Wednesday, October 23, 2013

Would I notice a rock slide if it were right in front of me?

I once emailed a link to one of my climate illustrations and told the recipient, "make sure you read the caveats tab." She replied, "everyone should have a caveats tab."

And so I continue to look for opportunities to test what I know, as well as what I remember.

Two years ago I started exploring a hiking route that involves some rock climbing and a lot of scrambling. Think if it a course of constant deep knee bends and limbo manuvers. After about a half year of exploring this route I noticed a rock slide:

This hike is in a canyon with a lot of loose rock and rapidly eroding slopes. Therefore, I stay away from these hazards. But still, I always look at where I walk and observe my surroundings, and I should have been looking out for something so obvious a hillside of newly exposed rock and dirt. Or would I notice such a thing?

Did I witness a significant erosion event in the short time I'd been exploring this canyon? Or did I fail to notice something that occurs on a longer scale? -- and therefore, need to examine my observation skills for overconfidence.

This rockslide also knocked over a cotton wood tree. Here is a photo of it sideways on the ground with a new shoot growing upright.

The photo above shows dead limbs (angled downward) and a new limb (angled at 2:00 ) which is actually vertical, though this isn't obvious in the photo. In fact, the tree had about a half dozens of these newly started vertically growing limbs. The presence of new vertically growing limbs when the rest of the tree is horizontal offered a proxy measurement of the date at which this tree was suddenly knocked over.

I selected one of the thickest limbs (the one in the photo above) and cut off a sample of the limb near the base. Below, I've counted and labeled the growth rings. I count three more than the time I've been visiting this rock slide.

So, I add this to my metaphorical caveats tab. I can miss the obvious. Do others?


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