Actually, Bamforth says he knows basically where two of the stone varieties came from and doesn't know where the other two (which make up only three of the objects) originated. One of the known varieties, tiger chert, came from northwestern Colorado or southwestern Wyoming — which means that some one carried it over the Rocky Mountains, possibly through the area now set off as Rocky Mountain National Park, along a route that passed by or across the glaciers.

Most of us encounter glacial ice only as a kind of novelty, when we're out hiking or climbing. But for thousands of years, people who lived in and near the western mountains knew it as an everyday companion. When the North Cascades must have been more heavily glaciated than they are today, some of those people traveled far up the Skagit valley into what is now North Cascades National Park to quarry chert. “In the northern portion of the North Cascades, numerous chert quarries have been found,” writes Mierendorf in a 1998 Updated Summary Statement of the Archaeology of the North Cascades National Park Service Complex. Mierendorf envisions “an industrial scale of tool-stone procurement” in the upper Skagit valley. Separating usable pieces of Hozomeen chert from bedrock would have required “a lot of hammering with fairly dense andesite.” He has found quarry sites dating back 8,400 years.

The people who went into the North Cascades to quarry stone that long ago “certainly traveled light by today’s standards,” he has written, “and without the benefit of maintained trail systems of the present; they lived through climatic events that we have never experienced and at a scale that we are only now becoming aware of.”

These were not people wandering aimlessly across the continent, or merely following big animals wherever they led. These were people who knew many square miles of the “wilderness” that they regarded as home, who carried maps of the mountains in their heads. The fact is that the people who quarried chert in the North Cascades, and those who quarried it on the west slope of the Rockies, had to know where the materials lay, and know how to get there. How did they know? It's “axiomatic for people connected to the land,” Mierendorf explains” “If you want to see what's up in the mountains, just look at the river channel bars.”

One imagines them, over the generations, wearing trails deep into the ground, like remnants of the old Indian route through Stampede Pass. This started a very long time ago. Mierendorf says that archaeological sites around Cascades Pass — now of course a popular hiking route across the North Cascades, but for millennia a corridor for practical travel — prove that people hauled quarried chert across the mountains there. He describes a Cascades Pass still scraped bare by the last continental glacier. There were no old-growth trees. Forests were just starting to form. There was virtually no soil. The pass would have been strewn with boulders, and granitic rocks at the top of the glacial till would have made the ground look pale. People carried chert through that landscape 9,600 years ago.

Even 13,000 years ago, the makers and users of stone tools must have returned periodically to the same places, again and again. Why else would someone have cached all those tools in what has turned out to be Boulder? “You don't do something like that,” Bamforth says, “if you're not expecting in some sense to be coming back.”

They evidently didn't make it. At the very least, they're really, really late. I can empathize.