinal properties. This led researchers to speculate that the village had a drug store of sorts. In Montana, we’ve found traces of ancient camping spots, kill sites and butcher sites. We’ve located quarries where stone tools were made, burial spots, and vision-quest sites.
Since excavating a feature destroys it, researchers go to great lengths to create a detailed record for further study. For every hour spent digging, a researcher might spend several hours in the laboratory, in the library, or at the computer trying to understand and interpret what was found.
Archaeologists also develop ways to get information without digging. They call these “noninvasive” approaches. For example, by using ground-penetrating radar they can “see” some of what lies beneath the surface without disturbing the earth. We have developed sensors that allow us to identify landscape features from aircraft and satellites that we cannot see with our eyes. Images gathered by radar mounted on a satellite can reveal archaeological features hidden by dense jungles or desert sands. Using computers to enhance such images, we can bring out poorly defined features and relationships so they are easier to understand. Looking for patterns similar to those found at known Paleoindian quarries, researchers recently used satellite images made in 1985 to locate eight previously undiscovered quarries in the Horse Prairie Valley in southwest Montana.
Even microscopic pollen has stories to tell. Each year pollen from plants falls into bogs, which are wetlands with poor drainage. At the end of the Ice Age, melting glaciers left shallow, wet areas where plants decayed slowly or incompletely because not much oxygen was available. Dead vegetation accumulated, forming peat.
Such peat bogs have preserved a detailed record of the past. Since different plants thrive as the climate gets wetter or drier, or warmer or cooler, and since the pollen grains from each plant look different, archaeologists can study the pollen in each layer, “reading” the climate year by year, almost like turning back the pages in a history book. Through such studies we have developed information about what plants were growing at various times in the past, and this in turn tells us how the climate has changed in Montana since the last Ice Age.4
Similarly, each year’s snowfall in the Arctic forms a new layer on the glacial ice, and these layers can be counted like tree rings. The thickness of each ring gives some indication of how much snow fell that year.
Also, since water contains two oxygen isotopes (atoms with different numbers of neutrons), and since how much of each isotope is present changes with the temperature, measuring the ratio between isotopes in each layer lets us estimate how warm or cold it was that year. We now have estimates for annual average temperatures going back about 200,000 years.
Of course, it’s not quite that simple. Since these isotope ratios are also affected by latitude, altitude, the time of year, and long-term climate changes, the temperatures we have are only estimates. A lot of knowledge is this way. We make assumptions or educated guesses and do calculations, but the final results include errors. It’s common for scientists to try to estimate even how much error their findings might contain by reporting them with a “plus or minus” range.
Our knowledge gets more accurate as we develop more information, more sophisticated theories, and better ways of making measurements. Usually, the intent is to get closer to the truth rather than to reach certainty. Few things are certain.
But some things are more certain than others. For example, about 6,800 years ago, Mount Mazama in the Cascade Mountains of Oregon erupted throwing tons of pumice over vast areas of the Northwest.5 The crater that it left is now called Crater Lake. The ash covered the landscape for hundreds of miles, and archaeologists still find Mazama ash when they do excavations.
Since volcanic ash can be carbon dated more accurately than many other things, when archaeologists find a white or gray band of volcanic ash in the sediment, they can date that stratum with confidence. Its presence is a good time marker.
Two other volcanoes in the Cascades have left ash in Montana soils that are also important for archaeologists: an eruption of Glacier Peak 12,000 years ago and an eruption of Mount St. Helens 3,400 years ago. As with other forms of evidence, archaeologists need to be a bit cagey to avoid being tricked. Soils can be moved by wind and water, and geological structures can slump and slide.
Some research methods don’t involve studying the landscape at all. Linguists and geneticists have been especially helpful. Careful examination of the Salish language spoken by the Flathead Indians has been used to shed light on disagreements among scholars about where their ancestral homelands might be. Some early twentieth century scholars said that they once lived east of the Continental Divide near today’s Three Forks. Others suggested that they came from farther west, nearer the Coastal Salish in today’s Washington State.
One approach to forming answers to such questions is to analyze the language that the Flatheads spoke. Since new words are often formed by using parts of older words, linguists have reasoned that the oldest words in a language would probably not be made up of smaller parts. Or, as the linguists say, they would be “irreducible” to smaller words. In 1916, linguist Edward Sapir argued that words such as “bow, arrow, spear, wheel…belong to a far more remote past than…such words as railroad, insulator, battleship, submarine…”6 By figuring out which words are not made up of simpler parts, we may get an idea of which words are oldest.
In a silly example, if the oldest words in Salish included names for such things as “cactus,” “sand dune,” and “armadillo,” we might suspect that a long time ago the Flatheads lived much farther south or that the climate in Montana was once much warmer.
Of course, the Flatheads did not have lots of words for desert plants and animals. However, they did have irreducible words for animals such as moose, that are native to Montana but not to Washington. This evidence supports those, including the Flatheads themselves, who believe the Flatheads have been in Western Montana for many centuries.
It doesn’t prove it, though. Not all irreducible words are ancient, and some words are simply taken from other languages. The farther back in time we go, the less information we have. For many questions, there are so few facts available that explorers of deep time can rarely be certain of their interpretations. Disagreements among scientists about how various facts might be explained happen all the time. In fact, such disagreements are what science is all about.
Nonetheless, error is slowly replaced by knowledge, and weaker interpretations give way to stronger interpretations. Some questions get settled to everyone’s satisfaction, and we all move on to new questions.While forming questions and playing with possible answers, scientists sometimes stand on mountains and look at the landscape, visualizing how the hills and valleys could have been shaped and formed, feeling the wind and rain and sun, and thinking how the forces that operate in the world today might have operated in the distant past. Their thought processes are the same as the thought processes we all use every day. What’s different is that they work systematically in a larger community of others who share the same questions and the same data.
What do we know about Montana?
The last Ice Age reached its peak about 20,000 years ago, and after that the huge ice sheet covering Canada and extending into Montana began melting. It took thousands of years for the ice to retreat to near its present extent. The glacier was gone from Lost Trail Pass in the Bitterroot Mountains by 12,000 years ago, which left a lake surrounded by a short grass prairie dense with sage brush. The lake eventually became Lost Trail Bog. From pollen fossils we know that within another 500 years forests of whitebark pine mixed with some fir and lodgepole pine replaced the prairie.
For decades, most archaeologists believed that the first inhabitants of America came through Beringia from Asia into Canada, dropping down into Montana. “Beringia” is the land, now under the waters of the Bering Strait, between Alaska and Northern Asia. During the Ice Age thousands of miles of forests grew there. The dry land was exposed because enormous ice sheets, spanning entire continents, had locked up so much water that the sea level fell.
For most of the Ice Age, Canada was covered by a vast layer of ice—the Cordilleran (mountain) Glacial Complex west of the Continental Divide and the Laurentian (continental) Ice Sheet east of the Divide grew together and formed a single sheet of ice thousands of miles across and thousands of feet deep.
During warmer periods enough ice melted to open a passage a few hundred miles wide between these two ice sheets, leaving a wide swath of land on the east slope of the Canadian Rockies. This ice-free corridor led from the far north directly into Montana. Many archaeologists thought it probable that bands of hunters moved south through the cold, wet landscape between the giant glaciers. This is the route referred to as “the Old North Trail.”
Scientists estimate that one of the times the ice-free corridor opened was near the end of the Ice Age about 14,000 years ago when the ice was melting. But this wouldn’t leave time for people to have populated South America by the time evidence of human presence begins to appear. Linguist Johanna Nichols claims that the languages spoken by Native Americans differ from each other too much to have come from a common tongue so recently. She believes that people might have had to be here by 35,000–50,000 years ago for the 143 Native American languages she has studied to be as different from each other as they are. Even if there were several migrations from different areas, she believes that people would need to have been here far more than 14,000 years.7 Her theories are not widely accepted though they steadily attract new people who find them plausible.
More recently, some archaeologists have theorized that early people skirted the glaciers by traveling south along the Pacific coast, maybe in skin boats, before dispersing into North and South America. This would have allowed faster movement south. However, no one has uncovered much tangible evidence to support this idea, which might not be too surprising since sea levels were much lower then. What was once the coast is now under water.
Many archaeologists now believe there isn’t a simple story that will explain what happened. Researchers have suggested that various groups migrated from various places over various routes and at various times (some genetic evidence indicates that Native Americans came not only from Asia but also from Africa, Australia, and Europe). Multiple migrations would help explain why Native American languages are so different from each other. Some spear points found in ancient France are similar to some found in America. This suggests that people migrated to America from Europe.
We are on a little firmer ground in trying to reconstruct the ecology of the past. The high water run-off caused by melting glaciers deposited large piles of gravel that remain today. As the ice retreated between 13,500 and 11,800 years ago, the climate, though warmer than it had been, was still cooler and wetter than today. As the world warmed, cold-climate plants and animals in Montana were gradually replaced by other species familiar to us today, but this transition took several thousand years to complete.
Much of Montana changed from semi-arid to arid. Depending on location, this change occurred between 11,000 and 8,000 years ago. At the Indian Creek Site, located in the Elkhorn Mountains of Montana near Townsend, an abrupt change from coniferous forest to sagebrush steppe occurred approximately 9,400 years ago.
Western Montana stayed cooler than present until about 7,000 years ago. Timber line occurred about 2,000 feet lower than it does today, and many of today’s forests today existed as sagebrush steppes. A steppe is a cold, dry landscape, usually with strong winds and frequent droughts. Steppes are also called shortgrass prairies. In the Northern Rocky Mountains, west of the Continental Divide and north of Helena and Missoula, ice-age conditions lingered longer in some of the more sheltered mountain canyons than on the prairie.
Most of the plants and animals we know today, such as pronghorn antelope, elk, and deer, existed then. But the world of the past also included many animals that have vanished—species like the giant short-faced bear, a very large type of bison called bison antiquus, and several species of camels. Wooly mammoths were here—fourteen feet high at the shoulder—and people hunted them with atlatls, or spear-throwing sticks.
The changing climate and possibly increased hunting pressure led to a sudden die-off of the Ice Age Megafauna. Sudden, that is, in geologic time. Most of the die-off occurred between 12,000 and 7,500 years ago. Camels and mammoths were gone by 11,000 years ago. Ground sloths and saber-tooth tigers may have lasted until 9,500 years ago. By 8,000 years ago, horses were gone. Altogether, thirty-three percent of existing mammalian species were lost.
The warming and drying trend intensified about 8,000 years ago, causing a great drought known as the “Altithermal.” It reached its peak about 7,000 years ago but lasted about 4,000 years. Its effects, including its local variations, aren’t well understood. But most researchers think that as this great drought continued, the Great Plains supported fewer grazing animals and thus fewer humans who depended on them. We find little evidence of human presence on the Great Plains during this period. Some of what we have found, though, such as mortars and pestles, suggest that people were processing more plants for food.
Evidence of human activity greatly increases for periods later than 3,500 years ago. Tipis became common and tipi rings are found in many places on the Montana landscape. Bows and arrows replaced atlatls, and small projectile points and stone quarries are found in many places. Communal hunting techniques, such as driving buffalo off of jumps or into corrals, became widespread. These have left large accumulations of bones and other artifacts.
For the most part, we go about our lives unaware of the mysterious presences in the landscape. But our own lives are richer and deeper when we invite thoughts about the other people who once hiked these mountain passes, built hunting camps along creeks, mined quarries for good stone, traded with others for goods not available near at hand, and worked together to corral wild bison. Their cairns and shelters and tools linger in the landscape, for the most part unnoticed by we moderns, whirring by on highways that, in whisking us from point to point, often narrow our view.
If we consider the 150 centuries since the first human came to America to be a day, then the American Revolution was thirty-six minutes ago. Interstate 90 has been here less than five minutes, less than a flicker in the earth’s history. Our lives are formed in part of patterns and forces we do not entirely, or even mostly, see. Interestingly, our knowledge of deep time increases every year, and so as the future unfolds so does the past.
Year by year, we move closer to, rather than farther from, those