The Kármán line is a commonly used definition of the edge of the earth's atmosphere, a kind of vast edge drear to borrow from Matthew Arnold where our cozy oxygen-rich environment turns into the the emptiness of space and it's right above your head, closer to us than many people's daily commute. If you go the other direction, straight down, you only need to go about half that distance before you hit the boundary between the earth's crust and mantle where you'll find it a balmy 400 to 700 degrees fahrenheit. I hate to get all Carl Sagan on you, but it is a pretty small sliver of hospitable space. One of the more interesting, if sometimes unsettling, aspects of living in Anchorage is that this sliver of hospitable space is equally limited horizontally. Anchorage sits on a little piece of coastal lowland which is surrounded by wilderness with only two land routes out of the city. It's a big enough place that it rarely induces claustrophobia, but from the air you quickly get a sense of how insignificant and fragile our little strip of civilization is from a geological point of view.

I went on a short flight seeing trip around the area east of Anchorage last week and took a few snapshots. The following photos are all from the headwaters of the Knik River before it flows into the Knik Arm of Cook Inlet which forms the northern border of Anchorage. We had pretty poor light for aerial photography, but I'm posting some photos because I find it more than a little amazing that all this is going on only 30 miles from my house—a house that would fit pretty easily in some of the crevasses seen in the photos. It makes a guy want to stockpile food.

Knik River and Glacier