Almost any kind of artifact can last 10 millennia if stored and cared for properly. We have examples of 5,000-year-old wood staffs, papyrus, or leather sandals. On the other hand, even metal can corrode in a few years of rain. For longevity a 10K year environment is more important than the artifact’s material. The mountain top in Texas (and Nevada) is a high dry desert, and below, in the interior tunnel, the temperature is very even over seasons and by the day (55 degrees F) – another huge plus for longevity since freeze-thaw cycles are as corrosive as water. Dry, dark and stable temperatures are what archivists love. It’s an ideal world for a ceaseless Clock.
For decades, economists have been warning us that when we buy at a distance, we do not tend to take the cost of our own time into account. All the way back in 1965, for instance, the economist John Kain wrote, it is "crucial that, in making longer journeys to work, households incur larger costs in both time and money . Since time is a scarce commodity, workers should demand some compensation for the time they spend in commuting." But we tend not to, only taking the tradeoff between housing costs and transportation costs into question.