It’s been a grand couple of weeks. Our pilgrimage to Grand Canyon has been filled with mind-numbingly grand values of time and space. We traveled by train — our first time doing so — taking Amtrak from Cleveland to Chicago to Williams, Arizona. The journey, 1,944 miles from home to hotel, took 44 hours counting delays and layovers. From the Grand Canyon to home, the journey took more than 62 hours, significantly longer than my trip home from Kenya a few years ago.

But there’s a certain serenity in having that much time. Our responsibilities were few. We didn’t have to worry about routes or weather or driving or (for the most part) making connections. There was just time. Lots of time. Time disconnected from life and work and friends and social media. Time to just be.

And as we moved west and south, the vastness of this country came into focus. In Ohio, we are not used to being able to see 60 miles or more to the horizon. But on the plains, we could see thunderstorms an hour away. We saw ranches of 1,000 acres: a size I have trouble visualizing. But we also saw ranches of 100,000 acres, and even 750,000 acres. Those are numbers I can’t understand. A single ranch that size is nearly as big as Rhode Island. The amount of land we use to raise and feed livestock is astounding, and makes me wonder whether our appetite for meat is really sustainable.

And yet, when we got to Grand Canyon, the numbers became even more unbelievable. The south rim is about 7,000 feet above sea level. The canyon is 4,600 feet deep at this point. That’s nine Washington Monuments. It’s three Empire State Buildings. The canyon is 270 miles long, an average of 10 miles across, and nearly a mile deep. We don’t generally think of volumes in terms of cubic miles, but 1,300 cubic miles is a really large number. That’s the amount of rock that has been eroded from the canyon. If we wanted to replace it with soil from Ohio, it would lower the entire state by 153 feet. Put another way, if we were to work together to fill it in, it would take more than 250 wheelbarrow loads from every person who has ever lived on Earth.

As we studied the geology of the canyon, we learned that the rocks at the base are 1.6 billion years old. That’s 1,600 thousand thousand years. The canyon itself is only six million years old. There are huge gaps in the geologic record, because more than two miles of rock have been completely eroded, including the complete fossil record for anything that came after single-cell protozoa. There are no dinosaur fossils in Grand Canyon because that rock was eroded millions of years ago, before the canyon was formed.

And so, coming home, thoughts turn to the end of summer, and the beginning of another school year. The education of these 4,100 students, 0.000058% of the world population, 0.0000038% of of the people who ever lived, who, if they live a long full life, will be here for 0.0000017% of the Earth’s existence.

And I wonder what I’m so worried about.