Friday photo

Ice on Rock. Hudson Mills Metropark, Dexter, Michigan, February 2011

Last Saturday I finally got out to do a little bit of skiing and decided to check out the Hudson Mills Metropark, a 1500 acre spot of woodlands northeast of Ann Arbor. It's a good thing I did, since the snow began melting that morning and, with several days near 50°, the snow has turned to puddles. In fact, I think we're halfway to flood stage around here.

The park doesn't have much in the way of hills, so the skiing was just a bunch of looping round a 5-mile trail system, with an occasional bit of glide. But there were a lot of novices out and it was fun to watch them approach these tiny little slopes, with their terrifying 5% grades. Knees locked, thighs stiffened, weight thrown forward, skis locked into wedge positions, pushing tentatively on the poles, probing for that point at which gravity will take over and speed them into reckless disaster. It was so cute.

I say that with compassion, because to this day I am not a strong skiier and I vividly remember how helpless you feel when you first bind boards to boots. Sure, you don't get going all that fast on a small slope, but since you have no control yet, anything is too fast. As soon as you begin to glide downhill, you're a passenger. I would regale coworkers with my latest crash: I didn't get my arms and legs fully extended, so I guess it wasn't a proper cartwheel ....

What astonished me after that first winter was to go back after the snow was gone and to realize how gentle many of those slopes were. Not that they weren't racy - there are some good speedy hills around the Old Faithful area. But they still didn't look as steep as they felt. Surely that slope at the bottom of the Fern Cascades trail was 45°, wasn't it? It was so fast! But it's probably closer to a 10°-15° slope.

I spent that summer examining all the hills I encountered with a sort of slideshow in my mind, one that would replace the grass with snow and imagine that I was about to hurtle down on my second-hand Rossignols. It's a funny thing, but the world's terrain just doesn't look as rugged as it feels. Which is why cartographers who want to portray relief often have to exaggerate the vertical scale relative to the horizontal; everything looks too flat otherwise, even in the mountains.

Here's an example by the cartographic artist Heinrich Berann, who did a series of panoramas for the National Park Service. He produced his view of Yellowstone in 1989:

That's a hell of a lot of vertical exaggeration, especially of the Tetons in the distance. But it gives you a more intuitive sense of the shape of the land than a truer representation would. Much like people may be more readily recognized from a caricature than from a photograph, I suppose.