We spent 9 days of May + June rafting the Grand Canyon this year, where the Colorado River cuts through more than a billion years worth of rock. 

6500 feet down in the canyon, floating on the cold Colorado, surrounded by Zoroaster granite marbled into Vishnu chist, and fluted columns of sandstone, you can count a billion years back into the past, through the layers.

We went to celebrate my dad's 70th. Nothing makes 70 seem insignificant like geologic time.  Happy birthay, Dad - we're now planning your 115th.