Sunday, October 7, 2007

In which I go hiking with the kid and see cool minerals... like ice

There’s a lot to be said for hiking with a four-year-old. Not in terms of aerobic conditioning, and not when the goal is to scout a new field area. And, yeah, it’s important to have the right food as a bribe, and to stop frequently. But fresh air, beautiful scenery, and family time... it’s hard to argue with that. Especially with scenery like this available on a mile-long hike.

Spud Lake is about a mile up a gentle trail, up in the aspens around 9700 feet. It’s high enough that there was frost on the ground today, even at mid-morning, and the high peaks surrounding it were dusted with snow. The trail was a bit muddy, though, so it was pretty slow going. We stopped to pick up a stick that looked like the letter “J,” and to scramble around on rocks, and to look at quartz veins.

My son was fascinated with the quartz, so I pointed out that the ice made crystals, too. We picked up a frost-blackened aspen leaf so he could see the crystals on its sides, and discovered that the entire bottom was covered with them. While he was looking at the leaves with a magnifying glass, another family walked by, and the boy said: “Have you seen THIS?”

He pointed to something that looked like white hairs on an over-excited yeti. Fibrous ice crystals, holding up pebbles and leaves and bits of frozen dirt. Every shadowed spot was covered with them, when we stopped and looked. On the hillsides, on the trail... everywhere.

They looked, actually, like vein fillings – fibrous vein fillings. Perhaps I shouldn’t be surprised – ice is, after all, a mineral, if one that melts readily under earth’s surface conditions. And like fibrous veins, I think I could figure out a deformational history from some of them.

A lot of the fibers were vertical – they came straight out of the ground, like hairs standing on end. But some of them were curved – sometimes all the way over, so that their pebble or dirt dangled from a curl. I have no idea how these form, but I’ll make a guess: the pebble or dirt is particularly cold, and the ice first nucleates on its bottom side. The crystal grows down, getting water from soil moisture. And sometimes, the pebble or dirt is heavy enough that the crystal bends under its weight. The crystal keeps growing straight up from the bottom, but the top becomes curved.

There were probably ways to test those ideas... but the four-year-old started getting impatient.

He smashed the ice in a few puddles, and then we headed up the trail.

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