Although social media has overshadowed snail mail, it has also given it a new and deeper meaning. It’s not about a postcard arriving quickly anymore. It’s about the intent.

The canyon exposes rock formations dating back nearly 2 billion years. Layer by layer, the Grand Canyon narrates the story of changing environments.

Just after 8 o’clock one spring morning, 2,000 feet below the rim of the Grand Canyon, Nate Chamberlain, wearing chaps and cowboy boots, emerged from the post office in Supai, Arizona, with the ...