As a girl I learned about treeline or timberline, a high altitude border somewhere between 11,000 to 12,000 feet on the mountain where conditions get so harsh that trees can’t grow. A little over a year ago we visited Acadia National Park in Maine, and a ranger talked about Mt. Desert — so named because trees don’t grow on top of it. Mt. Desert can’t be more than a hundred feet above sea level. How can it have a treeline?
Since then I’ve been noticing tree lines everywhere. Some run along the top of a hogback leaving one side of the hill naked while the other is thickly forested. Many mountains have tree lines at the bottom where they meet the arid plain. Clarity came at last somewhere along the Alaskan Highway: timberline is wherever the trees say it is.