Wednesday, December 3, 2014

Geo 730: December 3, Day 702: Unhealthy Forest

Continuing to drive up toward the pass north of Mount Hood, I suddenly realized we were traveling through a very unhealthy-looking forest. Unlike forests killed off by pine bark beetles (where pretty much all the trees are dead), this one ran the gamut of dead, dying, and damaged trees, with a few looking fairly well off. That, in addition to the long stretch of road work, had me puzzled for a bit. Then something clicked, and I remembered there had been a very damaging lahar in the area some years earlier. (I just checked- it was 2006. See the bottom of this page for a short description and a very impressive photo of the aftermath at the Route 35/Mount Hood Highway Bridge over the White River.) What I hadn't realized until this trip was that the debris flow inundated a large area of forest in the area as well. Burying a tree's roots, for most trees, causes them to slowly suffocate, explaining the problem here.

In the FlashEarth view, you can see why it's called White River, but that's all loose volcanic rubble, not snow. You can also see some post-lahar incision, and how the debris fanned out into the forest when it reached the vicinity of the highway.

Photo unmodified. October 10, 2012. FlashEarth Location (Approximate).

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